Maximum stress of stiff elastic plate in uniform flow and due to jet impact

Abstract

The liquid jet impact onto a clamped elastic plate is investigated. The two-dimensional jet of constant thickness and with flat vertical front is initially advancing towards the elastic plate along a flat, rigid, and horizontal plane at a constant uniform speed. The elastic plate of variable thickness is mounted perpendicular to the rigid plane. The maximum stress during the early impact stage is estimated for a given retardation time and a given relaxation time of the plate material. The stresses during the initial impact stage are compared with the static stresses in the plate placed in an equivalent uniform flow. It is shown that the static stresses are always smaller than the bending stresses during the early stage of impact for a given speed and thickness of the jet. This implies that if the stresses in the plate are smaller than the yield stress of the plate material with no plastic deformations in the plate occurring during the unsteady impact stage, then the plate behaves elastically after the impact and plastic deformations are not achieved. Approaching the plastic deformations is treated here as a damage to the plate. The maximum stress increases with an increase in jet thickness. A critical value of the jet velocity, below which the plate is not damaged by the jet impact, is obtained for given characteristics of the plate.