meshfreer's blog

 Hello, veryone. I am usint the VUMAT to define a new material behavior. There are questions about the calculation of shear stress.

The sheet metal forming was took as a plane stress problem in many relevant articles. So only three stress components:sigma_{11},sigma_{22},sigma_{12}

(sigma_{33}=0)are included in stress apdate algorithm such as the return mapping algorithm(J.C SIMO, R.L. Taylor. A return mapping algorithm for plane stress

Hi all, I am a new ABAQUS VUMAT user. Recently I try to define the matreial behavior in stamping of sheet metal  through the VUMAT. there are several questions about VUMAT.

（1）accoring to the ABAQUS user manual，for plane stress problem，stressnew(nblock,ndir+nshr), where ndir=3,nshr=1, but in fact,there are 5 stress commponents: sigma_{11},sigma_{22},sigma_{12},sigma_{23},sigma_{31}. how to match stressnew(*,i)(i=1,2,3,4) with the stress commponents: sigma_{11},sigma_{22},sigma_{12},sigma_{23},sigma_{31}?