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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. [ABSTRACT FROM AUTHOR]

The aim of this article is to study the variability in tensile, flexural, in-plane shear, and interlaminar shear properties of unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid and non-hybrid composite laminates. Six kinds of laminated composites of average thickness 5.5 ± 0.2 mm and total fiber volume fraction (VfT) = 37% were manufactured using hand lay-up technique and tested under tensile, bending, in-plane shear, and interlaminar shear loading conditions. The failure modes of all test specimens have been recorded and discussed. Two-parameter Weibull distribution function was used to statistically analyze the composite samples experimental results. Weibull graphics were plotted for each sample using experimental monotonic mechanical properties results. The Weibull distribution has also been employed to show both the failure probabilities as well as the scatter in the experimental results for the above mentioned composites. The obtained failure probability graphs for the manufactured composites under different static loading conditions are important tools for helping the designers to understand and choice the suitable material for the required design and development. [ABSTRACT FROM AUTHOR]

The present study investigates the effect of stacking sequence on the failure loads (strength) and modes of pinned-joints glass-fiber reinforced epoxy composite laminates. Specimens with [0/90]2S, [15/−75]2S, [30/−60]2S and [45/−45]2S stacking sequences were investigated both experimentally and numerically. A series of ASTM tests were performed on unidirectional [8]0 glass-fiber reinforced epoxy composite laminate to determine the properties of the single lamina that was needed for the finite element analysis. A 3D progressive damage model was built with the aid of ABAQUS software, failure criteria and property degradation rules to simulate the problem. The results showed that the [0/90]2S laminate has the highest ultimate strength. The minimum bearing and ultimate strength was observed for [30/−60]2S laminate. Loading the specimens up to the ultimate value lead to shear-out failure mode for [0/90]2S, [15/−75]2S and [30/−60]2S stacking sequences, while specimens with [45/−45]2S stacking sequence are characterized by bearing failure mode. The experimental and numerical results agree well with a maximum Euclidean error norm of 8.57%. [ABSTRACT FROM AUTHOR]

This article deals with the effect of drilling parameters (feed, speed, and drill pre-wear) on the machinability parameters (thrust force, torque, peel-up and push-out delaminations, surface roughness, and bearing strength) in drilling woven glass fiber-reinforced. The results show that at high feeds (0.45 mm/rev), the drill point acts as a punch that pierces the laminate with approximately constant push-out delamination size irrespective to the value of the thrust force. Surface roughness increases with the increase of drill pre-wear due to the generated heat that assisted by the low thermal properties of polymeric composites. Drilling at high feeds reduces the stiffness of the specimens and its ultimate bearing loads. Artificial neural network and multivariable regression models were developed for predicting the bearing strength of drilled holes. [ABSTRACT FROM PUBLISHER]

Thermoplastics and fiber-reinforced thermoplastics represent great deals in nowadays industries and applications where some of these applications are projected to wet environment. The present study investigates the effect of water moisture on the bearing strength (BS) of Polypropylene (PP) and glass fiber (GF) reinforced Polypropylene (GFRPP) composites. PP and GFRPP are produced by injection molding using different GF weight fractions (wt%), 10, 20, and 30 wt%, and two different initial fiber lengths 12 and 24 mm. A burnout test indicated that produced specimens with 12 mm long fibers have higher final fiber lengths than those made of 24 mm long fibers. More water was absorbed for higher GF weight fractions. The results of the dry bearing test showed higher bearing strengths for specimens with higher GF wt% and longer fibers. The same observation was obtained from wet tests, while, wet-tested specimens of all compositions have higher strengths than their dry counterparts. Strain-at-break seemed to be significantly reduced by water absorption for all specimens. Specimens tested in wet conditions have different fracture morphology than dry ones due to the change in the mechanical behavior of the materials after water immersion., (© 2022. The Author(s).)

This study is an investigation of weight fraction (wt%) and fiber feedstock length (FFSL) effects on the bearing strength (BS) of bolted joints in glass-fiber-reinforced (GFR) polypropylene (PP) composites manufactured by an injection molding technique. The investigation was made for holes produced either by molding or machining. For machined holes, the effect of drilling parameters (feed and speed) on BS was discussed. It is observed that BS decreased as FFSL increased. BS of both molded-in and drilled specimens was enhanced by increasing wt% of glass fiber. While slightly better BS was observed for molded-in specimens than drilled ones for all specimens. The drilling conditions' effect on BS was found to be insignificant for drilled holes in long fibers reinforced PP, where the most significant factor was wt%. However, for short fibers reinforced PP, the spindle speed was the most significant factor followed by feed, while wt% has the lowest effect. Failure morphology mode for specimens indicates that for molded-in specimens, neat PP specimens failed under pure bearing mode while GFR/PP specimens failed under the mixed-mode failure (bearing and net tension). For machined specimens, all specimens failed under mixed-mode failure except for the highest wt% specimens which failed under net tension., (© 2022. The Author(s).)