Browsing by Author "Ferreira, J. M."
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- Effect of process parameters on the strength of resistance spot welds in 6082-T6 aluminium alloyPublication . Pereira, A. M.; Ferreira, J. M.; Loureiro, A.; Costa, J. D. M.; Bártolo, P. J.In this study the microstructural and mechanical behaviour of resistance spot welds (RSW) done on aluminium alloy 6082-T6 sheets, welded at different welding parameters, is examined. Microstructural examinations and hardness evaluations were carried out in order to determine the influence of welding parameters on the quality of the welds. The welded joints were subjected to static tensile-shear tests in order to determine their strength and failure mode. The increase in weld current and duration increased the nugget size and the weld strength. Beyond a critical nugget diameter the failure mode changed from interfacial to pullout. Taking into consideration the sheet thickness and the mechanical properties of the weld, a simple model is proposed to predict the critical nugget diameter required to produce pull-out failure mode in undermatched welds in heat-treatable aluminium alloys.
- Mechanical Properties of Injection-Molded Glass Microsphere-Reinforced PolyamidePublication . Capela, Carlos; Ferreira, J. M.; Costa, J. M.; Mendes, N.This paper presents new studies of the physical and mechanical characterization of PA6 matrix composites with different volume fractions of glass microspheres (10, 15, 20, 25 and 30%), which have been processed in an industrial environment. The mechanical properties of different processed composites were obtained by three-point bending tests, and the influence of the time of immersion in water in the strength and modulus was analyzed. The mechanical properties obtained in static tests and DMA tests of the processed composites demonstrated significant increases with an increasing volume fraction of the glass microspheres. In fracture toughness tests, KIC values higher than 12% were obtained. On the contrary, the immersion in water for 20 days promotes a decrease in flexural strength and flexural modulus greater than 11 and 22%, respectively. Finally, the influence of the addition of glass microspheres to the polyamide matrix was analyzed, and the increase in Tg with increasing fraction of the glass microspheres was observed.