The influences of low‐velocity impact loading on the vibration responses of the carbon/glass fiber‐reinforced epoxy composites interleaved with various non‐woven thermoplastic veils

Abstract

Time‐dependent variable stresses that occur in composites subjected to mechanical and dynamic loads have devastating impacts on the material properties. Since these stresses reduce the service life, it is critical to detect and enhance structural responses before and after dynamic loadings. Therefore, the present study aimed to increase the toughness and delamination resistance of the conventional fiber‐reinforced composites by means of thermoplastic veil interleaves, thereby improving the vibration responses both before and after low‐velocity impact (LVI). In this context, carbon fiber (CF) and glass fiber (GF) reinforced epoxy composites interleaved with five different thermoplastic veils as Polyamide (PA), Polyetheretherketone (PEEK), Polyetherimide (PEI), Polyimide (PI) and Poly‐Phenylene Sulphide (PPS) were manufactured, and machined in accordance with the LVI standard. Composite specimens were subjected to the LVI tests, and then vibration tests were carried out for the non‐impacted and impacted specimens to determine dynamic properties. As a result, although thermoplastic veils generally have favorable effects on damping ratios of the GF composites, it has been revealed that these veils other than PPS and PI cause deterioration in CF composites. On the other hand, since vibration reduction depends on inherent damping and structural stiffness, this study also examined the storage‐to‐loss modulus ratios which denote the loss factors. In this respect, it was discovered that, while PPS, PEEK, PA, and PI thermoplastic veils included among the GF laminates ascend the loss factors of composites, only PI and PPS thermoplastic veils were shown to be positively effective in CF laminates. Moreover, CF and GF reinforced composites interleaved with thermoplastic veils generally exhibited higher natural frequency and lower damping ratio compared to the entirely CF or GF laminated composites. These results show that composite specimens gained bending stiffness due to local deformation hardening, and improved dynamic properties thanks to thermoplastic veil interleaved was attributed to increased toughness and delamination resistance.

Vibration Response of Thermoplastic Veil Interleaved Carbon Fiber Reinforced Epoxy Composites

“…In another study in which the hybridization of basalt fibers between carbon layers can be considered an interleaving process, it was observed that basalt fiber reinforcement improved the damping ratios of hybrid composites [17]. In a previous study conducted by our research group, the vibration responses after the impact of carbon and glass fiber composites interleaved with five different thermoplastic veils were examined, and significant improvements were noted, especially in the natural frequencies of the carbon composites [18].…”

“…In this study, the vibration response behaviors of PEEK and PA veil interleaved carbon composites were investigated. In the previous study carried out by our research group [18], the vibration response of specimens prepared for impact testing was discussed. This study investigated the natural frequency and damping ratio performances of vibration specimens prepared per the ASTM E756-05 standard [19].…”

Pultrusion preparation and properties of continuous glass fiber reinforced polylactic acid thermoplastic composites

“…The fiber reinforcements can be glass fiber, carbon fiber and metal fiber, and so forth, and they vary from short fiber, long fiber to continuous fibers in composite materials. [17][18][19][20][21] The earlier studies found that the mechanical properties of fiber reinforced thermoplastic composite materials are highly depends on the fiber length, and generally the longer length of the fiber, the higher mechanical properties of the thermoplastic composites. 22,23 Therefore, researchers normally prefer the longest length of fiber in the thermoplastic composites, especially for those thermoplastic composites used as structural materials requiring high mechanical properties.…”

“…Fiber reinforced thermoplastic composites is a big category of thermoplastic composite materials, which has been developing for half a century so far this year. The fiber reinforcements can be glass fiber, carbon fiber and metal fiber, and so forth, and they vary from short fiber, long fiber to continuous fibers in composite materials 17–21 . The earlier studies found that the mechanical properties of fiber reinforced thermoplastic composite materials are highly depends on the fiber length, and generally the longer length of the fiber, the higher mechanical properties of the thermoplastic composites 22,23 .…”

Effect of interface temperature on low‐velocity impact response of injection over‐molded short/continuous fiber reinforced polypropylene composites

“…4,5 In contrast, continuous fiber thermoplastic composites display a greater damage resistance and compression strength after impact. [6][7][8][9] Tarih et al 10 enhanced the energy absorption of carbon fiber reinforced composites by incorporating five different thermoplastic veils made of polyamide (PA), polyetheretherketone (PEEK), polyetherimide (PEI), polyimide (PI), and poly-phenylene sulfide (PPS). The increase in energy absorption was attributed to the improved interlaminar fracture toughness and ductility of the composites by incorporating thermoplastic veils.…”