The DCB(double cantilever beam) fracture test is a suitable experimental method for studying the interlaminar fracture of laminated composites under mode I loading. The main objective of this study is to investigate experimental methods to determine the mode I interlaminar fracture toughness and proper specimen size for the DCB test.
Because linear elastic fracture mechanics (LEFM) describes fracture behavior of an interlaminar plane, interlaminar fracture toughness is expressed by the strain energy release rate.
Experiments are performed with undirectional composites to confirm the validity of using data from multiple crack jump on a single specimen. Specimens with interface (0/0) of four thicknesses of three widths are used. Effect of composite thickness, width and end tab on interlaminar fracture is studied.
On the other hand, the (0/90) interface is used to characterize the behavior of the two types of interface, (0/0) interface and (0/90) interface.
Approaches for calculating the strain energy release rate are compared, among them; Determination of energy rate of the area method, empirical beam analysis (compliance method) and linear beam analysis (compliance). Interlaminar fracture toughness is overestimated by the compliance method.
Finally, the interlaminer fracture surfaces are investigated by means of SEM (scanning electron microscope).
