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:

Safaei, M., Lee, M.-G., & De Waele, W. (2015). Evaluation of stress integration algorithms for elastic–plastic constitutive models based on associated and non-associated flow rules. Computer Methods in Applied Mechanics and Engineering, 295, 414-445. doi: http://dx.doi.org/10.1016/j.cma.2015.07.014

Link: http://www.sciencedirect.com/science/article/pii/S0045782515002261

Hello,

I am running a simulation where I have a rigid body (shell elements) pushing into a deformable part. Unfortunately, the simulation aborts with the following error:

The dot product -0.19758 cannot be negative for element 30050 instance xzy with record ID 844 at step 2 inc 1 kitgen 5.

This element (C3D4H) belongs to the deformable part and is within the body, so no not close to the contact at all. At the point where the simulation aborts, this element is not deformed and the stress is basically 0 (E-6).

Has anyone an idea what the problem could be?

Thanks,
Andreas