拼焊形式车身薄壁管件变形吸能机制及碰撞安全性高效设计方法研究

Tailor-welded thin-walled structures have become the advanced automotive body light-weight structures due to the advantages of feasible distributions. At present, the studied viewpoints on the advanced structures focused mainly on the forming and manufacturing field. Unfortunately, the crashing safety design of tailor-welded structures has been not extensively performed. The published results have showed that the advanced structures are greater potential into the application of energy-absorbed tubular structures. However, the deformed mechanism has been clearly not revealed and there are also lack of high-efficiency design methods. In the project, based on the requirement of crashing safety and functional feature of tailor-welded structures, tailor-welded collapsed element and crushing theoretical model would be conducted. Thus, the crushing deformed performance and energy-absorbed mechanism could be uncovered. Then, the overall evaluation model of crashing safety would be carried out according to analytic hierarchy process (AHP) and linear weighted technique (LWT). In addition, the coupling relationship between the overall model and constraint condition would be reasonably carried out, and then the efficient characteristics function would be conducted. Further, the matching design of discrete design variables would be performed through flexibility performing the orthogonal array. The fundamental study would be helpful to deal with some key science problems in the concept design stage of passive safety for automotive body. And the relative methods would be greater scientific value to consummate automotive body light-weight design system of new-energy vehicles. Additionally, it would also be important engineering value to further extend the applied ranges of tailor-welded structures.

拼焊形式构件因灵活配置的优势已成为性能卓越的车身轻量化结构，目前对其研究主要集中在覆盖件成形制造领域，尚未广泛关注其碰撞安全性层面。本项目组以往研究表明，该新颖管件在碰撞吸能方面同样具有较大的应用潜能，然而尚不明确其变形吸能机制以及缺乏高效的设计方法。本项目拟根据车身碰撞安全性能要求并借助拼焊形式的功能特点，建立拼焊型超折叠单元初始构型和压溃理论模型，揭示拼焊形式薄壁管件的压溃变形特性及能量吸收机制；以该机制为依据，采用层次分析法和线性加权法构建碰撞安全性综合评价模型；通过罚函数法处理综合评价模型和约束条件之间的耦合关系并建立有效的特征函数，灵活运用正交试验方法对拼焊形式管件的离散型参数进行高效匹配设计。该基础性研究能够解决拼焊形式管件在车身结构被动安全性概念设计阶段的关键科学问题，对进一步完善新能源汽车车身轻量化设计体系和深入拓展拼焊形式结构的应用范围具有积极的科学意义和重要的工程价值。

拼焊形式构件因灵活配置的优势已成为性能卓越的车身轻量化结构，目前对其研究主要集中在覆盖件成形制造领域，尚未广泛关注其碰撞安全性层面。本项目组以往研究表明，该新颖管件在碰撞吸能方面同样具有较大的应用潜能。.本项目提出了一种考虑离散和连续混合变量的拼焊板前纵梁安全性设计方法，通过特征函数均值分析判定最新迭代的正交表，较好地解决了传统正交试验设计无法适用于多变量高水平的拼焊板耐撞性设计问题。提出了一种基于田口灰色关联分析的两阶段组合优化设计方法，继承了田口设计鲁棒性的优点，弥补了传统优化算法对拼焊板设计变量盲区和区间选择的缺点，实现了快速定位和高效优化。研究了拼焊结构精细建模技术，比较了不同焊缝建模方式对动态效应的影响，结合变截面轧制技术工艺特点构建了变厚度结构厚度分布显式参数化模型。研究了拼焊形式结构厚度分布渐进拓扑优化，结果显示优化后的拼焊结构具有明显的对称性，不同厚度区域重新分布，该方法在处理多厚度拼焊结构问题时具有可行性。研究了厚度幂指数分布管在多角度碰撞下的承载特性，评估了不同厚度梯度对峰值载荷和比吸能的影响。结果表明，厚度梯度变化对变形吸能特性有较大影响，可进一步提高变厚度构件抵抗弯曲变形的承载能力。研究了变截面制造工艺并给出了帽性构件厚度分布约束条件，分析了变厚度构件的弯曲吸能特性，开展了以变厚度构件的等厚区厚度、过渡区长度和位置参数为设计变量的优化设计，提出了变厚度构件弯曲耐撞性优化设计方法。.该基础性研究能够解决变属性尤其是拼焊形式管件在车身结构被动安全性概念设计阶段的关键科学问题，对进一步完善新能源汽车车身轻量化设计体系和深入拓展拼焊形式结构的应用范围具有积极的科学意义和重要的工程价值。