有限元学习
https://www.zhihu.com/question/27696855
https://wenku.baidu.com/view/ac816e9c360cba1aa911da3c.html
下面这么本书的下载地址：
https://zhidao.baidu.com/share/9a470b176f1f56f94c4a1c1fab2f10cc.html
https://wenku.baidu.com/view/857c4531a58da0116d17493a.html
