Journal Club April 2010: Negative Poisson's ratio materials

katia bertoldi's picture

Metamaterials are artificial materials engineered to provide properties which may not be readily available in nature and are attracting increasing attention. These materials usually gain their properties from structure rather than composition. Although the first metamaterials were photonic (i.e.  artificially fabricated, sub-wavelength, periodic structures, designed to interact with optical frequencies) and acoustic (i.e. artificially fabricated materials designed to control, direct, and manipulate sound), the idea may be extended to the mechanical  properties of materials defining mechanical metamaterials as artificially fabricated structures designed to achieve unusual mechanical properties.  Interesting examples of mechanical metamaterials are provided by negative Poisson’s ratio and negative thermal expansion materials. Here I will focus on negative Poisson’s ratio materials, while inspiring results for negative thermal expansion materials were reported by Sigmund and Torquato (1997) and Steeves et al. (2007).

 

When materials are compressed (stretched) along a particular axis they are most commonly observed to expand (contract) in directions orthogonal to the applied load (Fig. 1 - left). The property that characterizes this behavior is the Poisson's ratio which is defined as the ratio between the negative transverse and longitudinal strains. The majority of materials are characterized by a positive Poisson’s ratio which is approximately 0.5 for rubber and 0.3 for glass and steel. Materials with a negative Poisson’s ratio will contract (expand) in the transverse direction when compressed (stretched) (Fig. 1 - right) and, although they can exist in principle, demonstration of practical examples is relatively recent.


 

Figure1:   Left: The material elongates and contracts when stretched, leading to a positive Poisson's ratio. Right: The structure unfolds when stretched, causing lateral expansion and a negative Poisson's ratio.

 

 There is significant interest in the development of negative Poisson’s ratio materials because of potential in applications in areas such the design of novel fasteners (Choi and Lakes, 1991), prostheses (Scarpa, 2008), piezocomposites with optimal performance (Sigmund et al, 1998) and foams with superior damping and acoustic properties (Scarpa et al., 2004). Moreover, auxetic materials may lead to the design of stronger composite materials. The primary failure mechanism of composite materials is through reinforcement “pull-out“, a tensile failure caused by the reinforcing fibers getting narrower and pulling away from the matrix. Due to the fact that auxetic materials expand when stretched, however, the load required to cause structural failure will significantly increase.

Discovery and development of materials with negative Poisson’s ratio, also called auxetics, was first reported in the seminal work of Lakes in 1987 (Lakes, 1987). The auxetic behavior was achieved using a novel foam characterized by a reentrant microstructure (Fig. 2) that unfolds when stretched (Fig. 1-right), causing lateral expansion and negative Poisson's ratio. In the case of thermoplastic foams the transformation from the conventional to auxetic form is achieved by triaxial compression followed by heating of the compressed foam to above the softening point.

Lakes, R.S. Negative Poisson's ratio materials.  Science, 235, 1987.

Figure 2.  Stereo photograph of a reentrant foam with Poisson’s ratio -0.6 (left) and idealized reentrant unit cell (right)(Figure taken from Lakes (1987)

Negative Poisson’s ration materials occur also in nature. There are a growing number of natural materials that have been discovered to possess one or more negative Poisson's ratios. Baughman et al. (1998) revealed that 69% of the cubic elemental metals and some face-centered cubic (fcc) rare gas solids are auxetic when stretched along the specific [110] off-axis direction. The auxetic effect is correlated with the metal's work function and proposed that auxetic metals could be used as electrodes sandwiching a piezoelectric polymer to give a two-fold increase in piezoelectric device sensitivity.

Baughman, R. H., Shacklette, J. M., Zakhidov, A. A. and Stafstrom, S. Negative Poisson’s ratios
as a common feature of cubic metals. Nature , 392, 362, 1998.

More recently it has been found that natural layered ceramics (Song et al, 2008), ferroelectric polycrystalline ceramics (Tan et al, 2009) and zeolites (Grima et al, 2000) may all exhibit negative Poisson’s ratio behavior.

Moreover, several geometries and mechanisms have been proposed to achieve negative values for the Poisson’s ratio and a variety of man-made auxetic materials and structures have been fabricated and synthesized from the macroscopic down to the molecular, including foams with reentrant structures (Lakes, 1987), hierarchical laminates (Milton, 1992), polymeric and metallic foams (Friis et al, 1988), microporous polymers (Caddock and Evans, 1991), molecular networks (Evans et al, 1991) and many-body systems with isotropic pair interactions (Rechtsman et al, 2008). Negative Poisson’s ratio effects have also been demonstrated at the micron scale using complex materials which were fabricated using soft lithography (Xu et al, 1999) and at the nanoscale with sheets assemblies of carbon nanotubes (Hall et al, 2008).  A critical issue related to auxetic material is that their fabrication often requires embedding structures with intricate geometries within a host matrix. However, recently it has been shown that instability induced pattern switches in porous elastomeric structures characterized by an initial simple microstructures may lead to auxetic behavior (Bertoldi e al., 2010).

To conclude I would like to remark the difference between isotropic and anisotropic auxetic materials. From the standpoint of applications Isotropic auxetic materials are more attractive, since negative Poisson’s ratio is achieved for loadings applied along any direction. Energy arguments in the theory of elasticity may be used to show that their Poisson’s ratio  for isotropic materials cannot be lower than -1 and larger than ½. Differently, for anisotropic materials the bounds on Poisson's ratio are wider and Poisson's ratios smaller than -1 have been reported.

This journal entry provides a sampling of the research in a field that is active and growing.  Discussion on your experiences in this area and on your perceived future challenges is welcomed :)


References:

[1] Baughman, R. H., Shacklette, J. M., Zakhidov, A. A. and Stafstrom, S. Negative Poisson’s ratiosas a common feature of cubic metals. Nature , 392, 362, 1998.

[2] Bertoldi, K., Reis, P.M. , Willshaw, S., Mullin, T. Negative Poisson's ratio behavior induced by an elastic instability. Adv. Mat., 22, 361, 2010.

[3] Caddock B.D. and Evans K.E., Microporous materials with negative Poisson's ratio: I. Microstructure and mechanical properties. J. Phys. D: Appl. Phys. 22 1877, 1998.

[4] Choi, J. B. and Lakes, R. S. Design of a fastener based on negative Poisson's ratio foam. Cell. Pol., 10, 1991.

[5] Evans K. E. and Alderson A. Auxetic Materials: Functional Materials and Structures from Lateral Thinking! Adv. Mat., 126,17, 2000.

[6] Evans K. E.,  Nkansah M. K., Hutchison I. J., Rogers S. C..  Molecular network design. Nature, 353,124, 1991.

[7] Friis, E. A., Lakes, R. S., and Park, J. B., Negative Poisson's ratio polymeric and metallic materials. J. Mat. Sci., 23, 4406, 1988.

[8] Grima J.N., Jackson R., Alderson A. and Evans K.E.. Do zeolites have negative Poisson's ratios? Adv. Mat., 12, 1912, 2000.

[9] Hall, L.J., Coluci, V. B., Galvao, D. S., Kozlov, M. E., Zhang,,V S., Dantas O. and Baughman R. H. Sign Change of Poisson's Ratio for Carbon Nanotube Sheets. Science 320,504, 2008.

[10] Lakes, R.S. Negative Poisson's ratio materials.  Science, 235, 1987.

 [11] Lakes R.S. Deformation mechanisms of negative Poisson's ratio materials: structural aspects.  J. Mat. Sci., 26, 2287, 1991.

[12] Milton, G.,  Composite materials with Poisson’s ratio close to -1. J. Mech. Phys. Sol., 40, 1992.

[13] Rechtsman, M.C., Stillinger, F.H. and Torquato S. Negative Poisson's Ratio Materials via Isotropic Interactions. Phys Rev. Lett. 101, 085501, 2008.

[14] Scarpa, F . Auxetic materials for bioprostheses. IEEE Sig. Proc. Mag., 25, 128, 2008.

[15] Scarpa, F., Ciffo L., and Yates . Dynamic properties of high structural integrity auxetic open cell foam. J. Smart Mat. Struc., 2004.

[16]Sigmund, O., Torquato, S.  Design of Materials with Extreme Thermal Expansion using a Three-Phase Topology Optimization Method.  J. Mech. Phys. Solids 45 (6), 1037–1067, 1997.

[17] Sigmund O, Torquato S and Aksay I.A.  On the design of 1-3 piezocomposites using topology optimization. J. Mat. Res., 13, 1998. 

[18] Song, F.,  Zhou, J., Xu, X.,Xu, Y. and Bai, Y. Effect of a Negative Poisson Ratio in the Tension of Ceramics. Phys. Rev. Lett.,  245502, 2008.

 [19] Steeves, C.A., Lucato, S.L.D.S.E, He, M., Antinucci, E., Hutchinson, J.W., Evans, A.G. Concepts for structurally robust materials that combine low thermal expansion with high stiffness. J. Mech. Phys. Solids 55, 1803-1822, 2007.

 [20] Tan, X., Jo, W., Granzow T., Frederick J., Aulbach E. and Rödel. Auxetic behavior under electrical loads in an induced ferroelectric phase. J. Appl. Phys. Lett. 94, 042909,2009.

 [21] Xu, B., Arias, F., Brittain, S. T., Zhao, X-M., Grzybowski, B., Torquato, S. and Whitesides G.M..  Making negative Poisson's ratio microstructures by soft lithography. Adv. Mat., 11,1186, 1999.


Ajay Bangalore

Ajay Bangalore Harish


Doubts

Firstly, I apologize for the previous comment. I had some problems posting using Chrome & it did not allow me to delete it. I was reading some of the papers that have been linked in the article. It seems a pretty interesting line of research. I had two questions:

1.One of the ways this behavior is explained is by a hinge phenomenon. So as an extensional load is applied, this results in the hinge to open & causes a positive strain in the transverse direction. In that sense there would need to be a theoretical limit to this behavior (i.e. the negative poisson ratio)? If so, wouldn't it be more like two regimes (one where the poisson ratio is negative & then further over a certain load where it might go to a positive poisson ratio regime) or its like a fixed material property?

2.  Also how would these materials behave in the case of a cyclic loading (i.e. something like failure by fatigue)?

Thanks

Ajay


katia bertoldi's picture

Re: Doubts

Dear Ajay,

 1) you are right. Energy arguments in the theory of elasticity may be used to show that
the Poisson’s ratio for isotropic materials cannot be lower than -1
and larger than ½.

 2) the Poisson's ratio in most of the materials will evolve with deformation. Looking at the structure depicted in fig. 1-left in the Journal entry, we can see that initially when stretched the Poisson's ratio is negative, since it unfolds. However, with increasing deformation the absolute value of the Poisson's ratio will decrease, eventualy becoming positive.

3) About the behavior under cyclic loading: this depends on the material you use to fabricate your negative Poisson's ratio material (i.e rubber, metal etc.)


Design

This subject is indeed very interesting.

I find that most papers concern the design of materials with negative Poisson ratio. Thus there are so many types of NPR materials. Are there any more general and more theoretical researches on these materials?


katia bertoldi's picture

Re: design

Dear To Quy,

you are totally right. Most of the papers in the field focus either on the design of new materials exhibiting negative Poisson's ratio  or on the discovery of natural auxetic materials.

From a theoretical point of view,  it is known  since a long time that in isotropic materials values of Poisson's ratio larger than one half are thermodynamically inadmissible. Such values would lead to negative strain energy under certain loads.

katia


Mike Ciavarella's picture

Beautiful post Katia, but even better is Lake's web site!

 

A good intro, Katia, but you miss an important reference.  This web site .  A few lines from the site which has animations, etc. etc.


 

Negative Poisson's
ratio materials

 

[Rod Lakes,
University of Wisconsin]

Search tool

stretch normal foam
stretch re-entrant foam


stretch chiral honeycomb

 

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


katia bertoldi's picture

Lake's website

Michele,

 you are completely right and I apologize for not explicitly mentioning such an important source. Lake's  website is the Bible in the field:)


Mike Ciavarella's picture

For my MilleChili journal, do you think these are realistic?

Katia, for my MilleChili journal and project, I mean for a top performance car, or let's say even for a F1 car, with very large budgets, are these objects any realistic in the near future?

If not what are the limitations to real production?  Thanks for answer. Mike

Choi, J. B. and Lakes, R. S., "Design of a fastener
based on negative Poisson's ratio foam", Cellular Polymers, 10,
205-212 (1991).

In this article we make use of the negative Poisson's ratio of recently
developed cellular solids or spongy materials in the design of a
press-fit fastener. Insertion
of the fastener is facilitated by the lateral contraction which negative
Poisson's ratio materials exhibit under compression. Removal of the
fastener
is resisted by the corresponding elastic expansion under tension.
Get pdf

Lakes, R. S., "Design considerations for negative Poisson's ratio
materials" ASME Journal of Mechanical Design, 115,
696-700, (1993).

bend re-entrant honeycomb
This article presents a study of the implications of negative Poisson's
ratios in the design of load bearing structural elements. Stress
concentration factors are reduced in some situations, and unchanged or
increased in others, when the Poisson's ratio becomes negative. Stress
decay according to Saint Venant's principle can occur more or less
rapidly as the Poisson's ratio decreases. Several design examples are
presented, including a core for a curved sandwich panel and a flexible
impact buffer.
Get pdf
Curvature of negative Poisson's ratio honeycomb during bending is convex
in contrast to the saddle shape usually seen for positive Poisson's
ratio, and is shown in the animation at the right and in this video

 

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


katia bertoldi's picture

Auxetic

Michele,

hopefully these companies will make these objects realistic

 http://www.auxetix.com/

http://www.auxetictechnologies.co.uk/

 katia


Mike Ciavarella's picture

Well, perhaps the fabrics, but not the fasteners!

Sorry my post did not come out correctly.

I have seen the material from the company, but it seems to me the applications are vague, and being 20-30 years that this idea of negative poisson's material is around, I am very worried this may well be a "bluff" !!

Katia, do you have better information about how this is going to work in practise?  Which application?  I am all in favour of "curiosity - driven" research, do not worry.   But the real applications make a huge difference....

 

Mike

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


katia bertoldi's picture

Re: Well, perhaps the fabrics, but not the fasteners!

Dear Michele,

In the past years several applications have been identified where the use of negative Poisson's material could lead to a substanital improvment. I am thinking at the biomedical area where -for axample- auxetic materials could be used to design dilators to open up blood vessels during heart surgery. Another potential interesting area relates to the use of auxetic materials in piezoelectric sensors and actuators.

We have seen a number of patent applications from various companies all related to negative posson's ratio materials 

Toyota Chuo Kenkyusho KK, Japanese patent no. 10134102, 1998
Toyota Jidosha KK, Japanese patent no. 9037578, 1997
Yamaha Corp, Japanese patent no. 8019634, 1996
Mitsubishi Jukogyo KK, Japanese patent no. 6137799, 1994

few companies have been created to refine novel auxetic technologies

 http://www.auxetix.com/

http://www.auxetictechnologies.co.uk/

 but we are still far from the point where negative Poisson's ratio materials will have a real impact in our daily life.

 What is the reason for that?

In my opinion the manufacturing process has been a bottleneck in the practical development towards applications. Negative Poisson's ratio materials typically require complex material design and
construction. This motivated my recent work, where instabilities are used to create materials with tunable negative Poisson's ratio. In this wasy we are able to achieveauxetic bahavior starting from a simple microstructure.

I welcome discussions on this important point.

katia

 

 


Mike Ciavarella's picture

http://www.vcconfidential.com/2006/08/bootcamp_are_pa.html

I mention that site because it contains a list of crazy patents.

I don't remember the exact figure, but I think 1 of 250 patents only is worth  making something out of it

 "Patents are like nuclear bombs, you just got to have some.  I
have never seen patents make a business, but I have seen lack of
patents hurt a business on many occasions."

     -- Fred Wilson VC
Cliche of the Week

 

Specifically, you assume the problem is manufacturing, the instability-driven manufacturing would be the key revolutionary idea. Hard to beleive, what a coincidence it would be.  So your mental process was (i) I have this expertise on instability-driven design, now where to apply it?  The best would be neg Poisson's ratio material where this would be beneficial (iii) let's do it!

 

Or else (i) you were fascinated by neg. poisson's material (ii) were not sure what else to say (iii) thought about why not attempt to use my expertise of instability-by-design materials?

 

The two make HUGE difference... #2 is much less likely of success.  Generalization is an obvious process, generally not revolutionary.

 

But to tell you precisely, I would need to know more of this "instability"-designed materials.  And I would need to be convinced that the problem of auxectic materials is just their manufacturing.  I am still worried that their "gain" as sensors or actuator is limited.

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


katia bertoldi's picture

Another contribution in the field

Roberto ballarini pointed out another important contribution in the field

 Mullen, Ballarini, Yin ans Heuer, 'Monte Carlo Simulation of Effective Elastic Constants of Polycrystalline Thin Films', Acta mater 45, 2247-2255, 1997

In this paper Monte Carlo simulations are used to  predicts the nominal elastic constants  of thin films comprised of a finite assembly of cubic crystals. Interestingly it is observed that negative values of the effective Poisson’s ratio are realised as a result of the inherent anisotropy of the constituent grains.

 

 


Defects in metamaterials

I wonder if there's been any work in analyzing defects in  metamaterials. If one link breaks, how much do the properties change? Does it have to do with the connectedness of the force-network? If one link breaks, does the instability spread? Furthermore, can one think of imperfections analogous to edge dislocations and write down closed form expressions for resulting stresses as in  http://en.wikipedia.org/wiki/Dislocation

-Nachiket


katia bertoldi's picture

Defects in metamaterials

There have been studies on the fracture strength of lattice materials.

As an example, I report few contribution in the field (there are many more around)

Maiti, Ashby, Gibson. Fracture-Toughness of brittle cellalur solids.
Scripta Metallurgica, 1984

Fleck, NA; Qiu, XM.  The damage tolerance of elastic-brittle, two-dimensional isotropic lattices
Journal of the Mechanics of Physics and Solids, 2007.

 

 

 


Carl T. Herakovich's picture

Negative Poisson's ratios

Carl T. Herakovich, University of Virginia

You may be interested to know that negative Poisson's ratios were observed in laminated composites as early as 1984 ( J. Composite Marerials, Vol. 18, pp. 447-455, 1984). 


katia bertoldi's picture

Re: Negative Poisson's ratios

Dear Carl,

thanks a lot for the note. Nice piece of work:)

Here is the full reference of the work you pointed out

Herakovich, C. T., “Composite Laminates with Negative
Through-the-Thickness Poisson's Ratios”, Journal
of Composite Materials
, Vol. 18, Sep 1984, pp. 447-455.

 

katia


Mike Ciavarella's picture

Katia I don't get why you avoid my question... Nobel stuff or?

I guess it must be a difficult one, but you should be challenged then, instead of giving up already!

I mean is all this fuss about negative Poisson's a mathematical excercise, with curiosity, or is it a real breakthrough which can open new avenues in research, say in cancer, in malaria, in new materials like when the (last) Italian Nobel Prize winner Prof. Giulio Natta invented plastics?

Being at Harvard as a brigth and brilliant italian young promise, I am sure you should be aiming at Nobel prize type of research, not just avenues of research already exhausted.  This seems to me quite old stuff, has been postulated to work already 30 years ago if not earlier, companies are already there to try to something (but I suspect the turnover is minimal), so why should we waste more time with it?

Sorry to be direct, I guess you understand what I mean.

If not Natta, lookat Subra Suresh's research across the street from Harvard, and you'll find possibly Nobel prize research.  Or, stay at MIT, and look at the other italian brigth guy Francesco Stellacci.  Maybe he has elasticity problems which are really worth solving, worth ask him!

 

Francesco Stellacci begin_of_the_skype_highlighting     end_of_the_skype_highlighting

Francesco Stellacci
Paul M. Cook Career Development Associate Professor
of Materials Science and
Engineering

Doctorate, Materials
Science and Engineering, Politecnico
di Milano, 1998

 

 

Room 13-4053,
77 Mass. Ave., Cambridge, MA  02139
617-452-3704
(phone)
frstella@mit.edu

Professor
Stellacci's research group

Professor Stellacci's research interests are in
nano-science and nano-technology, specifically in the investigation of
the structure-property relationships that exist between nanostructured
molecular assemblies and their surface properties.

His research focuses on the
generation of new understanding on the assembly of molecules in
spatially defined arrangements and their interactions with organic and
bio molecules and with inorganic surfaces. The goal is to apply this
knowledge toward the development and the efficient fabrication of
original nano-size molecular-based materials and devices for a wealth of
applications. In order to build such devices, Stellacci’s group is
developing new materials (organic ligand coated nanoparticles and
nanotubes), and new soft-materials fabrication techniques (based on
molecular recognition and self-assembly). A specific example is the
discovery of novel materials whose outside shell spontaneously assembles
in ways that resemble the structuring of domains on viruses’ capsids.
Another example is the development of a nature-inspired stamping
technique able to transfer DNA patterns from a surface onto another.
This method has been tailored for the efficient production of
inexpensive DNA micro- and nano-arrays. A special emphasis in the group
is placed on the understanding of the nanoscale limitation of present
thermodynamic modeling of surface interactions.

Selected Publications

“Spontaneous assembly of sub-nanometre ordered
domains in the ligand shell of monolayer protected nanoparticles”,
Jackson, A. M.; Myerson, J. W.; Stellacci, F. Nature Materials,
3, 330-336, 2004.

“Supramolecular Nano-stamping: using DNA as
movable type”, Yu, A. A.; Savas, T. A.; Taylor G. S.; Guiseppe-Elie A.;
Smith H. I.; Stellacci F., Nano Letters, 5, 1061-1066,
2005.

“From Homo-Ligand to Mixed-Ligand Monolayer
Protected Metal Nanoparticles: a Scanning Tunneling Microscopy
Investigation”, Jackson, A. M.; Hu, Y.; Silva, P.; Stellacci F., J.
Am. Chem. Soc.
, 128, 11135–11149, 2006.

“Divalent Metal Nanoparticles”, DeVries, G. A.;
Brunnbauer, M.; Hu, Y.; Jackson, A. M.; Long, B.; Neltner, B.; Uzun,
O.; Wunsch, B. H.; Stellacci, F., Science, 315, 358–361,
2007.

 

 

Giulio Natta
From Wikipedia, the free encyclopedia

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Giulio
Natta

Giulio
Natta

Born
26
February 1903(1903-02-26)
Imperia, Italy

Died
2 May
1979 (aged 76)
Bergamo,
Italy

Nationality
Italy

Fields
Organic chemistry

Institutions
Pavia University
University of
Rome La Sapienza

Politecnico di Torino

Alma
mater

Politecnico di Milano

Known for
Ziegler-Natta catalyst

Notable awards
Nobel Prize in Chemistry (1963)

Giulio Natta (26 February 1903 - 2 May 1979) was an Italian chemist
and Nobel laureate. He who won a Nobel Prize in Chemistry in 1963
with Karl Ziegler for work on high polymers.

Contents
[hide]

//
[edit] Biography
[edit] Early years

Natta was born in Imperia, Italy. He
earned his degree in chemical engineering from the Politecnico di Milano university in Milan in
1924. In 1927 he passed the exams for becoming a professor there. In
1933 he became a full professor and the director of the Institute of
General Chemistry of Pavia University, where he stayed
until 1935. In that year he was appointed full professor in physical
chemistry at the University of
Rome
.

[edit] Career

From 1936 to 1938 he moved as a full professor and director of the
Institute of Industrial Chemistry at the Polytechnic Institute
of Turin
. In 1938 he took over as the head of the Department of chemical engineering at the Politecnico di Milano university, in a
somewhat controversial manner, when his predecessor Mario
Giacomo Levi
was forced to step down because of racial laws
against Jews being introduced in Fascist
Italy.

Natta's work at Politecnico di Milano led to the improvement of
earlier work by Ziegler and to the development of the Ziegler-Natta catalyst. He received
the Nobel Prize in Chemistry in 1963
with Karl Ziegler for their research in high polymers.

 

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


katia bertoldi's picture

I am not avoiding the question

Dear Michele,

I did not give up, I just did not have time. Sorry for that. I'll try my best to give quicker answers in the future.

 katia


Roberto Ballarini's picture

There have been other Italians since Natta

Natta was not the "last" Italian Nobel prize winner. There are numerous others.


Roberto Ballarini's picture

There are others after Natta

There are other Italian Nobel Prize winners since Natta, both male and female.


Mike Ciavarella's picture

well not in science and not in italy !

Katia & Roberto

 

there were a few in science of italian origins but working abroad of course (like it would be your case Katia and Roberto if you manage to be lucky!), but noone like Natta who was working in Italy.  Actually Natta is the single one in Chemistry ever!

 

There are, viceversa, a few in literature, working in Italy.  Notice the case of W.D. Phillips of italian origins, and sharing the Nobel prize with Steven Chu present Energy Minister with Obama....   Since it seems extremely difficult to have Carlo Rubbia as Minister of Energy of Berlusconi, despite his innovation in Energy is very interesting, at least we could have been luckier to have Phillips with Obama!

 

So good luck with Nobel from Negative poisson's ratio.  Which area could that be Physics or Chemistry or Medicine?

 

PHISICS

Carlo Rubbia     1984     "for their decisive contributions to the large project, which led to the discovery of the field particles W and Z, communicators of weak interaction" Rubbia shared the prize with Simon van der Meer.

William D. Phillips     1997     "for development of methods to cool and trap atoms with laser light"
Phillips shared the prize with Steven Chu and Claude Cohen-Tannoudji.

Riccardo Giacconi     2002     "for pioneering contributions to astrophysics, which have led to the discovery of cosmic X-ray sources"Giacconi received half of the prize while Raymond Davis Jr. & Masatoshi Koshiba each received 1/4 of the prize.

 

MEDICINE

Salvador E. Luria     1969     "for their discoveries concerning the replication mechanism and the genetic structure of viruses"
Luria shared this award with Max Delbrück and Alfred D. Hershey.

Renato Dulbecco     1975     "for their discoveries concerning the interaction between tumour viruses and the genetic material of the cell" Dulbecco shared this award with David Baltimore and Howard Martin Temin.

Rita Levi-Montalcini     1986     "for their discoveries of growth factors" Levi-Montalcini shared this award with Stanley Cohen.

Louis J. Ignarro     1998     "for their discoveries concerning nitric oxide as a signalling molecule in the cardiovascular syste"
Louis J. Ignarro shared this award with Robert F. Furchgott and Ferid Murad.

Mario R. Capecchi     2007     "for their discoveries of principles for introducing specific gene modifications in mice by the use of embryonic stem cells" Mario R. Capecchi shared this award with Sir Martin J. Evans and Oliver Smithies.

LITERATURE
Eugenio Montale     1975     "for his distinctive poetry which, with great artistic sensitivity, has interpreted human values under the sign of an outlook on life with no illusions"

Dario Fò     1997     "who emulates the jesters of the Middle Ages in scourging authority and upholding the dignity of the downtrodden"

ECONOMIC

Franco Modigliani     1985     "for his pioneering analyses of saving and of financial markets"

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


Chris W Smith's picture

Negative Poisson's ratios and thermal expansivity

Dear Katia,

Nice for you to have brought this up on iMechanica. 

I work on materials with negative Poisson's ratios (NPR) and negative thermal expansivity (NTE), and it's true that whenever I have what I think is a new idea I go to check Rod Lakes' web page.  More often than not I find Rod has done it and published it.... hey ho.

I like your recent work on symmetry breaking. Would you say that breaking of symmetry is neccessary for NPR ? (Am I right in thinking I can draw a honeycomb structure with a negative Poisson's ratio of -1 that does not change its symmetry ?) What do you think that  looking at symmetry tells you ? - I'm trying to explore your motivations here.

A significant technical hurdle that remains for NPR materials is their generally low stiffness. Making stiff materials with NPR has eluded everyone so far (to my knowledge). Is there a fundamental reason why this should be so ? (I think there might be). For instance, might you be able to design a fibrous composite which has both high stiffness and NPR via symmetry breaking ? (NPR composites from funny stack sequences have been around for a while but they're all low stiffness).

Nachiket above makes an interesting point about defects in structures that's close to my heart. We have been making NPR mateirals for some time, and some are very homgenous - honeycombs for instance, whereas others were very heterogeneous- foams for instance. We started to wonder how disorder affected Poisson's ratio, and in fact whether it is possible to deliberately use disorder to convert an otherwise+ve Poisson's ratio to -ve. It turns disorder has a strong affect upon Poisson's ratio and it can (probably) be used to generate -ve values 1, 2. Other publications by Neil Gaspar and Curt Koenders also explore this issue from a granluar mechanics standpoint. One thing that has emerged is that adding a small amount of disorder into an otherwise regular structure tends to generate effective structures of far larger scale than the starting base repeating unit. We're looking at some microCT data of deforming NPR foams to see if we can measure this effective structural size.

Concerning NTE - we looked at all the work on NTE and worked out that most if not all of the proposed structures exhibiting NTE could be described as colelctions of hinging or flexing beams. We then wrote down what we think are the base equations for such systems which if you know the geometry and constituent materials of such systems you can use to predict over all CTEs 3. Interestingly CTE is unbounded (a point first made by Rod Lakes) and very large +ve or -ve values are relatively easy to generate.

However many structures proposed for NTE are not stiff or are not weight efficient, something we're trying to investigate. Steeves in his recent JMPS paper addresses the issue of stiffness very well. Certainly the key questions I've been asked by industry on this subject have been about stiffness/strength and weight.

 

 1. Gaspar N, Smith CW, Behne EA, Seidler GT, and Evans KE, (2005b) “Quantitative Analysis of the Microscale of Auxetic Foams”, Physica Status Solidi b, 242/3, no. 05, pp 550-560.

2. Gaspar N, Smith CW, Evans KE (2003) “The effect of heterogeneity on the mechanical response of auxetic materials", Journal of Applied Physics 94 (9): pp. 6143-6149.

3. Miller W, Mackenzie DS, Smith CW, Evans KE (2008) “A Generalised Scale-independent Mechanism for Tailoring of Thermal Expansivity; Positive and Negative” Mech of Mat, 40, pp 351-361

 

Chris

Prof Chris Smith,
Associate Professor in Functional Materials School of Engineering, Computing
and Mathematics, University of Exeter, Exeter, Devon, EX4 4QF, UK.
tel +44 (0) 1392 263652, fax +44 (0) 1392 217965
http://www.secam.ex.ac.uk/profile/cwsmith


katia bertoldi's picture

Dear Chris, I found the

Dear Chris,

I found the work you pointed out on effect of disorder on the macroscopic properties extremely interesting. It is quite a long time I am thinking at how disorder affect instabilities in periodic structures. In fact, in perfectly periodic structure diffuse modes with a wavelength comparable with the size of the microstructure may take place, while in random microstructures localization occurs first. I find the investigation of the evolution from these two extreme situtations affascinating. In the papers you pointed out, I found both answers and inspiration:)

katia


Matt Pharr's picture

stiffness of npr materials

Katia,

 I am also curious about the stiffness of npr materials.  What are typical values of the modulus?  In the current state of npr materials, could they even be used in applications such as opening (fairly compliant) blood vessels?

Thanks,
Matt


Roberto Ballarini's picture

maybe in the paper Katia mentions above

Hi:

 I am not an expert on NPR materials. But is appears to me that they are soft because they are comprised of discrete elements. In the paper I wrote that Katia refers to above, we found NPR in polycrystalline materials with random orientation of anisotropic crystals. I did not pursue these further, but I believe because they are continuous in space they may not suffer from low stiffness as the other types that have been explored.

 

Just a thought. 


katia bertoldi's picture

Stiffness

I think here we are touching another critical issue: stiffness of NPR materials

 Typical cellular microstructures are used to achieve NPR, so that - as expected - the stiffness is not that high.

However, as roberto pointed out NPR Poisson's ratio has been found also in polycristalline materials and sheets assemblies of carbon nanotubes (see ref 9 in the review) and this are not typically considered as soft materials.

 Another issue could be related to resistance to fatigue. Often NPR is obtained through large rotations inside the microstructure. In the elastomeric samples we tested, we saw that after a while the thin ligements  tend to break.


Mike Ciavarella's picture

Have u checked these references? Just to make sure :)

Toward Negative Poisson Ratio Polymers through
Molecular Design

Chaobin He,
Puwei Liu,
and Anselm C. Griffin*

Departments of Chemistry & Biochemistry
and Polymer Science, University of Southern Mississippi, Hattiesburg,
Mississippi 39406

Macromolecules,
1998, 31
(9), pp 3145–3147

DOI: 10.1021/ma970787m

Publication Date (Web): April 11, 1998

Copyright © 1998 American Chemical Society

 

 

[PDF] Auxetic materials: Functional materials and structures from
lateral thinking!
162.105.153.160 [PDF]
KE Evans, A Alderson - Advanced
materials, 2000 - 162.105.153.160

Our everyday experience
tells us that when we stretch a material, for example an elastic
band, the material not only becomes longer in the direction of stretch
but also becomes thinner
in cross-section. Similarly, a material under com- pression usually
expands laterally (eg, ...
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Evidence
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wisconsin.edu [PDF]
TR Böhme, JJ de Pablo - The Journal of
Chemical Physics, 2002 - link.aip.org

Discontinuous molecular
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investigate the glass transition of ultrathin films and the mechanical
properties of nanoscopic
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[PDF] Toward molecular auxetics: Main chain liquid crystalline
polymers consisting …
kent.edu [PDF]
C He, P Liu, PJ McMullan, AC … -
Physica Status Solidi-B- …, 2005 - nlcmf2.lci.kent.edu

© 2005
WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ... Toward
molecular auxetics: Main
chain liquid crystalline polymers consisting of laterally attached
para-quaterphenyls ... Chaobin
He1, 2, 3, Puwei Liu1, 4, Philip J. McMullan1, 5, and Anselm C.
Griffin*, 1, 2, 5 1 ...
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[PDF] A triumph of lateral thoughtmit.edu [PDF]
A Alderson - Chemistry & Industry,
1999 - mit.edu

Materials can be divided into two basic
categories: struc- tural or functional. Development of
structural materials is focused on improving their mechanical or
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Auxetic behaviour from rotating semi-rigid units
JN Grima, V Zammit, R Gatt, A … - …
status solidi (b), 2007 - interscience.wiley.com

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Design of auxetic polymer self-assemblies
G Wei - physica status solidi (b), 2005
- interscience.wiley.com

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An alternative explanation for the negative Poisson's
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JN Grima, R Gatt, A Alderson, KE Evans - Materials Science
and …, 2006 - Elsevier

Materials with a negative Poisson's
ratio (auxetic) exhibit the unusual property of becoming wider
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kent.edu [PDF]
C He, P Liu, AC Griffin, CW Smith, KE
… - … Chemistry and Physics, 2005 - nlcmf2.lci.kent.edu

Chaobin
He,1a Puwei Liu,1b Anselm C. Griffin,1c Christopher W. Smith,*2 Kenneth
E. Evans2
1 Department of Chemistry and Department of Polymer Science, University
of Southern
Mississippi, Hattiesburg MS 39406, USA 2 School of Engineering and
Computer Science, ...
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Auxetic materials
KL Alderson, VR Simkins - US Patent 6,878,320, 2005 -
Google Patents

US 6,878,320 Bl 15 AUXETIC MATERIALS This
application is a 371 of PCT/GBOO/00814, filed
Mar. 6, 1999. This invention relates to synthetic auxetic materials,
that 5 is, to polymeric materials
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by application ...
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Modelling of the mechanical and mass transport properties
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bolton.ac.uk [PDF]
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… - Molecular …, 2005 - informaworld.com

Force field-based
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Dynamic
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Dynamic
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RJ
Davies, SJ Eichhorn, C Riekel, RJ Young - polymer, 2004 - Elsevier

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Auxetic
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Constitutive relationship of a material with unconventional
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TC Lim -
Journal of Materials Science Letters, 2003 - Springer

The
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microstructural
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duced materials with unconventional
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Modelling
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informaworld.com

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Empirical
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Alderson, … - Molecular …, 2005 - informaworld.com

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[PDF] Textile fibres engineered from molecular auxetic polymersntcresearch.org [PDF]
PJ McMullan, S Kumar, AC Griffin -
Project M04-GT21 - ntcresearch.org

Page 1. NTC Project:
M04-GT21 1 National Textile Center Annual Report: November
2004 Textile Fibers Engineered From Molecular Auxetic Polymers Philip J.
McMullan,
Satish Kumar and Anselm C. Griffin* School of Polymer ...

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Auxetic behaviour from rotating rhombi
D Attard, JN Grima - physica status
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Auxetic behaviour from stretching connected squares
JN Grima, PS Farrugia, C Caruana, R
Gatt, D … - Journal of Materials …, 2008 - Springer

Abstract
Systems with negative Poisson's ratio (auxetic) exhibit the unusual
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[PDF] Материалы с
отрицательным коэффициентом Пуассона (обзор)
narod.ru
[PDF]

ДА Конёк, КВ Войцеховски, ЮМ … - Механика …, 2004 -
konyok.narod.ru

Обобщены сведения о материалах, обладающих
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и дана их классификация, основанная на подобии деформационных механизмов
на ...
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On the atomic level deformations in the auxetic zeolite
natrolite

R Gatt, V
Zammit, C Caruana, JN … - physica status solidi ( …, 2008 -
interscience.wiley.com

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Negative Poisson's ratio structures produced from zirconia
and nickel using co- …

AT
Crumm, JW Halloran - Journal of Materials Science, 2007 - Springer

Abstract
Objects with a complex structure designed to display negative Poisson's
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bolton.ac.uk [PDF]
A Alderson, PJ Davies, KE Evans, KL …
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Force field based
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and
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Modelling the negative Poisson's ratio of compressed fused
fibre networks

M Tatlier,
L Berhan - physica status solidi (b), 2009 - interscience.wiley.com

Examples
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synthetic
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[PDF] On the effect of the Poisson's ratio (positive and
negative) on the stability of …
umd.edu [PDF]
B Ellul, M Muscat, JN Grima - physica
status solidi (b), 2009 - aerosmart.umd.edu

Page 1. Phys.
Status Solidi B 246, No. 9, 2025–2032 (2009) / DOI
10.1002/pssb.200982033
pss basic solid state physics b status solidi www.pss-b.com physica On
the effect of the Poisson's
ratio (positive and negative) on the stability of pressure vessel heads ...

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Stress-strain behavior in main chain liquid crystalline
elastomers: effect of …

W
Ren, PJ McMullan, AC Griffin - physica status solidi (b), 2009 -
interscience.wiley.com

Stress-strain results are reported for
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modulus, a ...
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On rotating rigid parallelograms and their potential for
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D Attard, E Manicaro, JN Grima - physica status solidi (b),
2009 - interscience.wiley.com

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ie exhibit a negative Poisson's ratio. One of the mechanisms which can
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胀材料研究的进展

魏高原 - 材料导报, 2003
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[PDF] Polimeri: un'innovazione o un'evoluzione naturale?aim.it [PDF]
LO di Gianluca Cicala, G Recca - Join
AiM! Adesione All'AiM - aim.it

13 I materiali a comportamento
auxetico hanno rice- vuto negli ultimi anni un crescente interesse
da parte di diversi gruppi di ricerca nonché di aziende operanti in vari
settori. Il comportamento
auxetico, postulato inizialmente in via teorica, è stato ottenuto
successivamente in ...
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A Liquid Crystalline Elastomer with a p-Pentaphenyl
Transverse Rod Laterally …

W Ren, PJ McMullan, H Guo, S … - Macromolecular …, 2008 -
interscience.wiley.com

An LCE with a p-pentaphenyl transverse
rod in the main chain was synthesized, in which the
rod can be oriented parallel or normal to the main chain under uniaxial
tension. DSC and WAXD
studies indicate a highly ordered lamellar structure typical of a
smectic A phase. Stress- ...
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e 3 le versioni

[CITAZIONE] An alternative explanation for the
negative Poisson's ratios in a- …
JN Grimaa, R Gatta, A Aldersonb, KE … - Materials science
& …, 2006 - Elsevier Sequoia

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Deformation
mechanisms leading to auxetic behaviour in the alpha-cristobalite and …

A Alderson, KE Evans - Journal of
Physics: Condensed Matter, 2009 - iop.org

Abstract Analytical
expressions have been developed in which the elastic behaviour of the
α-quartz and α-cristobalite molecular tetrahedral frameworks of both
silica and germania are
modelled by rotation, or dilation or concurrent rotation and dilation of
the tetrahedra. ...
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Negative Poisson's ratios in cellular foam materials
JN Grima, R Gatt, N Ravirala, A
Alderson, KE … - Materials Science and …, 2006 - Elsevier

Materials
with negative Poisson's ratios (auxetic) get fatter when stretched and
thinner when
compressed. This paper discusses a new explanation for achieving auxetic
behaviour in foam
cellular materials, namely a 'rotation of rigid units' mechanism. Such
auxetic cellular ...
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On the role of rotating tetrahedra for generating auxetic
behavior in NAT and …

JN
Grima, V Zammit, R Gatt, D Attard, C … - Journal of Non- …, 2008 -
Elsevier

Systems with negative Poisson's ratios (auxetic)
exhibit the unexpected feature of expanding
laterally when uniaxially stretched and becoming narrower when
compressed. Here, we examine
the role of the tetrahedra found in the frameworks of the predicted
auxetic zeolites ...
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[PDF] Auxetics-The
more you stretch them, the fatter they become
um.edu.mt [PDF]
JN Grima - um.edu.mt
Modelling
also makes it possible to attain a better understanding of the
underlying principles
responsible for auxetic behaviour in naturally occurring auxetics (or in
man-made materials where
the auxetic behaviour was obtained without an investigative modelling
phase). A ...
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On the effect of hydrostatic pressure on the auxetic
character of NAT-type silicates

JN Grima, RN Cassar, R Gatt - Journal of Non-Crystalline
Solids, 2009 - Elsevier

Materials with negative Poisson's
ratios (auxetics) exhibit the property of expanding laterally
when uniaxially stretched and becoming narrower when compressed. A
system which exhibits
this unexpected property is natrolite (NAT), a zeolite which is auxetic
in its (0 0 1) plane. ...
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[PDF] MOLECULAR DYNAMICS SIMULATIONS OF AUXETIC FERROGEL194.226.210.10 [PDF]
MR Dudek, B Grabiec, KW Wojciechowski -
Rev. Adv. Mater. Sci, 2007 - 194.226.210.10

Abstract. A
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mechanical properties …
um.edu.mt [PDF]
JN Grima, R Gatt, V Zammit, A
Alderson, KE Evans - Xjenza, 2005 - um.edu.mt

On the
suitability of empirical models to simulate the mechanical ...
Joseph N. Grima*, Ruben
Gatt and Victor Zammit Department of Chemistry, University of Malta,
Msida, Malta. www:
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On
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networked …

JN Grima, D
Attard, RN Cassar, L Farrugia, L … - Molecular …, 2008 -
informaworld.com

We simulate and analyse three types of
two-dimensional networked polymers which have been
predicted to exhibit on-axis auxetic behaviour (negative Poisson's
ratio), namely (1) polyphenylacetylene
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[CITAZIONE] Study of nano-scale systems using
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X Lu, C He, P Liu, AC Griffin - Journal of Polymer Science
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МОДЕЛИ ЭФФЕКТА ОТРИЦАТЕЛЬНОГО …
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Н академии наук Беларуси - МОСКВА, 2002 - konyok.narod.ru
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MOLECULAR
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H meiWu Gao-yuanWei - 高分子科学: 英文版, 2004 - cqvip.com
Three
new kinds of molecular networks are designed and predicted to exhibit
negative Poisson
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Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


Lifeng Wang's picture

Re: Stiffness of NPR materials

Dear Matt, Roberto, and Katia, 

 

I think in certain negative Poisson ratio materials, the stiffness could be high, such as in nacre (ref 18, Phys. Rev. Lett., 245502, 2008). Recently I have a study on a structural composite material inspired by the inner nacreous layer of seashells. We demonstrate this hierarchical mineral/polymer microstructure can be tailored to achieve not only stiffness and strength, but also lateral plastic expansion during tension (a negative “plastic” Poisson’s ratio) providing a volumetric energy dissipation mechanism. However, unlike many other examples of auxetic materials the negative plastic Poisson’s ratio is rarer and has a significant effect in promoting the plastic deformation capability and toughness of the composite.

This paper is available from http://dx.doi.org/10.1002/adfm.201000282

Bioinspired Structural Material Exhibiting Post-Yield Lateral Expansion and Volumetric Energy Dissipation During Tension, by Lifeng Wang and Mary C. Boyce, Adv. Funct. Mater. 2010.

Lifeng

 


Mike Ciavarella's picture

This is interesting -- I like new avenues & applications!

This is the way forward, keep thinking and speculating of applications!  This is the way imechanica is a nice forum in the old sense of Greek and Latin philosophers "forum -- is a latin word " like in the Roman Empire

 

The Roman Forum, also known by its original Latin designation (Latin: Forum
Romanum
, Italian: Foro Romano),
is located between the Palatine
Hill
and the Capitoline Hill of the city of Rome, Italy.
Citizens of the ancient city referred to the location as the "Forum
Magnum" or just the "Forum". 

 

The Forum Romanum. View facing North East from above the Portico Dii Consentes.

 Sorry for the digression, but being Katia, Roberto Ballarini and myself, italian, I became a little patriotic today in this forum!!  :)

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


Chris W Smith's picture

Stiffness and NPR

Dear Prof Ballarinia - your paper sounds very interesting. Perhaps I'm being stupid but which paper do you refer to  ? (I could not see you as an author in any of the papers Prof Bertoldi cites)

Am I right in thinking your argument about 'continuity in space' as being about density? I can't do it now but a survey of NPR materials on a density specific stiffness basis would be revealing. My feeling is they will probably still not compare well.

Prof Bertoldi does have a point, that most NPR materials studied to date have been inherently low modulus. I wonder though if we consider things on a relative basis, do NPRversions have lower moduli values than normal positive PR versions ?

Does anyone know the modulus of the CNT sheets? (My scan of the paper doensn't seem to reveal any).

Fatigue - I would tend to agree that the deformation mechanism leading to NPR (internal rotations) ought to lead to stress concentrations and thus low fatigue life. The only work I know on this is by Fabrizio Scarpa (Bristol) who, if memory serves, found enhanced lifetimes vs conventional versions. Hey ho...

Chris

 

Prof Chris Smith,
Associate Professor in Functional Materials School of Engineering, Computing
and Mathematics, University of Exeter, Exeter, Devon, EX4 4QF, UK.
tel +44 (0) 1392 263652, fax +44 (0) 1392 217965
http://www.secam.ex.ac.uk/profile/cwsmith


Roberto Ballarini's picture

reference

Chris:

 

it is not in Katia's first post. It is later on a few posts ahead of the current one. If you send me your e-mail address I can send you a pdf of the paper.

 

Regards, Roberto

 

 


Mike Ciavarella's picture

Scarpa:another italian,a reason why you are all adoing this?

Dr Scarpa is a member of the Aerospace Composites research group. His principal research interests are listed below.

Auxetic structures

Auxetic solids feature a negative Poisson's ratio (NPR) effect, expanding in all directions when pulled in only one. We design and manufacture cellular materials with auxetic characteristics to enhance the structural integrity, vibroacoustic signature and electromagnetic properties of novel concept of sandwich structures. Current programs involve also the design of NPR honeycombs cells with embedded MEMS for structural health monitoring and active electromagnetic compatibility. Cellular structures with NPR capabilities are also used to design novel concepts of morphing airfoils with continuous camber variation.
Sponsors: EPSRC, EU FP6, DTI, US Army ARO, QinetiQ plc

Passive and active NPR foams

We have modelled and manufactured samples of negative Poisson’s ratio foams using alternative production procedures from the ones illustrated in literature. Work on the area has focused on static and dynamic performance of mechanical properties, crashworthiness capabilities and absorption acoustic properties. Further studies have been carried out also on auxetic and conventional PU foams doped with magnetorheological fluid – both mechanical, acoustic and dielectric properties showed significant changes when loaded with external magnetic fields.
Sponsors: EPSRC, Royal Society, DTI HEFCE, British Vita plc, Xetal ltd

Shape memory alloy honeycombs

We have developed conventional and auxetic honeycombs made of 1 and 2 ways shape memory alloy material. The cellular structures provide changes of stiffness with temperature loading. Large recoverable deformations can be obtained, as well as increased damping capacity under random vibration excitation. The cores can be used in sandwich structures for crashworthiness applications and in satellite-type antennas with deployability capabilities.
Sponsors: EPSRC, US Army ARO

Analysis tools

We have developed numerical techniques to improve the vibroacoustic prediction of sandwich and smart structures in middle and high frequency domains, using Spectral Finite Elements or wavelet-based condensation techniques on classical FEM models. Damping characteristics of sandwich structures with viscoelastic material inserts are also simulated with numerical methods improving the initial estimate given by the Modal Strain Energy method applied to classical FEM models. Recent work has focused on homogenisation numerical techniques and the use of metamodelling strategies with Genetic Programming and Artificial Neural Networks to reduce the computational costs for material of microstructure composite design.
Sponsors: EPSRC, Rolls Royce plc

 

 

 

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella Editor, Italian Science Debate, www.sciencedebate.it blogs http://rettorevirtuoso.blogspot.com/ YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


Mike Ciavarella's picture

So Katia please make a summary here, I am loosing interest ;(

Did you conclude anything worth pursuing?

 

Michele Ciavarella, http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
blogs http://rettorevirtuoso.blogspot.com/
YouTube Channel http://www.youtube.com/user/RettoreVirtuoso


katia bertoldi's picture

too early for a summary....

Dear Mike,

it looks like it is too early for a summary, since new contributions are still coming along:) 

Thanks to all of you for the interesting contributions and the constructive discussion. 

I am very  far from being an expert in NPR materials and I lerned a lot from this discussion

 

katia


ruzzene's picture

Auxetics and Phononics

Katia and al.

 I would lilke to add to the discussion a few of my own papers (joint with F. Scarpa and other authors) which show interesting phononic properties of auxetic lattices:

 A. Spadoni, S. Gonella, F. Scarpa, “Phononic Properties of Hexagonal Chiral Lattices” Wave Motion, Volume 46, Issue 7, November 2009, Pages 435-450

 Ruzzene M., Scarpa F., 2005 “Directional and Band-Gap Behavior of Auxetic Lattices.” Physica Status Solidi B, 242, No. 3, 665–680

Ruzzene M., Soranna F., Scarpa F., 2003 “Wave Beaming Effects in Bi-Dimensional Cellular Structures.”, Smart Materials and Structures, 12, pp. 363-372 

Such properties include band gaps and directionality (wave beaming), which can be related to the anisotropic properties of re-entrant lattices, and to the unique deformation mechanism of chiral lattices. A direct relation between NPR and interesting phononic (wave guiding) properties is still missing.

Regarding possible applications of auxetic lattices (without a clear connection with NPR yet, here again):

 Ruzzene M., 2004 “Vibration and Sound Radiation Of Sandwich Beams With Honeycomb Truss Core.” Journal of Sound and Vibration, 277(2004), pp.741-763.

Scarpa F., Blain S., Lew T., Perrott D., Ruzzene M., and Yates J. R., 2006 “Analytical And Experimental Analysis On The Elastic Buckling Of Hexagonal Chiral Cell Honeycombs” Composites Part A: Applied Science and Manufacturing Volume 38, Issue 2 , February 2007, Pages 280-289

Spadoni A., Ruzzene M., 2006 “Static Aeroelastic Response of Chiral Truss-core Airfoils” Journal of Intelligent Material Systems and Structures, 5 2007.


R. Gabbrielli's picture

Rotating octahedra

Here is the structure of a 3D auxetic periodic material that uses rotating regular octahedra, from Adrian Rossiter's website, showing how also in this case stress concentration is necessary to achieve NPR. This is somewhat similar to the 2D lattice of connected rotating squares.

http://www.antiprism.com/misc/jit_cubo_oct3b.gif

http://www.antiprism.com/misc/jit_cubo_oct3c.gif

http://www.antiprism.com/misc/jit_cubo_oct4.gif

http://www.antiprism.com/misc/jit_cubo_oct4c.gif

All the animations refer to the same structure, the only difference is size and relative motion between bodies. Ignore the attachment/detachment of the vertices during the animation, this is only due to final and initial configurations being identical. Note that the auxetic behaviour is still 2D. Looking carefully, it is possible to spot the global rotational axis. There is no strain along this direction. Considering the fully open configuration, axis Miller indices are [111]. Contractions/expansions take place on its related plane, which is orthogonal to the axis.

Looking even more carefully, only two types of octahedra can be seen, rotating in opposite directions each other.

Although one might be led to think of a global torsional component, this is not present. Each octahedron, excluding those pierced by the rotational axis, moves only radially from its initial position to the outermost position (fully open configuration) and back to tightly pack closer to the axis. This is best shown in the third animation, where the octahedra pierced by the rotational axis are counter-rotating.

Auxetic components of this kind can be manufactured using a Schwarz P surface as a template, and cutting it between two parallel [111] planes.

For a reference on the better-known example of rotating squares, check this article.

Auxetic behavior from rotating squares. J. N. Grima and K. E. Evans., J. Mat. Sc. Lett., Vol. 19(17), 1563-1565

 

-- Ruggero Gabbrielli


katia bertoldi's picture

Re:Rotating octahedra

Ruggero

 nice animation

When you say that the auxetic behavior is still 2D, do you mean that the Poisson's ratio is negative only in one transverse direction?

katia


R. Gabbrielli's picture

Rotating octahedra

Yes. The strain in the direction of the rotational axis (call this z) is zero in any case.

I'm editing my previous post.

Adrian drew my attention on the rotating octahedra being a stack of layers of triangles. I now note that for the auxetic behaviour to be shown, the load should be applied along the principal lattice directions. This is true in any case, 2D (triangles and squares) but also for this 3D sample of rotating octahedra.

Looking through [1 1 1] you can see a hexagon. The three directions joining the vertices of this hexagon are those giving auxetic behaviour (actually their projection on the plane [1 1 1]), namely [2 -1 -1], [-1 2 -1] and [-1 -1 2].

Regarding the constructibility of such a material, here's an example. Consider a cubic sample such as Adrian's oct4. Make the fully-open configuration solid. Remove the spherical joints and thicken the points of contact between octahedra so you can actually build a specimen using an homogeneous material. Something like this below (bottom-right corner sample):

G, D and P affine surfaces (polyamide)


Chris W Smith's picture

groups active in NPR

Can we hang on to using English for a moment?

 

Perhaps it would help to list the groups active in research on NPR and its effects ?

So apart from those people who have already disclosed their interests so far in this thread, I know of  the following groups/people -

Anselm Griffin (Georgia Tech, USA)

Andy and Kim Alderson (Bolton Univ, UK)

Fabrizio Scarpa (Bristol, UK)

Krzysztof Wojciechowski  (IFM-PAN, Poznan, Poland)

Joseph Grima (Chemistry, Malta)

The order implies nothing, and I accept any blame for ommissions. Please feel free to add to this if you see an ommission.

 

Would a similar list for materials / structures with negative or unusual CTE be of interest to people ? (The trouble is this would include a lot of chemists and physicists who make/study materials with funny CTE).

I attempted to review this area recently in a paper in Journal of Materials Science (Journal of Materials Science 44 5441-5451 [DOI 10.1007/s10853-009-3692-4]) but I know it's already out of date.

 

Chris

Prof Chris Smith,
Associate Professor in Functional Materials,
College of Engineering, Mathematics & Physical Sciences, University of Exeter, UK.
tel
http://www.secam.ex.ac.uk/profile/cwsmith


Mike Ciavarella's picture

OK, let's stick to English, but let's also make a summary !

I see the discussion has gone into anisotropic material properties now.  It is all interesting, but every now and then, I need to know where we are aiming at.  I am still confused about applications.  Maybe Katia can help :=)

 

Michele Ciavarella, Politecnico di BARI - Italy, Rector's delegate.
http://poliba.academia.edu/micheleciavarella
Editor, Italian Science Debate, www.sciencedebate.it
Associate Editor, Ferrari Millechili Journal


Chris W Smith's picture

I'll try to offer up some

I'll try to offer up some suggested applications, and Katia et al can correct my mistakes & ommissions...

I'll also point Mike and others at two reviews i) in 2004 by Yang et al in J Mat Sci (vol 30, page 3269), and ii) by Evans and Alderson in Adv Mat in 2000 (vol 12, page 617).

It might be helpfull to divide up applications into those directly associated with the negative Poisson's ratio effect, and those arising indirectly from it.

Direct applications.

Composites with auxetic fibres might show high toughness or be able to use shorter fibres because  the auxetic fibres have higher frictional losses during pull out (they lock themselves into their cavities under tension). Such fibres may acts as balancing plies during manufacture because they may effectively reduce thermal expansivity (see recent papers and patents by Alderson). Negative Poisson's ratio in plane may also make draping of prepregs easier because they will naturally form synclastic curvatures (dome shapes) as opposed to anticlastic curvatures (saddle shapes) like positive PR versions.

Some other claims and verifications have been published for fracture toughness in compsoites with various NPRs. I'm not sure there is a large body of evidence for this and this is obviously an interesting avenue of work for someone.

Indentation. since auxetic material underneath a point load (in compression) will tend tomove inwards towards the line of compression rather than away form it as with a PPR material, the resistance to indentation tends to be higher and different with auxetics. This is a nice example of a smart materials response - localised stiffening. I see no reason why such benefits woudl not be seen at high strains rates also, eg for crash protection.

However this response is also in part a result of the increased shear modulus associated with NPR - that is for a given value of Young's moudulus, a NPR below -0.5 will engender a larger shear modulus. As you'll see from the relationship between these elastic constants if nu tends to -1 the shear modulus rises to infinite. Thus Poisson's ratio is a nice way to decouple Young's and shear moduli.

Tunable Deformation. Since the PR controls all deformations in axes other than that applied it offers a large degree of control over how a structure interacts with other structures or fluids. Applications seem possible in aerospace, marine atuomotive and locmotive applications where a particular structural response can be encodedinto astructure via PR especially if it is possible to functionally grade it across a structure.

Indirect applications.

These arise because PR has an influence on other properties or because the microstructure leading to NPR engenders other effects. For example I think both Rod Lakes and Fabrizio Scarpa (and possibly others) have deomonstrated improved acoustic absorption and viscoelastic loss in NPR foams and honeycomb sandwich panels, though in the case of the foams this was probably due to the more tortuous microstructure of the foams than any elastic property per se. We have done some nice work with Fabrizio Scarpa recently on vibration damping in NPR honeycombs which we expect to publish soon.

It has also becaome apparent that there are many advantages in NPR materials as hosts for ElectroMagnetic (EM) active inclussions, usually metallic objects. Control over deformation behaviour in plane in say a honeycomb, allows control over spacing and orientation of EM active elements and thus functionaliies such as absorbtion/relfection, beam steering, wave compression, etc. Perhaps most of this work has so far been done by Fabrizio Scarpa, though I have some ongoing in my laboratory at present. Interstingly, closely related resonance phenomena have been demonstrated for acoustic waves by Massimo Ruzzene (have a look at his webpage for a gorgeous example of beam steering in a chiral NPR honeycomb - http://www.me.gatech.edu/faculty/ruzzene.shtml).

NPR solids such as foams or honeycombs may also have application as separators for particles in fluids. With PPR solids it is possible only to clsoe down pores, but with NPR solids it is possible to open up pores as well. This could have some significant benefits over current filtration systems which usually have to be clsoed down for cleaning or replacement of filters. NPR filters could be cleaned in situ.

There has been some investigation of the benefits of using NPR materials in Piezoceramic composites. 

I'm sure I've missed several issues here, so please feel free to point out errors or ommissions.

Chris

 

Prof Chris Smith,
Associate Professor in Functional Materials,
College of Engineering, Mathematics & Physical Sciences, University of Exeter, UK.
tel
http://www.secam.ex.ac.uk/profile/cwsmith


katia bertoldi's picture

Direclty from Adrian (he had troubles posting the comment)

Hi

I noticed Ruggero's reference to rotating octahedron
animations that I made. Here are a few more animations
that may be of interest.

The rotating square and triangle arrangements

  http://www.antiprism.com/misc/tri_jit01.gif
  http://www.antiprism.com/misc/squ_jit01.gif

The rotating octahedron arrangement was actually made
by pasting octahedra onto the rotating triangles arrangement,
above or below depending on colour, and then repeating this
basic unit in planes.

The next two animations map these arrangements onto a torus.
I made them as an aid to visualisation. They have no geometric
significance. The expansion is simulated.

  http://www.antiprism.com/misc/tri_jit_tor1.gif
  http://www.antiprism.com/misc/squ_jit_tor1.gif

The rotating triangles work well when there are four
around the tube. The tiling in this case is a kaleidocycle.
This is another mocked up animation, but it would work with
rigid equilateral triangles. It includes the kaleidocycle
motion as well as the rotation of the triangles

   http://www.antiprism.com/misc/tri_jit_tor2.gif

I made a animation of Fuller's jitterbug to partner the
rotating octahedron animation. In this case the model
scales equally along the diagonals of the containing
cube (maximum at the icosahedron stage)

  http://www.antiprism.com/misc/jit_jb2.gif

For anyone especially interested in Fuller's jitterbug
I wrote a small program to explore it

  http://www.antiprism.com/link/jitterbug_gl

Finally, I thought the "cube" cell that Katia mentioned
looked interesting. I have made a basic animation of
some cells arranged like FCC

  http://www.antiprism.com/misc/aux_cell_fcc.gif

Adrian.


R. Gabbrielli's picture

Rotating cubes

From Adrian: 

The first is a "rotating cubes" model, which is like the
"rotating octahedra", but uses cubes and the rotating
squares transformation

  http://www.antiprism.com/misc/squ_jit_cubes01.gif

It looks familiar, but I am not sure from where.

I saw that the cubes could be augmented to form a packing
of rhombic dodecahedra, and these could be used in the
transformation instead

  http://www.antiprism.com/misc/squ_jit_rd01.gif

However, the rhombic dodecahedron can also be formed by
augmenting the octahedron, and the original "rotating
octahedra" transformation can also be modelled with rhombic
dodecahedra. These pack as before, but are connected
differently

  http://www.antiprism.com/misc/tri_jit_rd01.gif

Adrian
-- Adrian Rossiter
adrian@antiprism.com
http://antiprism.com/adrian


REG- CAE modeling of auxetic materials

Hi all,

 Does anyone know how to model the regaular foam as a auxetic foam using ls-dyna?which material card is used and what kind of  element type must be selected?

 Thanks in advance.

Karthik 


I wonder if there's been any

I wonder if there's been any work in analyzing defects in  metamaterials kidney stones