Learning Forum

[Tuan Nguyen]

Hello everyone! Is there any way to just ignore the bulk and shear modulus in UMAT of LS-DYNA when we define the user defined material? I need to assign different material property for each element by UMAT but got stuck in bulk and shear modulus defined.

[Andreas Koutras]

Hello Tuan,

The bulk and shear moduli should be specified. 

From Appendix A of the Manual:

"all user-defined material models require bulk and shear moduli for transmitting boundaries, contact interfaces, rigid body constraints, and time-step calculations."

[Tuan Nguyen]

Hi Andreas Koutras,

Thanks for your answer, since I am trying assign different Young's modulus on each element, so is there anyway to modify to assgin bulk and shear modulus on each element on UMAT.

I have assigned the young's modulus on each element like the image below.

Before, I have run the simulation of the model with ABAQUS UMAT and it give me quite good results. With LS-DYNA I cannot do that and I guess because of the affect of bulk and shear modulus so it is impossible to assign different Young's modulus on each element in LS-DYNA. My question: Is there anyway we also can assign bulk and shear modulus on each element (not on each part). If anyone use to face with the problem before please help me.

another example case:

 

von Mises stress