Pitting Corrosion And Its Numerical Simulation Based On Peridynamics

The metal material of aluminum and aluminum alloy is widely used in the national economy,and because the light weight,high strength,corrosion resistance and other properties of aluminum and aluminum alloy that is widely used in aviation,spaceflight,navigation,some as load-bearing components,some as parts,exposed to different service environment.Pitting corrosion is one of the most important forms of corrosion damage in aircraft structure,which not only affects the appearance,but even affects the flight safety and service life of the aircraft.Therefore,it has a great theoretical significance and practical application value to study the corrosion behavior and the corrosion rate of aluminum alloy.In this paper,the pitting corrosion test of LY12CZ aluminum alloy was carried out by referring to the standards of the American Institute of material testing.The control effect of change of three main factors of pitting during the experiment:the initial surface state,ambient temperature,corrosion time,and then establish the mixed model of peridynamic method and finite element method in COMSOL software to simulate the pitting,which that the purpose is to prove the reliability and accuracy of the simulation.Before the experiment,scanning the specimen using the shapix scanner.And using electrochemical workstation record polarization curve of electrochemical reaction of pitting in the experiment.After the corrosion experiment,the surface damage morphologies were observed and photographed by using a scanner and optical microscope for the morphology analysis.From the surface morphology of corrosion,we can see that the corrosion degree in high temperature conditions is generally more serious than low temperature.And we also derived from corrosion data,pitting corrosion rate under high temperature higher than at low temperature,which showed that under high temperature peridynamic bond between the nodes in the matrix of aluminum alloy is prone to fracture.The experimental results show that the surface damage is small under the temperature of 25 ? for 2 hours,and pitting pit is scattered,small in size.But with the extension of time,the number of pits be increases and the size increases.Under 40 ? and 55 ? and with corrosion time extension,pits enlargement and present as oval.And there will be interconnected phenomenon between pits,caused a large number of bond is fractured,metal dissolution and damage.In COMSOL software,the model be established which is combined with the peridynamics and finite element method and the pitting process of aluminum alloy be simulated.By setting the electrochemical parameters of the simulation,the corrosion process of the model with initial pit is simulated.From the simulation results,we can observe the change of the pit size and the evolution process of the pit profile,and the contour dimension of the pit gradually increases with time.The values of corrosion rate from the simulation compared with the experimental obtained are very close,which proved that the simulation model can make the pitting of the aluminum alloy were presented,to predict the corrosion rate,and the model can well reflect the actual situation.The results proved the feasibility of this simulation model.