High-speed impact of electromagnetically sensitive fabric and induced projectile spin

Abstract

This work deals with the dynamic contact of a rigid body with a deformable electromagnetically sensitive fabric structure, represented by a network model. Of particular interest are the electromagnetically induced forces generated on the fabric, which are proportional to the external electric field (E E X T ) and the velocity crossed with the external magnetic field (v × B E X T ). These forces transmit reactions to the rigid contacting object, which can induce rotational motion. Modeling and simulation of this effect can be useful in ballistic shielding applications, because the rotation of an incoming, ogival, projectile allows it to be more easily impeded. A modular formulation for the deformation of impacted fabric structures, represented by a network model, is developed in this paper, characterized by (1) stretching of interconnected yarn networks, described by simple constitutive relations, including yarn damage, (2) interaction with impacting objects, incorporating contact with friction and (3) electromagnetic sensitivity and actuation, demonstrating how the Lorentz force can be harnessed to break symmetric deformation patterns in order to induce spin onto an incoming object, whether that object is electromagnetically sensitive or not.

Electromagnetically-induced Deformation of Functionalized Fabric

“…For details on a wide variety of relaxed models, we refer the reader to works dating back to Pipkin [28], Buchholdt et al [8], Pangiotopoulos [27], Bufler and Nguyen-Tuong [9] and Cannarozzi [10,11], Steigmann [33], Haseganu and Steigmann [14][15][16] and Atai and Steigmann [1,2]. Relaxed formulations have served as a foundation for computational models describing rupture of ballistic fabric shielding in Zohdi [36,43,46], Zohdi and Steigmann [37], Zohdi and Powell [41] and Powell and Zohdi [29] and are the basis for the present approach.…”

“…The expression in (39) can also be used for time step enlargement, to reduce computational effort, if convergence is met in less than K d iterations. Numerous parameter studies of this algorithm can be found in Zohdi [38][39][40][41][42][43][44][45][46].…”

“…It is also desirable to simultaneously maximize the time-step sizes to decrease overall computing time, while obeying an error tolerance on the numerical solution's accuracy. In order to achieve this goal, we follow an approach found in Zohdi [38][39][40][41][42][43][44][45][46], originally developed for continuum thermo-chemical multifield problems where (1) one approximates η L+1,K ≈ S(Δt) p (S is a constant) and (2) one assumes that the error within an iteration to behave according to (S(Δt) p )…”

“…The simulations take on the order of four to five minutes on a standard laptop and the Fig. 5 Prestressing a segment of yarn computational algorithm scales extremely well for much larger fabric systems (see Zohdi [46] and Zohdi and Powell [41]). …”

“…Following Zohdi [46], in order describe the overall time-stepping scheme, we first start with the dynamics of a single (ith) lumped charged-mass. The equation of motion is given by…”