Reinforced Polymer Hybrid Composites Research Articles

Optimal design for the flexural behaviour of glass and carbon fibre reinforced polymer hybrid composites

A study on the flexural behaviour of hybrid composites reinforced by S-2 glass and T700S carbon fibres in an intra-ply configuration is presented in this paper. The three point bend test in accordance with ASTM D790-07 at various span-to-depth ratios was simulated using finite element analysis (FEA). For the purpose of validation, specimens of selected stacking configurations were manufactured following the hand lay-up process and tested in a three point bend configuration. The validated FEA model was used to study the effects of fibre volume fractions, hybrid ratio and span-to-depth ratio. It is shown that flexural modulus increases when the span-to-depth ratio increases from 16 to 32 but is approximately constant as the span-to-depth ratio further increases. A simple mathematical formula was developed for calculating the flexural modulus of hybrid composites, given the moduli of full carbon and full glass composites, and the hybrid ratio. Flexural strength increases with span-to-depth ratio. Utilisation of hybridisation can improve the flexural strength. A general rule is in order to improve flexural strength, the fibre volume fraction of glass/epoxy plies needs to be higher than that of carbon/epoxy plies. The overall maximum hybrid effect is achieved when the hybrid ratio is 0.125 ([0G/07C]) when both Vfc and Vfg are 50%. The strength increases are 43.46% and 85.57% when compared with those of the full carbon and glass configurations respectively. The optimisation shows that the maximum hybrid effect is 56.1% when Vfc=47.48% and Vfg=63.29%.

Environmental effects on the interlaminar fracture in polymer hybrid composites

A systematic experimental investigation has been carried out on glass/textile fabric reinforced polymer hybrid composites with different volume fraction of the reinforcements, in order to study the effect of hybridisation on the interlaminar delamination fracture. The interlaminar fracture behaviour has been studied under bending loading using short beam bend test specimen. The influence of normal water, sea water and the saline water immersion on the behaviour of fracture has been identified. The nature of fracture has been analysed with the aid of scanning electron microscopy. The results have revealed that the addition of the silk-based textile fabric to the glass fabric has increased the interlaminar shear strength (ILSS) and the flexural strength. It is identified that these properties are very much prone to the environmental conditions. The normal water and the sea water immersion has reduced the strength of these laminates, whereas, the saline water treatment has increased the strength. The nature of fracture as a function of the reinforcement volume and environmental conditions has been identified by the SEM scans.

Chemical resistance, void content and tensile properties of oil palm/jute fibre reinforced polymer hybrid composites

Tri layer hybrid composites of oil palm empty fruit bunches (EFB) and jute fibres was prepared by keeping oil palm EFB as skin material and jute as the core material and vice versa. The chemical resistance, void content and tensile properties of oil palm EFB/Jute composites was investigated with reference to the relative weight of oil palm EFB/Jute, i.e. 4:1, the fibre loading was optimized and different layering pattern were investigated. It is found from the chemical resistance test that all the composites are resistant to various chemicals. It was observed that marked reduction in void content of hybrid composites in different layering pattern. From the different layering pattern, the tensile properties were slightly higher for the composite having jute as skin and oil palm EFB as core material. Scanning electron microscopy (SEM) was used to study tensile fracture surfaces of different composites.

Plane Strain Fracture Behaviour of Fabric Reinforced Hybrid Composites under varied Notch Configurations

Utilization of fabric reinforced hybrid polymer composites has increased tremendously in many engineering fields. The present investigation is an attempt on fabric-reinforced hybrid composite laminates with different volume fractions of the constituent materials; epoxy resin, plain-woven glass fabric, and textile satin fabric. Fracture toughness of a material has immense importance in the determination of the resistance of the material to crack propagation. Hence in this article, impact behaviour and fracture toughness of the laminates were investigated as per ASTM-D256 standards. Specimen configuration includes selection of different notch depths, fiber proportion and orientations. The fracture toughness has been found to increase continuously with increased volumes of glass fabric and significantly dependent on the notch size. Experimental results are validated using analysis of variance (ANOVA) technique, and found that percentage contribution of glass content is approximately 80%, while notch depth and orientation have contributed only 16%.