中文摘要：

研究了均匀棒纯纵向运动方程半离散有限元法，利用椭圆投影，获得了半离散有限元逼近的一些最优误差估计。

英文摘要：

A Semi-discrete Finite Element Method for the purely longtudinal motion of a humogeneous bar is mainly discussed. By means of the elliptic projection, some optimal error estimates for the semi-discrete finite approximation are derived.