Impact Failure Mechanisms in Carbon Fiber/PEEK Composites

Abstract

Impact failure mechanisms in two thermoplastic matrix composites have been examined. These both had a PEEK matrix and were reinforced with AS4 and IM6 continuous carbon fibers. The IM6 fiber has higher stiffness and strength, and smaller diameter than AS4. Quasi-isotropic laminates were impacted using a low energy, in strumented falling weight apparatus and force-time curves were recorded. The impacted laminates were examined destructively and non-destructively to assess the impact damage.

Detection of Impact Damage in Thermoplastic-Based Glass Fiber Composites Using Embedded Optical Fiber Sensors

“…This is perhaps expected since the presence of the 90 fibers in the adjacent ply may have resulted in localised stressing of the optical fiber during the impact event. The increased tendency of the optical fiber to fracture when embedded in a cross-ply configuration has also been reported by other investigators [13,14,16]. It is perhaps not surprising that the light intensity level after the impact did not decrease linearly with increasing impact energy.…”

“…The tough thermoplastic matrix plays a significant role in determining the failure mode in the composite and hence the fracture response of the optical fiber. A detailed investigation by Curson et al [16] on a tough PEEK composite highlighted the effects of the matrix properties on the impact response of a composite structure. Clearly, the ratio of support diameter, s, to the specimen thickness, d, of the samples tested in this study is relatively high (s/d ¼ 13.9) rendering the specimen relatively stiff.…”

“…Clearly, the ratio of support diameter, s, to the specimen thickness, d, of the samples tested in this study is relatively high (s/d ¼ 13.9) rendering the specimen relatively stiff. Investigation by Curson et al [16] showed that there is an increased tendency for the thermoplastic-based composites to fail by compression in the upper region of the laminate as a result of high contact stresses. This clearly agrees with the response of the optical fibers observed in this study.…”

Impact fatigue, multiple and repeated low-velocity impacts on FRP composites: A review

“…From literature, it is clear that fibers with higher failure strains provide better impact resistance of the composites to high impact energy levels [39,70].…”

Impact Resistance of Fibre Reinforced Composite Railway Freight Tank Wagons

“…For minor impact events, these "shear cracks" are the only visible damage present. They are generally a superficial form of failure for a composite laminate, not significantly reducing its mechanical performance [70].…”