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arXiv 2103.08830math.OC
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基于随机变量的可靠性拓扑Optimization

Reliability-based Topology Optimization using Stochastic Gradients

Subhayan De, Kurt Maute, Alireza Doostan

摘要:

针对基于可靠性的结构拓扑优化(RBTO)的计算难题,提出了采用标准抽样方法对目标和约束的统计量进行估计的方法,克服了传统方法依赖于极限状态函数近似的精度问题。在这里,我们提出了一个随机的基于梯度的方法,我们估计在每隔几次迭代使用一个有效的采样策略的故障概率。为了估计失效概率相对于设计参数的梯度,我们应用贝叶斯规则,其中我们假设以失效为条件的设计参数的密度函数为参数指数模型。设计参数以及该密度函数的参数使用随机梯度下降方法来更新,该方法仅需要小的,例如,O(1),每次迭代的随机样本的数量,从而导致与标准RBTO技术相比计算成本的显著降低。我们说明了所提出的方法与基准的例子,有一个解析解,以及两个广泛使用的问题,在结构拓扑优化。这些例子说明了该方法在产生可靠设计方面的有效性。

英文摘要:

This paper addresses the computational challenges in reliability-based topology optimization (RBTO) of structures associated with the estimation of statistics of the objective and constraints using standard sampling methods, and overcomes the accuracy issues of traditional methods that rely on approximating the limit state function. Herein, we present a stochastic gradient-based approach, where we estimate the probability of failure at every few iterations using an efficient sampling strategy. To estimate the gradients of the failure probability with respect to the design parameters, we apply Bayes' rule wherein we assume a parametric exponential model for the probability density function of the design parameters conditioned on the failure. The design parameters as well as the parameters of this probability density function are updated using a stochastic gradient descent approach requiring only a small, e.g., O(1), number of random samples per iteration, thus leading to a considerable reduction of the computational cost as compared to standard RBTO techniques. We illustrate the proposed approach with a benchmark example that has an analytical solution as well as two widely used problems in structural topology optimization. These examples illustrate the efficacy of the approach in producing reliable designs.

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