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Henry Tan's picture

Size effect of energetic crystals in high explosives and solid propellants

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Energetic materials, such as solid propellants and high explosives, can be considered as composite materials with energetic particles embedded in polymeric binder matrix. These energetic materials display strong particle size effects. For example, large particles debond earlier than small ones in high explosives.

Zhigang Suo's picture

A field of material particles vs. a field of markers

In continuum mechanics, it is a common practice to view a body as a field of material particles, so that the continuum mechanics is phrased as an algorithm to determine the function x(X, t), where X is the name of a particle, and x is the place of the particle at time t.

MichelleLOyen's picture

New Biomechanics Journal

A new journal has been started, "Journal of the Mechanical Behavior of Biomedical Materials," to be published by Elsevier from November, 2007. From the Journal's website:

Arbitrary Lagrangian Eulerian modeling in large strain solid mechanics problems

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I am interested in Arbitrary Lagrangian Eulerian formulation in modeling large strain solid mechanics problems. Can any one recommend some good resource on this topic? Both theoretical and numerical implementation are desired. Thanks in advance.

Harold S. Park's picture

Deformation of FCC Nanowires by Twinning and Slip

We present atomistic simulations of the tensile and compressive loading of single crystal FCC nanowires with <100> and <110> orientations to study the propensity of the nanowires to deform via twinning or slip.  By studying the deformation characteristics of three FCC materials with disparate stacking fault energies (gold, copper and nickel), we find that the deformation mechanisms in

Jinxiong Zhou's picture

A subdomain collocation method based on Voronoi domain partition and reproducing kernel approximation

A subdomain collocation method based on Voronoi diagrams and reproducing kernel approximation is presented. The unkonwn field variables are approximated via reproducing kernel approximation. The body integration arising from the numerical evaluation of Galerkin weak form is converted into much cheaper contour integration along the boundary of each Voronoi cell. The Voronoi cells also provide an natural structure to perform h-adaptivity.

A short paper on T-stress of an interfacial crack in a bi-material strip

The attached file is on T-stress of an interfacial crack in a bi-material strip. The geometry of the problem is the same with that of Suo and Hutchinson (1990, IJF). Using a conservation integral technique, a formula for T-stress is derived with two numerical factors.

Interfacial Thermal Stresses in a Bi-Material Assembly with a Low-Yield-Stress Bonding Layer

An approximate predictive model is developed for the evaluation of the interfacial thermal stresses in a soldered bi-material assembly with a low-yield-stress bonding material. This material is considered linearly elastic at the strain level below the yield point and ideally plastic at the higher strains. The results of the analysis can be used for the assessment of the thermally induced stresses

On the thermomechanical coupling of shape memory alloys and shape memory alloys composites

Smart materials have received much attention in recent years, especially due to their various applications in smart structures, medical devices, actuators, space and aeronautics. Among these
materials, shape memory alloys exhibit extremely large, inelastic, recoverable strains (of the order of 10%), resulting from transformation between austenitic and martensitic phases. This
transformation may be induced by a change, either in the applied stress, the temperature, or both.

HCHan's picture

Adaptation of arteries to pressure changes

Arteries are living organs that can remodel themself in response to stress changes. Arterial remodeling is a big topic and this paper shows only a tip of the iceberg.

Harold S. Park's picture

Modeling Surface Stress Effects on Nanomaterials

We present a surface Cauchy-Born approach to modeling FCC metals with nanometer scale dimensions for which surface stresses contribute significantly to the overall mechanical response. The model is based on an extension of the traditional Cauchy-Born theory in which a surface energy term that is obtained from the underlying crystal structure and governing interatomic potential is used to augment the bulk energy.

figures

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rupture strain of films

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rupture of Cu films

Dear Prof. Li, i have made two figures about rupture strains of  films on elastomer according to the datas shown in your papers-- "Deformability of thin metal films on elastomer substrates" International Journal of Solids and Structures 43 (2006) 2351–2363. and "Stretchability of thin metal films on elastomer substrates" APL85(2004). According to the papers, the stiffer or thicker the elastomer substrates, the larger rupture strains, then where would be the curve with H/h =200? Whether the rupture strain is even large, according to your simulations?

Blood Clot Mechanics at the Molecular Level

Cross-posted to Biocurious a blog about biology through the eyes of physicists.

The function and dysfunction of blood clots are often directly related to their mechanical properties: clots stop blood from flowing through wounds but can also break away (embolize) and block blood vessels causing stroke. Strength and plasticity are both important for ensuring the former is more common than the latter and so people have been studying the mechanics of clots for over 50 years. 

Solution of system of Differential equations

Dear Wei and Mogadalai,

As mentioned earlier I am trying to solve for a vector {x} from

{x'}=[A(t)]{x}

where [A(t)] is known matrix of size (2X2) at the max 4x4, elements and are functions of "t".

{x} is a vector (nX1) function of 't'

{x'} is derivative of {x} with respect to 't'.

Analytical derivation on the stress of the adhesive layer based on beam/plate therories?

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I just came across the lecture notes from Professor Nix on Mechanical Properties of Thin Films. It is very educative and helpful. I wonder if anyone could recommend some analytical derivation on the stress of the adhesive layer between two similar/dissimilar adherends (sandwiched specimen) under mechanical or thermal loading.

Many thanks ...

Jie Wang's picture

Phase field simulations of polarization switching-induced toughening in ferroelectric ceramics

Polarization switching-induced shielding or anti-shielding of an electrically permeable crack in a mono-domain ferroelectric material with the original polarization direction perpendicular to the crack is simulated by a phase field model based on the time-dependent Ginzburg-Landau equation. The domain wall energy and the long-range mechanical and electrical interactions between polarizations are taken into account. The phase field simulations exhibit a wing-shape- switched zone backwards the crack tip.

Ashkan Vaziri's picture

"Wrinkled hard skins on polymers created by Focused Ion Beam", PNAS , January 2007

A stiff skin forms on surface areas of a flat polydimethylsiloxane (PDMS) upon exposure to focused ion beam (FIB) leading to ordered surface wrinkles. By controlling the FIB fluence and area of exposure of the PDMS, one can create a variety of patterns in the wavelengths in the micrometer to submicrometer range, from simple one-dimensional wrinkles to peculiar and complex hierarchical nested wrinkles. Examination of the chemical composition of the exposed PDMS reveals that the stiff skin resembles amorphous silica. Moreover, upon formation, the stiff skin tends to expand in the direction perpendicular to the direction of ion beam irradiation. The consequent mismatch strain between the stiff skin and the PDMS substrate buckles the skin, forming the wrinkle patterns. The induced strains in the stiff skin are estimated by measuring the surface length in the buckled state. Estimates of the thickness and stiffness of the stiffened surface layer are estimated by using the theory for buckled films on compliant substrates. The method provides an effective and inexpensive technique to create wrinkled hard skin patterns on surfaces of polymers for various applications. Click here for access to the full article. See also the press release: Applied scientists create wrinkled 'skin' on polymers

Call for papers: Mahalanobis-Taguchi System Analysis

Call for papers: Mahalanobis-Taguchi System Analysis.  A special issue of the International Journal of Industrial and Systems Engineering (IJISE).

With rapid advances in technology, use of automated data collection methods is on a steep rise. Situations that call for decision-making with voluminous datasets involving several variables are being encountered in an ever-increasing number of fields. Mahalanobis-Taguchi System (MTS) analysis provides an effective decision-making methodology in such situations. It is being successfully used by engineers in companies such as Nissan, Ford, Delphi, Xerox, and Yamaha, to name but a few.  This special issue invites submission of papers that could be state-of-the-art, new contributions, technical notes, review papers, or case studies in the area of Mahalanobis-Taguchi System analysis. For more information, please see the Journal Call for Papers website.

International Journal for Computational Vision and Biomechanics

International Journal for Computation Vision and Biomechanics - Announcement and First Call for papers

ISSN: 0973-6778

Subject: Computational Vision and Biomechanics

Frequency: 2 issues per year

Start date: First trimester of 2007

Dear Colleague,

It is a pleasure to announce the new International Journal for Computation Vision and Biomechanics (IJCV&B) and its first call for papers.

Lift weight using less energy

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As shown in figure(energyefficiency1.jpg) sliding plates can slide over fixed plates. Stationary plate is simply supported horizontaly on sliding plates. Lubrication is provided at contact surfaces of stationary plate and sliding plates. Weight or load or force (mg) is applied at center of stationary plate. This load is equally devided and applied on each sliding plate in vertical downward direction (mg/2). This mg/2 cos(alpha) helps  sliding plate to slide in nearly downward direction.

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