Composite Fracture Toughness Testing

ASTM D5528 – This test method describes the determination of the opening Mode I interlaminar fracture toughness, G_Ic, of continuous fiber-reinforced composite

materials using the double cantilever beam (DCB) specimen

This test method is limited to use with composites consisting of unidirectional carbon fiber and glass fiber tape laminates with brittle and tough single-phase

polymer matrices.

This limited scope reflects the experience gained in round-robin testing.

This test method may prove useful for other types and classes of composite materials

Significance and Use

Susceptibility to delamination is one of the major weaknesses of many advanced laminated composite structures.

Knowledge of a laminated composite material’s resistance to interlaminar fracture is useful for product development and material selection.

Furthermore, a measurement of the Mode I interlaminar fracture toughness, independent of specimen geometry or method of load introduction, is useful

for establishing design allowables used in damage tolerance analyses of composite structures made from these materials.

This test method can serve the following purposes:

To establish quantitatively the effect of fiber surface treatment, local variations in fiber volume fraction, and processing and environmental variables on G _Ic of a

particular composite material.

To compare quantitatively the relative values of G_Ic for composite materials with different constituents.