Evaluation of Filled Hole Compressive Fracture Behavior in Pin-Inserted CFRP Laminates with High-Speed Photography and Strain Measurements

To propose a test method for evaluating the filled hole compressive (FHC) property of laminated carbon fiber reinforced plastics (CFRPs), compression tests were conducted that simultaneously recorded stress-strain and recorded high speed photographic images. The effects of “clearance ratio,” which is defined as the ratio between the diameters of the metal inserting pin and specimen hole, was experimentally investigated. Despite exhibiting similar final fracture appearances, specimens with different clearance ratios demonstrated distinct fracture processes. These differences were captured through synchronized high-speed photography and stress-strain evaluation. The strain distribution and local fracture behavior varied significantly with clearance ratio. Based on these findings, a appropriate strain gage location was proposed for evaluating the FHC fracture behavior.