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Abstract(s)
As ligações adesivas têm vindo a substituir métodos tradicionais de ligação, tais como, a soldadura, ligações aparafusadas e rebitadas na conceção de estruturas mecânicas das mais variadas indústrias, destacando-se a aeronáutica, espacial e automóvel. Esse método de união apresenta várias vantagens relativamente aos outros métodos tais como, facilidade de fabricação, maiores cadências de produção, menores custos, facilidade em unir materiais diferentes, melhor resistência à fadiga, elevada capacidade de amortecimento de vibrações, melhor distribuição das tensões e elevada resistência a corrosão. As juntas adesivas tubulares têm aplicações variadas, como em treliças, eixos de máquinas e tubulações. Esta dissertação teve com principal objetivo comparar o desempenho à tração, de juntas adesivas do tipo varão-tube de alumínio (AW6082-T651), considerando a variação dos principais parâmetros geométricos: comprimento de sobreposição (L0) e espessura do tubo (ts), diâmetro do varão (vd), existência de chanfro inteiro adesivo e tipo de adesivo (Araldite® 2015, Araldite® AV138 e SikaForce®472 FR). O método de Taguchi foi empregue na elaboração do desenho de experiências utilizado. Esta técnica permite identificar as variáveis que têm verdadeira influência no desempenho da junta. Para comparar o desempenho das juntas varão-tubo, procedeu-se a uma análise numérica utilizando um programa de elementos finitos (EF). As tensões de arrancamento (σy) e de corte (τxy) na camada adesiva foram obtidas através de modelos puramente elásticos. Através da utilização de modelos de dano coesivo, foi possível obter a variável de dano (stiffness degradation ou SDEG), a resistência e energia dissipada das juntas adesivas em estudo. Como resultado da aplicação do método de Taguchi, a configuração de junta que apresentou uma melhor combinação de propriedades foi a junta tubular com o Araldite® AV138, com um L0=40 mm, vd=20 e ts=3mm.
Adhesive bonding has been replacing traditional jointing methods such as welding, bolting and riveting connections in the design of mechanical structures in industries like automotive, aerospace and aeronautics. This joining method has several advantages over other methods such as ease of manufacture, higher production rates, lower costs, ease of joining different materials, higher fatigue resistance, high vibration damping capacity, better stress distribution and high corrosion resistance. Tubular adhesive joints have varying applications, such as in trusses, machine axles, and piping. This thesis compares the tensile performance of adhesively-bonded aluminum rod-tube joints (AW6082-T651), considering the variation of the main geometric parameters: overlap length (L0), tube thickness (ts), rod diameter (vd), adhesive fillet and type of adhesive (Araldite® 2015, Araldite® AV138 and SikaForce®472 FR). The Taguchi's method was employed in the elaboration of the design of experience applied. This technique allows identifying the variables that have a real influence on the mechanical performance of the joint. To compare the behavior of the rod-tube joints, a numerical analysis was done through a finite element program (FE). Peeling (σy) and shear (τxy) stresses in the adhesive layer were obtained applying a purely elastic models. Through the use of cohesive zone model it was possible to obtain the damage variable (stiffness degradation or SDEG), the strength and dissipated energy of the adhesive joints under study. As a result of applying the Taguchi method the adhesive joint that showed the better overall performance in configuration with Araldite® AV138, L0=40 mm, vd=20 and ts=3mm.
Adhesive bonding has been replacing traditional jointing methods such as welding, bolting and riveting connections in the design of mechanical structures in industries like automotive, aerospace and aeronautics. This joining method has several advantages over other methods such as ease of manufacture, higher production rates, lower costs, ease of joining different materials, higher fatigue resistance, high vibration damping capacity, better stress distribution and high corrosion resistance. Tubular adhesive joints have varying applications, such as in trusses, machine axles, and piping. This thesis compares the tensile performance of adhesively-bonded aluminum rod-tube joints (AW6082-T651), considering the variation of the main geometric parameters: overlap length (L0), tube thickness (ts), rod diameter (vd), adhesive fillet and type of adhesive (Araldite® 2015, Araldite® AV138 and SikaForce®472 FR). The Taguchi's method was employed in the elaboration of the design of experience applied. This technique allows identifying the variables that have a real influence on the mechanical performance of the joint. To compare the behavior of the rod-tube joints, a numerical analysis was done through a finite element program (FE). Peeling (σy) and shear (τxy) stresses in the adhesive layer were obtained applying a purely elastic models. Through the use of cohesive zone model it was possible to obtain the damage variable (stiffness degradation or SDEG), the strength and dissipated energy of the adhesive joints under study. As a result of applying the Taguchi method the adhesive joint that showed the better overall performance in configuration with Araldite® AV138, L0=40 mm, vd=20 and ts=3mm.
Description
Keywords
Adesivos Juntas adesivas tubulares Método de Elementos Finitos Modelos de Dano Coesivo Parâmetros geométricos Adhesive Tubular adhesive joint Finite element method Cohesive zone models Strength prediction Geometric parameters