Experimental investigation on the low-velocity impact response and the residual strength of CFRP tubes

With the help of the high-speed camera and self-designed fixture, it was investigated that the effects of the impactors in a variety of shapes on the mechanical behavior and failure mode of carbon fiber-reinforced polymer (CFRP) tubes with a range of inner diameter during the low-velocity impact (LVI) of four impact energies. Then, the three-dimensional digital image correlation (3D-DIC) system was carried out to monitor the damage evolution of the LVI-damaged specimens under compressive and flexural loading. In addition, the residual compressive and flexural strength of all kinds of cases were compared and discussed. The results show that the increase in wall thickness can improve the LVI, compression-after-impact (CAI), and flexure-after-impact performance. The failure mode of compression changes to brittle fracture failure at the impact circumferential region. The CAI strength of the specimen damaged by a flat impactor is 23.89% less than that of a hemispherical one, but there is little difference in flexural loading.Highlights Mechanical behavior on in & post LVI of CFRP tubes varying wall thickness and impactor. Due to point-line contact for flat impactor, two peak forces are in the F-D curves. LVI property and residual strength are improved with the increase of wall thickness. Compressive failure mode is brittle fracture at the impact circumferential area. Flexure-after-impact strength mainly depends on the no-impact surface of tubes. To investigate mechanical behavior on in & post impact of CFRP tubes varying wall thickness and impactor, low-velocity impact (LVI), compression-after-impact (CAI), and flexure-after-impact (FAI) tests were conducted and three main conclusions can be obtained. First, because of the point-line contact for flat impactor, two peaks are found in the force-displacement curves. Second, the failure mode of CAI is brittle fracture at the impact circumferential area. Third, FAI strength mainly depends on the no-impact surface of tubes. image