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zichen's picture

Fast nastic motion of plants and bio-inspired structures

The capability to sense and respond to external mechanical stimuli at various timescales is essential to many physiological aspects in plants, including selfprotection, intake of nutrients and reproduction. Remarkably, some plants have evolved the ability to react to mechanical stimuli within a few seconds despite a lack of muscles and nerves. The fast movements of plants in response to mechanical stimuli have long captured the curiosity of scientists and engineers, but the mechanisms behind these rapid thigmonastic movements are still not understood completely.

Mohammad Aramfard's picture

Disclination mediated dynamic recrystallization in metals at low temperature

Recrystallization is one of the most important physical phenomena in condensed matter that has been utilized for materials processing for thousands of years in human history. It is generally believed that recrystallization is thermally activated and a minimum temperature must be achieved for the necessary atomic mechanisms to occur. Here, using atomistic simulations, we report a new mechanism of dynamic recrystallization that can operate at temperature as low as T = 10 K in metals during deformation.

Abhishek Saini's picture

PhD Querry

I am currently a M.Tech (Mechatronics, Department of Mechanical Engineering) student in IIT Patna. I have strong interests in Applied Mechanics with special focus on Dielectric Elastomer Actuators. I am expecting to graduate by May 2016. Currently i am working on dielectric elastomer actuators and want to continue this in my PhD also. Are there any opportunities for PhD positions available at Harvard Solid Mechanics? What are the essentials needed for the above.

Thanks

Matlab to abaqus

Choose a channel featured in the header of iMechanica: 

Dear all

I want to ask if it is possible to produce an inp
file from Matlab and then export to ABAQUS so as to
recognize the geometry.

Thanks 

Meisam. Asgari's picture

Constitutive Modeling of Soft Materials: Wormlike Micelles

Self-assembly of amphiphilic molecules into various supramolecular nano-structural aggregates has drawn the attention of chemists, physicists, and engineers in recent decades.

Amir Abdollahi's picture

Fracture toughening and toughness asymmetry induced by flexoelectricity

Cracks generate the largest strain gradients that any material can withstand. Flexoelectricity (coupling between strain gradient and polarization) must therefore play an important role in fracture physics. Here we use a self-consistent continuum model to evidence two consequences of flexoelectricity in fracture: the resistance to fracture increases as structural size decreases, and it becomes asymmetric with respect to the sign of polarization. The latter phenomenon manifests itself in a range of intermediate sizes where piezo- and flexoelectricity compete.

azadpoor's picture

Mechanics of Additively Manufactured Biomaterials and Implants: Special issue of J Mech Behav Biomed Mater

Additive manufacturing (AM) has emerged as a powerful technique for manufacturing of various types of biomaterials and implants. Using AM, it is now possible to fabricate biomaterials with arbitrarily complex shapes at different scales. The inventory of biomaterials that can be used in this way continues to increase, extending the possible range of products and applications.

Work of adhesion/separation between soft elastomers of different mixing ratios

Adhesion between soft matter is a universal mechanical problem in bio-engineering and bio-integration. The Johnson–Kendall–Roberts (JKR) method is widely used to measure the work of adhesion and work of separation between soft materials.

Shutao Qiao's picture

Conformability of a Thin Elastic Membrane Laminated on a Rigid Substrate With Corrugated Surface

When laminating a thin elastic membrane on a substrate with surface roughness, three scenarios can happen: 1) fully conformed, i.e., the membrane completely follows the surface morphology of the substrate without any interfacial gap; 2) partially conformed; and 3) nonconformed, i.e., the membrane remains flat if gravity is not concerned.

mohamedlamine's picture

Reinforced Concrete Strength

The composite strength of Reinforced Concrete which is a mixture of two main materials can be calculated by the formula given by Tsai : X=(vf+vm*Em/Ef)*Xf  where vf is the fiber (steel) fraction and vm is the concrete (cement+sands+gravels) fraction. Xf is the yield strength of Steel and Xm is the compressive strength of the Concrete matrix. For the application case: vf=0.01911, vm=0.98089, Xf=270 MPa, Xm=40 MPa, Ef=207.000 GPa, Em=30.798 GPa we obtain X=44.563 MPa.

Shape Bifurcation of a Spherical Dielectric Elastomer Balloon under the Actions of Internal Pressure and Electric Voltage

Under the actions of internal pressure and electric voltage, a spherical dielectric elastomer balloon usually keeps a sphere during its deformation, which has also been assumed in many previous studies. In this article, using linear perturbation analysis, we demonstrate that a spherical dielectric elastomer balloon may bifurcate to a nonspherical shape under certain electromechanical loading conditions.

Xuanhe Zhao's picture

EML Special Issue on 3D Assembly by Cutting, Bending and Folding

EML Special Issue on 3D Assembly by Cutting, Bending and Folding

When patterned with different materials, gradients or cut-outs, thin structures such as sheets and rods can bend or fold either spontaneously or by actuation in response to a force or stimulus to form a pre-designed three dimensional structure. This special issue addresses the design and mechanics of these structures with a special emphasis on programmability and non-linearity.  

Manuscript Submission:

Bin Liu's picture

The surface-forming energy release rate based fracture criterion for elastic-plastic crack propagation and interpretation on paradox of Rice

The J-integral based criterion is widely used in elastic-plastic fracture mechanics. However, it is not rigorously applicable when plastic unloading appears during crack propagation. One difficulty is that the energy density with plastic unloading in the J-integral cannot be defined unambiguously.

Matlab code for intermetalic layer thickness

I need a matlab code for measuring intermetallic layer thickness of Cu-Sn binary alloy during soldering.

I will use the result for Characterization of intermetallic layer and also time based analysis of mechanical failure.

I would be really grateful to the person who can help me over this issue.

 

Thanks a lot in advance.

Teng zhang's picture

Predicting fracture energies and crack-tip fields of soft tough materials

Soft materials including elastomers and gels are pervasive in biological systems and technological applications. Whereas it is known that intrinsic fracture energies of soft materials are relatively low, how the intrinsic fracture energy cooperates with mechanical dissipation in process zone to give high fracture toughness of soft materials is not well understood. In addition, it is still challenging to predict fracture energies and crack-tip strain fields of soft tough materials.

SHPB testing: speed of plastic waves in short cylinders

Dear iMechanica community,

I came across a problem in plasticity for which I am unable to find a reference in the literature and kindly ask your advice.

azadpoor's picture

Additive Manufacturing (3D printing) lab at TU Delft

After several years of research in the area of additive manufacturing, biofabrication, and additively manufactured biomaterials and implants, I finally put up the first version of the website of my lab. I will gradually improve the website, but there is already links to all publications coming out of my lab in the general area of AM.

 

How to contact between solid elements after cohesive elements failed?

      Hi, I have used langrangian framwork proposed by Needleman in 1994 to model materials' failure under compression. In this model cohesive elements were inserted along solid elements boundary.

keyhani's picture

For some educational purposes, I need a 2D Dislocation Dynamics Matlab Code.

For some educational purposes, I need a 2D Dislocation Dynamics Matlab Code. Where can I get it?

Simpleware case study: 3D FE Model of the Diabetic Neuropathic Foot

Diabetic foot represents a complication of diabetes that can lead to foot ulcers and other serious conditions. 3D Finite Element (FE) analysis enables dynamic characterisation of different loads within the foot.

Amir Abdollahi's picture

Constructive and Destructive Interplay between Piezoelectricity and Flexoelectricity in Flexural Sensors and Actuators

Flexoelectricity is an electromechanical effect coupling polarization to strain gradients. It fundamentally differs from piezoelectricity because of its size-dependence and symmetry. Flexoelectricity is generally perceived as a small effect noticeable only at the nanoscale. Since ferroelectric ceramics have a particularly high flexoelectric coefficient, however, it may play a significant role as piezoelectric transducers shrink to the sub-micrometer scale.

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