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Weak form

During the study of FEM, I found the term "weak form" of differential equation, which is the integral form of a differential equation along with the boundary conditions for a boundary value problem. Now my question is that why the term "weak" has been used.

Jayadeep U. B.'s picture

Continuum mechanics, Micromechanics and Nanomechanics

Hi all,

Can anyone explain me the characteristic features of continuum mechanics, micromechanics and nanomechanics?  My present level of understanding is:

Meshing Solid46 in ANSYS

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how do I Determine Z axis ( blue axis ) of the element coordinate ( with solid46 ) in  outward Direction .

in Attached file put the cross section of the Model .


Cai Shengqiang's picture

Poroelasticity and diffusion in elastic solids

These are slides of poroelasticity and diffusion in elastic solids for final presentation based on ES241 notes.

Yuhang Hu's picture

advanced elasticity 2009 slides (polyelectrolyte gels)

These slides are based on an on-going paper written by Wei Hong, Xuanhe Zhao and Zhigang Suo and Suo's talk in ucsb.

2 Questions about VUHARD and VUMAT

I am trying to implement an analytic formulae of dynamic flow stress in material plasticity in abaqus. The model is similar to FlowStress=K*(PlasticStrain^n)*(StrainRate^m). 

Could you provide help for these 2 questions?

1: Is it OK to define Young's modulus (E) and v in "Elastic" and choose "User" in "Plastic-->Hardening" with the subroutine "VUHARD", instead of by "VUMAT" with plasticity criterion and calculation of delta stress and strain?

cracked rotor


can i find natural frequencies of cracked rotating shaft in ansys.i am using contact elements to model crack due to which nonlinearity comes into picture.since modal and harmonic analysis cannot solve nonlinear problems,so please tell me in detail the steps to find natural frequency .

my project submission date is on 15th june and i have no results.pls reply as soon as possible

it will be yr great help.

thanks in advance


iit roorkee

Zhigang Suo's picture

A course on Advanced Elasticity, with emphasis on thermodynamics and soft active materials

In the field of Solid Mechanics, Harvard has a sequence of 5 graduate courses:

The first course goes over linear elasticity, finite element method, vibration, waves, viscoelasticity, as well as some ideas of finite deformation.

hyperelastic model

I am wondering a problem slove by ogden hyperelastic model.

Stroh formulation

I want to know about the basics of stroh fromulation and its application in Piezoelectric material.I didn't find the basic lecture notes or the material regarding that on the internet.

kuldeep sharma 

chepatilio's picture

Heat Simulation and Analysis of a Railway tunnel

hello eve1,

i m facing some problem while trying to mesh a horse shoe type structure,  when i define the element type as solid 8 node 70 (brick8 node 70) it gives me error saying cannot apply coz it violaets the ASME code or some hting like that....plz help me out wiht what element type has to be defined for the HORSE SHOE type structure...............or whether to define the semi-circular portion seperately (with wat typr ) and the bottom portion seprate.

Strain Based Fracture Mechanics


I`m new to this webpage, and hope for some good answers for use in my masters degree within fatigue. Currently I`m working on calculating the total life of a gusset specimen using strain based fracture mecahnics. I`ve read som articles on the topic, but have some difficulties on understanding the calculations itself. I`m using Excel in the calculations. If anyone has an excel-sheet, or other ways of helping me, I would hihgly appreciate it.

Thanks, Sean Angus

Flow Rate through a gas pipe

Hi I'm trying to work out the following problem

The pressure at the start of a 180Km stainless steel natural gas pipeline is 4MPa and at the end is 2MPa.  If the diameter of the pipe is 0.4m, what will be the gas flow rate through the system? (ignore losses other than friction)

(for natural gas, density = 40 Kg/m3, viscosity = 11x10-6)

This is from an exam paper and at the end of the paper there's a moody diagram with roughness values, the closest to stainless steel is commercial steel and has a k value of 0.045 mm.

how to use subroutines in abaqus

I will be highly grateful if u will say me how to link subroutines with abaqus....... intel fortran compiler is there.......... how to proceed now????????

I want to choose a book on Tensor Analysis

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Tensor analysis is a very useful tool for continuum mechanics as well as other courses. I wonder which book is best for me. 

I have background of anvanced mathematics, linear algebra.  The book should be comprehensible.

Implicit and Explicit finite element method

i am not clear about implicit and explicit FEM
kindly let me know the difference of two and where to use which one

Help modeling a viscoelastic material in Abaqus

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I'm trying to model indentation of a viscoelastic material in Abaqus.

I have (1) stress-relaxation curves for the material and (2) force-displacement curves for the material from a real indentation experiment.

From this I can readily calculate the elastic modulus (infinite) and the elastic modulus (instantaneous) for the material.

I'd like to fit a Prony series based on this data that I can enter into Abaqus to model the material.

How would I go about fitting the Prony series from the force-displacement and stress-relaxation curves?

ravi-talawar's picture

Modal Frequencies

Hi All

How to find the modal frequencies of a wind turbine blade,

-Ravi Talawar

how to show the stress in the thickness direction when you use the shell element with abaqus


  •      i simulate some process using shell elment, i find the results have big difference between abaqus and lsdyna. the abaqus results always show the stress in the thickness direction is zero. but the lsdyna is not. i don't know why? if some one know that, please give me some suggestions. i heard that the abaqus can not show that stress component. if not, how can i do to calculate that and fill it into the results file (.fil file). thank you!


Problem with my Abaqus Double Layer Composite Identation Simulation

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Hi everyone,


I currently using Abaqus/CAE 6.8. I currently doing my final year
project about indentation test on double layer composite material. The
top layer of the material is Pasta (elastic) and bottom layer is Gel
(hyperelastic). I manage to simulate the model and completed the
process. The stress of the Gel does not change as it undergoes
deformation. As shown in the clip i attached. Any idea to solve this
problem? Any suggestion is welcomed.. Thanks

Right click the indentation.jpg and save target as....

Impact analysis of bus body-ansys ls dyna

I am a  B.Tech student at VIT.Presently doing a project on Impact analysis of Bus body using ansys ls dyna.I am getting many errors.If any one is having complete tuturial about above topic, pls send it to me.



I am facing some problem in ABAQUS. How can i use Vumat subroutine and how can i findout sresses.Please help me

Nonlinear Analysis

Hello,In order to nurture you in an effective manner regarding the Newton-Raphson method I recommend you to consult the excellent treatise of I. M. Smith et al. entitled "Numerical Methods for Engineers ", ISBN-13: 9781584884019.Furthermore this method is elegantly elaborated in Finite Element Formulation in the outstanding book of I. M.

Detonation &knocking

 hello dosto,

               i am studying in B-tech 2nd year (mech.) in DCE . I want to know  about detonation and knocking of fuels in detail.

thank you

shankar Gupta

Elementary Mechanics and Basic Engineering Thermodynamics

I suppose it is acceptable to announce the work I have online to assist students in learning mechanics and thermo.  The site is  Please take a look if you are interested.


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