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.

The utilization of lightweight construction is one of the keys to increase the fuel efficiency and reduce the environmental effect of automobiles. Natural fiber composites are replacing expensive synthetic fibers increasingly commonly in the automotive sector. To further lower the weight and price of the vehicle without losing rigidity and strength, basalt (B) fiber could be incorporated into jute (J) fiber composites. For the generation of hybrid composite laminates, woven textiles made of J-fiber and B-fiber were combined with an epoxy matrix. The primary mechanical features of the J-B/epoxy composite laminates, including tensile, bending, shear, and bearing characteristics, were investigated. Hand lay-up approach was used to prepare the hybrid composite laminates. The impact of the number of J-plies relative to the number of B-plies on the mechanical properties was explored. The findings proved that the basalt/epoxy composite has the maximum ultimate tensile strength, young’s modulus, toughness modulus, bending strength, bending modulus, in-plane shear strength, and bearing strength. Whereas the J/epoxy composite showed the maximum failure strain and bending strain. Hybridizing J-fiber with B-fiber improved the tensile, bending, in-plane shear, and bearing characteristics of the prepared composite. The maximum specific tensile, bending, in-plane shear, and bearing strengths are displayed by 3B-2 J-3B, followed by 2B-4 J-2B.

Mechanical properties of flax/basalt/E-glass fibers reinforced epoxy composites were studied in this paper. Vacuum bagging technique was adopted for the fabrication of hybrid composite laminates. The effects of fibers relative amounts and stacking sequence on the tensile, flexural and impact properties were investigated. Results showed that the developed hybrid composites display enhanced tensile, flexural, and impact performance as compared to flax fiber/epoxy composite. The tensile, flexural, and impact strengths increase when partial laminas from flax fiber/epoxy laminate are replaced by basalt and/or glass fiber reinforced epoxy laminas. Incorporating high strength fibers to the composite outer layers leads to improved flexural and impact resistances, whilst the opposite was noticed for tensile properties. The fabricated hybrids show economical and specific mechanical properties benefits. Fibers relative amounts and stacking sequence have noticeable effects on the studied mechanical properties.

This work investigates the impact of infill pattern structure on the crashworthy performance and deformation history of 3D-printed tubes subjected to a quasi-static axial compression load. The proposed tubes were made from polylactic acid (PLA) using a 3D printing technique. Five infill pattern structures were adapted, i.e. circular, square, triangle, zigzag and cross patterns with 50% infill density. The crashworthy analysis was carried out by assessing different indicators, i.e. peak force ( $${\mathrm{F}}_{\mathrm{ip}})$$F ip ) , mean crush force ( $${\mathrm{F}}_{\mathrm{m}})$$F m ) , total absorbed energy (U), specific absorbed energy (SEA), and crushing force efficiency (CFE). It was found that the square infill pattern shows the maximum $${\mathrm{F}}_{\mathrm{ip}}$$F ip , $${\mathrm{F}}_{\mathrm{m}}$$F m , U and SEA with values of (24.38 kN, 20.58 kN, 673.38 kJ, and 26.52) while zigzag infill pattern shows the highest CFE with a value of 0.91. The optimal infill pattern is determined using a Multi-Attribute Decision Making (MADM) method called Complex Proportional Assessment (COPRAS). The COPRAS results showed that the square infill pattern is the most effective energy absorbing structure.