基于FEPG的有限元方法.FEPG系统是基于虚位移原理（即弱形式）而不是变分原理，要求用户书写弱形式的微分方程表达式-FEPG Based on the finite element method. FEPG system is based on the principle of virtual displacement (ie, weak form) rather than the variational principle, require users to write the weak form of differential expression