变厚度车身结构“材料-工艺-性能”全耦合稳健优化设计方法研究

How to adjust and optimize the thickness distribution according to force and performance requirements of automotive components and truly efficiently, accurately and robustly realize the material usage of maximum potential in meeting the rolling and formability of parts, which is a key fundamental science problem need to be addressed urgently in the application of tailor rolled blanks. The project is based on the fact that the non-uniform essence of cross-sectional thickness and material properties of tailor rolled blanks. We will first analyze the variation of the indentation response at different thickness, and reveal the relationship between the indentation response and material properties. Then, a mathematical model and the corresponding algorithm can accurately obtain the material properties of tailor rolled blank is established. By investigating the flow law and plastic instability mechanism of tailor rolled blanks, the three dimensional forming limit stress diagram which can predict effectively the formability of tailor rolled blanks is established. By analyzing the coupling relationship among material, process and performance in the parts of tailor rolled blanks, the fully coupled simulation strategy that can precisely calculate responses is developed. By analyzing the effect of the fluctuation and propagation of uncertainty factors on the performances, robust optimization mathematical model coupled full material-process-performance is established and parallel solution algorithm based on GPU platform is developed. It is an important significance to promote the application of tailor rolled blanks and achieve energy saving and emission reduction.

在满足可轧制性和零件可成形性的前提下，如何根据汽车零部件的受力和性能需求来合理调整和优化零件的厚度分布，真正高效、精确和稳健的实现板厚分布的“量身定做”和“材尽所用”是变厚度板应用中迫切需要解决的关键基础科学问题。本项目从变厚度板的截面厚度和材料性能分布的非均匀性出发，研究不同厚度处压痕响应的变化规律和表征模型，揭示压痕响应与材料性能之间的关联关系，建立能精确获取变厚度板材料性能的数学模型和高效求解算法；研究变厚度板材料的流动规律和塑性失稳机理，建立能有效预测变厚度板成形能力的三维成极极限应力图；研究变截面零件“材料-工艺-性能”之间的耦合关系，提出能精确计算其响应的“材料-工艺-性能”全耦合仿真策略；研究不确定因素的波动及传播对性能的影响，建立“材料-工艺-性能”全耦合的稳优优化数学模型，并在GPU平台上开发出高效的并行求解算法。研究结果对推动变厚度板的应用，实现节能、减排具有重要意义。

在满足可轧制性和零件可成形性的前提下，根据汽车零部件的受力和性能需求来合理调整和优化零件的厚度分布，真正高效、精确和稳健的实现板厚分布的“量身定做”和“材尽所用”是变厚度板应用中迫切需要解决的关键基础科学问题。本项目从变厚度板的截面厚度和材料性能分布的非均匀性出发，研究了不同厚度处压痕响应的变化规律和表征模型，揭示了压痕响应与材料性能之间的关联关系，建立了能精确获取变厚度板材料性能的数学模型和高效求解算法，提出了一种获得变厚度板材料参数的方法体系，该方法主要包含显微压痕试验、有限元模型以及参数优化理论等，结果表明该方法可以有效获得变厚度板材料参数，能有效减少物理实验成本，并具备较高精度；研究了变厚度板材料的流动规律和塑性失稳机理，建立了能有效预测变厚度板成形能力的三维成极极限应力图；研究了变截面零件“材料-工艺-性能”之间的耦合关系，提出能精确计算其响应的“材料-工艺-性能”全耦合仿真策略，系统研究了连续变厚度薄壁结构耐撞性设计问题，采用实验、数值仿真、理论解析方法开展了变厚度结构在横向载荷下的压溃响应分析，通过三点弯曲和四点弯曲试验，研究了不同厚度梯度的变厚度圆管抗弯曲行为和能量吸收特性，并开展车身变厚度多胞防撞梁总成的优化设计，实现轻量化和耐撞性的均衡提升；研究了不确定因素的波动及传播对性能的影响，建立了“材料-工艺-性能”全耦合的稳优优化数学模型，并在GPU平台上开发出高效的并行求解算法，提出了一种基于可靠性优化的多目标设计策略，为变厚度结构在汽车轻量化设计中的适用性和有效性提供指导意见，促进变厚度结构在工程中的有效应用。相关研究结果还被拓展应用到新能源汽车用碳纤维新材料变厚度结构中，对推动变厚度板和新材料的应用，实现节能、减排具有重要意义。