Experimental study on flexural fatigue behavior of glass fibers/epoxy hybrid composites with statistical analysis

Potentiality of halloysite nanoclay on crashworthiness performance of polymer composite tubular elements

The recent article investigates the impact of the presence of halloysite nanoclay (HNC) on crashworthiness performance of glass/epoxy energy absorbent composite tubes. Specimens filled with 0,1,2,3, and 4 wt. % of HNC were manufactured via wet-wrapping process and tested under quasi-static axial loadings. The crush load-displacement response, initial crushing load [Formula: see text], average crushing load ([Formula: see text]), crushing force efficiency ( CFE), absorbed energy ( U), and specific absorbed energy ( SEA) for the proposed composites were determined. The crushing behaviors for all specimens were traced. It was indicated that the specimens’ failure mechanisms and the energy absorption capacities of nanofilled glass/epoxy composites are highly dominated by the wt. % of the embedded HNC. The inclusion of HNC enhances the energy absorbing capacities of glass/epoxy composites during the crushing process. Composite tubes filled with 4 wt. % of HNC has the highest load carrying and energy absorption capacities which are, respectively, 32.75 kN and 1110.84 J. So, they are the most suitable materials for energy dissipating elements. The inclusion of 1, 2, 3, and 4 wt. % of HNC to glass/epoxy composite tubes exhibits, respectively, an enhancement of 8.56, 35.76, 37.96, and 53.33% in [Formula: see text] and an enhancement of 169.29, 215.76, 204.60, and 254.19% in the [Formula: see text]. Also, an improvement in the energy absorbing by, respectively, 220.43, 270.09, 249.11, and 320.98% was attended. The purpose of this work is to experimentally study the applicability of HNC in the energy dissipating composite tubular elements.

Mechanical characterization of hybrid composites based on flax, basalt and glass fibers

An experimental study on tensile, flexural and impact properties of flax-basalt-glass reinforced epoxy hybrid composites is presented in this paper. Test specimens were fabricated by vacuum bagging process. The effects of reinforcement hybridization, fiber relative amounts and stacking sequence on the mechanical properties were investigated. Morphological studies of the fabricated and fractured surfaces through thickness were performed using scanning electron microscopy. Results showed that the developed hybrid composites display enhanced tensile, flexural and impact performance as compared with flax reinforced epoxy composite. The flexural strength increases when partial laminas from flax/epoxy laminate are replaced by basalt/epoxy and/or glass/epoxy laminas. Also, it is realized that incorporating high-strength fibers, i.e. glass or basalt, to the outer layers of the composite leads to higher flexural resistance, whilst the opposite was noticed for tensile properties. The fabricated hybrids were found to have economical and specific mechanical properties benefits. Fiber-relative amounts and stacking sequence have great effects on the mechanical properties. The mechanical properties of hybrid laminates are proven to be highly dependent on the position of the flax layers within the hybrid composite. The Hybridization with basalt and/or glass fibers is an effective method for enhancing the mechanical properties of flax/epoxy composites.

Wear behavior of glass–polyamide reinforced epoxy hybrid composites

The abrasive wear performance of glass–polyamide fibers/epoxy composites was experimentally studied using a pin-on-disc wear tester at different applied normal loads. Specimens were fabricated in inter-ply configuration using the hand layup technique. Specimens were subjected to distilled water and sea water immersion at room temperature for 200 days. The effects of the reinforcement hybridization, stacking sequence, and relative fiber amounts on the wear behavior of dry and wet specimens were discussed. Temperature rise at the specimen pin–disc interface has been measured. The morphologies of the worn surfaces were investigated with scanning electron microscopy (SEM). Results showed that distilled water and sea water uptake of glass/epoxy composite is 2.5 and 2 times those of polyamide/epoxy counterparts. Correction factor decreases the diffusion coefficient by about 24% and 26% for, respectively, polyamide/epoxy and glass/epoxy composites. Hybridizing glass fiber composite with polyamide fiber could reduce the specimen’s weight loss during wear test for dry and wet specimens. Water uptake induces a significant decrease in wear resistance of the studied composites. Stacking sequence has a slight effect on wear resistance, while relative fiber amounts have a noticeable effect. The maximum temperature at the specimen pin–disc interface (21.5°C) was noticed for glass/epoxy composite under applied load of 10 N. As the applied load and the sliding time increase, the wear resistance of the composites decreases but the temperature at the specimen pin–disc interface increases. SEM observations show debonding, cracks, fiber fracture, and debris formation.

Water absorption effect on the in-plane shear properties of jute–glass–carbon-reinforced composites using Iosipescu test

The main objective of the present paper is to study the water absorption of jute–glass–carbon-reinforced epoxy composites and its subsequent effect on the in-plane shear performance of these composites. The effects of the reinforcement hybridization, stacking sequence and relative fabric amounts on the shear behavior of dry and wet conditioned composite specimens are reported and discussed. Composites have been fabricated in inter-ply configuration using the hand lay-up process. The prepared specimens have been subjected to distilled water and sea water immersion at room temperature for 60 days. Results indicated that water uptake of jute-reinforced composite and its hybrids with glass and/or carbon follows Fickian-like behavior. Water uptake induces a significant decrease in the in-plane shear strength. Hybridizing jute fabric with glass and/or carbon fabrics improves the in-plane shear properties of both dry and wet specimens. The stacking sequence and relative fabric amounts have a noticeable effect on the studied shear properties. Also, the hybrid composite with jute as facings and glass as core, JGJ, offers the most balanced set of properties on a cost-effective basis compared to the other studied hybrids.

Flexural fatigue performance of hybrid composite laminates based on E-glass and polypropylene fibers

An experimental investigation has been conducted to understand the effect of water aging on flexural fatigue performance of unidirectional polypropylene (PP)-glass (G) fiber–reinforced epoxy composites. Test specimens were fabricated using hand lay-up process with a constant total fiber volume fraction. The effects of the reinforcement hybridization, hybrid configuration, and stacking sequences on S–N curves were investigated. Deflection-controlled flexural fatigue tests with a frequency of 25 Hz at zero mean stress have been conducted. A 20% reduction of the initial applied moment was taken as a failure criterion. In the first stage, the flexural fatigue properties of un-aged composite specimens were studied in ambient temperature. In the second stage, flexural fatigue properties were investigated after a preliminary aging step in distilled water for 350 days. The specimen surface temperature rise was measured to ensure that there is no early damage happened in the tested specimens. Results indicated that the hybridization of PP fiber–reinforced composite with G fiber improves its flexural fatigue resistance but increase water uptake. Inter-intraply hybrid laminate with G-fiber layers at the specimen outer faces and PP-fiber layers in the specimen core exhibits the most favorable flexural fatigue behavior, that is, the highest cost ratio and the specific fatigue endurance strength. The water-sorption step induced a significant decrease in fatigue properties of the fabricated specimens. The highest measured temperature rise was observed to be about 9°C for G fiber–reinforced composite.