Effects of Lay-Up, Temperature, and Loading Rate in Double Cantilever Beam Tests of Interlaminar Crack Growth

Abstract

The increasing interest in the problem of delamination in composites has led to many experiments designed to help characterize and evaluate interlaminar crack growth. For the particular area of predominantly Mode-I type loading, most studies have focused on various versions of the double cantilever beam (DCB) geometry [1–6]. In order to establish this test as a general quantitative method, however, it is necessary to examine in a complete and systematic way all of the parameters that may affect the results. These parameters include fiber orientation, specimen size and shape, fiber volume fraction, matrix and fiber type, temperature and loading rate, environmental effects, and data analysis methods. Although some of these parameters have been examined, the results are often incomplete or not reported in the open literature. As a result, a cooperative program involving the National Bureau of Standards, NASA Langley Research Center, the University of Illinois, Hercules Inc., and other industrial suppliers was initiated to examine the DCB specimen in a comprehensive way. This note reports some preliminary results with respect to the effects of fiber lay-up pattern, test temperature, and loading rate on interlaminar fracture as measured by this specimen.