The gap between piston rod and cylinder is an important factor which affects the stability of a hydraulic cylinder.With the effects of gap, bending was caused in piston rod and cylinder under axial and lateral forces. Based on buckling differential equations for hydraulic

cylinder, a deflection nonlinear equation for piston rod and cylinder was proposed for calculating the critical load.Under the condition of known volume constraints and critical

load,the parametric finite element method was used to establish and analyze the mechanical model of hydraulic cylinder.A nonlinear quadratic programming method was applied

 for the optimum design of the structures. Compared with the size which calculated by

Ritz and verified by stability test, the results show the method is applicable for calculation of stability for hydraulic cylinders.

针对液压缸活塞杆与缸体由于受轴力和横向力的共同作用而产生弯曲变形导致液压缸整体失稳的问题,分别对活塞杆和缸体建立挠曲性微分方程,确定活塞杆与缸体间隙处最大挠度,再建立关于挠度的非线性方程组,获得计算液压缸临界载荷的超越方程。结合参数化有限元优化设计技术,获取体积约束条件下液压缸的合理尺寸,通过与Ritz法计算结果比对和实验验证可知,该算法能够较好地优化液压缸结构参数,满足工程实际应用需要。

液压缸, 挠曲微分方程, 临界载荷, 优化设计