中文摘要：

针对于汽车起重机吊臂采用何种截面形状能够提高其局部稳定性的问题,利用非均匀有理B样条（NURBS）曲线进行其截面形状的建模,并使用ANSYS软件进行了吊臂的局部稳定性分析。首先,通过积累弦长法求得三次NURBS曲线的节点矢量,使用反求技术算出三次NURBS曲线的权因子及其控制点,从而构造出汽车起重机伸缩吊臂下盖板截面的三次NURBS曲线函数;其次,利用APDL命令流控制技术,通过调节三次NURBS曲线控制点的坐标和权因子的大小,得到了多种形状的曲线形吊臂截面,通过计算其屈曲特征值后,获得了吊臂的临界应力值及其变化规律;最后,得到了吊臂截面形状由六边形变换到十二边形,再到曲线形时临界应力的提高程度。研究结果表明,该方法较好地解决了起重机曲线形吊臂的局部稳定性问题。

英文摘要：

Aiming at the problem of which cross-section shape needs to be used in order to increase the local stability of boom of truck crane, the non-uniform rational B-splines （NURBS）curve was exploited to model the cross-section shape of boom and ANSYS software was applied to the analysis of local stability of boom. Firstly, the knot vector of cubic NURBS curve was obtained by accumulated chord length method, then the weights and control points were worked out by reverse technology, thus the cubic NURBS curve function of the lower cover cross-section of truck crane＇s telescopic boom was established. Secondly, with APDL command flow, various curve shaped cross-section of boom were gotten by adjusting the cubic NURBS curve＇s coordinates of the control points and the size of the weights, then the buckling eigenvalue was calculated, so the critical stresses of boom and its variation were gained. Finally, the increased value of the critical stresses from a hexagonal cross-section to a dodecagon cross-section, then to a curve cross-section was obtained. The results indicate that the method can solve the problem of the local stability of curve shaped cross-section boom of crane.