The rigid bodies with the reference nodes contained in node set ErrNodeRefNodeNoMass have no mas。。。

事故背景：

        我设置了一个刚体板，我想让刚体板下压一个材料，一切就绪，结果仿真报错：

The rigid bodies with the reference nodes contained in node set ErrNodeRefNodeNoMass have no mass associated with them and some degrees of freedom of the reference node are not restrained. Either mass must be defined or all of the translational degrees of freedom must be constrained. See the status file for further details.

解决方法： 

        找到刚体板的part，在property界面，1.选择special，2.inertia，3.选择板的参考点，4-5手动给它加上Mass和rotary inertia（数是我随便给的，我也不懂）