ON THE STIFFNESS INCREASE OF FIBRE-REINFORCED COMPOSITE STRUCTURES

Abstract

The paper presents theoretical and experimental approaches regarding the stiffness increase of fibre-reinforced composite structures with application to a sandwich which presents the following plies sequence: 1 x RT500 glass roving fabric/ 2 x RT800 glass roving fabric/ 1 x 450 g/m2 chopped glass fibres mat/ nonwoven polyester mat as core/ 1 x 450 g/m2 chopped glass fibres mat/ gelcoat layer. The sandwich structure manufactured at COMPOZITE Ltd., Brasov, Romania is formed of twelve curved shells and presents dissimilar skins. Three-point bend tests have been carried out to determine the most important features of this structure, as well as a finite element analysis. Stresses and strains have been measured using strain gauges applied on a curved shell subjected to bending. The experimental researches accomplished on specimens manufactured from the same material as the structure present a twelve times increase of the flexural rigidity against the upper skin one.