高速锤击体积变形过程的有限元分析

Finite element analysis of the deformation process in high impact hammering

为了研究金属高速锤击变形过程,基于连续介质力学,开发了弹塑性动力显式有限元程序,在平衡方程中引入惯性力来考虑高速变形中惯性效应的影响,同时根据能量原理计算变形期间的锤头速度.使用开发的程序对OF-HC铜块体的高速锤击变形过程进行有限元分析,研究试样构形、质点位移和内部等效塑性应变分布规律,并与未考虑惯性效应的静态模拟结果进行对比.利用所开发的程序分析了高速锤击变形过程中锤头速度、工件变形能和锤击载荷的变化规律.研究结果表明,高速锤击时受惯性力的影响,变形集中于试样上部;由于应力波传播,变形初期下模载荷滞后于上模.这说明所开发的有限元程序能够模拟金属高速锤击变形过程.

To study the process of metallic deformation on a high-impact hammer machine, an elastoplastic dynamic-explicit finite element analytical program was developed, based on continuum mechanics. In the program, the inertia was introduced in the equilibrium equation, to analyze inertia effects on high-impact deformation, and hammer velocity was calculated according to the energy method. The resulting FEM program was used to study the deformation process of OFHC copper when struck by a high-speed hammer. The deformation of the billet, the distribution of displacement, and the effective plastic strain in the workpiece were investigated. Simulation results were compared with those obtained by the program without taking account the inertia effect. Subsequently, the effect of changing parameters of hammer speed, strain energy, and impact load were obtained through simulation. The results show that deformation is mainly present on the impacted surface of the specimen, due to inertial effect, and the load in the lower body of the die lags behind that in the upper part of the die at the initial stage of deformation owing to stress wave propagation. The improved FEM program can successfully simulate the metallic deformation process of high-impact hammering.