车身结构钢铝异种材料温热胶铆复合连接技术及服役失效研究

This project aims to solve the connection problems faced in the application of multi-material lightweight body structures. A warm clinch-adhesive joints (WCAJ) method for steel/aluminum dissimilar materials has been proposed, and the research on the corresponding key issues on the connection technology and the service process of joints are conducted. A set of cure degree-temperature coupling constitutive equations for adhesive which can predict the deformation and damage evolution based on damage mechanics is established to study the properties, damage modes and damage mechanisms of adhesive under different cure degrees and temperatures. A finite element model of clinch-adhesive joints for connection process simulation is established to study the effect of riveting process parameters on joint dimensions. A detailed finite element model of steel/ aluminum clinch-adhesive joints which can predict their service failure behavior is established to study the effect of connection process on the failure modes and properties. A finite element model of thermal expansion for clinch-adhesive joints is establish to study the structural deformation and pre-stress problems induced by different thermal expansion coefficients and to compensate or limit the thermal deformation of base metals by optimizing the clinch-adhesive technology. A simplified model for crash failure of clinch-adhesive joints and failure criteria are established to study the effect of mechanical properties of joints on the body crashworthiness and structural deformation. This will provide scientific basis and technical guidance for the selection of connection scheme and process design of dissimilar materials for body structures.

本项目以多材料轻量化车身结构所面临的连接问题为背景，提出一种钢铝异种材料温热胶铆复合连接方法，并针对连接技术和接头服役过程中的关键问题开展研究。建立一套基于损伤力学的固化度-温度胶接剂本构方程，预测胶层变形和损伤演化，研究胶接剂不同固化度和温度下的性能、损伤模式和损伤机理；建立胶铆接头连接工艺模拟有限元模型，研究铆接工艺参数对接头尺寸的影响规律；建立钢铝胶铆连接精细有限元模型，预测胶铆连接的服役失效行为，研究胶铆连接过程对接头失效模式和性能的影响；建立胶铆连接接头热膨胀有限元模型，研究由于异种材料热膨胀系数不同引起的结构变形和预应力问题，优化胶铆连接技术实现对母材热变形的补偿或抑制；建立胶铆连接碰撞简化失效模型和接头失效准则，研究接头力学性能对车身抗撞性和结构变形的影响。为车身结构异种材料连接方案选择和工艺设计提供科学依据和技术指导。

本项目以车身钢铝异种材料连接问题为背景，联合胶接和铆接两种不同形式的连接方式，提出一种钢铝异种材料温热胶铆复合连接方法，并针对连接技术和接头服役过程中的关键问题开展研究。本项目建立胶接剂固化度和温度相关的本构模型，预测铆接过程中胶层变形。进行胶接剂在不同固化度和温度下的接头成形试验，研究钢铝异种材料胶铆连接接头成形和服役力学性能。建立钢铝异种材料胶铆接头有限元模型，研究工艺参数对接头形貌尺寸的影响。建立钢铝异种材料胶铆接头热膨胀有限元模型，测定钢、铝、胶接剂的热膨胀系数，研究由热膨胀系数不同引起的钢铝胶铆复合连接结构的热变形。进行准静态和高速载荷作用下的钢铝胶铆接头拉伸试验，建立拉伸剪切有限元精细模型，研究高速冲击对胶铆接头失效行为的影响，并建立胶铆接头简化模型，提高有限元计算效率。本项目对温热胶铆连接技术进行了深入研究，实现结构轻量化设计和先进连接技术的结合，为异种材料连接结构设计提供科学依据和技术指导。