MODELLING OF LINEAR ELASTICITY AND VISCOELASTICITY OF THERMOSETS AND UNIDIRECTIONAL GLASS FIBRE-REINFORCED THERMOSET-MATRIX COMPOSITES – PART 1: THEORY OF MODELLING
Marian Klasztorny, Daniel B. Nycz
Quarterly No. 1, 2022 pages 3-15
DOI:
keywords: thermoset, unidirectional glass fibre-reinforced thermoset-matrix composite, rheological modelling, constitutive equations of linear elasticity-viscoelasticity, analytical modelling
abstract The paper presents advanced analytical modelling of the linear elasticity and viscoelasticity of thermosets and unidirectional long glass fibre-reinforced thermoset-matrix (UFRT) composites. New non-aging materials fully relaxed after the curing and post-curing processes are considered. Quasi-static long-term isothermal reversible viscoelastic processes under normal condi-tions are modelled. The thermosets are isotropic materials with viscoelastic shear strains and elastic bulk strains, and the fibres are isotropic and elastic. New rheological models for thermosets and UFRT composites, described by the smallest possible number of material constants, are developed. The viscoelastic generic function for shear/quasi-shear stresses is assumed as the Mittag-Leffler fractional exponential function in an integral form. The thermoset is described by two elastic and three viscoelastic parameters. The homogenized UFRT composite is described by five elastic and five viscoelastic parameters. Conjugated/unconjugated standard/inverse constitutive equations of the linear elasticity/elasticity-viscoelasticity governing thermosets and UFRT composites are formulated. The equations are mutually analytically transformable.