Study Of Damage Process Of Lap Joint Under Environmental Effect

Metal lap joint is a kind of force-bearing mechanism which connects metal components together by rivets and bolts.Under the action of environment this mechanism is easy to corrode between metals and cause structural expansion,which reduces its load-carrying capacity.In order to solve this problem,this paper firstly simulates the corrosion damage evolution process of iron and aluminium materials under environmental action by using cellular automata method,using MATLAB programming and Nernst equation,and obtains the topological diagram of corrosion damage evolution of two metal surfaces under different temperature and water humidity and the volume expansion ratio of corrosion products.The results show that with the increase of time,the corrosion rate of aluminium decreases gradually,while that of iron increases gradually;the corrosion products of aluminium expand about 6 times as much as that of matrix,and the corrosion products of iron expand about 4 times as much as that of matrix;the corrosion surface morphology of the two metals becomes more complex with time.Based on the above simulation results,the evolution process of corrosion products expansion and construction deformation of overlap joints made of metal iron and aluminum under environmental action was simulated.The stress of overlap plate and rivet of overlap joints was analyzed with beam theory.The results show that when crevice corrosion occurs between the interface of iron and aluminium lap joints,the expansion of corrosion products results in bending deformation of the lap plate,and the corrosion rate of iron increases with time,while that of aluminium slows down.The calculation and analysis show that the main factors causing the failure and failure of the overlap structure are the tension of the overlap plate and the bending moment at the end of the overlap plate.In this paper,the mainly work as follow:1.The background and significance of research on corrosion damage of lap joints are introduced.The main contents and research directions of corrosion damage of lap joints at home and abroad are summarized.Using metal standard electrode potential as material parameter of metal,the parameters that characterize metal material and its dissolution rate in simulation program-dissolution probability,environmental factors,temperature and water humidity are defined.2.The corrosion morphology and evolution of corrosion products of iron and aluminium under different environmental conditions were simulated.Based on the simulation results,the corrosion damage evolution process of two kinds of metal lap joints was simulated,and then the evolution law of mechanical properties of components with time was analyzed.