Stress concentration in bending of sandwich orthotropic panels under pointforces

Analytic expressions for flexural characteristics and stresses of sandwich panels under loading by point forces with taking into account local effects have been found. A refined discrete-layer model for bending of a three-lay er panel that is composed of orthotropic face layers and intermediate middl e layer with low rigidity of the latter is proposed. The outer layer made o f composite material and high rigidity not so much in tension and shear in the transverse direction as in longitudinal direction characterize it. Cont ractility of a normal in the model is deduced in terms of a difference betw een deflections of face layers. Equations of the model, having four degrees of displacement freedom are of 12th order. The specific features of the st ress from point forces in cylindrical bending are considered using the oper ational Laplace method with the generalized Dirac function. The boundary pr oblem of a panel supported along the surface of its lower face layer with f ree ends is reduced to the Cauchy problem. Variants are examined for the li miting transformation of the model parameters leading to a qualitative chan ge in its kinematics and the corresponding simplified bending models. (C) 1 999 Elsevier Science Ltd. All rights reserved.