Surface Waves In Homogeneous Visco-Elastic Media Of Higher Order Under The Influence Of Gravity And Surface Stresses

The aim of the present paper is to investigate the surface waves in a homogeneous, isotropic, visco-elastic solid medium of nth order, including time rate of strain under the influence of gravity and surface stresses. The theory of generalized surface waves is developed to investigate particular cases of waves such as the Stoneley, Rayleigh and Love waves. Corresponding equations have been obtained for different cases. These reduced to classical results, when the effects of gravity, surface stresses and viscosity are ignored. Keywords: Gravity, Surface waves, Visco-elasticity, Surface stresses

Effects of hygrothermal stress on the failure of CFRP composites

This paper investigates the hygrothermal effects on the failure mechanisms in bending of carbon fibre reinforced polymer (CFRP) composites. Accelerated diffusion testing was carried out by immersion at 50 °C constant temperature and 70 bar hydrostatic pressure to study the effects of fresh or sea water diffusion into pre-preg CFRP laminates. Consequently the composite laminates were tested in bending after 1 and 3 months’ immersion. A three-dimensional finite element analysis (FEA) model was developed to couple the moisture diffusion, hygrothermal expansion and bending. Optical and field emission scanning electronic microscope (SEM) were employed to analyse the failure mechanisms of CFRP composites in bending after immersion. The study showed that the mechanical properties are significantly reduced after short term immersion due to the edge effects, while the damage to the fibre/polymer interface becomes more significant to laminate degradation after longer-term immersion