ABSTRACT
Composite materials have largely been used in relatively thin laminate forms (i.e., as two-dimensional structural elements). Even so, delaminations and free-edge effects have been of concern. Now, as applications of composites continue to expand, there is increasing interest in the use of increasedthickness laminates as well and determination of how they respond to through-the-thickness stresses. This includes sandwich structures as well as solid laminates. Thus, it has become necessary to develop and standardize corresponding through-thickness material property characterization tests. Numerous instances of premature failure of laminated composites have been reported due to the low through-the-thickness tensile strength. Kedward et al. (1989) report values as low as 3% of the in-plane tensile strength of laminates.
