叶轮强度的有限元法计算

本文将空间曲面叶片用变密度夹层材料代替,叶轮被简化成一种复合材料的回转体,然后用轴对称有限元法进行计算,同时还对轴对称单元在半径r→0时的奇性问题作了处理。从算得的夹层材料中的节点位移场经过换算得出叶片中的应力场,从而可一次算得轮盘、叶片、轮盖中的应力场,进而还可同时算出与叶轮配合的转轴内的应力与位移。通过对实际使用的多种型号叶轮的计算,并作了超速强度试验,证明计算结果与实际试验结果相符。表明本文的有限元计算具有可靠性、准确性、计算简便等优点。

多目标规划在财力分配中的应用

地方财政部门每年把地方财力分配(贷款)给有关部门时,一般都是凭旧有资料和当前情况进行定性研究,从而确定分配方案的。这不仅会产生许多不合理之处,而且也不可能使有限的财力充分发挥作用。某财政研究部门提出:应该如何把地方(如省级)每年的财力资金适度地分配给多个生产部门?这个适度的“度”又应该如何确定?我们认为:在当前情况下,这个适度的“度”的衡量标准就是在财政资金一定的条件下,分配(贷款)给各个部门,应使其总的利润与税收之和最大,并使固定资产增值也最多。这显然是一个多目标优化问题。

A FINITE ELEMENT METHOD FOR STRESS ANALYSIS OR ELASTOPLASTIC BODY WITH POLYGONAL LINE STRAIN——HARDENING

In this paper, the stress-strain curve of material is fitted by polygonal line composed of three lines. According to the theory of proportional loading in elastoplasticity, we simplify the complete stress-strain relations, which are given by the increment theory of elastoplasticity. Thus, the finite element equation with the solution of displacement is derived. The assemblage elastoplastic stiffness matrix can be obtained by adding something to the elastic matrix, hence it will shorten the computing time. The determination of every loading increment follows the von Mises yield criteria. The iterative method is used in computation. It omits the redecomposition of the assemblage stiffness matrix and it will step further to shorten the computing time. Illustrations are given to the high-order element application departure from proportional loading, the computation of unloading fitting to the curve and the problem of load estimation.