板簧卷耳断裂分析与研究

Analysis and research on fracture of coil ear of plate spring

对国内某主机厂VAN类商用车可靠性试验过程中后钢板弹簧前卷耳(下卷耳结构)多次断裂故障进行研究。由板簧断裂样品断口理化检验判定断裂原因并非制造工艺;对板簧卷耳进行理论应力校核,并结合其传统国标台架试验的故障模式,重点分析板簧悬架系统的结构形式、运动特性;通过多体动力仿真分析建立卷耳局部坐标系,针对板簧卷耳分解挠度形变分析各工况下的冲击形变量,分析悬架在车轮紧急制动、转向和垂向冲击过程中对板簧卷耳扭转、剪切应力的影响;对下卷耳式板簧结构进行受力分析,并完成板簧悬架系统多通道台架试验。提出通过增加主簧卷耳厚度方式降低卷耳弯曲应力的解决措施。

The failure of the front roll lug(bottom roll lug structure) of the rear leaf spring during the reliability test of VAN commercial vehicle in a domestic OEM was analyzed and studied.First of all,the physical and chemical test of the fracture sample of the leaf spring(hereinafter referred to as "leaf spring") was preliminarily analyzed,and it was preliminarily determined that the manufacturing process of the leaf spring was not the true cause of fracture.Secondly,combined with the fatigue performance of the spring in the traditional bench test and the stress impact check of the coil lug theory,the structural form and movement characteristics of the spring suspension system were analyzed.At the same time,the local coordinate system of the coil lug was established through multi-body dynamic simulation analysis,and the impact shape variables under various working conditions were analyzed according to the decomposition deflection deformation of the coil lug of the plate spring,and it was determined that the suspension had a significant impact on the torsion and shear stress of the coil lug of the plate spring during the process of emergency braking,steering and vertical impact.The force analysis of the lower coil lug type leaf spring structure of this model was made,and the comparison showed that the lower coil lug type leaf spring had a larger bending moment than the traditional upper coil lug and flat coil lug structure.Moreover,the theoretical analysis had been effectively replicated in the multi-channel bench test of the leaf spring suspension system.Finally,by increasing the thickness of the main spring coil ear,the bending stress of the coil ear was effectively reduced,and the fatigue life of the coil ear was effectively increased.