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***ERROR: Bad Material definition: Zero or negative initial dilatational modulus caused by bad material data. Please check your.



I'm conducting hypoplastic VUMAT model in abaqus. It always has the following problem. 

***ERROR: Bad Material definition in element number 1: zero or negative
initial dilatational modulus caused by bad material data. Please
check your material input and any initial conditions if necessary.

hossein_r's picture

How to create a threaded bolt in Abaqus or ansys

Hi everone

I want to molel an implant. I want to create a bolt in Ansys or abaqus. but I cant create its threades. can you help me ?


IOSO Optimization Presentation Video Shots

Dear Colleagues,

We are going to demonstrate the possibilities of IOSO Design Optimization Software. Very quick video shots. Just take a glance at it.


Optimization of 3D serpentine cooling passage in turbine blade. 42 design
variables in total.

Abaqus: How to lower the stiffness linear curve of load vs deflection of concrete slab

Dear all,

Iam modelling a simply supported RC slab with Abaqus using Concrete Damaged Plasticity subjected to a concentrated load at the top surface of the slab. I have used element type C3D8R for concrete and truss elements to represent steel bars.


I found the result of FEM showed that the linear part of load versus deflection, i.e. from zero load up to yield load shows a very stiff curve compare to the experimental test results.


Methodology of simulation post-processing for metal parts in Abaqus

I mesh most of my parts in C3D8R. My simulation are quasi-static, and involve a lot of contacts. To model steel, I use a classic elastic-plastic behavior, coming from stress-strain curves we measured. I have the yield strength of the material and the strain at break. My questions concern post-processing.

Hot embossing in ANSYS

dear all,


Finally i found out the way to simulate PMMA embossing using Mooney Revlin constants at several tempature. Now i am trying to include Prony model and shift function with Hyperelastic model in ansys. I tried using static and transient analysis but it is not giving viscoelastic flow behaviour. If anyone done this kind of simulation in Ansys please help me. I am sending mooney revlin and prony model constants in ansys WB.

 To be included in command file.. 



Variables definition in Abaqus


I am working on a 3D contact problem where a spherical part is pressed against another spherical surface. I was wondering what variables may be interesting to study for this problem. I decided to look at the contact area CAREA, the contact pressure CPRESS and the stress S but I am not able to find how Abaqus defines and calculates these variables, does anyone know?


about using hashin criteria in abaqus

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Dear all, Hi

An Introduction to ATOM: Nonlinear Structural Optimization for Improved, Rapid Product Design (FREE WEBINAR)

Register for this FREE webinar to learn how the Abaqus Topology Optimization Module (ATOM), from Dassault Systemes SIMULIA, delivers advanced capabilities for nonlinear structural optimization and provides important benefits to engineers and product designers by identifying the optimized topology and shape of a structure.

For more information, visit:, or -> events -> webinars.

How to achieve creep crack growth in the ABAQUS

Recently, I have worked on the creep crack growth coupled with CDM. In the references, it says that when the element reached to the critical damage, the E of the element was reduced to 0. However, when I used this method in my UMAT, it can achieved creep crack growth in some elements. As the number of damaged elements increases, the damaged eelments distorted too large,as shown in attachment. Therefore, the calculation is stoped.

Does anyone know how to resolove this problem.


HussamNasreddin's picture

Plain concrete failure

Hello all,


I am trying to model concrete as an elastic material in ABAQUS. The model can be any simple structure (cube, beam or column) but the main feature is that concrete behaviour is elastic up to a limiting strain (St. Venant's theory). Which of the  Failure criteria in ABAQUS i should be using (Elasticity or brittle cracking)? if neither would you mind explaining other options?





New release now available for the Mimics Innovation Suite

Leuven,Belgium, May 31, 2011. Materialise is proud to announce the newest release of the Mimics Innovation Suite. The software solution, already renowned for being the fastest  and easiest method for getting accurate 3D surface models from imaging data, is now faster and more user-friendly than ever. An example of the improved features is that several

nonuniform load in abaqus


Iwant to know if there is any other way except user subroutine for applying nonuniform load in a 2 dimesional abaqus model.


How to simulate compaction process of powder mettalurgy in Abaqus?

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I am doing ph.d work related to powder mettalurgy 

I want to simulate the compaction process ( in powder mettalurgy) by using ABAQUS.It is very essential to find a way to create a model which will behave as such as PM part.

Simple Cell Traction Force Script for Elastic Micropatterned Substrata

Hi readers, 

 This is MATLAB code that was written by myself and collaborators that we've sought to make available to the wider research community. The program is intended to track the displacements of micropatterned dots on a substrate in a similar manner to that performed by  Maloney et al. in "Influence of Finite Thickness on cellular adhesion-induced deformation of an compliant substrata". Physical Review E. 2008.

sweep mesh of a dome in ANSYS

I am dealing with a partial sphere dome in ANSYS, I created the volume by extruding half of an arch area along the axis at the dome center. I am using SOLID65 elements. The problem I am facing now is how to properly sweep mesh the whole volume ( actually, there are four 90 degree partial sphere together after the extrude of the area), because if I simply sweep the volume, the elements around the top center of the sphere will cause element shape warning in the static analysis.

Dose anyone have any idea about how to deal with the mesh around the center? 

Looking for detail process for creating aircraft wing with given airfoil co-ordinate using CATIA V5 R18 Software



 I am looking for detail process to create aircraft wing with given airfoil co-ordinate(*.txt) file using CATIA V5 R18 software. If anyone know then please email me your method.


 Thanks in advance. 

  Bhavin Patel



Output of ABAQUS for contact of a rigid surface with a poroelastic layer

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Hello, I am modeling the spherical indentation of a poroelastic layer. I am modeling the indenter as a rigid analytical surface. As you know, the total pressure in a porous medium at each point is the sum of the elastic stresses from the matrix, and the pore pressure caused by fluid pressurization. Abaqus provides both the pore pressure and of course the rest of the stress quantities.

Johannes T.B. Overvelde's picture

Abaqus Script Manual/Tutorial

I have written a introduction manual/tutorial on Abaqus Scripting. I got some good feedback from my colleagues. Therefore, I would like to share the manual.The manual should give a short introduction (it will not take more than one hour) to Abaqus script in Python.

You can find the manual here:

Abaqus Script Manual

Via the same link you can also find more information on the connection between Matlab and Abaqus

Good luck!

Defining density as a solution dependent variable in VUMAT (Abaqus/Explicit)?

Hi All,

I am trying to simulate tooth deformation. It involves that the density of tooth changes with deformation. I want to know is it possible to define density as a solution dependent variable in VUMAT?

 Thank you in advance!


Simulation of wave propagation in ABAQUS/CAE

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Hi, I am working on modeling wave propagation in ABAQUS/CAE.

I am not expert on ABAQUS and trying to figure out how it works.

I have a 2D Shell steel plate (1 centimeter by 1 centimeter) and try to obtain wave speed at any points of plate.

I put the material properties in and used ABAQUS/Explicit analysis.

Time steps are 1E-009 seconds and there are 2 steps (impulsed at the first step and propagates at the second step).

The load pluged at the amplitude with equaily spaced for 0.1 micro seconds (so it becomes impulse load).

ABAQUS CAE specialist please help

Hello every,

I am trying to create the model in ABAQUS CAE with cohesive elements. I try a simple 2D case.I did the following

1. i create two parts a) rectagular part

                              b) a line whick suppose to be cohesie elements later

2. I create two materials , elastic and cohesive

 Then i create to sections Solid section and cohesive section

When i make section assignment for solid part it is ok, i see the material, but when i make section assignment to the cohesive part, no section name apears in the window.

orthotropic nonlinear viscoelasticity/creep in Ansys


 I would like to know if there is any chance to simulate orthotropic nonlinear viscoelasticity/creep of CFRP in ANSYS (e.g. by means of user programmable features (UMAT subroutines) or using the software DIGIMAT or others)? For the nonlinear part I would like to use Schapery's method.

 Many thanks for yor help!



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