Understanding the effect of moisture variation on the hygromechanical properties of porosity-controlled nonwoven biocomposites

Dry vs. wet: Properties and performance of collagen films. Part I. Mechanical behaviour and strain-rate effect

“…5) depicts three main characteristic stages, with a failure region at the end: (a) Stage I -up to ε 1 (initial non-linear region): the modulus (initial or maximum modulus, E max ) decreases abruptly, which is related to the sudden rupture in collagen fibrillar bundles; (b) Stage II -ε 1 − ε 2 (quasi-linear region): the modulus remains nearly constant (linear modulus, E II ) throughout this region, indicating a gradual stress transfer between the fibrils (c) Stage III -ε 2 − ε UTS (failure region): there is a sudden drop in the modulus, reflecting the ultimate breakage of the fibrils. A similar non-linear response was observed in flax-reinforced composites with structural hierarchy (Gager et al, 2019;Jeannin et al, 2019). ε 1 , ε 2 and ε UTS denote the strain levels corresponding to at the end of Stage I, II and III (ultimate tensile strain), respectively.…”

“…Thus, this should not be considered as a characteristic stage. A similar response was observed in flax-reinforced composites due to the complex fibrillar structure of flax (Gager et al, 2019;Jeannin et al, 2019). ε 1 and ε 2 are the strain levels percent at the end of Stages I and II, respectively, while ε 0 denotes the strain generated at the end of the transitional regime.…”

Investigation about the Effect of Manufacturing Parameters on the Mechanical Behaviour of Natural Fibre Nonwovens Reinforced Thermoplastic Composites

“…For all these reasons, the use of compression moulded non-woven PP/flax biocomposites is greatly appreciated in vehicle manufacturing. However, mechanical properties of these products (PP/Flax needle-punched nonwoven) at the dry scale (before compression moulding) and at the composite scales (after compression moulding) are very dependent on several parameters, which include the parameters associated with the process (such as the needle-punching density, depth of punching), the characteristics of manufactured nonwovens (such as areal density and fibre orientation distribution), and the parameters linked to the final composites (fibre volume fraction or porosity content) [21,22].…”

Thermo-mechanical behaviour of flax/green epoxy composites: Evaluation of thermal expansion coefficients and application to internal stress calculation

“…So far, many research studies for example on the mechanical and ageing characterisation of flax fibres are well reported by numerous au-thors (Abida et al, 2019;Cadu et al, 2019;Chilali et al, 2018b;Gager et al, 2019;Saidane et al, 2016b;Van Schoors et al, 2021). However, in spite of this current knowledge, there is little information about the transverse and longitudinal coefficients of linear thermal expansion (CLTE) of flax fibres and their reinforced composites.…”