I have implemented a VUMAT code for definition of material constitutive equation. My code works very fine for one element but it does not work for more than one element. ABAQUS throws the Error: "Bad Material definition in element number 1 instance PART-1-1: zero or negative initial dilatational modulus caused by bad material data. Please check your material input and any initial conditions if necessary."
I really appreciate your help.
Ali
Fortunately, I could solve my problem. The problem was not choosing appropriate name for one of my variable and a problem in defining my iteration variable.
Hi Ali,
This error often shows that there is something wrong with your routine. Zero or negative dilatational (bulk) modulus practically means that your material will grow in size under hydrostatic pressure... Are you sure that the one-element results are correct even for complex load histories? Are you perhaps near incompressible material properties?
Regards,
George
Dear Goerge;
Thanks for the reply. I have checked the code for compression and simple shear mode for one element and my run completed to the end. However, I don't know how much reasonable is the answer.
Hi Ali,
I don't know what your code is doing, but the best practise is to compare your results with test results if available. If not, use engineering judgement and apply more complicated load histories (e.g. biaxial tension). Also try to "push the code to its limit" where things might get unstable. A failure is helpful for understanding what can be wrong.
Regards,
George
Fortunately, I could solve my problem. The problem was not choosing appropriate name for one of my variable and a problem in defining my iteration variable.
Hi Ali,
I have same problem, Could you please explain it, how did you solve your problem?
Regards,
Mehdi
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