随机载荷作用下铁路起重机伸缩臂模糊可靠性分析

箱形伸缩式吊臂的可靠性分析是铁路起重机设计中的重要部分。在载荷随机情况下,利用摄动随机有限元,结合板壳元,推导单元应力的均值和方差的计算公式,计算铁路救援起重机基本臂最大应力单元主应力的均值和方差,并与强度试验结果进行比较;在强度为随机变量的情况下,把结构从安全状态到失效状态的过渡性考虑成一模糊事件,采用线性隶属函数,计算了QTJS160铁路起重机伸缩式吊臂的模糊可靠度。计算结果表明,结构可靠性与载荷离差及相关系数有很大的关系;把载荷处理为随机载荷,把失效事件处理为模糊事件,符合实际情况。

Fuzzy Reliability Analysis of Railway Crane Telescopic Jib under Stochastic Load

The reliability analysis of the box type telescopic jib plays a key role in the railway crane design. Perturbation stochastic finite element method is adopted t o deduce the formulas for the calculation of the mean value and deviation of the element stress under the stochastic load of plate and shell element. The mean v alue and deviation of the first principal stress in the maximum stress element i n the telescopic jib of QTJS160 Railway Crane is calculated and compared with th e results of the corresponding strength experiment. The fuzzy reliability of the telescopic jib of QTJS160 Railway Crane is calculated,taking the material stren g th as a stochastic variable and considering the transition from safety state to failure state a fuzzy matter and the membership function a liner function. The results show that the reliability of the structure is closely related to the dev iation of the load and the correlation coefficient. It conforms with real situat ion to take the load as stochastic variable and the failure process a fuzzy matt er.