The Response Characteristic Of High-speed Groovedtapered Projectile Penetrating Into The Concrete

In this dissertation,the mechanical model of high-speed grooved-tapered projectile penetrating into the concrete as well as the structure response and trajectory deflection are studied with the experiment research,numerical simulation approaches and theoretical analysis.The cavity expansion theory with shear-dilatancy is established,then the mechanical model of the grooved-tapered projectile with high and low velocity is built.Both the dynamic structure response and the trajectory stability of the grooved-tapered projectile are analyzed as well.The research results provide a theoretical basis for predicting the depth of penetration,structure response and trajectory stability when projectile penetrating the concrete with high speed.(1)The dynamic spherical/cylindrical cavity expansion models are established in view of both the shear-dilatancy and compressibility of the concrete.The response status of concrete in different conditions can be reflected by the model which describes projectiletarget interaction mechanism well.And the model can provide the theoretical basis for calculating the force exerted on the surface of the grooved-tapered projectile.The influence of the strength parameters and compression factor on depth of penetration are also analyzed.(2)Based on the cavity expansion theory and the experimental phenomena,combined with interaction mechanism between projectile and target,the models of the petaling penetration with low speed and round-hole penetration with high speed are put forward in this dissertation,where the spherical cavity expansion and cylindrical cavity expansion theory are applied on the nose and tapered body respectively.The influence of the structural elements on depth of penetration is discussed with rigid hypothesis.The results show that the model can accurately describe interaction mechanism when grooved-tapered penetrating the concrete.(3)The dynamic response of projectile with different structures(grooved-tapered,conic,cylinder)are researched from macro perspective and the transient perspective.In macro perspective,the rigid plastic theory is built for projectile with different structures.In the view of transient,numerical experiments are conducted with LS-DYNA where the axial force,moment and shear force of each section of the projectile are calculated.The applicability of yield function and rigid plastic theory are verified.The critical condition of maintaining structural stability based on the rigid plastic theory is obtained for grooved-tapered projectile oblique penetration the concrete in different conditions.(4)The trajectory calculation model for rigid projectile with different structures is established according to the thought of target separation and cavity expansion theory with shear dilatancy.The experiments of penetration trajectory with different structures of projectile are conducted,where both the trajectory calculation model and projectile-target interaction parameters are verified.The influences of the approaching angle,conic angle,groove radius,angle of oblique and angle of yaw on the trajectory and attitude angle are all investigated.The penetration trajectory of grooved-tapered,conic and cylinder projectile are compared,providing the reference for projectile structure design in this dissertation.