A Study On Damping Mechanism Of Magnesium Alloy Based On Molecular Dynamics

With the development of the industry and transportation,the vibration and noise problems become increasingly serious and are urgently needed to solve.The development and application of high damping alloys is one of the effective measures to achieve vibration and noise reduction.High damping alloys can be directly used to make structural parts subject to vibration without additional damping measures,and can work well in the harsh working conditions.Mg alloys,as the most promising light metal in the 21 st century,are widely used in the aerospace industry,automobile manufacturing,and electronic field because of its excellent damping performance.However,the high damping capacity and good mechanical properties of Mg alloys cannot be acquired simultaneously.How to optimize mechanical and damping properties of Mg alloys is important.In this study,the models of Mg and Mg alloy containing alloy phase are constructed.The molecular dynamics(MD)method was used to study the damping mechanism in Mg alloys at the atomic scale.The result shows that the energy dissipated within Mg are mainly from the nucleation and motion of dislocations and defects friction.Different kinds of defect have different effects on the dislocation damping and defect friction damping.And the damping capacity of Mg have temperature and amplitude dependency.Besides,the effect of content and the degree of solidification of alloy phase on damping capacity of Mg alloy under different ambient conditions was studied.The specific work is as follows:(1)The traditional LAMMPS internal modeling method was analyzed by building Mg model,and a modeling method based on Fortran programming was proposed.Based on this method,the models of Mg-Al alloy containing alloy phase were constructed.(2)Models of Mg containing different kinds of defect were established,and subjected to tensile strain.Based on the system energy exchange and the observation of the defects motion,the dislocation energy dissipation was investigated.Frictional energy dissipation between different kinds of microscopic defect was studied by using non-equilibrium oscillatory shear deformation simulations.And then,the temperature and amplitude dependency of Mg damping was investigated.(3)The models of Mg-Al alloy containing alloy phase were constructed.The effect of temperature,frequency,amplitude,and the content and degree of solidification of alloy phase on the damping of Mg alloy was studied.The research in this paper can provide theoretical guidance for the future design and fabrication of high strength,high damping Mg alloys.