ASTM D5528 is a test method, which determines the opening Mode I interlaminar fracture toughness of continuous fiber - reinforced composite materials. It USES a a double cantilever beam (DCB) specimen. Susceptibility to delamination is one of the major weaknesses of many advanced laminated composite structures.
Before conducting ASTM D5528, it is important to read the - specification. The Standards can be obtained from the appropriate standard authorities.