Compressive fracture aspect of thick quasi-isotropic carbon fiber reinforced plastic laminates

The compressive fracture aspect for the thick quasi-isotropic carbon fiber reinforced plastic (CFRP) laminates was investigated using a high-speed camera to clarify the progress of the brooming fracture. The compressive fracture types of the laminates could be classified into two groups, i.e., the fractures initiating from the innermost 0 degrees ply and those initiating from the fixed sections of the specimen. The standard deviation of the compressive strength for the innermost 0 degrees ply-initiated fracture type was larger than that for the fixed-section fracture type, although the average compressive strengths for each fracture mode were similar. The initial fracture in the innermost 0 degrees ply was caused by the microbuckling of the fibers. The numerical results demonstrated a considerable out-of-plane shear stress around the free edges of the specimen, especially for the innermost 0 degrees ply. Such a shear stress is thought to cause the microbuckling at the innermost 0 degrees ply, with the crack subsequently propagating toward the outer plies of the specimen. The compressive strength of the innermost 0 degrees ply was an important factor affecting the fracture behavior of the thick quasi-isotropic CFRP laminates.