To increase the range of applicability of decoupling strategies for reliability-based design optimization (RBDO), a sequential optimization and moment-based reliability assessment (SOMRA) is proposed. In this approach, a moment method based on the univariate dimension reduction method (UDRM) and probability density function (PDF) estimation is employed. Meanwhile, a corresponding mathematical model and a PDF-based method of calculating the shifting scalar are developed to decouple the reliability assessment from the optimization process. The shifting scalar is corrected according to the nonlinear degree of the limit state surface of the performance function before reconstructing the mathematical model for the next iteration of optimization. This approach uses statistical moments to check whether the constraints are active, and rather than assessing the reliability and calculating the shifting scalars for all constraints, only the active constraints are considered for the PDF estimation and shifting scalar calculation. Three numerical examples and an automobile crashworthiness lightweight design problem are presented to demonstrate the effectiveness of the proposed method.

为了扩大基于可靠性的设计优化（RBDO）的解耦策略的适用范围，提出了一种顺序优化和基于矩的可靠性评估（SOMRA）。在这种方法中，采用了基于单变量降维方法（UDRM）和概率密度函数（PDF）估计的矩方法。同时，开发了相应的数学模型和基于PDF的移位标量计算方法，以将可靠性评估与优化过程脱钩。根据性能函数的极限状态面的非线性程度，对移位标量进行校正，然后为下一次优化迭代重建数学模型。这种方法使用统计矩来检查约束是否有效，而不是评估所有约束的可靠性和计算移位标量，PDF估计和移位标量计算仅考虑活动约束。给出了三个数值例子和一个汽车防撞轻量化设计问题，以证明该方法的有效性。