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Advisor(s)
Abstract(s)
A constante evolução da indústria e a necessidade de se utilizar novos tipos de materiais fazem com que as ligações adesivas sejam cada vez mais aplicadas. A possibilidade de unir uma vasta gama de materiais dissimilares, elevada resistência à fadiga, facilidade e elevada cadência de produção ou a distribuição mais uniforme das tensões sobre o total da área colada são algumas das vantagens das ligações adesivas em relação às ligações convencionais. Relativamente às juntas adesivas tubulares, a sua utilização tem crescido também bastante, apesar de os estudos desenvolvidos neste tipo de juntas serem muito escassos, principalmente na área do impacto. Assim sendo, é de primordial importância conseguir prever e potenciar este tipo de juntas para poder resistir a estes esforços pontuais. Neste trabalho será estudada a resistência ao impacto de juntas adesivas tubulares em aderentes de alumínio na liga AW6082-T651. Para esse efeito, será considerada a alteração dos parâmetros geométricos principais e a alteração da geometria das juntas. Os parâmetros geométricos principais são o comprimento de sobreposição e a alteração da espessura do tubo exterior. A alteração da geometria da junta será testada através da adição de chanfros interiores e exteriores nos aderentes, e a adição de filete de adesivo nas extremidades da sobreposição. Para poder avaliar as alterações implementadas às juntas, serão utilizados três adesivos de propriedades distintas. O adesivo AV138 de elevada rigidez, o adesivo DP8005 de elevada ductilidade e o adesivo XNR6852 E-2 de elevada tenacidade. Pela análise conseguiu-se retirar as distribuições das tensões de corte e arrancamento que se instalam na camada adesiva, para os adesivos citados. A previsão da resistência das juntas tubulares foi realizada por modelos de dano coesivo. Depois de retirados os resultados será feita a análise dos mesmos, de forma a averiguar quais as geometrias de junta ótimas em função do adesivo aplicado. No final do estudo concluiu-se que o adesivo XNR6852 E-2 foi o que conseguiu melhores resultados, tendo sido a adição de um filete de adesivo a 15° a alteração de geometria da junta que maximizou a resistência da junta adesiva tubular ao impacto. Por outro lado, a técnica de modelos de dano coesivo foi validada para a previsão da resistência de juntas adesivas tubulares ao impacto.
The constant evolution of the industry and the need to use new types of materials mean that adhesive bonds are increasingly applied. The possibility of joining a wide range of dissimilar materials, high resistance to fatigue, ease and high cadence of production or the more uniform distribution of stresses over the total of the bonded area are some of the advantages of adhesive bonds over conventional bonds. Regarding tubular adhesive joints, their use has also grown considerably, although studies on this type of joint are very scarce, especially in the impact area. Therefore, it is of extreme importance to be able to predict and enhance this type of joints to be able to resist these specific efforts. In this work, the impact resistance of tubular adhesive joints on aluminum adhesives in the AW6082-T651 alloy will be studied. For this purpose, the alteration of the main geometric parameters and the alteration of the joint geometry will be considered. The main geometric parameters are the overlap length and the change in the thickness of the outer tube. The change in the geometry of the joint will be tested through the addition of internal and external chamfers in the adherents, and the addition of an adhesive fillet at the ends of the overlap. To evaluate the changes implemented in the joints, three adhesives with different properties will be used. The high rigidity AV138 adhesive, the high ductility DP8005 adhesive and the high tenacity XNR6852 E-2 adhesive. Through the analysis it was possible to determinate the distribution of the cutting and lifting stresses that are installed in the adhesive layer, for the aforementioned adhesives. The resistance prediction of tubular joints was performed using cohesive damage models. After removing the results, their analysis will be carried out, to ascertain which are the optimal joint geometries depending on the adhesive applied. At the end of the study it was concluded that the XNR6852 E-2 adhesive was the one that achieved the best results, with the addition of a 15 ° adhesive fillet that maximized the resistance of the tubular adhesive joint to impact. On the other hand, the cohesive damage model technique was validated to predict the resistance of tubular adhesive joints to impact.
The constant evolution of the industry and the need to use new types of materials mean that adhesive bonds are increasingly applied. The possibility of joining a wide range of dissimilar materials, high resistance to fatigue, ease and high cadence of production or the more uniform distribution of stresses over the total of the bonded area are some of the advantages of adhesive bonds over conventional bonds. Regarding tubular adhesive joints, their use has also grown considerably, although studies on this type of joint are very scarce, especially in the impact area. Therefore, it is of extreme importance to be able to predict and enhance this type of joints to be able to resist these specific efforts. In this work, the impact resistance of tubular adhesive joints on aluminum adhesives in the AW6082-T651 alloy will be studied. For this purpose, the alteration of the main geometric parameters and the alteration of the joint geometry will be considered. The main geometric parameters are the overlap length and the change in the thickness of the outer tube. The change in the geometry of the joint will be tested through the addition of internal and external chamfers in the adherents, and the addition of an adhesive fillet at the ends of the overlap. To evaluate the changes implemented in the joints, three adhesives with different properties will be used. The high rigidity AV138 adhesive, the high ductility DP8005 adhesive and the high tenacity XNR6852 E-2 adhesive. Through the analysis it was possible to determinate the distribution of the cutting and lifting stresses that are installed in the adhesive layer, for the aforementioned adhesives. The resistance prediction of tubular joints was performed using cohesive damage models. After removing the results, their analysis will be carried out, to ascertain which are the optimal joint geometries depending on the adhesive applied. At the end of the study it was concluded that the XNR6852 E-2 adhesive was the one that achieved the best results, with the addition of a 15 ° adhesive fillet that maximized the resistance of the tubular adhesive joint to impact. On the other hand, the cohesive damage model technique was validated to predict the resistance of tubular adhesive joints to impact.
Description
Keywords
Juntas adesivas tubulares Adesivo estrutural Método de elementos finitos Modelos de dano coesivo Análise de tensões Previsão de resistência Impacto Alterações geométricas Tubular adhesive joints Structural adhesive Finite element method Cohesive zone models Stress analysis Strength prediction Impact Geometrical modifications