Rigid particles have been incorporated into laminated composites, especially to enhance their bending performance attributed to the stiffening of the matrix phase (i) and the increased interlaminar shear resistance (ii). In order to better evaluate the improvement mechanism provided by the particulate inclusions, this work investigates the incorporation of micro-sized silica on the top, bottom and both surfaces of glass fibre laminates, mitigating the interference of the interlocking effect. Three-point bending, and impact tests are performed to evaluate the hybrid glass fibre composites containing 5, 7.5 and 10 wt% of micro silica. In addition, the effect of the micro silica particles into epoxy polymers is verified under tensile, compressive and abrasion tests. A finite element model is developed to simulate the three-point bending test and to better assess the behaviour of the composite laminate. Although silica particles lead to increased compressive modulus of the epoxy polymers, their positive effect on glass fibre composites under flexural loads is more evident when placed on the bottom side of the laminates subjected to the maximum tensile stress. The incorporation of 7.5 wt% silica microparticles at the bottom surface of the laminates achieves higher flexural strength and lower impact resistance.

Este trabalho tem como objetivo estudar o efeito de cordonéis de poliéster, poliamida, poliaramida e híbrido poliamida/poliaramida como reforço de elastômeros utilizados na fabricação de mangotes. O comportamento do tubo elastomérico reforçado com cordonéis sob pressão interna foi simulado com análise por elementos finitos (FEA) utilizando-se elementos chamados reinforcement bars. Foram realizados ensaios para se obter as propriedades em tração dos cordonéis para alimentar o modelo. O cordonel de poliaramida apresentou a maior tensão de ruptura, o de poliamida maior deformação na ruptura, e o híbrido apresentou valores intermediários. O critério de falha adotado para o tubo consistiu na análise do nível de carga no cordonel. Foram avaliadas, principalmente, a pressão e a deformação de ruptura do tubo elastomérico simulado frente à variação do ângulo de orientação dos cordonéis. Os resultados mostraram que ângulos próximos a 55° tornam o tubo mais resistente porém menos rígido no sentido longitudinal.

This work investigates the effect of polyamide, polyester, polyaramid and hybrid (polyamide and polyaramid) cords as reinforcement for elastomers used in the production of marine hoses. The behavior of the elastomeric pipe reinforced with these cords under internal pressure was simulated with finite element analysis (FEA) using elements called reinforcement bars. To obtain input data for the model, tensile properties of the cords were evaluated. The polyaramid cord showed the highest ultimate stress, the polyamide the largest elongation at break, and the hybrid cord showed intermediate values. The failure criterion adopted for the pipe consisted of examining the allowable force in the cord. The analyses focused on the variation of pressure and strain at burst of the pipe with the orientation angle of the cords along the elastomeric tube. The results showed that angles close to 55° yielded stronger pipes but less rigid in their longitudinal direction.