Based on the geometrically nonlinear theory of axially extensible elastic rods, the governing equations of post_buckling of a clamped_free rod with variable cross_sections, subjected to a combined load, a concentrated...Based on the geometrically nonlinear theory of axially extensible elastic rods, the governing equations of post_buckling of a clamped_free rod with variable cross_sections, subjected to a combined load, a concentrated axial load P at the free end and a non_uniformly distributed axial load q, are established.By using shooting method, the strong nonlinear boundary value problems are numerically solved. The secondary equilibrium paths and the post_buckling configurations of the rod with linearly varied cross_sections are presented.展开更多
The key technique of a kinetic energy rod(KER) warhead is to control the flight attitude of rods. The rods are usually designed to different shapes. A new conceptual KER named profiled rod which has large L/D ratio is...The key technique of a kinetic energy rod(KER) warhead is to control the flight attitude of rods. The rods are usually designed to different shapes. A new conceptual KER named profiled rod which has large L/D ratio is described in this paper. The elastic dynamic equations of this profiled rod flying at high velocity after detonation are set up on the basis of Euler-Bernoulli beam, and the aeroelastic deformation of profiled rod is calculated by semi-analytical method for calculating the vibration characteristics of variable cross-section beam. In addition, the aeroelastic deformation of the undeformed profiled rod and the aeroelastic deformation of deformed profiled rod which is caused by the detonation of explosive are simulated by computational fluid dynamic and finite element method(CFD/FEM), respectively. A satisfactory agreement of these two methods is obtained by the comparison of two methods. The results show that the semi-analytical method for calculating the vibration characteristics of variable cross-section beam is applied to analyze the aeroelastic deformation of profiled rod flying at high velocity.展开更多
A slender rod suffers global vibration in impact.In this study,we present the experimental,numerical,and theoretical studies of the axial responses of a 316 stainless steel rod during vertical impact with a rigid flat...A slender rod suffers global vibration in impact.In this study,we present the experimental,numerical,and theoretical studies of the axial responses of a 316 stainless steel rod during vertical impact with a rigid flat.Combining the contact models and the one-dimensional(1D)wave equation,we first develop a semi-analytical vertical impact model for the rods based on a unified theoretical framework,which considers different geometries of the impacting end including the hemispherical nose,the truncated conical nose,and the flat end.Furthermore,we perform free-drop experiments on these rods and numerical simulations to verify the theoretical models.The results show that the strain-rate effect hardens the rod nose and should not be ignored even at a velocity as low as a few meters per second.After the proposal of a dynamic correction factor to adjust the quasi-static contact model,the theoretical,numerical,and experimental results agree well with one another.Also,the threedimensional(3D)FEM simulations show that the slight deviations between the experimental and the predicted results are due to the slight obliqueness of the rods in the drop.Additionally,we leverage the theoretical tool and FEM simulations to compare the mechanical responses of rods with different impacting ends,and suggestions about the selection of rod noses are obtained.展开更多
文摘Based on the geometrically nonlinear theory of axially extensible elastic rods, the governing equations of post_buckling of a clamped_free rod with variable cross_sections, subjected to a combined load, a concentrated axial load P at the free end and a non_uniformly distributed axial load q, are established.By using shooting method, the strong nonlinear boundary value problems are numerically solved. The secondary equilibrium paths and the post_buckling configurations of the rod with linearly varied cross_sections are presented.
文摘The key technique of a kinetic energy rod(KER) warhead is to control the flight attitude of rods. The rods are usually designed to different shapes. A new conceptual KER named profiled rod which has large L/D ratio is described in this paper. The elastic dynamic equations of this profiled rod flying at high velocity after detonation are set up on the basis of Euler-Bernoulli beam, and the aeroelastic deformation of profiled rod is calculated by semi-analytical method for calculating the vibration characteristics of variable cross-section beam. In addition, the aeroelastic deformation of the undeformed profiled rod and the aeroelastic deformation of deformed profiled rod which is caused by the detonation of explosive are simulated by computational fluid dynamic and finite element method(CFD/FEM), respectively. A satisfactory agreement of these two methods is obtained by the comparison of two methods. The results show that the semi-analytical method for calculating the vibration characteristics of variable cross-section beam is applied to analyze the aeroelastic deformation of profiled rod flying at high velocity.
基金supported by the National Natural Science Foundation of China(Grant Nos.12102046 and 12272203)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(CAST)(Grant No.YESS20220046)China National Nuclear Corporation(CNNC)Young Talents Program(Grant No.2022-379-3-THU-YE)。
文摘A slender rod suffers global vibration in impact.In this study,we present the experimental,numerical,and theoretical studies of the axial responses of a 316 stainless steel rod during vertical impact with a rigid flat.Combining the contact models and the one-dimensional(1D)wave equation,we first develop a semi-analytical vertical impact model for the rods based on a unified theoretical framework,which considers different geometries of the impacting end including the hemispherical nose,the truncated conical nose,and the flat end.Furthermore,we perform free-drop experiments on these rods and numerical simulations to verify the theoretical models.The results show that the strain-rate effect hardens the rod nose and should not be ignored even at a velocity as low as a few meters per second.After the proposal of a dynamic correction factor to adjust the quasi-static contact model,the theoretical,numerical,and experimental results agree well with one another.Also,the threedimensional(3D)FEM simulations show that the slight deviations between the experimental and the predicted results are due to the slight obliqueness of the rods in the drop.Additionally,we leverage the theoretical tool and FEM simulations to compare the mechanical responses of rods with different impacting ends,and suggestions about the selection of rod noses are obtained.
