考虑可靠度的等温热成形液压机上横梁轻量化设计

Light weighting design for upper beam of isothermal forming hydraulic press based on reliability

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。

When design the upper beam of isothermal forming hydraulic press with complicated internal structure,the traditional method which increases safety coefficient to improve reliability will result in heavy structures and material waste,to solve this problem,a method of light weighting design based on reliability for the upper beam of isothermal forming hydraulic press is put forward.Monte Carlo simulation technique with high precision is used in the reliability analysis of the upper beam for its stiffness reliability and reliability sensitivity.For the problem of that the reliability of upper beam cannot explicitly expressed in the process of optimization design,an indirect expression method of reliability based on sensitivity is proposed.By using the design parameter Z to describe the weight of lightweight and reliability in the process of optimization,reliability index is reflected in the design variables.Thus with the weight of reliability and mass considered at the same time,lightweight design of the upper beam considered reliability is realized with the minimum weight as the goal and the stiffness meeting the design requirements as the constraint.Simulation results show that the reliability is still 100% while the weight reduced by 7.4% after optimization.The method could be useful references for the reliability optimization design of large structures such as beam.