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Composite laminates have found extensive application in various industries, and numerous studies have been conducted to investigate their behavior in flat sheet configurations. The present study aims to extend this research by examining the behavior of convex composite specimens subjected to high velocity impact (HVI), and comparing their energy absorption and failure area to that of flat sheets made of glass fibers. Additionally, we seek to investigate the influence of curvature diameter on the energy absorption and fiber failure percentage of the composite specimens. Four series of composite laminates with distinct geometries, comprising a flat specimen and three convex composite specimens, were fabricated with nine layers each and diameters of 10, 15, and 20 cm. All specimens were fully clamped and subjected to empirical gas gun impact tests at three different velocities of 200, 250, and 300 m/s. The velocity values before and after the impact were measured using velocity sensors, and the energy absorption of the laminates was computed. Of the tested composite specimens, those with smaller diameters and greater curvature exhibited reduced fiber damage percentage and increased energy absorption. Compared to the flat specimens made of glass fibers, the convex specimens with a diameter of 10 cm exhibited an energy absorption increase of approximately 47%, while the specimens with diameters of 15 and 20 cm showed approximately energy absorption increases of 42% and 7%, respectively. The results were confirmed through simulation using finite element software ABAQUS/Explicit. Highlights: Curved E‐glass laminates studied under high velocity impact which is done experimentally and numerically.Convexity increases energy absorption capacity of E‐glass reinforced epoxy composites.The results show that convexity can absorb more energy compared to flat panels.The damaged area of curved laminates are smaller than the flat one.The findings suggest that convexity can be a useful design feature for improving impact resistance in various applications. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the prediction of the elastic constants of carbon fibre-reinforced epoxy laminated composites using a simple mathematical approach. For this purpose, a Matlab Calculation Code (MCC) has been developed in MATLAB, which provides sufficient capabilities for analysis of the mechanical behaviour of composite materials. The MATLAB code enables a variety of fibre orientation angles to be generated and a wide variety of fibre volume fractions to be analyzed under mechanical loading. In order to validate the accuracy of prediction results, a commercial grade epoxy resin (Araldite LY-5052) and unidirectional carbon fibre (Torayca T700) were used to fabricate some samples of laminated composites with cross-ply configuration using the hand lay-up method. Experimental results such as elastic modulus, tensile strength as well as elongation at break were compared with the theoretical data extracted from MCC. The theoretical analysis were verified with experimental results for the same type of composites. Although the values were different, excellent agreement in the trends of the changes was found for the two approaches. Therefore, it was concluded that the MCC is capable of predicting the elastic constants of laminated composites with a high level of confidence for a wide range of fabricating conditions. The results also showed that the tensile properties of composites made with 3-layer were generally greater than those of the other evaluated composites. This kind of behaviour may be explained by bondline defects, which adversely influence the mechanical properties. [ABSTRACT FROM AUTHOR]

The objective of this research work was to gain a better understanding of the mechanical properties of epoxy resin composites reinforced with carbon fiber. For this purpose, the effects of fiber orientations, resin types, and number of laminates on mechanical properties of laminated composites have been investigated. In the sample preparation, composites were manufactured by hand lay-up process, using a fiber-to-resin ratio of 40:60 (w:w). To investigate the effect of fiber orientation, angles of 0°, 35°, 45°, and 90° were selected. Results show that the mechanical properties, in terms of tensile, flexural and impact strengths, were mainly dependent on the fiber orientations followed by the number of laminates. At a similar fiber orientation, the composites made with EM500 epoxy resin showed the highest mechanical properties (such as tensile and flexural and impact strengths) compared to other evaluated composites. However, the differences were not highly significant. The results indicated that the mechanical properties of composites made with five-ply were generally slightly greater than three-ply composites. It may be due to the bondline defects, which adversely influence the mechanical properties. Scanning micrographs of the composites showed that the epoxy matrix material was fully adhered to the fibers, indicating a strong interface. It can be concluded that the order of increment parameters in the mechanical properties of the composites is fiber orientation > number of laminates > resin type. In addition, the tensile and flexural properties were superior in case of ±35° fiber orientations. [ABSTRACT FROM PUBLISHER]