Study On Dynamic Mechanical Properties Of Magnesium Alloy And Its Application In The Car

In recent years,with the rapid development of economy in China,the numbers of car continue to increase.People travel is becoming more and more convenient.While the increasing of automobile population caused some social problems,especially more and more serious environmental pollution which is related to the sustainable development of human beings.So reduce fuel consumption and reduce vehicle emissions has become the main direction of automotive engineering.One of the most effective measures to solve the above problems is automobile lightweight,which mainly includes lightweight structural design and lightweight materials in two ways.For the former,there is little improve space after a long time of study and improving.However,the latter brings a broader development space for automobile lightweight with the development of science and technology and the emergence of new materials.This paper focuses on the study of the new magnesium alloy materials.One of the main obstacles to the application of magnesium alloys is the complex plastic deformation mechanism and failure criterion.The poor flexibility of Magnesium alloy makes it easy to fracture in the collision.This has become a most important proplem for automobile safety.In order to reduce development costs,nonlinear large deformation finite element simulation is used to accurately predict the deformation and fracture of magnesium alloy in automobile structure design stage.The key is the plasticity and fracture model of magnisum alloy material.There is no better material model about this material in the world,so this is one of hot topics.In view of the above situation,this paper analysis the mechanical properties of AZ31 B magnisum alloy which showed obvious anisotropic characteristics by many material tests(including tensile,compressive,shear and notch tests).The JC model and the Hill48 model with the associated flow rule were compared with the experimental data.The Hill48 constitutive model has higher accuracy for predicting the material properties of AZ31 B magnesium alloy.Finite element simulation of tensile,compression,shear and notch test have been done by LS-DYNA software comparing with test data to validate the accuracy of the model.Material card which is made by the Hill48 model and LS-DYNA software are used to design the front beam tube by replacing the material of the front beam tube.studying the safety performance of automobile front beam tube before and after replacement.In addition,optimal thickness is determined to make sure the automobile front beam tube having the better safety performance compared to that before the material is replaced.Only simulation of vehicle collision is finished due to the limitation of the experiment condition.The material research results show that AZ31 B magnesium alloys have low elongation and obvious tension-compression asymmetry.There is no obvious neck shrinkage in the experiment.Magnesium alloy showed a significant positive strain rate correlation with the increase of the strain rate.And with the increase of the tensile strain,the anisotropy of the material decreases.Isotropic JC model is not suitable for AZ31 B magnesium alloy materials,the anisotropic model Hill48 model can be more accurate to predict the properties of AZ31 B magnesium alloy materials.