Microstructure, hygrothermal, and mechanical properties of interlaminar toughening of CFRP composite using polyamide veil

Abstract

The addition of polyamide veil (PAV) to the interlaminar area of carbon fiber (CF) fabric/epoxy composites can effectively increase their toughness with high accuracy. Vacuum-assisted resin infusion (VARI) was used to fabricate composite structures. VARI was applied to obtain a PAV, which is an interleaf between fabric piles of CFs. The thermoplastic PAV was dissolved in epoxy when the PAV was cured at high temperature. A phase-separated morphology with a PAV-rich secondary phase was formed during the curing process. Experimental results indicated that compression after impact (CAI), which is the average value of CAI, increased by threefold when two layers of PAV were added. The thermal and mechanical characteristics of the composite were analyzed and compared at room temperature and high-temperature wet conditions.

Electrospun nanofiber interleaving through double infusion method to induce pseudo‐ductile damage resistance response in carbon/epoxy composites

“…An optimum areal weight of 17.35 g/m 2 evidently offered simultaneously improvement in load-bearing response and interlaminar fracture toughness. 20,39 Apparently, higher than optimum interleave thickness facilitated higher epoxy concentration in interlaminar regions thus contributing to bulk modulus of the composite and inducing matrix-dominated brittle damage modes such as intra-interleave cracks (Figure 8D). This reduced the specific total toughness for 46.70 NC sample.…”

“…A survey of the literature shows that two reported works on quasi-static indentation damage resistance of electrospun nanofiber interleaved composites were limited in scope and conclusions as they reinforced bottommost interlaminar regions only. 18,20 However, the top half of the laminate experienced compressive stresses, under out-of-plane loading, which had been identified to be the most critical stresses for delamination growth besides fatigue. Delamination growth, after local buckling of sub-laminate under compression, had been reported to be associated with sudden loss of load-bearing capacity.…”