Physical and mechanical properties of laminar composites depending on the production methods: an experimental investigation

In this study, the effects of different manufacturing methods on the physical and mechanical properties of carbon/epoxy composite laminates were investigated. The hand lay-up, compression moulding, and vacuum bagging methods with two different vacuum characteristics were selected as the applied methods. The fibre volume fraction (V-f), density, and void content of the composites were measured. The results showed that different manufacturing methods yielded different V-f results. As the V-f values increase, the composite density increases, and the void content within the laminates decreases. Also, the actual and the theoretical density values get closer with increasing V-f values. The tensile and flexural properties of the laminated composites were obtained with mechanical testing as per the ASTM standards. The higher the V-f value, the higher mechanical properties were obtained. The reduced void content within the composite structure could be attributed to better wet out of fibres with the matrix; hence, improved fibre-matrix interfacial bonding was obtained. The higher mechanical properties were achieved due to better load transfer between the fibre and matrix. A single objective optimization was conducted with ANOVA, and empirical equations were derived. The empirical equations can now be used to quickly estimate laminate density, strength, and the modulus of the composites depending upon the V-f, which is directly related to the manufacturing technique. The results help the manufacturers to decide the selection of suitable manufacturing methods.