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New publication for UMAT and VUMAT in ABAQUS

We performed a comprehensive study of a large class of Implicit and Explicit integration algorithms for Elastic-Plastic behaviors in Finite Element Analysis (FEA) developed in UMAT and VUMAT for ABAQUS and presented various unique results. We also showed detailed integration algorithms for both Associated and Non-Associated Flow Rules with mixed isotropic and kimenatic hardening with expandable number of internal variables (damage and etc).

Full bibliographic details:

User subroutine for Calculix explicit

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I want to use Calculix explicit for large deformation problem. I want to use a user subroutine similar to vuhard (in ABAQUS) to model the material behaviour. Calculix documentation metions uhardening, but there is nothing similiar to vuhard.

Is there a way to do this?

Recover wall clock time in Abaqus/Explicit

Dear All,

Does Anybody know how to recover the wall clock time of an Abaqus/explicit analysis? I do not understand why for implicit analyses is easy (log file) while for explicit there is no information.

Thank you,


explicit analysis critical time-step Ansys


 I am trying to solve a simple cantilever beam (2D)  in ansys.

I wish to find out the critical time-step that can be used to explicitly solve a transient problem. 


I started with modal analysis to determine the maximum natural frequency of the model. I then computed dt < 2/Wmax.

I use this dt with beta = 0.0 and gamma = 0.25 (Newmark parameters). However the solution is unstable.

I am including my apdl script with this post.

Electric Potential B.C. in the Dynamic/Explicit Step

Hey all,

I am trying to apply an Electric Potential B.C. to a surface. I want to use the dynamic/explicit analysis type, however, when I select that as my step type, the Electric Potential B.C. option disappears from the edit B.C. window! Is that due to a license limitation or an error I might have made in one of the definitions?

Thank you!

Newmark scheme beta and gamma parameters

Concerning the Newmark method with central difference for an explicit resolution I want to know where the parameters beta and gamma come from ?

I have found this :
but how do these parameters appear ?

Using RADIOSS, the theory manual says the remainder of the taylor's series is computed using numerical integration but I don't know which rule is used.

manz_0's picture

Cylinder inflation using Abaqus

Hi All,

 I am trying to model the inflation of an enclosed elastic cylinder. The only example I have came close to in the Abaqus support documentation is the air bag inflation test. However, even reading the documentation, I am still unsure on how to model the airbag before an inflation force is applied. Can someone help me with this? You can also e-mail directly:

Any help would be much appreciated and thanks all for your time to look at this post :) 

Manaliac's picture

Plywood box under pressure on ABAqus


Hello everyone,


I am working right now on a plywood box simply supported by wedges under a uniform pressure of 1 MPa.

The pressure is applicated through a rigid shell part layed on the top of the box ( a surface to surface contact). The bottom of the box is on contact (surface to surface) with the rigid shell wedges (2 on the corner of the box and 1 on the middle).  

As a boundary condition, all the DOF's of the wedges are constrained.    

ADINA: Automatic Dynamic Incremental Nonlinear Analysis

The ADINA System offers comprehensive capabilities for linear and nonlinear finite element analysis of solids & structures, CFD, fluid-structure interactions, multiphysics, and complete pre- and post-processing with interfaces to various CAD and CAE systems. It also offers user subroutines for material models, elements, loads...

Abaqus, bridge-truck analysis.... help

Hi everyone!

I need advice, I have to carry out a bridge-truck interaction analysis in ABAQUS FOR CATIA. I don´t know where I can start, the thing is that now I´m going to try doing it, in a simplified model in order to don´t loose time.

Can you help me? Can you give me some advices? how to model de truck? I need more or less precission on the bridge not in the truck. I know how to modelice the bridge, the type of element, the meshing, the connectors... but what I don´t know is how to manage Explicit,

Ansys Ls-Dyna

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I am using
Ansys Ls-Dyna to solve a case where a rigid indentor in the shape of bow
penetrates double skinned structural models. I want to use UPF (User
Programmable Features)
in order to define a custom failure criterion. From the “Guide
to Ansys User Programmable Features” I read that the specific subroutine (usrfc6)
for defining custom failure criteria is available only with shell99, solid46
and shell91
. However in Ansys Ls-Dyna, the user cannot use neither of the above
shell elements. The only shell element that is used in explicit dynamics is
shell163. Is there any way to program or use my failure criterion in Ansys

Implicit Vs Explicit

Dear Sir,

             1.  In FEM, I have not understood the exact difference between Implicit and Explicit techniques, though I have used both type of solvers.... Can u pls help me out in this?

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