Research On Life Prediction For The Weld Structure Of Overhead Travelling Crane Girder

Overhead travelling crane is a requisite engineer equipment of the industrial transport in out country and it broadly used in dockyard and port as a large handling equipment to improve the capacity of handling operation. The box girder of the overhead travelling crane is a typical large welded structure. It is inevitably exist welding defect, such as inclusion, snick, crimping, crack and so on. The fatigue damage such as open welding, cracking or fracture will lead to fatigue failure of bridge crane metal structure. The girder of overhead travelling crane has a complex structure so it inevitably existence the stress concentration region. These region easiness to emerge cracks and eventually lead to fracture when endure the random alternating loads. Therefore, the welding position and stress concentration region of the main girder is the focus of our testing.In view of the complex structure of the overhead travelling crane girder, it is inevitable appear stress concentration position. And those position may prior appear fracture when endure random alternative load. So the detection should attach importance to stress concentration position. Carried out a numerical analysis using the finite element software ANSYS. By analyzing, found the stress and strain distribution and definitude risk position of the girder. And proceed evaluate to static and dynamic properties of overhead travelling crane girder.Because of the girder endures random alternative load, original load data cannot directness design to fatigue life prediction and fatigue experiment. So must proceed counting dispose to the original load data. According to the result of measurement and finite element analysis, using the method of rain-flow and fluctuation central to compile the open-type stress load spectrum of the fracture in girder. It provide important basis for fatigue experiment and fatigue life prediction.Application of VC++ compiled the bridge girder state evaluation and life prediction system. The main basis for the state evaluation system is"Requirements and methods of crane supervision and inspection", and the system can evaluate the overhead travelling crane whole working condition and supply basis for fatigue life prediction. The main basis for the life prediction system is local stress-strain method,fracture mechanics and linear fatigue cumulative theory. Incorporation load spectrum and material property parameter, the system can convenience prediction fatigue life of fracture initiation phase and crack propagation phase. Apply the system and the open-type stress load spectrum of one fracture in girder to predict the crack propagation life of the girder.