The Single Cantilever Beam test for sandwich composites
In recent years, there’s been increasing interest in the development and standardization of new test methods for sandwich composites, including fracture mechanics, notch sensitivity and damage tolerance tests. This recent trend for sandwich composites resembles the period of development (and later standardization) of the same test methods for polymer matrix composites (PMC) in the 1980s and 1990s. In both cases, these developments were driven by new applications for which these properties were important design considerations. In this column, we focus on a Mode I fracture mechanics test for sandwich composites that’s approaching ASTM standardization — the Single Cantilever Beam (SCB) test.
For starters, fracture mechanics test methods are used to measure a material’s resistance to growth of an existing crack. For PMCs, the Mode I fracture mechanics test method is the Double Cantilever Beam (DCB) test, standardized as ASTM D55281 in 1994. This test is used to measure the resistance to growth, or fracture toughness, for an existing delamination within a unidirectional laminate under an opening-mode (Mode I) loading.