Research On Dynamic Constitutive Model At High Temperatures And High Speed Impact Performance Of GH4169

The containment of Aeroengine casing is a necessary requirement to ensure the safety and reliability of engine work.Turbine casing will be subjected to dynamic impact when turbine blades fly off to impact turbine casing.Therefore,it is very important to study the dynamic mechanical properties and constitutive models of casing materials at high temperatures.The typical material of the turbine casing in aeroengine is GH4169 superalloy,Taking GH4169 as the object the research on the impact resistance of single and double GH4169 target plates under normal temperature and high temperature is of great reference value for the research of turbine containment.In this paper,the following work is completed in combination with the experiment,theoretical analysis and numerical simulation.(1)The quasi-static and dynamic mechanical properties of GH4169 materials were studied and the dynamic constitutive model of GH4169 superalloy was fitted.By using MTS composite loading fatigue test machine,the quasi-static tensile test of GH4169,through GH4169 smooth specimen tensile test,obtained elastic modulus and failure strain.Through GH4169 notched specimen tensile test,GH4169 stress and failure strain of three axis is obtained.Taking the separated Hopkinson test device as the research platform,the mechanical properties of GH4169 superalloy under high strain rate were studied under the temperature of 20~500 ? and the strain rate of 10-3 ~ 4000/s.The stress-strain curve of the alloy at different temperatures and different strain rates were obtained.The experimental results show that GH4169 superalloy meets the strain rate hardening effect and temperature softening effect.(2)Johnson-Cook constitutive model and Zerilli-Armstrong constitutive model are used to establish the dynamic constitutive relation of GH4169 superalloy.The two models can effectively describe the material deformation behavior of GH4169 superalloy at different temperature and strain rate range.(3)The high-speed impact test of single-layer and double-layer GH4169 superalloy simulator casing under high temperature environment was carried out.The single-layer and double-layer high-speed impact tests were carried out to study the relationship between velocity or loss kinetic energy of simulated flat blade and temperature.At the same impact velocity,the higher the temperature,the greater the residual velocity of the simulated blade,the less the loss kinetic energy of the simulated blade.The impact resistance of the double-layer GH4169 target plate is stronger than that of the single GH4169 target.The double-layer GH4169 target with 6mm spacing is better than the double-layer GH4169 target plate with the spacing of 4mm.(4)The numerical simulation model was established by LS-DYNA.The Johnson-Cook constitutive model parameters and the Johnson-Cook failure model parameters were fitted.The simulation results were compared with the experimental results.The simulation results show that the simulation results are in good agreement with the experimental ones on the remaining velocity of blade and on the kinetic energy loss of the blade,with a slight difference in the damage morphology.The reason for this is that the simulated flat blade has yaw angles when impacted on the target plate,which leads to the difference of the damage morphology.Through double-layer high-speed impact simulation,the containment performance of 6mm spacing double GH4169 target plate is stronger than that of 4mm spacing.The enhancement of containment performance is mainly due to the increased energy absorbed by the outer target plate,while the energy absorbed by the inner target plate is not very different.