Stochastic simulation of the influence of cure kinetics uncertainty on composites cure

Stochastic multi-objective optimisation of the cure process of thick laminates

“…In the particular setup addressed in this work there two pairs of correlated variables. These are the autocatalytic reaction order (m) and the initial degree of cure (α 0 ) with a correlation coefficient of 0.55 and the autocatalytic activation energy (E 2 ) and reaction order (m) with a correlation coefficient of −0.84 [19]. In each realisation, the surrogate model is executed calculating the process outcomes (cure time and temperature overshoot) and subsequently computing their first and second statistical moments (Table 5) cure time as a function of the first and second dwell temperature; (b) PDF of absolute differences between surrogate and FE model for Case 1 (c) Case 2 (Table 5) temperature overshoot as a function of first dwell temperature and ramp; (d) PDF of absolute differences between surrogate and FE model for Case 2.…”

“…Table 2 summarises the role and ranges of parameters and variables considered in the surrogate model. The cure kinetics parameter ranges reported in Table 2 were set taking into account their average and standard deviation as quantified in a previous study [19]. The outputs of the surrogate model, which correspond to the two variables considered in the optimisation, are the cure time (t ) cure and the maximum temperature overshoot (ΔT ) max .…”

“…Uncertainty in preform architecture, such as fibre misalignment, can cause variability in residual stresses and also in final distortion of the cured part [18]. Variability in cure kinetics parameters, such as initial degree of cure, activation energy and reaction order, can induce significant variations in temperature overshoot reaching coefficients of variation of approximately 30% [19]. Uncertainty in surface heat transfer and tool temperature can cause significant variability in cure time reaching a coefficient of variation of 20% [20].…”

Stochastic heat transfer simulation of the cure of advanced composites

“…10 A study preceding the work presented here has shown that even in the case of high specification epoxies cure kinetics variability can influence significantly the occurrence of exothermic effects leading to temperature overshoots in thick and ultra-thick components. 11 These findings have highlighted the considerable potential practical importance of uncertainty in the cure step and the need for an approach that can be utilised to simulate the overall effect of variability in the outcome of this stage of the process.…”

Effects of layer shift and yarn path variability on mechanical properties of a twill weave composite

“…Yarn path variability has been shown to be responsible for variability in manufacturing processes such as forming, 10 mould filling 11 and curing. 12 These numerical studies were based on creating geometric models using statistical models of the reinforcement's geometry. The statistical models can be as simple as a Taylor expansion of the yarn path as proposed by Endruweit and Long the reinforcement geometry in a textile pre-processor as was done, for example, by Vanaerschot et al 14 Variability of the positions of layers relative to each other in a woven composite, often referred to as layer shift, has also been recognised as a source of variability in mechanical properties.…”