High-velocity impact response of CFRP panels reinforced with stiffeners

With a goal of reducing the weight of fan blade containment system for jet engine, the high-velocity impact response of carbon fiber reinforced polymer (CFRP) panels reinforced with stiffeners were tested and analyzed. Ballistic impact tests on stiffened panels have been carried out with cylindrical Ti-6Al-4V projectiles at different velocities (210 m/s, 70 m/s and 90 m/s). Results showed there was a significant influence observed due to different impact velocities on the response of the panel skin and the stiffener, and the middle stiffener played an important role in impact energy absorption. Numerical simulations were conducted to provide further insight into the target response by employing a user subroutine VUMAT with revised Hou criteria in commercial finite element (FE) software ABAQUS. The stiffened CFRP panel was found to possess a 14% higher critical penetrating velocity than the CFRP laminated plates with same mass by using validated FE models. Combining with detailed discussion of high-velocity penetration process, the energy absorption mechanism of the stiffened panel under high-velocity impact was analyzed, indicating that the improvement on high-velocity impact response is due indirectly to structural alteration induced better energy absorption by less punch-shear laminate breakage and more fiber tensile failure.