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Mismatch between built-in linear-elastic material behaviour and tutorial VUMAT in ABQ/Explicit using truss elements
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Hello dear all,
for my master's thesis I'd like to write a simple VUMAT for a material with nearly zero compression stiffness.
So for a better understanding of VUMAT subroutines I did the ABQ tutorial for a VUMAT with isotropic, isothermal elastic material behaviour and compared the results with the built-in material definition.
There is a discrepancy of almost 35% of the S11 stress. ABQ Manual says that both times the Green-Naghdi stress-rate formulation is used.
beam-column joint
finish
/clear
/title,study of beam-column joint
/prep7
! define element type & real constants
ET,1,link8 ! element type 1
R,1,0.000153938 ! real constant 1
R,2,5.02654e-005 ! real constant 2
ET,2,solid65 ! element type 2
R,3 ! real constant 3
ET,3,solid45 ! element type 3
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Faculty Positions
Mechanical Engineering
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opprecunity study
I am a Vahid Reza Hosseini PHD student in China. My major is mechanic and I am working on fractions and mesh method and meshless method. I have been looking for opprecunity study for 6 months or more. If you have a position for me,please let me know
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Email: V.r.hosseini [at] gmail.com
Educational iPad app on structural mechanics
I would like to share with fellow mechanicians an educational iPad app I recently developed. The name of the app is Truss Me! and the main goal is to help students, all the way from high school to college, to build intuition on how truss structures behave. The video below highlights some features of the app:
The app utilizes state of the art simulation techniques to provide the most realistic behavior for the structures.
How to get the update the local material coordinate in large deformation for hyperelasitc rubber-like materials?
Hello,
I want to ask things about the updation of local material coordinate in large deformation.
Does there exist two ways for this?
1. Polar decomposition of Gradient Deformation Tensor F to get the rotation tensor.
2. Update each basis vector of local material coordinate system using modified Gradient Deformation Tensor F_bar = F*J^(-1/3).
What I cared about is the second method, is the second method available?
Wish someone could help me, : ). Thanks!!
Compatibility: Surface-Based Cohesive Behavior in UEL
Hi all,
I have been trying to model the surface interaction between two blocks of material using surface-based cohesive elements (*cohesive behavior). This works well in ABAQUS CAE (standard) when I set the material properties as "Mechanical, Elastic" so no problem with that.
However, I would now like to use the material properties from a fortran code. To do this, I was planning on defining the elements using *UEL with an overlay to record all the values. Is this compatible with cohesive zone elements?
Questions about tensors and matrices
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Hello,
I am having questions with tensors. I know that not all matrices are tensor. Tensor is a homogeneous, linear and vector valued function. So my questions are:
- Are all 3*3 matrices tensors?
- Are all anisymmetric second order tensors orthogonal?
Thanks.
Stresses interpretation in ABAQUS
Hi,
I am doing the beam tutorial in ABAQUS and I get the mises stress output as given in the tutorial document (ABAQUS manual appendix B).
I am trying to understand the S11, S22 and S33 outputs from this model. The document I am using for my steps are attached. Couldn't attach my .cae file here.