The ratio of deformation speed to wave speed exceeds 1.0000？这怎么解决？

magiciansf

The ratio of deformation speed to wave speed exceeds 1.0000 in at least one element. This usually indicates an error with the model definition. Additional diagnostic information may be found in the message file.这是错误信息，不晓得问题出在哪里？
下面的是警告信息：

The option *boundary,type=displacement has been used; check status file between steps for warnings on any jumps prescribed across the steps in displacement values of translational dof. For rotational dof make sure that there are no such jumps. All jumps in displacements across steps are ignored
35 elements are distorted. Either the isoparametric angles are out of the suggested limits or the triangular or tetrahedral quality measure is bad. The elements have been identified in element set WarnElemDistorted.
There are 2 warning messages in the data (.dat) file.  Please check the data file for possible errors in the input file.
Boundary conditions are defined at the the nodes contained in node set WarnNodeBcIntersectKinCon. In addition the nodes are also part of a surface involved in kinematic contact. The kinematic contact constraint will be overridden by the boundary conditions in case of a conflict. Penalty contact may be used instead.
The slave surface nodes in node set WarnNodeMassRatio3fix-Step1 have much larger masses than the nodes on the master surface. Significant contact noise may result. Suggested workarounds include setting the WEIGHT parameter so that what was the master surface becomes a pure slave surface in the contact pair, using mass-scaling to adjust the ratio of nodal masses, or using the penalty contact algorithm. See the status file for further details.
The slave surface nodes in node set WarnNodeMassRatio3fix-Step2 have much larger masses than the nodes on the master surface. Significant contact noise may result. Suggested workarounds include setting the WEIGHT parameter so that what was the master surface becomes a pure slave surface in the contact pair, using mass-scaling to adjust the ratio of nodal masses, or using the penalty contact algorithm. See the status file for further details.
望高手解答？

shenglivict

是不是质量属性设置有问题，或者质量缩放过头了

hustlk

这个一般是单元大变形引起的，看一下提示发生错误的element，很有可能出现负体积了。
it's better to refine the elements!

magiciansf

2# shenglivict
我模型里面没有定义质量单元，只是材料属性里定义了密度而已。

magiciansf

3# hustlk
我再把网格细化写，单元就太小了

wang4416

我也曾今遇到过，查看odb中已算好的step，发现模型的一个部分震颤得很厉害，这与实际不符，我干脆将震颤很厉害的部分约束了一下，好了。