iMechanica - Deformation gradient - Comments

decomposition of F

Xiaoteng Wang — Mon, 06 Oct 2008 06:20:33 -0400

Hi Zhangli,

Sorry I missed the V when I read your VUMAT thread.:)

Anyway I think you can achieve the decomposition of F. VUMAT provides the stretch tensors at both current step and previous step.

Another thing is the deformation gradient is objective (rotation free), so you dont need to rotate it.

Wang

Thanks. Rotation tensor

zhpeng — Fri, 03 Oct 2008 14:57:04 -0400

Thanks.

Rotation tensor is not provided in VUMAT, and I think polar decomposition of F is still required.

Also ROTSIG is for ABAQUS Stand. I am using VUMAT (Explicit).

Zhangli

Hi Zhangli, The

Xiaoteng Wang — Thu, 02 Oct 2008 23:59:27 -0400

Hi Zhangli,

The deformation gradient F is already provided by ABAQUS and you can directly use it in UMAT programming. I think the rotation and stretch tensor is also provided. Since you are using Hyperelastic hypothesis, you should define your own configuration using UMAT. ABAQUS provides a utility routine ROTSIG to rotate the stress or stress like tensor such as back stress, etc.., but maybe that utility routine is based on Hypoelastic decomposition. Please refer to ABAQUS manual and I hope you can get some ideas. Good luck.

Xiaoteng Wang