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FEA Improves Reliability of Flip-Chip Packaging

Submitted by Zhen Zhang on
industry
reliability
FEA
flip-chip

On Aug 10, 2009, Semiconductor International (SI) Newsbreak published a report on my work in AMD about 3D fracture study of underfill delamination as the top story in that issue.  I have never imagined that. Except the pleasure I received from this good news, I wonder if this work is also interesting to iMechanica community.  For that reason, I attach here the SI news report and the original paper published on ITherm2008 Proceedings. Welcome any comments and thoughts.

 

PhD Dissertation Positions in Nanomechanics at Northwestern University

Submitted by Horacio Espinosa on
job
nanomechanics
Nanoscale properties

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
job

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
research
suo group research
hydrogel
gel

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
research
xfem

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
Forums
Computational Mechanics Forum

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.

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