随机变量和区间变量共存条件下的复合材料可靠性设计

Reliability optimum design of composite structures with the mixture of random and interval variables

当得不到足够数据的统计信息时,将结构的不确定参数描述为区间变量,结合区间变量的性质,对结构的可靠度进行分析是可靠性分析中的一个新的研究重点。在复合材料的可靠性设计中,考虑5个强度参数为随机变量,纤维方向角和弹性模量为区间变量,将区间变量的取值范围内,区间变量的最差组合下的可靠度定义为结构的可靠度,则混合可靠度的分析可以看成一个双重优化问题。两个算例说明混合可靠度设计在信息不全的情况下,给出了较保守的结果,保证结构的安全可靠。

There are many uncertainty factors that influence the reliability of composite materials. In cases that only limited information is available, the interval analysis is an effective method to deal with the uncertainty factors. In the reliability-based design of composites in this paper, the five strength parameters are considered as random parameters, and the fiber orientation and the elastic modulus are treated as interval parameters. The reliability under the condition of the worst case combination of interval variables is taken as the mixture reliability. Reliability-based design of composites is then formulated and solved. Numerical examples show that the worst combination scenario gives conservative results of the optimal design.