最近，运用ANSYS中的谱分析（PSD）计算结构的随机振动，但求解过程中总是出现如下警告提示：One or more diagonal terms of the modal covariance matrix (i.e., when mode i = mode j) is negative. The 1 sigma results may be incorrect as a result of the input PSD
One or more diagonal terms of the modal covariance matrix (i.e., when
mode i = mode j) is negative.
The 1 sigma results may be incorrect as a result of the input PSD
curve being improperly represented.
我是真弄不懂到底为什么会出现这样的提示？
因为我按实例的步骤一步一步往下做的，但模型不一样。
希望高手或者哪位遇到过同样问题的，给予帮助
在此先谢谢各位了！！！
