A Study on Effects of Various Factors on Tensile Strength and Compressive Strength for Scarf Joint of CFRP Laminate Composite

Recently, Carbon Fiber Reinforced Plastic (CFRP) composites are applied to the pressure equipment such as pressure vessels and pressure pipes, etc., not only aircraft structure. If these pressure equipment and aircraft structures made of CFRP laminate composite material are damaged, the bonded repair is applied as one of the repair treatments.<br>In this study, focusing on the repair treatment with scarf joint which is a bonded repair method and used also for the repair of the aircraft structure damage, the tensile strength and compressive strength of the bonded scarf joints were examined by using the two-dimensional scarf joint specimens which simulate the cross-section of an actual repaired part with scarf joint with flat conical shape, and the effects of the scarf angle, doubler patches and impact load on these strengths were investigated. The following results are obtained.<br>⑴ The tensile strengths of the bonded CFRP scarf joint with scarf angle 3 and 4.5 degrees are about 50% of that of CFRP laminate composite base material. ⑵ The doubler patches are effective in the tensile strength improvement of bonded CFRP scarf joint with scarf angle 3 degrees, the tensile strength of the scarf joint is reinforced about 10 % by attaching doubler patches but there is no improving effect of doubler patches on the compressive strength. ⑶ The bonded CFRP scarf joints with scarf angle 3 degrees is almost not affected negatively on the tensile strength by impact loading.