Influência da disposição de pinos depositados por soldagem CMT-PIN em união híbrida metal-compósito

Abstract

Composite materials, especially those of polymer matrix, are currently used in a wide range of industrial sectors, especially in the area of transport in which light structures are indispensable. Due to this reason and the coexistence of metal parts in these types of structures, this work aims to evaluate the performance of hybrid metal-composite joining in terms of the disposition (inclination and distribution) of pins deposited by CMT-PIN welding in comparison to adhesive bonding. Simple overlap joints were used, the metallic constituent being AISI 304 stainless steel plates and ER309LSI pins and the composite constituent formed by 15 layers of fiberglass fabric pre-impregnated with epoxy resin (7781-38″-F155). Pins with the shortest possible length and of the ball-head type were used, deposited in a group of 25 with three different inclinations (90°, 60° and 120°) in relation to the surface of the metal. Two deposition distributions were also considered, with the pins deposited with uniform spacing and in a concentrated manner at the edges of the joints. To evaluate the performance, a tensile shear test was used in joints in water-aged and not aged condition. As a way to evaluate the failure mode of the hybrid joints, real and thermal images were captured during the mechanical tests. The pins used for hybrid joining were able to significantly improve the shear performance of the metal-composite hybrid joints in terms of shear energy, maximum supported load and maximum and final (total) displacements, with water aging only attenuating the results. The disposition of the evaluated pins did not have, in general, any relevant effect, and the actual inclined pins (60 ° and 120 °) had adverse effects, which cancelled possible positive or negative consequences of the inclination. It was also verified that the presence of the pins avoids the catastrophic rupture of the metal-composite joints, providing a residual resistance coupled with the increase in the deformation capacity of the joint, without practically any significant increase in weight.