An Evaluation System For Fatigue Life Of Crane Metal Structures

In recent years,with the improvement of industrial productivity,the crane is used more frequently than in the past.In most cases,moreover,the metal structures of crane are subjected to high stresses.Therefore,the fatigue damage often occurred in the metal structures of crane,which might cause serious safety accidents.Aiming at the evaluation of fatigue life of metal structure,the researchers have done a lots of works which can be found in many issued publications.Some of them only focus on the theoretical studies and can't be directly applied to design metal structures of crane.In order to solve the problem,the primary techniques for evaluation the fatigue life of crane metal structures are studied comprehensively in this thesis,and then a special software package is developed using Visual Basic and secondary development tool APDL provided by ANSYS.In the package,the real operation conditions and technical requirements of crane are considered.The Engineering applications in design of overhead crane and gantry crane show that the package can improve the design efficiency and quality of metal structures.The main contents of this thesis are listed as follows:(1)In this paper,the research status of fatigue life of metal structure are summarized,and the fatigue life prediction methods are classified.This paper also generalized the theoretical knowledge which is applied in subject research,including parametric technology,finite element analysis technology,Visual Basic secondary development technology.(2)By means of ANSYS,the parameterized models of metal structures of two kinds of cranes are established and then their static analysis is carried out.As the engineering examples,one overhead crane QD15/6.5t-25.5m and one gantry crane MG30/20t-22 m are used to demonstrate the correctness of our parameterized models.(3)Under the premise of the metal structure satisfying the requirements of structural strength,three evaluation methods of fatigue life are presented,which are Paris Formula,mixed method combining Paris Formula with Miner linear cumulative damage theory and spot stress method.This paper also analyses and discusses the factors affecting the results of fatigue life.(4)By means of VB,the user-machine interface of the package is developed,which cover the numerical simulation and evaluation progress.The structural optimization module of metal structure is also added.The interface should be helpful for the automation and parameterization of evaluation of fatigue life.