Submitted by SERGIO RICARDO DE PAIVA null (sergio.paiva@embraer.com.br) on 2018-03-01T23:18:05Z No. of bitstreams: 1 Dissertação Sergio Paiva_Versão Final_F_Alterações.pdf: 4152807 bytes, checksum: bd7266ab07460bb304ec051893e2dce2 (MD5) / Approved for entry into archive by Pamella Benevides Gonçalves null (pamella@feg.unesp.br) on 2018-03-02T12:14:34Z (GMT) No. of bitstreams: 1 paiva_sr_me_guara.pdf: 4152807 bytes, checksum: bd7266ab07460bb304ec051893e2dce2 (MD5) / Made available in DSpace on 2018-03-02T12:14:34Z (GMT). No. of bitstreams: 1 paiva_sr_me_guara.pdf: 4152807 bytes, checksum: bd7266ab07460bb304ec051893e2dce2 (MD5) Previous issue date: 2018-01-26 / O processo de rebitagem é largamente utilizado na indústria aeronáutica para fabricação de fuselagens de aviões. Durante esse processo deformações locais são introduzidas nas estruturas por meio da expansão dos rebites devido sua conformação. A deformação plástica causa uma expansão no rebite e consequentemente na estrutura circundante onde o mesmo foi inserido. Este trabalho tem como objetivo analisar o efeito da anisotropia na propagação da deformação induzida em corpos de prova de ligas 2024 que passaram pelo processo de rebitagem, em chapas de alumínio termicamente tratadas. O experimento avaliou como a geometria do grão, relacionadas ao tamanho e forma dos mesmos, assim como o efeito do tratamento térmico, influenciam na expansão diametral. Foram empregados corpos de prova de liga de alumínio 2024 com tratamento térmico T3 e TO, comumente utilizadas pela indústria aeronáutica, em diferentes direções de grãos, longitudinal e transversal, onde foram cravados rebites e avaliado o alongamento dos corpos de prova pelo efeito da rebitagem. Os resultados obtidos comprovam que a anisotropia exerce uma influência significativa no fator expansão e que a deformação plástica na direção transversal de laminação foi aproximadamente 60% maior que na direção de laminação para os dois tratamentos térmicos analisados. Também foi constatado que o tratamento térmico do material influencia no fator expansão. Verificou-se que a expansão dos corpos de prova recozidos foi o dobro nas direções transversal e longitudinal quando comparados com os corpos de prova de condição envelhecida / The riveting process is wide used at Aerospace industry during airplane fuselage construction. During this process, local deformations are introduced in the structures by the rivet expansion, due the plastic deformation. The plastic deformation makes the rivet expand inside the hole and consequently, the structure around the rivet expand too. The goal of this research is to analyses the anisotropy effect in the squeezing force propagation in specimens of 2024 alloys that were submitted to the riveting process, in aluminum plates heated treatment. The research analyzed the grain geometry related to size and form, and how the heat treatment effect influences the hole diameter expansion. It was used specimens of aluminum alloy 2024 T3 and TO, commonly used in aerospace industry, in different grains directions, longitudinal and transversal. Rivets were installed and the specimen stretching was analyzed. The results prove that the anisotropy have a significative influence in the expansion factor, the plastic deformation in the transversal rolled direction was about 60% bigger than rolled direction for the two heat treatment analyzed. Also, it was verified that the material heat treatment influences the factor expansion. According the results the expansion in the relieved specimens condition were the double in the transversal and longitudinal direction than the aging specimens condition

Les mécanismes hyperstatiques sont souvent utilisés dans l’industrie pour garantir une bonne tenue mécanique du système et une bonne robustesse aux écarts de fabrication des surfaces. Même si ces assemblages sont très courants, les méthodologies d’analyse de tolérances de ces mécanismes sont difficiles à mettre en oeuvre.En fonction de ses écarts de fabrication, un assemblage hyperstatique peut soit présenter des interférences de montage, soit être assemblé avec jeu. Dans ces travaux de thèse, nous avons appliqué la méthode des polytopes afin de détecter les interférences de montage. Pour un assemblage donné, le polytope résultant du mécanisme est calculé. Si ce polytope est non vide, l’assemblage ne présente pas d’interférence. Si ce polytope est vide, l’assemblage présente des interférences de montage. En fonction du résultat obtenu, deux méthodes d’analyse distinctes sont proposées.Si l’assemblage est réalisable sans interférence le polytope résultant du mécanisme permet de conclure sur sa conformité au regard de l’exigence fonctionnelle. Si l’assemblage présente des interférences de montage, une analyse prenant en compte la raideur des pièces est réalisée. Cette approche est basée sur une réduction de modèle avec des super-éléments. Elle permet de déterminer rapidement l’état d’équilibre du système après assemblage. Un effort de montage est ensuite estimé à partir de ces résultats pour conclure sur la faisabilité de l’assemblage. Si l’assemblage est déclaré réalisable, la propagation des déformations dans les pièces est caractérisée pour vérifier la conformité du système au regard de l’exigence fonctionnelle.La rapidité de mise en oeuvre de ces calculs nous permet de réaliser des analyses de tolérances statistiques par tirage de Monte Carlo pour estimer les probabilités de montage et de respect d’une Condition Fonctionnelle. / Over-constrained mechanisms are often used in industries to ensure a good mechanical strength and a good robustness to manufacturing deviations of parts. The tolerance analysis of such assemblies is difficult to implement.Indeed, depending on the geometrical deviations of parts, over-constrained mechanisms can have assembly interferences. In this work, we used the polytope method to check whether the assembly has interferences or not. For each assembly, the resulting polytope of the mechanism is computed. If it is non empty, the assembly can be performed without interference. If not, there is interferences in the assembly. According to the result, two different methods can be implemented.For an assembly without interference, the resulting polytope enables to check directly its compliance. For an assembly with interferences, a study taking into account the stiffness of the parts is undertaken. This approach uses a model reduction with super elements. It enables to compute quickly the assembly with deformation. Then, an assembly load is computed to conclude on its feasibility. Finally, the spreading of deformation through the parts is calculated to check the compliance of the mechanism.The short computational time enables to perform stochastic tolerance analyses in order to provide the rates of compliant assemblies.