Finite Element Analysis And Welded Fatigue Life Prediction Of Hydraulic Excavator Working Device

Hydraulic excavator is a important construction engineering machinery, which is widely used in building industry, railway, water conservancy, the mining industry, national defense project, and urban construction and so on, which played a decisive role in the modern engineering construction. Hydraulic excavator working performance is mainly decided by the working device. Because of its working Characteristic, the working device of excavator generates failure with the severely shock vibration, such as resonance, structural deformation, fatigue wear and so on. So excavator working device’s performance is directly reflected by reasonable structure and flexible reliable and durable working process. Therefore, the study of excavator working device has a very essential significance.The research object of this paper is a medium hydraulic excavator working device. First, the excavator’s digging resistance and theory excavating force are calculated by theoretical analysis. A calculation model for combined work condition is established. Second, Full threedimensional integrated finite element model(3-D FEM) for the hydraulic excavator was established using ANSYS Parametric Design Language(APDL). Static analysis of four dangerous working conditions was carried out. The detailed stress distribution and deformation of the excavator could be obtained. Natural frequencies and vibration modal shapes of the structure are also derived from the modal analysis. Next, the 3D model of equipment was imported into ADAMS by interface software Solidworks, the paper does dynamics simulat ion systematical y. Then stress time history of fatigue assessment points were calculated in the finite element software of ANSYS by using results of hinge point force of the working device by simulation calculation.The load history of the working device of each fatigue sssessment points are obtained in the paper. Finally, the welded fatigue theory and the fatigue assessment standards Institute of Welding IIW standard and British Steel structure BS standard which are widely used in the current international are introduced. and the obtained stress time histories are analyzed with rain-flow counting method. Based on Miner damage theory, the welding fatigue life of the working of each fatigue assessment points is estimated by using above two kinds of fatigue assessment standard.The methodology developed in this study can be used to provide useful guidance to the design of other cranes of the same or similar types.