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ABAQUS: Access stress of integration point of elements during calculation

Submitted by Linhbkxd on Thu, 02/16/2017 - 04:28

Hi all,

I'm using ABAQUS and UMAT for structural simulation. I used quadratic element (CPS4) with 4 integration points (IP).

During the calculation (which calling my UMAT), at each time step, for each element, I need to calculate the average stress of these IPs and produce a state variable for these IPs from this average stress. Then, I would need to update this state variable back to these IPs in that element. But as far as I know, the ABAQUS call UMAT for every IP and calculate everything within this current IP.

Prony series with temperature dependent stiffness

Submitted by augustus on Tue, 02/14/2017 - 21:31

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linear viscoelasticity

thermoviscoelasticity

Hello,

I have implemented a viscoelastic model (Simo/Hughes approach: Prony series for small strain)

in Abaqus using Umat and it works fine for dynamic isothermal simulations (I validated with the Prony series implemented in Abaqus).

Now, I want to consider thermal loads (I have temperature dependent stiffnesses from a DMA experiment).

How should I use these temperature dependent stiffnesses in the model?

On a systematic approach for cracked rotating shaft study: breathing mechanism, dynamics and instability

Submitted by saberelarem on Sun, 02/12/2017 - 14:44

Nonlinear dynamic analysis

We present a systematic approach to deal with the modelling and analysis of the cracked rotating shafts behaviour. We begin by revisiting

the problem of modelling the breathing mechanism of the crack. Here we consider an original approach based on the form we give to the energy of the system and then identify

the mechanism parameters using 3D computations with unilateral contact conditions on the crack lips. A dimensionless flexibility is identified which makes the application

Drucker Prager Plasticity model

Submitted by setareh on Sat, 02/11/2017 - 23:24

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Drucker Prager

Plasticity

Hi All,

I am trying to code the Drucker prager plasticity model for the 2D plane strain case using consistent tangent modulus. I am using C++, therefore I would appreciate if anyone could share relevant materials which I could use and preferrably for the 2D case so it is not unnecessarily complicated.

3D Printing Grand Challenge

Submitted by Mike Ciavarella on Fri, 02/10/2017 - 15:26

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3D printing

Abstract Submission Extended to March 1st 2017

Issues with the implementation of Strain gradient plasticity framework of Niordson and Hutchinson (2003) in ABAQUS UEL

Submitted by Suman.Guha on Thu, 02/09/2017 - 05:33

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strain gradient plasticity

Abaqus User element UEL

I have implemented the rate-independent strain gradient plasticity framework of Niordson and Hutchinson (2003) in UEL. I was able to validate the results of the shear of infinitely wide thin layer between two rigid surfaces (Niordson and Hutchinson, 2003). However, the UEL subroutine fails to converge for the more complex problem of the shear of finite width slab. I suspect the convergence issues are arising out of internal elastic-plastic boundary conditions and the yield criteria. I have few doubts in this regard.

Call for Abstract Submission to the USNCCM14: Modeling Materials with Coupled Physics

Submitted by sergkuznet on Tue, 02/07/2017 - 18:15

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Dear Colleagues:

The 14th U.S. National Congress on Computational Mechanics (USNCCM14) will be held at the Palais des Congrès de Montréal, QC, Canada, July 17-20, 2017 (http://14.usnccm.org/).

As a part of this meeting, we are organizing a mini-symposium to address recent advances in Modeling Materials with Coupled Physics (http://14.usnccm.org/MS709). Topics of particular interest include (but not limited to)

“Deflecting elastic prism” and unidirectional localisation for waves in chiral elastic systems

Submitted by Giorgio Carta on Tue, 02/07/2017 - 15:41

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elastic wave propagation

For the first time, a design of a “deflecting elastic prism” is proposed and implemented for waves in a chiral medium. A novel model of an elastic lattice connected to a non-uniform system of gyroscopic spinners is designed to create a unidirectional wave pattern, which can be diverted by modifying the arrangement of the spinners within the medium.