铝合金自冲铆成形过程最大冲压载荷的反演模型

Inversion Model of Maximum Riveting Force in Aluminum Alloy Self-piercing Riveting Processes

基于材料塑性变形虚功原理并结合上限定理,展开自冲铆成形过程最大冲压载荷的反演分析。以成形接头几何特征参数(钉脚张开度、铆钉几何尺寸参数、被连接材料的厚度)、铆钉和被连接材料力学性能参数以及冲头与铆钉的接触面接触条件为反演计算模型的控制量,建立最大冲压载荷的反演计算模型;同时,针对多种铝合金自冲铆成形开展最大冲压载荷的验证试验研究。结果表明:所建立的反演模型计算值与试验值的平均误差为7.82%,验证了最大冲压载荷反演计算模型的有效性;最大冲压载荷与铆钉的强度、长度成正比,与铆钉内腔深度成反比,为获得静力学性能较优的自冲铆接头应适当增加铆接最大冲压载荷。此外,在相近的最大冲压载荷作用下,较低硬度的被连接材料搭配较低硬度的铆钉,易获得大张开度的接头。

Based on the virtual work principle of material plastic deformation and the upper bound theorem,the inverse analysis of maximum riveting force in the SPR processes was carried out.The inverse calculation model of maximum riveting force was established by taking the geometric characteristic parameters of the joints,such as rivet flaring,rivet geometry parameters,thickness of the connected material,mechanics properties of rivet and connected material,contact conditions between punch and rivet as the model control parameters.At the same time,the verification tests were carried out on the maximum riveting force for a variety of aluminum alloy SPR processes.The results show that average error between the model calculation value and test value is as 7.82%,which verifies the validity of the inversion model for the maximum riveting force.The maximum riveting force is proportional to the strength and length of the rivet and inversely proportional to the depth of the rivet cavity.To obtain self-piercing riveted joints with higher static performance,the maximum riveting force should be appropriately increased.In addition,under the action of near maximum riveting force,the connection materials with lower hardness and rivets with lower hardness are easy to obtain joints with large rivet flaring.