Study On Damage Constitutive Model Of Mild Steel Under Low Velocity Impact Loadings

The steel structures construction regarded as "green building" has been favored by many real estate developers.The steel structure has been widely used in all kinds of buildings due to its unique advantages.Nevertheless,during its service period,steel structure may suffer the lateral collision from vehicles,vessels and other dynamic loads.The steel structures under impact or sustained high strength loading will produce unrecoverable damage.Many researchers nationally and internationally have pay more attention to dynamic resistance of tubular structures or damage constitutive model of steel.However,There are a few studies concerning the joint-effect of impact-loading and damage on steel structures.Therefore,it is of great engineering significance to study the damage constitutive model of steel under impact loading.This research aims to study damage constitutive model of low carbon steel under low velocity lateral impact loading.The main aspects are listed as follows.(1)Based on continuum damage mechanics theory,Lemaitre strain equivalence principle,Von Mises yield criter,the theory of isotropic damage and so on,the damage constitutive model of mild steel after the ultimate strength is presented.According to the original Cowper-Symonds model,the Cowper-Symonds model simultaneously considering both the damage and strain rate effects is provided under impact loading.Experimental tensile test of steel under static loading and dynamic loading was conducted.The damage model is verified by comparing the model results with the experimental data.In addition,the data in the literature was calculated by the model presented in this paper,which aimed to verify the correctness of the model.The results show that the model results agree well with the experimental results,the model presented in this paper is feasible.(2)Experimental test of circular tube under lateral impact loading was conducted through the drop hammer rig.This experimental test provided experiment background in validating whether the damage constitutive model presented in this paper can be applied to the finite element model of the component.The mechanical mechanical persented by the experimental results were analyzed.(3)Finite element(FE)models of considering or non-considering on damage are established by using finite element software ABAQUS,and the finite element simulation results are compared with the experimental results.Based on the verification,the finite element simulation results considering damage are closer to the experimental results.In order to further verify the reliability of the constitutive model,the constitutive model of steel in the literature is modified into a constitutive model considering damage,the finite element simulation results considering damage are compared with the experimental results and the previous simulation results.It is proved that the damage constitutive model presented in this paper is reliable.