Crane Structure Failure Diagnosis Based On Finite Element Method And Fracture Mechanics

In recent years,along with the highly developed economy of our country,the production of steel rises increasingly,the load works of cranes have enlarged in metallurgical enterprises-At the same time,there appear all kinds of metal problems.Among these problems the most common and also the most serious is the trouble in crane metal structures which mostly are troubles of fatigue crack.This paper engage in the analysis of crack on the 70/20t-16.5m overhead crane in the second rolling mill of Ma steel Corp.For the prime causes of crack on the overhead crane, use finite element method to establish the finite element method (FEM) of metal structure of the overhead crane fram, different models of load under different working conditions is presented by finte element analysis,find out pinpoint the cause of the trouble from the contrast and analysis of the static loads and fatigue life,on this basis,further study on propagation behaviour of overhead crane fram fatigue crack by numerical analysis,provide the theory basis for the restoration and improvement design of the overhead crane and the same type. This paper has completed the following research work to solve the problems:1) Presents the analysis and research on the fram metal structure crack to find out the reasons of the fracture,use the ABAQUS finite element software to perform the overhead crane fram metal structure static analysis,It was found on analysis that the large height difference of wheels bearing point is the main reason of causing crack.2) Mostly researched extended finite element method(XFEM) theory and the computational Method of Stress intensity factors(SIFs) in recently, to set off by contrast on FEM computational Method of SIFs and XFEM computational Method of SIFs to show the high efficiency and practicality of XFEM this new technique on the SIFs calculation, provide a technology support for the overhead crane fram fatigue crack growth numerical analysis.3) According to theory of engineering rupture mechanics,consider the Initial Defect of the overhead crane metal structure, fatigue crack growth of the fram under cyclic stress are studied,modelâ… modelâ…¡and modelâ…¢Stress intensity factors(SIFs) of cracks having different length are calculated by using extended finite element method(XFEM),then fatigue crack propagation curve was gained by the Mixed Mode fatigue crack growth theory,fundamental laws of fatigue crack growth with the object of study was described precisely, established function between crack length and the number of alternating stress cycle, numerical analysis on propagation features of the fatigue crack.4) The repair plan and specific repair measures was gived basis on the crack arrest theory and method,and calculated the stresses distribution of the fram where the danger crack after the repairment, the results indicated that the strength of overhead crane fram meets the requirement.