Abstract
The classical continuum mechanics theory cannot sufficiently describe the effect of pebbles on projectile, which leads to a large calculation error. In this paper, an orthogonal curvilinear coordinate system is constructed, which effectively describes and perfects the normal cavity expansion theory. A couple stress theory based on the normal cavity expansion is proposed in which not only the tangential movements but also the rotations of the concrete medium are considered. According to the high-speed impact of pebble concrete, combined with dynamic equations and the FE simulation, the theoretical and simulation results of pebble particles scale on warhead resistance are compared. It is shown that, the larger the scale of pebble particles, the stronger the effect of rotation on the resistant force applied on the warhead.
Highlights
Introduction of Penetration againstIn earlier research on the penetration resistance characteristics of concrete target, several explorations were carried out on many aspects, such as penetration depth and projectile mass loss, and research results such as semi-empirical formulas and projectile mass loss characterization models accumulated
In order to analyze the penetration of the concrete media containing pebbles effectively, this paper proposes the continuum mechanics theory of the couple stress [19,20,21,22]
To establish the couple stress model of continuum mechanics based on the normal cavity expansion, the following assumptions are made: (1) the shock expansion wave expands in the normal direction of warhead surface at the wave velocity cx, (2) the velocity of material particles in the response region includes the component along the normal direction and that along the tangent direction of the cavity, (3) there is a asymmetric stress pφ caused by the viscous force in the meridian direction of the warhead surface, (4) there is a rotational motion of the material particles caused by the viscous force in the circumferential direction and (5) the rotations in the other two directions can be ignored
Summary
In earlier research on the penetration resistance characteristics of concrete target, several explorations were carried out on many aspects, such as penetration depth and projectile mass loss, and research results such as semi-empirical formulas and projectile mass loss characterization models accumulated. The cavity expansion theory does not consider the rotation of the target medium and the translation along the tangent direction of the warhead surface. In order to analyze the penetration of the concrete media containing pebbles effectively, this paper proposes the continuum mechanics theory of the couple stress [19,20,21,22] It considers both additional tangential translational motion and additional rotation of media particles based on the theory of normal cavity expansion. The wave front propagates along the normal direction of warhead surface at a wave velocity Target medium. (b) The effect of particles on the surface of the warhead
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