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针对内部结构复杂的等温热成形液压机上横梁,传统设计方法以增加安全系数来提高可靠度而导致结构笨重和材料浪费,研究了考虑可靠度的上横梁轻量化设计问题。采用精度较高的蒙特卡罗模拟技术对上横梁进行可靠性分析,得到其刚度可靠度以及可靠性灵敏度信息;针对上横梁可靠度在优化设计过程中无法显式表达问题,提出基于敏感度信息的可靠度间接表达方法,利用设计参数Z描述优化过程中可靠度和轻量化的权重,从而将可靠度指标体现在设计变量中;同时考虑可靠性灵敏度和质量占比,以质量最小为目标、刚度满足设计要求为约束,实现了考虑可靠度的上横梁轻量化设计。仿真分析结果表明,优化后上横梁刚度可靠度依然为100%,而质量下降了7.4%。该方法可为横梁等大型结构件的可靠性优化设计提供有益借鉴。
In view of the complicated cross-beam structure of isothermal thermoforming hydraulic machine, the traditional design method increases the reliability by increasing the safety factor, which leads to the heavy structure and material waste. The lightweight design of the upper beam considering the reliability is studied. The Monte Carlo simulation technology with high accuracy is used to analyze the reliability of the upper crossbeam and obtain the stiffness reliability and the reliability sensitivity information. In view of the problem that the reliability of the upper crossbeam can not be explicitly expressed in the process of optimization design, The reliability of indirect expression method, the use of design parameters Z to describe the process of optimization of the reliability and weight of lightweight, so as to reflect the reliability index in the design variables; taking into account the reliability of sensitivity and quality of the proportion of the minimum quality as the goal, Stiffness to meet the design requirements as a constraint, to achieve the reliability of the light beam on the lightweight design. The simulation results show that the optimized stiffness of the upper crossbeam is still 100%, while the mass is decreased by 7.4%. This method can provide a useful reference for the optimization of the reliability of large structural members such as beams.