In the literature, FEM has sometimes been characterized as a local approach, but IMO this needs to be corrected.
The piecewise continuous trial-functions of FEM can be looked at from two different viewpoints:
Last fall, Elsevier launched SciTopics. It is a web site devoted to providing research summaries of current topics by experts, allowing for public interaction through comments. Anyone can become a member and post comments, or request to author a page.
In many ways, it resembles iMechanica. Authors pen SciTopic pages in their area of expertise. SciTopics leverages Scirus , which is Elsevier's free, science-specific search engine.
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 ??
I am writing user-defined element using ANSYS. Are any general guidelines available? Kindly help me.
Subramanian
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.
My question is how we can predict the crack growth rate and direction for a structure under cyclic loading in such a way that both plasticity and creep has been built in it.
Journal of Mechanics and MEMS, Published by Serials Publications, http://www.serialspublications.com/journal_form.asp?jid=286&jtype=1
Editor-in-Chief
Prof. Bohua Sun
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.
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.
