Numerical Analysis Of Mechanical Properties Of Cylindrical Shells Under Low Speed Lateral Impact Load

Cylindrical shell structure is favored by civil and national defense industries because of its special structural form and good mechanical properties.However,during the normal working period,the cylindrical shell structure may be subjected to accidental loads such as impact force and explosion force,resulting in the loss of stability and overturning of the structure,or structural fracture and damage,which has caused great harm to people’s life and property safety.Therefore,numerical simulation method is used to study the mechanical properties of cylindrical shell structure under low-speed lateral impact load.The main work contents are as follows:(1)The finite element model of cylindrical shell structure under lateral impact load is established.The results show that the finite element model established in this paper can well simulate the dynamic response of cylindrical shell structure under lateral impact load.It is found that changing the local refined mesh size,strain rate parameters and material strength at the constraint position will have a great impact on the dynamic response of the structure.(2)The verified finite element model is used to analyze the dynamic response of cylindrical shell structure under single lateral impact load.The main research contents include deformation mechanism,impact force and mid span displacement,stress development,strain rate distribution and energy change.The results show that the cylindrical shell structure mainly produces the coupling deformation of local depression and overall bending under the action of single lateral impact load.The plastic region is mainly concentrated in the impact position and constraint position,forming an obvious "three plastic hinge" mechanism,Therefore,the strain rate at the plastic hinge is large,the material stress level is high,and the main energy dissipation mechanism of the structure is the plastic deformation of "three plastic hinges".The main parameters affecting the dynamic response of cylindrical shell structure under single impact load are analyzed.The results show that the parameters drop weight,drop speed,structure diameter and structure wall thickness have a positive correlation with the peak value of impact force and deflection of impact part,and a negative correlation with impact time;The span of parametric structure and impact position are just the opposite.(3)The dynamic response of cylindrical shell structure under multiple lateral impact loads is analyzed.The results show that before the appearance damage does not appear,with the increase of impact times,the impact peak value of the structure gradually increases,while the impact duration gradually decreases,the midspan displacement in each impact process gradually decreases,and the energy absorption capacity of the structure gradually increases.(4)The finite element model of residual bearing capacity of cylindrical shell after impact is established.The mechanism of residual bearing capacity of cylindrical shell after impact is analyzed.The results show that the residual bearing capacity of cylindrical shell after impact decreases due to the existence of second-order effect,and finally V-shaped overall instability failure occurs.Through the investigation of the parameters affecting the residual bearing capacity of the structure after impact,it is found that the falling weight mass,falling speed,impact position and end restraint position have a positive correlation with the residual bearing capacity,and the structural wall thickness has a negative correlation with the residual bearing capacity.(5)Through the collation and analysis of the example results,it is found that there is a strong regularity between the residual bearing capacity of the structure after impact and the deflection under impact,so the prediction formula of the residual bearing capacity is fitted.