Numerical and theoretical studies on axial impact between rods with various noses and a rigid wall

Rod drops at times and collides with a substrate, which induces vibration within the rod. The vertical impact between slender rods with different noses and a rigid flat is theoretically and numerically investigated. Equivalent linear contact model for different rod noses are established, based on which a semi-analytical model describing the longitudinal vibration of the rods are derived using 1D wave equation. The predicted displacements agree well with the numerical results. Plastic deformation is mainly concentrated in the rod nose, and the cylindrical part of the rod basically remains elastic. The displacement difference between the top and bottom point represents the compression extent of the cylindrical part, whose variation tendency is consistent with strain energy of the rod. Vibration responses and energy shares of the rods are compared, and sharper truncated-cone nose exhibits better buffering effect. Hemisphere nose is preferred when the plastic dissipation and compression extent are similar due to lower impulse.