Modelling the influence of temperature and relative humidity on the time-dependent mechanical behaviour of a short glass fibre reinforced polyamide

Abstract

WOSInternational audiencePolymer matrix composites, and especially short glass fibre reinforced polyamides, are widely used in the automotive industry. Their application on structural components requires a confident mechanical design taking into account the sensitivity of the mechanical response to both temperature T and relative humidity H. In this paper, the constitutive model already developed by the authors (Launay et al., 2011) is applied to describe the non-linear time-dependent behaviour of a PA66-GF35 under various hygrothermal conditions. The extensive experimental database involves testing conditions under and above the glass transition temperature Tg. An equivalence principle between temperature and relative humidity is applied and validated, since the non-linear mechanical response is shown to depend only on the temperature gap T-Tg(H)

In situ damage mechanisms investigation of PA66/GF30 composite: Effect of relative humidity

“…The noticeable differences on the strength and modulus of PA66/ GF30 by variation of RH are assumed to be due to damage and plasticization effect. Indeed, the RH = 0%, 50% and 100% specimens represent the conditions where the composites are respectively in glassy (T g > T room ), glass transition (T g % T room ) and rubbery states (T g < T room ) [26,27]. Strain to failure in RH = 50% and 100% specimens are higher than that in RH = 0% specimen, whereas no significant difference is observed between the strain to failure at RH = 50% and 100% specimens.…”

“…composite microstructure, damage mechanisms, polymer rheology, hygrothermal conditions, loading level and paths, etc. [21][22][23][24][25][26].…”

“…The RH = 0%, 50% and 100% specimens represent approximately conditions where the composites are respectively in glassy, glass transition and rubbery states, according to the RH effect on the glass transition temperature [26,27]. For a confirmation purpose, the results of lCT on the RH = 0% and 50% specimens will be presented.…”

Phenomenological multi-mechanisms constitutive modelling for thermoplastic polymers, implicit implementation and experimental validation

“…This type of material is well known to be highly sensitive to the environmental conditions (Launay et al, 2013c;Arif et al, 2014a), especially the relative humidity (RH) and the temperature (T ). In the present case, the following environmental conditions were considered: RH = 50% and T = 23 o C (room temperature).…”

“…They also appear to be sensitive to the environmental conditions, namely relative humidity and temperature (Launay et al, 2013c;Arif et al, 2014a). Investigations showed that these materials are also subjected to stiffness reduction during loading caused by the existence of damage mechanisms related to the initiation, the growth and the coalescence of micro defects (Detrez et al, 2011).…”