自动振打除灰装置冲击接触模型有限元分析

Finite element analysis of impact contact model of mechanical rapping ash removal devices

为解决自动振打除灰装置活塞杆与撞击杆的接触面因撞击导致损伤无法继续工作的问题,对两杆的接触模型进行了研究和优化.运用软件ansys/ls-dyna建立了机械振打器冲击部分的有限元模型,并分别对现有接触模型和改进后的接触模型下两杆的冲击过程进行有限元分析.对比不同情况下端面上的最大Von-Mises应力,发现活塞杆端面损坏的原因是撞击杆具有轴向夹角,通过改变活塞杆的端面形状可以有效改进现有的冲击接触模型,使活塞杆端面的应力集中现象明显减轻.当撞击杆右端面仍为圆平面,活塞杆左端面改为半径是2m的球面时,接触模型可以有效避免活塞杆端面出现过大应力集中,从而将振打器的寿命延长到设计范围.

To solve the problem of the contact surface between stricken rod and transitive rod of rapping device becoming invalid for the damage coming from shock, it is needed to research and modify the contact model of two rods. The finite element model of rapping device was built by using ansys/ls- dyna, and the whole impact process under existing contact model and modified contact model was analyzed separately. Through comparing the maximum stress on the end surfaces under different conditions, it is found that stricken rod with an axial angle is the cause for the damage, using the method of adjusting the shape of the left end surface which belongs to the piston rod could improve the current contact model and mitigate the phenomenon of stress concentration. When the right end surface of stricken rod is a circle plane and the left end surface of piston rod is a spherical with radius of 2m, phenomenon of stress concentration could be avoided effectively, then the lifetime of rapping device could be extended to the design range.