Impact penetration test and residual tensile strength of CFRP

Abstract

The high-pressure hydrogen tank for fuel cell vehicles is made by the prepreg winding method using carbon fiber reinforced plastics (CFRP). Unexpected destruction may occur in the high-pressure hydrogen tank due to internal pressure if an impact load is applied from the outside of it. Therefore, in this study, failure aspects occurred in the cross-ply and quasi-isotropic CFRP laminates by an impact penetration test and residual tensile strength were evaluated. In the impact penetration test, a steel ball was collided with the CFRP laminate using a gas gun. Then, fiber breakage and splitting failure occurred on the impact and back surfaces of the laminate were observed and interlaminar delamination was investigated by a cross-sectional observation. After the impact test, the CFRP laminate was cut into a strip-shaped specimen, and the residual tensile strength was measured. The residual tensile strength tends to decrease as the impact energy increases, and the strength of the penetrated specimens are about 27% (cross-ply) and 14% (quasi-isotropic) lower than that of the non-impact specimens. Finally, the damage propagation behavior of the penetrated specimens including fiber breakage, splitting failure and interlaminar delamination was analyzed by a finite element method. Damage initiation and propagation behavior of the specimens could be simulated, but the maximum loads obtained from the numerical results were lower than the experimental ones. From the results, the prediction method for residual tensile strength of penetrated CFRP laminates was discussed.

Keywords

• cfrp
• ballistic impact
• tension after impact
• residual strength
• finite element analysis