双层铝合金板的圆柱铆钉式新型平底铆压连接塑性变形机理及材料流动行为

It is not suitable to use resistance welding process for joining aluminum alloy sheets on the light-weight automobile. Therefore, plastic joining process using plastic deformation to form the mechanical interlock becomes the main solution for joining aluminum alloy sheets on the light-weight automobile. However, the strength of the traditional mechanical clinching is low, and the price of the rivet used in the self-pierce riveting process is high. In addition, the bottom of the self-riveted joint is not flat. Thus, a new flat riveting process with a cylindrical rivet was proposed. The evolution law of stress field, strain field and velocity field and material flow behavior in the flat riveting process will be investigated, and the internal microstructure, grain size and microstructure evolution of the flat riveted joint will be gotten. The influence law of geometrical parameters of the mechanical interlock, microstructures, and mechanical properties of the joint will be revealed. The influence of rivet parameters, processing parameters, die parameters, and sheet parameters on the plastic deformation and material flow will be revealed, and the reasonable joining parameters will be gotten. The mechanical state of mechanical interlock under different loads will be analyzed. The calculation formula for tensile and shear strength of the flat riveted joint will be derived. The influence factors and mechanism for the strength of the flat riveted joint will be revealed.

轻量化汽车铝合金板材覆盖件的连接不宜采用电阻焊的工艺方式，因此，依靠塑性变形原理形成机械锁实现连接的塑性成形连接方式已成为连接轻量化铝合金车身的主要解决途径。但传统的无铆钉塑性连接方式连接强度低，而冲铆塑性连接方式采用的中空式铆钉价格昂贵且连接点底部不是平面。为此，本项目提出了圆柱铆钉式新型平底铆压塑性连接方式。研究双层铝合金板圆柱铆钉式平底铆压塑性连接过程中应力场、应变场、速度场的演化规律和材料流动行为，得到平底铆压塑性连接点内部微观组织和晶粒度的演变规律，揭示机械锁结构参数、微观组织演变和连接点力学性能之间的影响规律；揭示不同铆钉参数、工艺参数、模具参数和板材参数对平底铆压连接塑性变形和材料流动行为的影响规律及机制，得到适用于平底铆压连接的合理连接参数；分析机械锁结构在不同加载方式下的受力状态，构建平底铆压连接抗拉和抗剪强度数学表达式，揭示平底铆压连接强度的影响因素及作用机制。

轻量化汽车铝合金板材覆盖件的连接不宜采用电阻焊的工艺方式，因此，依靠塑性变形原理形成机械锁实现连接的塑性成形连接方式已成为连接轻量化铝合金车身的主要解决途径。但传统的冲铆塑性连接方式采用的中空式铆钉价格昂贵且连接点底部不是平面。为此，本项目提出了圆柱铆钉式新型平底铆压塑性连接方式。研究了双层铝合金板圆柱铆钉式平底铆压塑性连接过程中应力场、应变场、速度场的演化规律和材料流动行为，揭示了机械锁结构参数和连接点力学性能之间的影响规律；揭示了不同铆钉参数、工艺参数、模具参数和板材参数对平底铆压连接塑性变形和材料流动行为的影响规律及机制，得到了适用于平底铆压连接的合理连接参数；分析了机械锁结构在不同加载方式下的受力状态，揭示了平底铆压连接强度的影响因素及作用机制。本项目的研究给铝合金板材的连接问题提供了新的解决方案，有利于推动铝合金材料及其连接技术在工程领域内的广泛应用。