Effects of the Long-Time Immersion on the Mechanical Behaviour in Case of Some E-glass / Resin Composite Materials

Abstract

The chapter deals with the actual and difficult problem of analysing the mechanical structures from the perspective of using composite materials in aggressive environment. Optimising the mechanical structures, made by composite materials is a great actual and important problem that includes two of the most modern, difficult and demanded aspects in mechanical engineering. If we point out this subject, meaning the aggressive environment, we already have the complete image of an extreme actual, important and special complexity subject. The major studies in the field of structural optimising of the components made of composite materials, followed to obtain structures of components having higher strength and rigidity, lower weight, under conditions of a lower cost. There have been analysed composite material components, for which have been varied the material structure for fibre and matrix, the orientation of the fibres in layers, the shape of component, etc. The present study proposes an objective and supplementary criterion: the conservation of the mechanical characteristics of strength and rigidity under the long time action of the aggressive environment factors. The results presented within this chapter address to the researchers and specialists in the field of the composite materials, to the ph.d. students and students from master, etc. Concurrently, reading of this working, may establish a point of start in the researching activity in this direction because it notes some important remarks regarding the effects of the aggressive environment (humidity, basic and acid solutions, temperature, thermal cycles, electrons radiation, UV rays etc) on the degradation of the mechanical characteristics of some composite materials. The specialists interested in the field of composite materials will find a rich source of information by establishing a method of testing the specimens made of composite materials, subjected to statically forces after maintaining in aggressive environment; recommendations concerning the polymeric composite structure, having long durability under the action of the humidity and variations of temperature. When an organic matrix composite is exposed to humid air or to a liquid, both the moisture content and temperature of the composite material may change with time. These changes affect the mechanical characteristics (Corum et al., 2001; Pomies et al., 1995; Cerbu, 2007; Takeshige et al., 2007).