There are many groups working on FGM and applications.  Recently from my study we foudn that the FGM can be used in devices with distinct properties.  There are tremendous literatures on FGM and it is relatively easy to trace the new directions of such groups.

Ji Wang

Hi,

i am also working in the area of FGM. Let me know if we can share the knowledge.

sandy

  Is optimization of Material Profile for funtionally graded material to reach    maximum Transmission loss or maximum critical frequency coud be interesting topic?

Dear Roozbeh,

 Can u tell us in details?

Sandyg 

Dear Sandy and Roozbeh

Nice to know you both on imechanica. Our group is working towards understanding the effect of material property inhomogeneity on fracture of FGMs.

We are trying to understand both the effect of inertia (dynamic fracture mechanics) and material inelasticity (plastic fracture mechanics).

In our dynamic fracture mechanics simulations of rapid crack propagation, we assume a known mathematical function for the material property inhomogeneity. This study has enabled us to understand that the inhomogeneous material property variations affect the crack opening, displacement, velocity of propagation and the energetics of propagation. We predict that a crack grows faster in an FGM when the material progressively becomes softer and less denser away from the crack plane. While a reverse is predicted for an FGM in which the material progressively stiffens.

We have been looking into the asymptotics around a crack in a ductile FGM. In this, we are interested to understand the near-tip singularity in graded materials. As in elastic FGM's we see that the most singular (HRR) term in the asymptotic expansion remains unaltered even in a ductile FGM. A distinct second less-singular term (unlike a non-singular term in LEFM) exists for only a few cases of the material property gradations.

Please post your research interests and topics pursued in your group so as to enable us interact on imechanica.

Thanks

Kubair

http://www.aero.iisc.ernet.in/cdfm

Functionally graded materials are investigated in literatures in two cases:

1- Mechanical behaviour under thermal conditions

2- Mechanical behaviour without considering the thermal loading (Free vibration, dynamic response, static response...)

I want to know if thermal loading can be seperated from FGM analysis and studying FGM structures without thermal loading is applicable?

And also I want to know which method is more usefull in dynamic analysis of functionally graded structures?

Ahmad Rafsanjani Abbasi

each funtionally graded material have material profile that shows how material distributes over the material. this profile could be optimized in order to reach a purpose. i want to optimize it in order to reach maximum transmission loss or critical frequency.

is it an interesting objective?

Dear Ahmad,

FGM analysis without considering themal stresses is available in the literature. The following are representative examples

1. JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME 73 (5): 783-791 SEP 2006
2. INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 43 (13): 3920-3939 JUN 2006
3. EXPERIMENTAL MECHANICS 46 (2): 179-196 APR 2006
4. JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME 72 (4): 461-467 JUL 2005
5. INTERNATIONAL JOURNAL OF FRACTURE 141 (1-2): 11-25 SEP 2006
6. EXPERIMENTAL MECHANICS 46 (2): 269-281 APR 2006
7. EXPERIMENTAL MECHANICS 46 (2): 137-154 APR 2006
8. JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME 72 (2): 237-248 MAR 2005
9. EXPERIMENTAL MECHANICS 45 (2): 153-159 APR 2005
10. INTERNATIONAL JOURNAL OF PLASTICITY 21 (6): 1195-1254 2005

Hope the above list is helpful

Thanks

Kubair

http://www.aero.iisc.ernet.in/cdfm

Hi all,

nice to see all of u here. I am working on the mechanical properties of FGM and material is epoxy resin and Microballoons. we are into fabrication and testing of these materials. I finished one project recently and that was flexural testing of FGM. I do understand a little bit what Roobeh is saying but probably need more reference on these kind of works. Is there any good journal paper? I would suggest to start with some problem and discuss on that so that we can learn some good stuff here. so if everyone thinks its a good idea then post one problem. 

Sandy 

Dear Zhen,

The paper that describes the asymptotics around a mode 3 crack in a ductile FGM is available online in the ASME JAM

the details are

JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME 72 (4): 461-467 JUL 2005

I do have a PDF file formatted by the journal (cannot post due to copyright), in case you have trouble in downloading from the JAM site, I can mail you the same. I will also read your post carefully about the split singularities and then we can discuss.

Kubair 

http://www.aero.iisc.ernet.in/cdfm

Dear Sandy,

 It is a good idea to discuss on some research problem of common interest.

One topic that comes to mind is how to determine (experimentally) the material property gradient. I have not come across a straight forward answer to the above. Most experimental works available in the literature on FGMs manufacture their own specimen and the material property gradient is controlled while manufacturing. If say, one obtains a FGM of the shelf and wants to characterize, how can it be done. Is it possible to determine the inhomogeneity by performing macroscopic tests, like say a tensile test.

In some of our analysis we see that the mechanical response of FGM systems is dependent on the boundary conditions (one would expect not to be). Say for example, one gets different results by applying either a traction or a displacement boundary conditions in a multiple isoparametric FEM framework. If anyone has some experience  on this, please do share it with us.

Kubair 

http://www.aero.iisc.ernet.in/cdfm

I think the advantages of FGM materials is behined its response due to thermal loading. in many cases however many researches performed their researches on FGM materials without considering thermal condition of the problem but in most cases it is obviuos that using functionally graded materials will not only improve mechanical properties of the structure but also makes it worse (if there is not thermal loading). I think the aim of design of FGMs is to be capable to prevent stress concentarion and some sharp behaviour in the systems. unfortunately in many cases the papers published in this field are far from reality and are not applicable in industrial scales. thanks to Mr Kubair for sending these usefull references.

If you have any other opinion about this topic, o not hesitate. let me know.

Best regards,

Ahmad Rafsanjani Abbasi

I think the advantages of FGM materials is behined its response due to thermal loading. in many cases however many researches performed their researches on FGM materials without considering thermal condition of the problem but in most cases it is obviuos that using functionally graded materials will not only improve mechanical properties of the structure but also makes it worse (if there is not thermal loading). I think the aim of design of FGMs is to be capable to prevent stress concentarion and some sharp behaviour in the systems. unfortunately in many cases the papers published in this field are far from reality and are not applicable in industrial scales. thanks to Mr Kubair for sending these usefull references.

If you have any other opinion about this topic, o not hesitate. let me know.

Best regards,

Ahmad Rafsanjani Abbasi

Kubair,To answer your question on how to measure the mechanical properties like elastic modulus and poisson’s ratio, you can use the ultrasonic probe which gives the shear and longitudinal velocities which then can be used to calculate modulus and poisson ratio.I hope I understood your question correctly.  Thanksnitesh

nitesh

Different types of armor are used to protect different areas of the vehicle, partly to reduce weight for a given amount of protection and partly to combine projectile protection with load-bearing capability. These protection system components will consist of combinations of metals, ceramics, and polymers.

Functionally graded metal/ceramic composite materials can combine the beneficial properties of a metal toughness, ductility, heat conductivity with those of a ceramic hardness, stiffness, heat resistance. The ceramic side would be brought into contact with the external agent and the metal side would provide integral structural support.

 Dear Dr. Bharadwaj,

The following book Fundamentals of functionally graded materialsS Suresh and A Mortensen 

is a very good book to start. 

http://www.aero.iisc.ernet.in/cdfm

I am glad to see there are overwhelm interests in the FGM and applications.  We have been working on FGM for about two years with sponsored projects.  Major research work are being done by Prof Zheng Zhong, Tongji University, Prof Weiqiu Chen, Zhejiang University, with a number of collaborators in other schools.

The basic approach has been usual: particular pattern of FGM which can give you analytical solutions first, then extended to other schemes.

For myself, I am intersted in FGM in acoustic wave devices, which may lead to new device structures.  We have some results and publications, and more results are in the pipeline.

What we have found is also usual: the differential equations fromthe complicated material property change can be solved by Forbenius Method.  Lately, we are tryign to use the HAM (http://numericaltank.sjtu.edu.cn/) for the equations to be solved.

For books, one by GR Liu, CRC Press, maybe closer to the analysis and FEM part.

It is always great to meet colleagues on the same subject.

Hi,

i'm interested in numerical analysis of fgm. but i need apdl codes for describe material properties of fgm.

Can you help me?

Thanks.

Ulukoy,

we carried out some numerical simulations of deformation and damage behavior of Functionally graded Composites. In so doing, we considered first a particle reinforced composites with graded particle distribution and non-percolating microstructures, and then graded interpenetrating phase composites. You can download papers from http://www.risoe.dk/afm/personal/lemi/, in particular, http://www.risoe.dk/afm/personal/lemi/papers/voxel-paper.pdf and http://www.risoe.dk/afm/personal/lemi/papers/paper_fgm.pdf.

Best Regards

Leon Mishnaevsky, Denmark

Dear Mishnaevsky,

Thanks for the papers. I will examine power law fgm first,  and then

sigmoid and exponential fgm.

Hi all,

I want to know which factories product FGM.

Thanks.

hi,

our group is studying 3D cracks problem in fully coupled electromagnetothermoelastic multiphase composites about 8 years.

perhaps i think we can solve shell crack problem byhypersingular integral equation method

if you interested this method you can find related papers on web: Noda, N.A; Taiyan Qin; Renji Tang; Mengcheng Chen; Chaojin Yue; Chunhui Xu; Pan ernian et al

Hi,

In the theoritical/computational analysis, one or more propertis are assumed to vary according to some function. I was interested to know (mainly from manufacturing/experimental groups), what are the properties that may be varied or if they may be varied according to any mathematical function or not. It will be helpful to get some works regarding this.

Sandip Haldar

i would like to have some assistance from all regarding crack propagation in annular disk at tang location using ABAQUS

Hi,

i am working on fracture in FGM shell element applying cohesive zone model. So, i am including the rotation effect in the Xu and Needleman´s potential  and using 3D interface line element. I´d like to know if there are someone doing something similar.

Thanks for all