Fatigue Life Inspection Of Bridge Crane Girder

Bridge crane is an important freight transport machinery in modern industry, which can save physical labor and improve working efficiency. It is widely used in mineral and metallurgical industries, and therefore is known as the “industry backbone”. Under the high load and frequency working condition, stress concentration regions of the crane girder are prone to fatigue damage, which may lead to fatigue failure. Usually, the fatigue failure occurs suddenly without obvious plastic deformation and result in accidents and casualties easily. Therefore, monitoring force data and fatigue damage of the crane in the using process have an important significance to predicate the fatigue life of girder accurately.According to the car positions,this paper performs a finite element analysis of 50/10 t bridge crane girder model by ANSYS Workbench to carry out stress and deformation nephograms in several working conditions. Analysis results show that the maximum stress appears in condition 3, in which the car is at the quarter of girder. The max stress is 143.37 MPa and the max deformation is 5.2 mm. According to the stress nephograms and deformation nephograms of girder in all working conditions, the stress concentration regions are located in the girder ends of variable cross-section areas. The stress of the joint between web and cover plates is also bigger than other parts of girder. These regions are prone to fatigue damage, which should be paid more attention in subsequent girder stress test and be distributed the measuring points.After the girder stress concentration positions, a bridge crane girder strain data acquisition system is designed based on Virtual Instrument. This system can realize the data real-time acquisition and continuous storage, obviously meeting the girder fatigue life analysis requirements. In the steel factory, girder strain data of several positions during several days were measured and acquired in real time by this the measurement system. In the process of testing strain data, channel data for transmission signal run stability, and database is preserved completely. With the data processing in laboratory ending, it finally obtained the girder fatigue life by the girder material S-N curve of Q235-B and fatigue damage cumulative rule.In order to predicate fatigue life of the girder, the project provides a significant guidance for testing, repair and accurate scrap, which can avoid potential safety caused by crane overtime service, prevent the resources waste of crane ahead scrap, ensure the normal production of enterprise and arrange tasks more reasonably.