Experimental and analytical study of nonlinear bending response of sandwich beams

The practical value of the geometrically nonlinear higher-order theory is demonstrated using four-point bend tests carried out on sandwich beam specimens comprised of aluminum face sheets and a PVC foam core. The experimental results were compared with the predictions of classical sandwich theory, and with linear and geometrically nonlinear higher-order sandwich panel theory. The analytical predictions based on the higher-order theory are in excellent agreement with the experimental results. Response parameters show fundamentally distinct behavior with increasing external load, both in the particular section and along the span. Considering the longitudinal displacements, there is a significant geometrically nonlinear stage of the response that precedes the appearance of the material nonlinearity. The peeling stresses also exhibit significant geometrical nonlinearity in the vicinity of the internal supports. The linear higher-order theory can be used efficiently to estimate the vertical displacements of the soft-core sandwich beams up to high load levels with a great accuracy. Premature failure of sandwich beam specimens with weak adhesive layers is caused by high peeling stresses in the upper interface layer at the ends of the specimen, and the loading capacity decreases by more than 40%. (C) 2003 Elsevier Science Ltd. All rights reserved.