Dynamic finite cylindrical cavity-expansion models for cellular steel tube confined concrete targets normally impacted by rigid sharp-nosed projectiles

Cellular steel-tube-confined concrete (CSTCC) targets show improved anti-penetration performance over single-cell STCC targets due to the confinement effect of surrounding cells on the impacted cell. Dynamic finite cylindrical cavity-expansion (FCCE) models including radial confinement effect were developed to predict the depth of penetration (DOP) for CSTCC targets normally penetrated by rigid sharp-nosed projectiles, and stiffness of radial confinement was achieved with the elastic solution of infinite cylindrical shell in Winkler medium. Steady responses of dynamic FCCE models were obtained on the assumption of incompressibility of concrete, failure of comminuted zone with Heok–Brown criterion and two possible response modes of the confined concrete in the impacted cell. Furthermore, a DOP model for CSTCC targets normally impacted by rigid projectiles was also proposed on the basis of the dynamic FCCE approximate model. Lastly, relevant penetration tests of CSTCC targets normally penetrated by 12.7 mm armor piecing projectile (APP) were taken as examples to validate the dynamic FCCE models and the corresponding DOP model. The results show that the DOP results based on dynamic FCCE model agree well with those of the CSTCC targets normally penetrated by rigid conical or other sharp-nosed projectiles.

Non-stationary dynamics of anisotropic Kirchhoff-Love type shel

Строится нестационарная функция прогиба для тонкой бесконечной цилиндрической оболочки постоянной толщины при воздействии на ее боковую поверхность вынужденной нестационарной движущейся нагрузки, распределенной по прямоугольной области. Материал рассматриваемой цилиндрической оболочки принят упругим и анизотропным, обладающим симметрией относительно ее срединной плоскости. Теория тонких упругих оболочек строится на гипотезах Кирхгофа-Лява. Для математического описания мгновенно приложенной нагрузки используются дельта-функции Дирака. A non-stationary deflection function is determined for a thin infinite cylindrical shell of constant thickness under the influence of non-stationary moving pressure. The pressure is distributed over a rectangular region, which belongs to the side surface of the shell. The shell material is elastic, anisotropic, and has symmetry to the median surface. The theory of thin elastic shells is based on the Kirchhoff-Love’s hypotheses. The Dirac delta-functions are used to describe an instantaneously applied pressure.

Axisymmetric Longitudinal-Bending Waves in a Cylindrical Shell Interacting with a Nonlinear Elastic Medium

A nonlinear differential equation is derived which describes the propagation of axisymmetric stationary longitudinal-bending waves in infinite cylindrical shell of Timoshenko type, interacting with the external nonlinear elastic medium. A modified perturbation method based on the use of diagonal Pade approximants was applied to build exact solitary-wave solutions of the derived equation in the form of traveling front and the traveling pulse. Numerical solutions of the equation, obtained by means of finite difference method, are in good agreement with the corresponding exact analytical ones.

The Critical Velocity for an Infinite Cylindrical Shell under a Moving Load

The critical velocity for an infinite cylindrical shell subjected a moving load with a constant velocity is analyzed in this paper. It is found that the critical velocity problem can be translated into a distribution of the real roots of a quadruplicate equation, which can be solved by using Descartes sign method and complete discrimination system for polynomials. Our research shows that the number of the critical velocities for an infinite cylindrical shell always is even number. Furthermore the longitudinal wave velocity is not one critical velocity for the shell. Our results are different from the conclusion drawn by other authors that there are three critical velocities in an infinite shell, and the longitudinal wave velocity is the maximum critical velocity. Then further studies are needed to clarify these questions.

Active Control of Input Power Flow to the Cylindrical Shells Based on Piezoelectric Actuator

The dynamic models of the infinite cylindrical shell with integrated piezoelectric actuator are derived firstly in this paper, then, the total input power flow is calculated and expressed as the Hermitian quadratic form to act as the objective function to implement the control. The optimum set of secondary force is obtained by using feed-forward quadratic optimal theory, and the total input power flow with control was calculated for different locations of the actuator. The results show that different axial and circumferential locations will induce different influences on the control effect, and the results are greatly related to the vibration type and the circumferential mode.