壁板局部失稳的优化设计

整体壁板设计问题困难在于如何合理地选择设计参数,即筋条高度,筋条宽度,间距和蒙皮厚度等,使壁板作为一个整体,临界应力符合设计要求并尽可能地高,而重量尽可能地轻,用计算机作优化设计的程序尽可能地简单、可靠,内存占用能符合计算机的容量。 本文介绍对某型机机翼油箱等截面薄壁柱受轴压时的局稳优化设计。用有限条元法进行局稳临界应力分析,可使单元划分数较少,占用内存少,即使用矩阵特征值法求解,计算的机时也较短,其结果能符合工程要求,比有限元素法有显著的优势。采用非线性规划的直接法如随机方向法和单纯形法都有相同结果。本文着重介绍单纯形法求设计变量,结果满足设计要求,通过了全机静力试验,并将用于某型机的改型机。

The Optimal Design with Local Instability

The difficulty of designing an integral panel is how to choose reasonably its designing parameters, such as the height, width and spacing of the stiffened strip to increase the critical buckling stress as high as possible above the required level, to decrease the weight as low as possible, and to design a simplest computer program which is reliable and suitable for computer capacity.This paper deals with the optimal design of a constant-section, thin-walled skin which is the fuel tank of an aircraft wing with local instability under compression. Finite strip method is used to do the critical stress analysis of local instability.In this way, a smaller number of elements is used and a smaller computer storage is needed. Even by, matrix eigenvalue method, the computer time is not very long, and the results can meet the engineering requirements. So it has a remarkable advantage over the finite elenient method. The same results are obtained by direct methods of nonlinear programming, such as Random Direction Method and Simplex Method. In this paper, Simplex Method is introduced. The re'sult has met the design requirement successfully, and passed the aircraft static test, and this result will also be used in the modified type of this aircraft.