Abstract
The open-hole compressive (OHC) strength is used as a design allowable for aircraft structure designs that use CFRP laminates. In many cases, fillers such as fasteners are inserted into the holed CFRP parts of actual structures. The filled-hole compressive (FHC) strength, which is higher than the OHC strength, has potential as a design allowable for lighter structural designs. However, the FHC strength depends on the gap (clearance) between the CFRP laminate filler and the hole walls, and the mechanisms that cause its value to change are still unclear. This is a significant issue in standardizing test methods and in estimating mechanical joint strengths. In this study, we observed the changes in the FHC strength with changes in the clearance and explored the mechanism causing the increased FHC strength. We confirmed that the FHC strength increased as the clearance decreased. At the same time, we also confirmed that the FHC strength increase was mitigated when the clearance fell below a certain level. We determined that the FHC strength was governed by the transmitted load, which changes with the amount of clearance and with the contact area fracture state of the CFRP laminates.
https://ror.org/059yhyy33 
