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In 1D wave propagation problem, how to find the curl of a given source function?

Submitted by Sundaraelangov… on
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Computational Mechanics Forum
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I am trying to solve 1-D wave equation by calculating potentials ϕandψxϕandψx for displacement field ux=∇ϕ+∇×ψux=∇ϕ+∇×ψ. I am trying to decompose my source function fxfx (such that fx=∇b+∇×hxfx=∇b+∇×hx) in terms of potentials bandhxbandhx, using which I can can compute ϕandψxϕandψx. While decomposing source term fxfx, trying to calculate bandhxbandhx, I have a problem/confusion in finding the curlcurl of hxhx. Please see the manual hand-written picture attached here 

On Weingarten-Volterra defects

Submitted by Amit Acharya on
research
continuum mechanics
defects
disclinations
dislocations

Amit Acharya

(in Journal of Elasticity)

The kinematic theory of Weingarten-Volterra line defects is revisited, both at small and fi nite deformations. Existing results are clari fied and corrected as needed, and new results are obtained. The primary focus is to understand the relationship between the disclination strength and Burgers vector of deformations containing a Weingarten-Volterra defect corresponding to di fferent cut-surfaces.

Discussion of “Measuring and Understanding Contact Area at the Nanoscale: A Review” by Tevis D. B. Jacobs and Ashlie Martini

Submitted by Antonio Papangelo on
research
adhesion; contact mechanics; rough contact

M. Ciavarella(1) and A. Papangelo(2)

(1) Politecnico di BARI, Center of Excellence in Computational Mechanics, Deparment of Mechanics, Mathematics and Management. Viale Gentile 182. 70125 Bari (Italy)

(2) Hamburg University of Technology, Department of Mechanical Engineering, Am Schwarzenberg-Campus 1, 21073 Hamburg, Germany

michele.ciavarella [at] poliba.it, antonio.papangelo [at] poliba.it

How to Realize Volume Conservation During Finite Plastic Deformation

Submitted by Bin Liu on
research
Plasticity

Volume conservation during plastic deformation is the most important feature and should be realized in elastoplastic theories. However, it is found in this paper that an elastoplastic theory is not volume conserved if it improperly sets an arbitrary plastic strain rate tensor to be deviatoric. We discuss how to rigorously realize volume conservation in finite strain regime, especially when the unloading stress free configuration is not adopted in the elastoplastic theories.

Mechanical Reading of Ferroelectric Polarization

Submitted by Amir Abdollahi on
research

The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the polarization of a ferroelectric should not change its mechanical response. Strain gradients, however, introduce an additional source of asymmetry that has mechanical consequences.

Metallic and highly conducting two-dimensional atomic arrays of sulfur enabled by molybdenum disulfide nanotemplate

Submitted by Shuze Zhu on
research
2D materials

https://www.nature.com/articles/s41524-017-0041-z

Element sulfur in nature is an insulating solid. While it has been tested that one-dimensional sulfur chain is metallic and conducting, the investigation on two-dimensional sulfur remains elusive. We report that molybdenum disulfide layers are able to serve as the nanotemplate to facilitate the formation of two-dimensional sulfur.

Time Integration scheme for non constant M, C and K matrices?

Submitted by abbhuiya on
research
time integration

Can anyone suggest a time integration scheme for non constant mass (M), stiffness(K) and damping (C) matrices? I am trying to solve a dynamic system (Ma+Cv+Ku=R) where the matrices M,C and K are time dependent.

 

Any thoughts/ideas will be highly aprreciated. Thank you. 

Time integration scheme for XFEM? (dynamic crack propagation)

Submitted by abbhuiya on
research

Hello everyone,

 

Can somebody suggest an implicit/explicit time integration scheme when the matrices involved(M,C,K) are time dependent? (They change at every time step because of the crack tip enrichment functions which are time dependent).

 

I used the implicit Newmark scheme (trapezoidal/constant average acceleartion method) but just discovered that all my matrices (M,C,K) are time dependent where the original scheme is probably for constant M,C and K matrices. I used the scheme as in reference [1]. 

 

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