Statistical analysis of monotonic mechanical properties for unidirectional glass fiber (U)/random glass fiber (R)/epoxy hybrid and non-hybrid polymeric composites

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. </jats:p

Mechanical properties of inter-ply hybrid composites reinforced with glass and polyamide fibers

The aim of this study is to explore the possibility of using polyamide (PA) as a reinforcement with glass (G) fiber to form new hybrid composites with improved physical and mechanical properties. PA-G–reinforced epoxy hybrid composites were designed, fabricated using the hand layup technique in inter-ply configuration and their mechanical properties were investigated. Results are presented regarding the tensile, flexural, and in-plane shear behaviors of the fabricated composites with a particular consideration of the effects of the stacking sequence and PA-fiber relative volume fraction, ( vPA/ vtot). The experimental results reveal that the existence of G-fiber at the composite external layers and PA-fiber in the core improves the tensile and flexural properties but worsens the shear properties. Also, increasing ( vPA/ vtot) upgrades the tensile properties but deteriorates the flexural and shear properties. The merits of the hybridization in the current study are lesser cost compared to pure PA-composite and lightweight and better ductility compared to pure G-composite with improved mechanical properties. As a result, these hybrid composites are suitable for medium load applications.</jats:p

Experimental and numerical analysis of pinned-joints composite laminates: Effects of stacking sequences

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%. </jats:p

Analysis of curaua/glass hybrid interlayer laminates

This study compares the mechanical properties of curaua, glass and hybrid curaua/glass laminates evaluated experimentally with those obtained theoretically using commercial software for composites. Hybrids laminates were produced varying the fiber layer stacking sequence with the aim of optimizing the combination of vegetable and synthetic fibers. Composites were compression molded using eight layers of glass and/or curaua fiber mats and mechanically tested as per ASTM standards. The combination of curaua and glass fibers produced a material with intermediate properties and, depending on the type of mechanical loading and the stacking sequence, some hybrids showed properties close to the pure glass fiber composites. Furthermore, hybrid composites with glass layers closer to the surfaces showed the best overall results.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPERGSUniv Fed Rio Grande do Sul, PPGEM, BR-91501970 Porto Alegre, RS, BrazilUniv Estadual Paulista, Fatigue & Mat Res Grp, Guaratingueta, SP, BrazilUniv Caxias do Sul, Lab Polimeros, Caxias Do Sul, RS, BrazilUniv Estadual Paulista, Fatigue & Mat Res Grp, Guaratingueta, SP, Brazi