汽车起重机螺栓副失效振动试验研究

Vibration Testing Analysis on the Fracture of Truck Crane's High Strength Bolt

汽车起重机回转机构在运行时会发生振动,通过对靠近高强度螺栓联接副部位振动物理量如振动加速度或位移等的测量,可以获得高强度螺栓联接副受力状态的信息,分析该信息来诊断高强度螺栓发生故障的原因是可行的。模拟实时现场事故工况振动测试分析结果表明,在港口吊装现场发生的一起进口大型汽车起重机高强度螺栓断裂失效事故的原因是:由于在起吊过程中运行速度过快,产生了较大的冲击载荷,由此导致起重机在较宽频率范围内的振动幅值过大,引起螺栓预紧力发生变化,从而导致个别螺栓高周低应力弯曲疲劳断裂或松动。动栽作业过程中的冲击载荷以及超负荷因素的综合作用所导致了该故障的发生。

Truck crane＇s slewing gear produces vibration signals in operation,which consist of plenty of information about its bearing force of high strength bolt, and it can be measured by transducers such as accelerator or displacement transducer. Therefore, it is necessary that fault diagnosis be based on bearing force signal in high strength bolt. The vibration testing analysis is applied to stimulating the operation mode of the failure happening. The above analyses demonstrated the cause of the fracture of imported large scale truck crane＇s high strength bolt happened on the scene of truck crane boom＇s hoisting at port：Due to crane boom＇s running too fast and lifting frequently, a greater impact load caused the high vibration amplitude in a wide frequency range, leading to a few bolts＇high cycle bending fatigue fracture with low stress or loosening when the required prestressing force changes. The combination factors of the impact load and overload caused the fault during the dynamic lifting process.