Multi-Objective Optimisation of Curing Cycle of Thick Aramid Fibre/Epoxy Composite Laminates

Aramid fibre-reinforced epoxy composites (AF/EP) are promising materials in the aerospace, transportation, and civil fields owing to their high strength, high modulus, and light weight. Thick composite laminates are gradually being applied to large composite structures such as wind turbine blades. During curing, temperature overheating is a common problem in thick composites, which leads to matrix degradation, thermal residual stresses, and uneven curing. This paper proposes a signal-to-noise ratio (SNR) method to optimise the curing cycle of thick AF/EP laminates and reduce the overheating temperature. During curing, the temperature and strain evolution in a thick AF/EP laminate were monitored using fibre Bragg grating sensors. The effects of the curing factors on the overheating temperature of the thick AF/EP laminate were evaluated using the Taguchi method and predicted via the SNR method and analysis of variance. The results indicate that the dwelling temperature is the main factor affecting the overheating temperature. The optimal curing cycle involves an overheating temperature of 192.72 °C, which constitutes an error of 2.58% compared to the SNR method predictions. Additionally, in comparison to the initial curing cycle, the overshoot temperature in the optimised curing cycle was reduced by 58.48 °C, representing a reduction ratio of 23.28%.

The Energy-absorbing Characteristics of Single Spherical-roof Contoured-core (SRCC) Cell with Composite Materials

It is a challenging task to manufacture the novel lightweight sandwich panel with different composite materials. The aim of this paper is to study the energy-absorbing characteristics of single spherical-roof contoured-core cell with carbon, glass and aramid fibre reinforced plastics, which were fabricated through compression moulding technique. The quasi-static compression test was carried out to investigate the compressive properties and crushing behaviour of the single contoured-core cell. It was demonstrated that the single spherical-roof contoured-core with aramid fibre reinforced plastic provided the highest specific energy absorption value of 0.69 kJ and the lowest compressive stiffness of 30.43 kN/mm compared to carbon and glass fibre reinforced plastics. Furthermore, it was observed that matrix cracks, fibre fracture and laminate bending are the main failure modes of the single contoured-core cell under quasi-static loading.

Effect of the factors affecting high-performance p-aramid fibre dyeing and their optimization

Purpose This study aims to evaluate the dyeing of the p-aramid fibre with cationic dyes and investigate the effect of dyeing in the protection of the fibre from ultraviolet (UV) light. Design/methodology/approach P-aramid fabric has been dyed with cationic dyes using benzyl alcohol as swelling agent to promote the penetration of dye molecules into the fibre. The fabrics were evaluated against colour strength (K/S) value and colour fastness properties after dyed with cationic dyes using full factorial design. This design was used to study the effect of factors that affect the response variables as well as to study the interactions among the factors on response variable. The bursting strength, scanning electron microscopy analysis and X-ray diffraction analysis of undyed and dyed p-aramid fabric were performed before and after exposure to UV light to investigate the changes in mechanical behaviour. Findings The results show that the p-aramid fabric dyed with cationic dyes has good K/S values and good fastness properties. The exposure of undyed p-aramid fabric to UV light causes serious loss in strength over short duration i.e. 40 h. Dyeing of p-aramid fabric enhances the resistance to UV light which reduces the loss in strength. Originality/value Most of the work is patented and no one has done the process optimization for the industry, so this study offers promising outcomes concerning the dyeing of p-aramid fabric with enhanced shade depth and good colour fastness characteristics.