The effect of fibre-content gradient on the mechanical properties of glass-fibre-mat/polypropylene composites

Glass-fibre-mat reinforced polypropylene (PP) composites have been manufact ured with spatially-graded distributions of fibre content. Flexural and imp act tests were carried out to investigate the effect of these fibre distrib utions on the load-direction-dependent mechanical properties of the composi tes. Isotropic composites with uniform fibre content distribution through t he spe cimen thickness were also prepared for comparison with the spatially -graded composite. When the face of a sample with high glass fibre content was loaded, the flexural strength and the impact energy of the composite sh owed improved values by comparison with those of the isotropic composite. O n the other hand, poor flexural strength and impact energy were observed wh en the face of the sample with low fibre content was loaded. Finite-element analysis was performed to investigate the stress/strain distribution of th e deformed model structure with the variation of moduli through the thickne ss. Despite having the same fibre content, the glass-fibre-mat/PP composite s could have the characteristic mechanical properties with different spatia l distributions of fibre content. (C) 2000 Elsevier Science Ltd. All rights reserved.