I made an FEA model in Abaqus 6.8 of a pre-curved Nitinol needle being pulled through a hollow steel cannula. I used beam elements to model the Nitinol needle and shell elements for the cannula. I used the Abaqus VUMAT subroutine ABQ_SUPER_ELASTIC_N1D as described in answer 1658 on the SIMULIA my support page for my Nitinol Model.
I am having several issues with the model. First, the straight portion of the needle was wobbly while being pulled through the needle. When I reduced the density it seemed to stabilize, but there is a significant amount of Plastic Dissipation (about 60% of the internal energy), even though neither the steel nor the nitinol model includes plasticity.
Please help me figure out why I am seeing plastic dissipation and how I can correct my model.
I am having several issues with the model. First, the straight portion of the needle was wobbly while being pulled through the needle. When I reduced the density it seemed to stabilize, but there is a significant amount of Plastic Dissipation (about 60% of the internal energy), even though neither the steel nor the nitinol model includes plasticity.
Please help me figure out why I am seeing plastic dissipation and how I can correct my model.