起重机箱形伸缩臂整体稳定性分析

起重机伸缩臂由多节可轴向相对滑动的变截面箱形臂套接组成.箱形伸缩臂承受全部弯矩,而轴向力是通过搭接处的摩擦力与内置油缸共同承受,其力学模型不等同于变截面阶梯柱模型和完全由油缸承受轴力的变截面箱形臂模型.如何准确计入油缸支撑作用及搭接摩擦力的影响,对起重机箱形伸缩臂稳定性分析计算具有十分重要的意义.从挠度微分平衡方程出发,给出起重机箱形伸缩臂三种计算模型的欧拉临界力的分析推导,并着重讨论考虑油缸支撑和伸缩吊臂间搭接摩擦力协同作用的变截面箱形伸缩臂计算模型.分析结果表明,考虑油缸支撑和箱形吊臂间搭接摩擦力协同作用时吊臂的失稳临界力介于完全由油缸承受轴力的变截面箱形臂模型与变截面阶梯柱模型的失稳临界力之间.

Global stability analysis on crane telescopic boom

The crane telescopic boom is composed of several tapered box-booms with axial sliding. There-fore, the telescopic boom is suffered from the entire bending moment, while the axial force is loaded and shared by the joint friction and inner cylinder. As such, relevant mathematical expression is neither equivalent to the tapered step-column model, nor to the tapered box-boom model with entire axial force towards cylinder. To consider the cylinder supporting and joint friction, the boom stability analysis secures a crucial position. Based on the deflection differential equilibrium equation, the Euler＇s critical force is deduced for three boom models, particularly accounting for the collaboration between cylinder supporting and joint friction. Eventually, it is indicated that the critical force for boom instability is interposed between the force from tapered step-column model and the force from the tapered box-boom model.