Strength analysis of multilayer glazing of vehicles at impact loading

Abstract

The paper presents an effective analytical method for investigation of dynamical strength of a multilayer glazing for flight and land vehicles.

The multilayer glazing is considered as a constant-thickness non-closed cylindrical multilayer shell. In the coordinate surface, it occupies the complex domain limited by the boundary . An indenter with a semispherical end is dropped onto the shell from some height. Contact approach is found by solving Hertzian problem on ball indentation into an elastic semispace.  The behaviour of the multilayer shell is described by the first-order theory accounting for transverse shear strain, thickness reduction and normal element rotation inertia in each layer. The equations of motion of the shell affected by impact load, well as the respective boundary conditions are derived by the variational principle. The analytical solution of the problem is obtained by the immersion method. According to this method, a non-closed cylindrical multilayer shell is immersed into an auxiliary enveloping cylindrical shell with the same composition of layers. To satisfy actual boundary conditions, additional distributed compensating loads, the intensity of which are to be found, are applied to the auxiliary shell over the boundary . Displacements and loads are expanded in the auxiliary shell domain in trigonometric series for functions satisfying simply supported conditions. The compensating loads are expanded into a series along the boundary . The method potentialities are demonstrated by calculating the stresses in a five-layer glazing. Experiments are based on the dynamic wide-range strain measurement technique. A good match of theoretical and experimental results confirms the feasibility and effectiveness of the method offered.