Effects of environment on fracture toughness of glass fiber/polyster composite

Abstract

The experimental determination of the resistance to delamination is very important, since composite materials have superior properties only in the fiher dircetion, The resistance to delamination is known as the fracture toughness or fracture resistance. Fracture toughness of a matcrial has immense importance in the determination of the resistance of the material to crack propagation. The fracture and damage proee~~can be influenced by many parameters, In thi~ thesis, an experimental investigation has been carried out on the fhleture toughness of chopped strand mut glass fibre reinforced composite aner exposing to various adverse environments, like, water, saline water, acidic water, organic fud, ice temperature and hot air of 600C, for different durations using single edge notched (SEN) specimcns. The specimens were prepared from the fabricated glass fiber reinforced composite plate, The sharp notch of different length size~, namely, 2nml, 4 mm, 6mm, \.ere ent in different specimens. Microscopic examination has been carried out to verify unifOffillength of the notches. 'Ihe required number of speeimen~ with single edge sharp notch wa~ made in the same \.ay. It has been drawn a number of important inferences from this work. Fracture toughness is independent of crack ~ize. There is a sizcahle effect of environments on mechanical properlies and On fracture toughness. The environmental effects depend on the type or environment, hostility, corrosivity and constilncnt ingredients. After exposure to various envirorunents, the highe~t amount of degradation in fracture tOliglUlCShSas bcen recorded in ucidie water and then in low temperature follewed hy water, saline "ater, high temperature and organic fueL A relationship between fracture toughness and duration of exposure under these adver,;e environmeuts has been established. The fracture toughness h"" been I(mndte decreas" continuously with increased duratien of environmental exposure, whereas the fracture touglme.<,shas been found to be independent ofpre-naek length.