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Abstract(s)
As ligações adesivas são frequentemente utilizadas em diversas indústrias, uma vez que oferecem vantagens significativas relativamente a outras técnicas de união como a soldadura ou ligações aparafusadas. Até à data, foram apuradas vantagens como a redução do peso, a capacidade de colar e vedar simultaneamente e unir materiais dissimilares sem danificar as suas estruturas. Existem diferentes geometrias de juntas adesivas, nomeadamente juntas tubulares, onde um tubo de diâmetro inferior é introduzido num tubo com diâmetro superior, de forma a criar uma junta tubular de sobreposição. Este tipo de juntas confere à ligação elevado rácio resistência/peso, diminui a concentração e apresenta boa resistência à corrosão. A presente dissertação compara numericamente o desempenho dos adesivos Araldite® AV138, Araldite® 2015 e SikaForce® 7752 em juntas tubulares de sobreposição com aderentes de CFRP (Polímero Reforçado com Fibra de Carbono), alumínio AW 6082- T651 e aço DIN 55Si7, considerando a variação dos parâmetros geométricos da junta, nomeadamente o comprimento de sobreposição (LO) de 10, 20 e 40 mm. A dimensão total da junta, a geometria do substrato e as espessuras dos tubos interiores (tSI) e exteriores (tSE) foram mantidos ao longo do desenvolvimento do trabalho realizado. A análise numérica, realizada no software ABAQUS® com recurso a modelos de dano coesivo (MDC), foi inicialmente validada por comparação com dados experimentais obtidos em trabalhos anteriores. O trabalho numérico desenvolvido permitiu obter as tensões de arrancamento (σy) e as de corte (τxy) na camada adesiva com recurso a modelos puramente elásticos. De seguida, por MDC foi analisada a variável de propagação de dano (stiffness degradation ou SDEG) e foi realizada uma previsão da resistência e energia dissipada das juntas adesivas tubulares. Após diversos ensaios realizados concluiu-se que a rigidez do material e do adesivo influenciam proporcionalmente a resistência da junta adesiva. Nos ensaios realizados nesta dissertação, a junta composta por aderentes de aço DIN 55Si7 e o adesivo Araldite® AV138, apresenta valores de carga máxima superiores.
Adhesive joints are often used in many industries as they offer significant advantages over other joining techniques such as welded or bolted joints. To date, advantages such as weight reduction, the ability to simultaneously bond and seal, and join dissimilar materials without damaging their structures, have been found. There are different geometries of adhesive joints, namely tubular joints, where a tube with a lower diameter is introduced into a tube with a larger diameter, to create an overlap tubular joint. This joint geometry promotes high ratio strength/weight, uniform stresses distribution and good corrosion resistance. The present dissertation numerically compares the performance of the adhesives Araldite® AV138, Araldite® 2015 and SikaForce® 7752 in overlap tubular joints with CFRP (carbon fiber reinforced polymer), AW 6082-T651 aluminum and DIN 55Si7 steel adherends, considering the variation of the geometric parameters of the joint, namely the overlap length (LO) of 10, 20 and 40 mm. The total dimension of the joint, the geometry of the adherends and the thickness of the inner (tSI) and outer (tSE) tubes were kept constant throughout the development of the work carried out. The numerical analysis, performed in the ABAQUS® software using cohesive zone models (CZM), was initially validated by comparison with experimental data obtained in previous works. The developed numerical work enabled to obtain the peel (σy) and the shear stresses (τxy) in the adhesive layer using purely elastic models. Then, by CZM, the damage propagation variable (stiffness degradation or SDEG) was analyzed, and a prediction of the strength and dissipated energy of the tubular adhesive joints was performed. After several tests carried out, it was concluded that the stiffness of the material and the adhesive directly influence the strength of the adhesive joint. The joint composed of the adherends DIN 55Si7 steel and the adhesive Araldite® AV138 showed higher maximum load values.
Adhesive joints are often used in many industries as they offer significant advantages over other joining techniques such as welded or bolted joints. To date, advantages such as weight reduction, the ability to simultaneously bond and seal, and join dissimilar materials without damaging their structures, have been found. There are different geometries of adhesive joints, namely tubular joints, where a tube with a lower diameter is introduced into a tube with a larger diameter, to create an overlap tubular joint. This joint geometry promotes high ratio strength/weight, uniform stresses distribution and good corrosion resistance. The present dissertation numerically compares the performance of the adhesives Araldite® AV138, Araldite® 2015 and SikaForce® 7752 in overlap tubular joints with CFRP (carbon fiber reinforced polymer), AW 6082-T651 aluminum and DIN 55Si7 steel adherends, considering the variation of the geometric parameters of the joint, namely the overlap length (LO) of 10, 20 and 40 mm. The total dimension of the joint, the geometry of the adherends and the thickness of the inner (tSI) and outer (tSE) tubes were kept constant throughout the development of the work carried out. The numerical analysis, performed in the ABAQUS® software using cohesive zone models (CZM), was initially validated by comparison with experimental data obtained in previous works. The developed numerical work enabled to obtain the peel (σy) and the shear stresses (τxy) in the adhesive layer using purely elastic models. Then, by CZM, the damage propagation variable (stiffness degradation or SDEG) was analyzed, and a prediction of the strength and dissipated energy of the tubular adhesive joints was performed. After several tests carried out, it was concluded that the stiffness of the material and the adhesive directly influence the strength of the adhesive joint. The joint composed of the adherends DIN 55Si7 steel and the adhesive Araldite® AV138 showed higher maximum load values.
Description
Keywords
Epóxido Poliuretano Juntas adesivas tubulares Método de Elementos Finitos Modelos de Dano Coesivo Parâmetros geométricos Epoxy Polyurethane Tubular adhesive joints Finite Element Method Cohesive Zone Models Geometric parameters