Análise comparativa da performance de elementos resistivos na soldagem por resistência elétrica em compósitos PEI/fibras de carbono

• Autor(a) principal: Quan, Natália Di Giuseppe [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/156828; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2018-08-16/000902491.pdf
• topic: Soldagem; Fibras de carbono; Compósitos poliméricos; Termoplasticos; Microscopia; Welding

The electrical resistance welding is already known and widely used in the process of joining sheet metal. However, composites do not conduct electrical current, making it difficult to use this method for their union. Consequently, it requires the introduction of a resistive material to promote the passage of the current in the interface to be welded. This heating element is considered a crucial part of the process for composite electric resistance and it is essential for transmitting the energy required for the welding of these materials. Since the metal mesh cannot be removed after the weld, it is considered as a contaminant, nonetheless is the foremost contributor to the quality of the joint. Therefore, the aim of this study was to comparatively evaluate the performance of two heating elements (stainless steel of different metal mesh and carbon fibers) in electrical resistance welding of composite PEI (polyétherimide) reinforced with carbon fibers. Mechanical testing (Lap shear and Iosipescu) and thermal analysis (DMA- dynamic mechanical analysis and TMA - thermomechanical analysis) were conducted together with morphological analysis of optical microscopy. In addition, composites samples produced with stainless steel metal mesh were submitted to both ultraviolet radiation chamber and hygrothermal chamber for further evaluation by the same mechanical tests, thermal and microscopic analysis. The heating element more appropriate for the electrical resistance welding of composite PEI/carbon fibers was the stainless steel of 300 metal mesh. The highest shear strength values of Iosipescu and Lap shear were obtained with this metal mesh. In general, samples submitted to hygrothermal conditioning in a climatic chamber with the stainless steel of 200 and 300 metal mesh showed lower values of glass transition temperature, coefficient of linear thermal expansion, shear and tensile strength, compared ... (Complete abstract click electronic access below)