ABAQUS SPRINC Function Question


I am writing a UMAT in ABAQUS and I would like to obtain the eigenvalues of a matrix (it is the left Cauchy-Green matrix used for hyperelastic formulations, to be specific.) I know that this is a strain matrix, and the documentation for ABAQUS 6.12 says to call the SPRINC function, which runs fine, but what I am confused about is: why one would need to specify whether the input matrix to that function is a stress or a strain matrix? I tried specifying it as a either type of matrix, and it outputs different results for those two cases. What I want to know is, what is different about the way that ABAQUS calculates the eigenvalues in those two cases. I would appreciate it if someone out there knows and could tell me. Thanks!



how transform umat to vumat

please if some one can help i want to transform this umat to vumat ( see file attachements)


how transform umat to vumat

please if somme one can help me i want to transform this umat to vumat

modelling and analysing the laminated composite using ansys

I want to do research work in analysing composite using the ansys or similar software.I want to get the details regarding modelling the laminated composites.

And also details regarding  analsing the properties of composite for cyclic load,fatique load,and torsion.

which ansys version is suitable



Robert Lipton's picture

Dynamic Brittle Fracture as a Small Horizon Limit of Peridynamics

Overview: The peridynamic formulation is a
spatially nonlocal derivative free model for simulating problems of free crack
propagation.Material points interact through short-range forces and the
formulation allows for discontinuous deformations. Here the short-range forces
are initially elastic and soften beyond a critical relative displacement. We
upscale this peridynamic model to find the macroscopic (a.k.a. small horizon)
limit. It is shown that the limiting macroscopic evolution has bounded energy
given by the bulk and surface energies of brittle fracture mechanics. The
macroscopic evolution corresponds to the simultaneous evolution
of the fracture surface and linear elastic displacement away from the crack

Curvature effect on nitinol aortic stent

high i am a student doing a project on curvature effect on thoracic stent. I want to curve the nitinol stent in abaqus. I am using RSURFU and doing static analysis. But am not able to curve it. Also when using implicit dynamic analysis with quasi static apllication my KE is high and comparable to IE. So can any body help me. Crimping and expansion is not a problem.


J integrale evalution on Abaqus

Good mourning, i am using Abaqus software to inverstigate a crack propagation problem using Abaqus, in this regards i have created a seam crack iner the geometrie which is a plate  under a plane stress condition, my problem is how to mesh around the crack tip in order to have a regular mesh around the crack tip so i can evaluate J integral for multiple contours, the Abaqus documentation mention the swept meshing technique but i coudn't find something about a 2D problem since the sweapt meshing technique nead to mesh a section and swept it over the rest of the body, and in 2d problem we have eages, so how to use it 'some basics rules' in order to creat a regular mesh around the crack tip, i am waiting for any answer from you guys, thank you

ABAQUS Post processing

I have modeled a pile which was made to penetrate at a constant rate (Displacement controlled loading) into the soil. The steps were divided into geostatic, contact and Applied load steps. After the program runs successfully, i am facing difficulty in extracting the results.

 I want to plot the load vs. displacement curve at the bottom of the pile.  After i have summed up all the nodal forces at the bottom of the pile, the total load was coming quite less as compared to the applied Load/Displacement.

Kindly suggest me, how to compute the Load vs.  Displacement curve from displacement controlled loading at pile base.


Thanking you,

Tanmoy Kr. Deb

ABAQUS Analysis

How to differentiate between the analysis of a "hollow pile with closed top and an open end" with "vented top and open ended pile".


After applying compressive load at both the pile tops (closed and vented), i have obtained/observed that the vented pile is offering higher resistance to penetration as compared to closed top pile.


 The sequence of steps i have followed are Geostatic, Contact and Compressive loading respectively. How to Model/Analyze the hollow pile with vented top so that it offers lesser resistance as compared to hollow pile with Closed top.


Ansys Mechanical: Anisotropic Hyperelasticity Material Model

I am currently researching the
fluid-structure interaction (FSI) of fistula and av-grafts in the region
of the brachial artery in dialysis patients. I will be using ANSYS
Mechanical and FLUENT as the coupling offered is strong/implicit which
is necessary for my model. I'm having some trouble implementing the
anisotropic hyperelastic material model for the artery. This material is
in the 'Special Hyperelastic Materials' section and thus needs to be
inputed through command snippets. I get a solution, but it is not behaving as it should because my command snippet material is being ignored..

My issues are the following:

Stochastic modeling of damage evolution in composites under environmental ageing

Stochastic modeling of damage evolution in composites under environmental ageing

R. Rahman, A. Haque, Z. Wu

Journal of Engineering Mathematics

April 2013, Volume 79, Issue 1, pp 153-166


Daniel Kiener's picture

Detwinning in full view: Twins, seen as dark areas in the left image, disappear upon tensile loading (right image).

Detwinning in full view: Twins, seen as dark areas in the left image, disappear upon tensile loading (right image).

Reversible cyclic deformation mechanism of gold nanowires by twinning–detwinning transition evidenced from in situ TEM

Micromechanics of Composites


Can somebody suggest me a good book for micromechanical modeling of composites?


Abrasive Simulation


I'm trying to do simulation on Abrasive sand paper. I want to calculate the amount of material removed from the workpiece after some  number cycles.

 Can any one help me how can I start this simulation in abaqus.



ABQ Python Scripting to create mesh definition without geometry

Dear iMecanica community,

with ABQ I'd like to create a mesh part without an associated geometry using the bottom-up-technique.

I already found the Python commands to add nodes to an orphaned mesh (from an inp-file).

In order to this I must first import an existing part and make node definitions on the orphan mesh part.

Is there a way in ABQ to define nodes, elements, etc. directly using scripting commands without

creating an orphan mesh part (by importing a model)?

I would be glad for any help, thank you very much in advance!



ICE's Engineering and Computational Mechanics general call for papers!

Dear Colleague,

Engineering and Computational Mechanics is currently looking for papers on the theme of Disaster and Hazard engineering for publication in 2014. Sub-topics include risk analysis and pre-emptive disasters.

Other themes EACM is interested in are: Fluid Structure interaction especially ringing phenomenon; Energy and renewable energy including offshore and waves; and review papers covering the themes in the call for papers.

If you are interested in submitting a paper, please see the call for papers via the link below:

If you have any questions, please do not hesitate to contact me.

AndreaBergamini's picture

Phononic crystal with adaptive connectivity: A new approach to 'smart' materials

In recent times, mechanical metamaterials and a phononic crystals have attracted the attention of some groups, as they allow to exploit on a larger scale phenomena known from solid state physics, such as the creation of band gaps at certain frequencies. The peculiarity of metamaterials is that their effective properties emerge from the periodic geometric organization of their unit cells rather than from the constituting bulk materials. Furthermore, metamaterials can be built in any size, ranging from the nanometer to the meter scale, and out of any material to suit different needs.

Konstantin Volokh's picture

Navier-Stokes model with viscous strength

In the laminar mode interactions
among molecules generate friction between layers of water that slide with
respect to each other. This friction triggers the shear stress, which is
traditionally presumed to be linearly proportional to the velocity gradient.
The proportionality coefficient characterizes the viscosity of water. Remarkably,
the standard Navier-Stokes model surmises that materials never fail – the transition
to turbulence can only be triggered by some kinematic instability of the flow. This
premise is probably the reason why the Navier-Stokes theory fails to explain

Payam Soltani's picture

Effect of geometric parameters on the stress distribution in Al 2024-T3 single-lap bolted joints- Outstanding Paper Award Winner

 The article entitled “Effect of geometric parameters on the stress distribution in Al 2024-T3 single-lap bolted joints” published in International Journal of Structural Integrity 

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