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

Abstract

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%.

Sensitivity Analysis and Multi-Objective Optimization Strategy of the Curing Profile for Autoclave Processed Thick Composite Laminates

“…Meanwhile, to ensure that the overall curing of the composite material components was complete after the curing stage was completed, the minimum value of DoC should be greater than 0.9: Find X = (dt 1 , dt 2 , T 1 , T 2 , r 1 , r 2 ) Min T max , t cycle S.T. DoC ≥ 0.9 (13) The steps of the multi-objective optimization design of the curing process were shown in Figure 2: Firstly, the Latin hypercube technique was used to generate random samples in the design space. Then the sample was re-organized to generate Python scripts for an efficient finite element simulation.…”

“…With the composite increasingly used in complex structures, the thickness would exceed the applicable range of curing parameters recommended by Manufacturer Recommended Cure Cycles (MRCC) [9][10][11]. It will inevitably lead to thermal gradients, overshoot, and insufficient curing or energy consumption [12,13]. Therefore, it is of great importance to analyze the curing process comprehensively and to develop an optimization approach.…”