求解Cohesive单元VUMAT总是出现bad material的错误

songshangyu

附件是我自己写的cohesive单元的vumat以及测试所用的inp文件，但在data check的时候，cohesive单元总是出现bad material的错误，如下：
Bad Material definition in element number 38 instance PART1: zero or negative initial dilatational modulus caused by bad material data. Please check your material input and any initial conditions if necessary 。

恳请懂的朋友帮忙看下是vumat本身的问题还是cohesive单元材料属性的问题，谢谢了。

mrwoodeast

For *tie pair (assembly_s_surf-14-assembly_m_surf-14), adjusted nodes with very small adjustments were not printed. Specify *preprint,model=yes for complete printout.大神 这种问题你知道是咋回事儿么

52811

楼主的问题解决了吗？我也遇到了这个错误。

筑梦丶小丑

Dilatational modulus is the Bulk modulus or the
modulus of incompressibility. If you get an error of
"Bad Material definition: zero or negative ..." that
simply means that your material data is problematic.
If you get it for a VUMAT your material response as a
consequence of bad material data is unphysical.

IsaacHuo

你的dent变量计算有问题，当小于0以后，相当于第一个增量步没做，后面就没然后了，直接报错。