High velocity impacts against cables: nonlinear investigation of the safety conditions

This paper analyses the high velocity impact against a cable in order to define the lirnits of the impacting particle velocity to avoid the sudden cut of the cable. The mathematical model is based on the characteristic method in order to describe the nonlinear 3D dynarnics of the cable (large deformations). The impacting object is considered as a point mass. The global system, cable impacting mass, is described trough a quasi-linear system of hyperbolic partial differential equation with boundary condition of inertial type (the particle motion). The impact is assumed perfectly anelastic and the cable longitudinal constitutive stress-strain relationship follows the Young's law. The solution algorithm is developed on the characteristic piane trough a discrete grid of characteristic curves solved by a trial-and-error procedure. The investigations were accomplished by multiple simulations, varying the impact velocity in order to define the relation velocity-peak stress in the cable cross section. As a principal result, a parabolic relationship exists between the impact velocity and the cab le stress, in particular we can state that there exists a range of velocities where the cable stress is very sensible to the impact velocity, below of such range the influence is sensibly lower. All allows to define the range of safety conditions.