Loading rate effect on the mode-I interlaminar fracture toughness

The rate dependence of mode I interlaminar fracture behavior for unidirectional carbon fiber/epoxy composite laminates has been investigated over a wide range of loading rates from quasi-static to impact loading condition. Two types of specimen were used to study the loading rate dependence of interlaminar fracture behavior, one is wedge insert fracture (WIF) and the other is double cantilever beam (DCB) specimens. Impact WIF tests were carried out with split Hopkinson pressure bar(SHPB) system. And DCB specimens were loaded using an electromagnetically driving split Hopkinson tensile bar (SHTB) which can impose symmetrical displacements to the two arms of the DCB, limiting the vibrations of the sample. The high-rate tests were photographed using a high-speed camera to record the deformation of the laminate and the opening displacement field.