Abaqus的VUMAT 中，出现如下列警告和错误是什么意思？

A material defined in user subroutine VUMAT must be defined as purely elastic (using the initial elastic modulus) at the beginning of the analysis (stepTime=0). This is an informative message. It does not necessarily indicate that user subroutine VUMAT is incorrectly defined.error：The elements contained in element set ErrElemExcessDistortion-Step1 have distorted excessively.There is only one excessively distorted elementThe elements contained in element set ErrElemExcessDistortion-Step1 have distorted excessively.Abaqus/Explicit Analysis exited with an error - Please see the  status file for possible error messages if the file exists.