طراحي براي قابليت اطمينان: بهينه‌سازي سازه‌هاي بحراني با استفاده از تحليل فاصله بي‌نظمي

Design for reliability: optimization of critical structures using cross-entropy reliability analysis

در اين مقاله، يك روشِ طراحي براي قابليت‌ اطمينانِ سازه‌هاي بحراني ارائه شده است. روش فاصله بي نظمي براي تحليل قابليت‌اطمينان ارائه شده و در چارچوب مناسبي با الگوريتم بهينه‌سازي تلفيق شده-است. عليرغم پيشرفت‌هايي كه در زمينه قابليت‌اطمينان و بهينه‌سازي صورت گرفته، هنوز در حوزه سازه هاي بحراني چالش‌هاي محاسباتي وجود دارد. در روش فاصله بي‌نظمي، واريانس نمونه‌هاي تصادفي لازم براي شبيه‌سازي مونت‌كارلو كاهش يافته و امكان تحليل قابليت‌ اطمينان قيود بحراني فراهم مي‌شود. اين روش بر روي دو نمونه طراحي سازه‌اي پياده‌سازي شده و نتايج نشان مي‌دهد كه اين روش در مقايسه با روش ضريب اطمينان، قابليت‌ اطمينان سازه را افزايش مي‌دهد.

This article presents an efficient reliability-based optimization method for critical structural design, in which, the probability of failure (Pf) should remain in a small bound. Critical structures should be designed to be optimal and reliable. Despite significant progress in reliability and optimization techniques, their interaction, which is considered in reliability-based optimization (RBDO), is faced with several challenges, especially in reliability analysis of critical constraints (constraints with Pf less than 10-5). To address this issue, in this paper the cross-entropy method is intended for reliability analysis and is combined with Genetic Algorithm in a double-loop framework to implement RBDO. The cross-entropy method is based on Monte Carlo simulation, except that the variance of sampling is reduced, which leads to a faster and more accurate reliability analysis method. The proposed RBDO method is demonstrated on two structural design. The obtained results show a high capability in reliability-based optimization of critical structures. In addition, using the proposed method, in comparison with traditional safety factor method, provides a more substantial manner in reliability improvement.