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VUMAT Error

Submitted by priyadd84 on

Hi all ... I did a simple one element elastic simulation of VUMAT and everything
(force balance) is fine.My aim is to change
young's modulus during runtime using strain rate data. So i want to
write VUMAT for the elastic model only and plastic model
(Drucker-Prager) and damage models i want to use the inbuilt one. But
when i tried to run *drucker prager along with my VUMAT i got the
following error.

The option *user material,type=mechanical completely
defines the material behavior. It can not be used with an option that

VUSDFLD + Error in connection to analysis

Submitted by priyadd84 on
Hi all ... Am trying to run a model with VUSDFLD+vgetvrm to get
strain components from the odb. But am getting an error "ERROR in job
messaging system: Error in connection to analysis". If someone can point out a
possible reason for this error, that may help me to resolve the issue.
Also if anybody is interested  in looking the problem more closely , I
am open to sending the source files. thank you.

Priya

State of hydrostatic stress along shear zone.

Submitted by priyadd84 on
research
Shear
Hydrostatic

Dear all,

          I did a three point bending test on a brittle rod. I observed an oblique fracture (slant approx 45 degrees). It can be an easy conclusion that this 45 deg crack is due to shear failure. But i have the following questions

1. Can a shear band  occur in  bending mode? as in literature very frequently shear bands are reported in pure tension and compression.

Slope of Contact force Vs time curve too steep.

Submitted by priyadd84 on
research
ABAQUS
contact

Dear all,

           I did a 3 pt bending impact simulation with an elasto plastic model. But the slope of contact force vs time curve is too steep at the beginning of the impact. One trivial way of reducing the slope is by reducing the young's modulus of elements in the vicinity of contact or the impactor. Also reducing the mass of the impactor and the impact velocity did not help in reducing the slope.

Is there any other non-trivial parameters that controls the slope of contact force vs time plot? Thanks ina dvance.

 

Prony series for viscoelasticity in Abaqus.

Submitted by priyadd84 on
research

Hi all,

     My first question is i have a set of stress Vs strain data for different strain rates (100/s to 350/s). Can prony series be extracted using these data? Or is there a way in Abaqus i can enter directly this data?

    After reading for a while a came to know that stress relaxation data is needed for defining pony series. My second question is can stress relaxation data can be obtained for high strain rates in the order of 100 to 350/s?

Thanks all 

 

Coupled Euler-Lagrangian FEA to simulate fluid entering micro pores in Abaqus/Explicit

Submitted by priyadd84 on
research
ABAQUS

Hi all,

         How to model a pipe which has pores in its internal surface, when the pipe is filled with water and closed at the both ends. Now when the pipe is impacted in the 3 point bending mode water will enter in side the pores and will cause some damping (resist bending).

Pros and Cons of element deletion in Abaqus

Submitted by priyadd84 on
research
Pros and Cons of element deletion in Abaqus

Hi all ... i have been doing element deletion extensively in my analysis but was wondering ... wat are the Pros and Cons of using this method. To my knowledge was wondering how the deleted mass and energy are conserved through out the analysis. Thank you all.

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