Experimental Bending Analysis of Strip Sandwich and Laminated Composite Plates

Simple theories have been developed so far for prediction of bending strains of the sandwich structures, under specific loading and support conditions. although the theoretical predictions are often accurate enough, the role of experimentally validating of results of the theories on progress of the plate/beam theories cannot be ignored. the main goal of the present paper is presenting a test procedure for minimization of error of the data acquisition process and the relevant analyses. in this regard, effects of the specimen thickness, location of the strain gauge installation, and type of the strain gauge are investigated. identification of the mechanical properties of the test specimens is another goal of the present study. classic theories are used to validate the tests results and vice versa. based on the large number of tests conducted on the samples, the results show that the major source of discrepancy between the experimental and theoretical results may be incorrect installation of the strain gauge. a method to check this issue, is comparing results of the loading and unloading conditions. using a circuit with three wires omits the error of wire resistance. the test results of the composite specimens, obtained by strain gauges of tml company, showed small differences with the results obtained by strain gauges of blh company. the discrepancies between the experimental and theoretical results of the sandwich specimens increased by increasing the core thickness, while the measurements obtained from the strain gauges were not reliable in compression. an important result was the fact that a half-bridge installation of the strain gauge decreases the error remarkably.