The effect of moisture ingress on through-thickness residual stresses in unsymmetric composite laminates: A combined experimental–numerical analysis

The influence of hydrothermal conditioning on the Mode-I, thermal and flexural properties of Carbon/Benzoxazine composites with a thermoplastic toughening interlayer

“…Furthermore, the ingress of water causes swelling of the matrix which -in the presence of reinforcing fibres -can lead to internal stresses which could potentially lead to a reduction in strength of the sample [38]. The generation of internal stresses due to swelling and the effect that moisture has on this is a complex topic that is outside the scope of this paper; however, in-depth research has been conducted on this subject by Telford [54,55]. As was mentioned in the previous section, the maximum service temperature of the BZ9130 samples is much higher than the BZ9120 samples, yet saturated BZ9130 samples experienced a much larger reduction in stiffness than the BZ9120 samples.…”

Analysing thermally induced macro-scale residual stresses in tailored morphing composite laminates

“…The profiles themselves are typical of what has been already observed and described in a previous work [15] and thus will not be described in detail. By studying the stress profiles of the laminates it is evident that a tailored laminate configuration impacts upon the residual stresses of a partition comprising a certain lay-up.…”

“…A local material orientation was then assigned to each ply according to the ply stacking sequence for that laminate. Orthotropic and linear-elastic material properties were used to represent the HTA 6376 material, as in Table 1 [15]. The material's longitudinal CTE (a L ) was deliberately left undefined at this stage, and was later used as a calibration parameter to reproduce as closely as possible the curvatures of the manufactured laminates.…”

“…continuum approach. Additionally, complex environmental factors that influence residual stresses (such as moisture absorption) can require a transient analysis, to which a continuum approach lends itself by use of the analogy between heat transfer/thermal expansion and moisture diffusion/moisture-induced swelling [13][14][15].…”

“…This work aims to build upon a previously developed experimental-numerical approach to predict dry and saturated through-thickness residual stresses (and thus the shapes) of unsymmetric laminates [15] by expanding it to predict tailored lay-up laminate shapes, and subsequently extract and analyse macro-scale through-thickness residual stresses. A number of different laminate configurations are explored with varying laminate thickness and discontinuous ply orientations (with the transition being both normal to the laminate thickness and tapered).…”