Post‐curing and fiber hybridization effects on mode‐II interlaminar fracture toughness of glass/carbon/epoxy composites

Carbon fiber‐reinforced epoxy composites (CFECs) continue to grow in demand for aerospace, mass transportation, electric vehicle, and energy efficient architecture due to their lightweight, high strength, and high modulus. However, CFECs are susceptible to delamination upon impact which can lead to premature structural failure. This paper investigates the interlaminar fracture toughness of unidirectional CFECs based on reactive polyetherimide (rPEI) modified multifunctional epoxy matrix system. The matrices were cured formulations of tetraglycidyl diamino diphenyl methane, triglycidyl para‐amino phenol, rPEI having different molecular weights (MW) and diaminodiphenyl sulfone. Multi‐phase morphologies were observed from the resin castings and CFECs containing different MW rPEI modifiers. Results show that the mode I fracture toughness (GIC) of the rPEI‐toughened CFECs can be increased by as much as 150% over the unmodified CFECs based on the MW and type of phase morphology that promotes crack‐bridging mechanism. In addition, rPEI‐modified CFECs exhibit better property retention (~80% of GIC) after prolonged solvent exposure.Highlights A processing‐structure–property relationship based on CFECs is established. The amine‐terminated rPEI facilitates the formation of a strong bonding. The molecular weight effect of rPEI on the phase morphology was investigated. The rPEI enhances the interlaminar fracture toughness of the composites. The rPEI particle bridging is found to be responsible for the toughening effect.

Section: Introductionmentioning

confidence: 99%

Fracture behavior of high‐performance carbon fiber composites toughened by reactive polyetherimide

Chen,

Bajaj,

Patil

et al. 2023

Quasi‐static axial crushing of multi‐tubular foam‐filled carbon fiber reinforced composite structures

Khan,

Alshahrani,

Abd‐Elaziem

et al. 2023

Self Cite

In automotive design, a key aspect in limiting injuries in the event of collision is the ability of vehicle's structures to absorb high quantities of energy. Recently, automobiles have been designed with materials such as carbon fiber‐reinforced polymers to replace the conventional metallic materials, to boost structural safety and fuel efficiency. In this study, various combinations of carbon fiber‐reinforced plastic and Kevlar‐reinforced polymer composite tubes were assembled to form multi‐tubular composites and their crushing properties were investigated under quasi‐static axial compression. A total of five different combinations were designed and tested. The results showed that the addition of intermediate tubing system in the hollow composite tubes significantly improved the load‐bearing and energy absorption capabilities of the composite tubes. In addition, these configurations were also filled with polyurethane (PU) foam. It was shown that, apart from specific energy absorption (SEA), all the other parameters, such as peak load, mean load, crushing force efficiency, and overall energy absorption ability, were enhanced with the addition of foam. The SEA parameter showed inconsistent behavior, and this was attributed to the weight addition caused by the addition of foam in the composite tubes.Highlights This study examined the crashworthiness properties of multi‐tubular structures. Placing of intermediate tubing showed great improvement in absorption capacity. The system with carbon‐based intermediate tubes performed the best. Filling PU foam within the structures also improved the load‐bearing properties. The SEA was seen to reduce with the addition of PU foam.

Study of impact performance of composite sandwich structure fabricated partially with natural fiber facesheet

Ashraf,

Ishak,

Khan

et al. 2023

Self Cite

Composite structures with a pure glass composite facesheet and an aluminum honeycomb core are widely used in aircraft interiors. Because impact‐related problems are related to structural integrity and safety performance, the behavior of these structures under impact loading is critical. Due to their promising performance, lower cost, and low environmental impact, hybrid composites have recently become one of the most widely researched composite materials in the research field. This paper aims to investigate the impact behavior of nonhybrid glass and the glass partially replaced with a flax and kenaf hybrid composite facesheet caused by a low‐velocity impact. The specimens were impacted with different impacted energies, such as 10, 20, and 30 J. All nonimpacted and impacted samples were tested and compared for postimpact flexural (three‐point bending) behavior to analyze the residual strength of sandwich structures after impact. The results revealed that the hybrid composite face sheet outperformed the glass composite sandwich structure. The hybrid composite face sheet allowed the impactor to penetrate deeper, resulting in better energy absorption than the glass composite. Compared to nonimpacted specimens, the glass and hybrid face sheet combinations demonstrated comparable residual bending performance.Highlights Experimental analysis shows the impact resistance (low‐velocity impact test) and residual load‐carrying capacity (three‐point bending test) of glass and hybrid composite face sheets. Hybrid face sheets show excellent energy‐absorbing capability compared to glass one. The residual flexural strength of the glass and hybrid composites was comparable to that of nonimpacted samples. The peel strength achieved in this study using the pre‐cure fabrication process was significantly higher than the peel strength achieved using prepreg face sheets. Reinforcing the composite face sheet of the sandwich structure by partially replacing the glass with flax and kenaf fiber exhibited comparable performance.