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PhD Dissertation Positions in Nanomechanics at Northwestern University

Submitted by Horacio Espinosa on

Description

Applications are invited for graduate studies within the Micro and Nano Mechanics Laboratory in the Department of Mechanical Engineering, Northwestern University.  The successful candidate will join a vibrant interdisciplinary research group and be involved in projects addressing atomic scale experimentation and modeling of advanced materials.  We seek motivated, talented and independent individuals interested in pursuing a PhD in one of the following areas:

•    Mechanics of Graphene and applications

PhD Dissertation Position in Dynamic Failure of Advanced Materials at Northwestern University

Submitted by Horacio Espinosa on

Description

Applications are invited for a research assistant position within the Micro and Nano Mechanics Laboratory in the Department of Mechanical Engineering, Northwestern University.  The successful candidate will join a vibrant interdisciplinary research group and be involved in projects addressing multiscale experimentation and modeling of advanced materials.  We seek a motivated, talented and independent individual interested in conducting research on the characterization of material instabilities and failure.

A theory of constrained swelling of a pH-sensitive hydrogel

Submitted by Cai Shengqiang on

Many engineering devices and natural phenomena involve gels that swell under the constraint of hard materials. The constraint causes a field of stress in a gel, and often makes the swelling inhomogeneous even when the gel reaches a state of equilibrium. To analyze inhomogeneous swelling of a pH-sensitive gel, we implement a finite element method in the commercial software ABAQUS.  The program is attached here.  Contact Shenqiang Cai (shqcai [at] gmail.com) for a description of the program.

Dear Omid and Sepehr

Submitted by Arash Zamani on

I think a non-zero entry in the stiffness matrix doesn't necessarily imply dependence of ith DOF on the jth DOF. This is the case also for standard FEM (without any enrichments). For example for a quadrilateral 2D element the x component of displacement has interaction with y component at each node, but as we know, two independent values of translation in x and y directions can

kinematic vs Isotropic hardening

Submitted by Vijay Kumar Sutrakar on

Hi

Isotropic hardening means, sigma_yield ll be same under both the tension (sigma_tension_yield) and compression loading(sigma_comp_yield). and the total sigma_y=sigma_tensio_yield+sigma_comp_yield.

In the case of isotropic hardening, If you increase the tensile yield strength by some means, at the same time your compressive stress ll also get increased. Hence, you get a increased radius of the yield surface. with the same shape with increased size of yield surface. and your total sigma_y ll no more remain constant. It ll get increased.

Some questions about wave propagation

Submitted by LG on

Dear Sir,

As we know, periodic signals are best analysed in the frequency domain while stochastic signals are usually more profitably analysed in the time domain. The analysis in the frequency domain usually concern only one signal while in the time domain often involves the comparison of several different signals.

1) what are the general methods for transforming the frequency domain into time domain, and which should be superior?

Isotropic hardening and kinematic hardening

Submitted by kajalschopra on

I've been trying to figure out difference between isotropic and kinematic hardening.

As I see,kinematic hardening can model reversible nbehaviour of metals (Bauschinger effect).

In isotropic hardening, the yield surface increase in size, but remain the same shape, as a result of plastic straining.

That is, if the yield surface is represented by a cylinder of radius "A" then an increase in the radius denotes an increase in the yield stress as a result of plastic straining.