熱應力分析的邊界問題

pippenchu

模型是四分之一的PCB板,上面有包含晶片,

使用的元素是45和185,

需要做一個0度C到100度C的三次循環,

在求解的過程中總會出現不收斂的現像而停止求解,

請問這類熱循環的模型應該如何設他的邊界條件呢?

現在的做法是在X=0及Z=0的面積上設對稱邊界,

二個面相接的底部設所有自由度皆為0,

pippenchu

One or more elements have become highly distorted.  Excessive           
distortion of elements is usually a symptom indicating the need for     
corrective action elsewhere.  Try incrementing the load more slowly     
(increase the number of substeps or decrease the time step size).  You  
may need to improve your mesh to obtain elements with better aspect     
ratios.  Also consider the behavior of materials, contact pairs,        
and/or constraint equations.  If this message appears in the first      
iteration of first substep, be sure to perform element shape checking.


錯誤訊息如上,  該如何修改呢?