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How to consider gravity in a dynamic analysis?

Submitted by Shuang Li on
Forums
Computational Mechanics Forum

This question may be a little simple. But it confuses me.....

In my case,the analysis is a time-history analysis of a structure under earthquake.

First, gravity analysis, and then, dynamic analysis with constant gravity load (stress and deformation obtained by dynamic analysis will superimpose on those obtained by gravity analysis). However, if the structure is damage, the superimposition is not rational.

1. the equilibrium equation is Mx''+Cx'+Kdx = -Ma - Mg -R or Mx''+Cx'+Kdx = -Ma -R ??

The Fundamental Physical Bases of the WR Approach (and, Consequently, of FEM) in General

Submitted by Ajit R. Jadhav on
FEM
physics
Weighted Residual
WR
physical bases

It has been quite some time (more than 1.5 years) that I had touched upon the topic of the physical bases of FEM in general, and of the general weighted residual (WR) approach in particular, at iMechanica (see here).

The position I then took was that there is no known physical basis at all for the WR approach---despite its loving portrayals in mathematical terms, or its popularity.

Journal Club Theme of February 2009: Finite Element Methods in Quantum Mechanics

Submitted by N. Sukumar on
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Journal Club Forum
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research
Free Tags
quantum mechanics
FEM
electronic structure
DFT

Welcome to the February 2009 issue. In this issue, we will discuss the use of finite elements (FEs) in quantum mechanics, with specific focus on the quantum-mechanical problem that arises in crystalline solids. We will consider the electronic structure theory based on the Kohn-Sham equations of density functional theory (KS-DFT): in real-space, Schrödinger and Poisson equations are solved in a parallelepiped unit cell with Bloch-periodic and periodic boundary conditions, respectively.

Why do we often use Jaumann rate instead of Truesdell rate?

Submitted by Rong Tian on
opinion

In the attachment, we show that Truesdell rate can by simplified to Green-Naghdi rate by assuming F .=. R and can be further simplified to Jaumann rate by assuming W .=. R(.)R(T), where .=. means approximately equal

In a stretch dominant deformation, the three rates give different stress rate. This is usually explained by that we need a different tangential modulus for different objective rate. However, it is hard to understand why we need to change "material" modulus when we use a different "mathematical" form of objective rate as they are all supposed to be equivalent.

Call for papers: a series of monograph in the field of engineering mechanics

Submitted by sunbohua on
research
Call for papers for Advances in Engineering Mechanics (AEM)
Advances in Engineering Mechanics (AEM)
a series of monograph in the field of engineering mechanics

published by Nova Science Publishers, Inc, 400 Oser Ave. Suite 1600, Hauppauge NY, 11788-3619, USA

Chief Editor: Prof. Bohua Sun
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