Avaliação de dano por fadiga baseado na abordagem das tensões de hot-spot em juntas tubulares KT offshore

• Ano de defesa: 2021
• Autor(a) principal: Bianca Vieira Ávila
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; Brasil; ENG - DEPARTAMENTO DE ENGENHARIA ESTRUTURAS; Programa de Pós-Graduação em Engenharia de Estruturas; UFMG
• Palavras-chave em Português: Estruturas offshore; Fadiga; Tensões de hot-spot; Acumulação de dano simplificado; Análise de elementos finitos; Engenharia de estruturas; Deformações e tensões; Método dos elementos finitos
• Link de acesso: http://hdl.handle.net/1843/36003; https://orcid.org/0000-0003-0630-7487

The expansion of the offshore industry has been noticeable in the last few decades, whether in the production of oil and gas or wind energy. Due to the environment to which they are inserted, these structures are subjected to cyclical loads of environmental origin such as winds and waves, and consequently, they are subject to fatigue damage that can result from the growth of cracks to the structure collapse. Nominal stresses have long been used in the assessment and study of fatigue strength; however, this approach is limited and does not consider the effects of geometric discontinuities and stress concentration. On the other hand, the hot-spot stress approach has been proposed in codes and recommendations as in IIW (2016) and DNV (2019) for presenting more reliable results. For this reason, this study aims to assess the fatigue damage of a tubular KT-joint that integrate a jacket-type offshore support structure. For this, the joints are studied analytically and numerically using the ABAQUS software through the hot-spot stress method described in the IIW (2016) and DNV (2019) recommendations. In the numerical modelling, the influence of the weld geometry is also evaluated. The hot-spot stresses are calculated using the analytical method proposed by DNV-RP-C203 (2019) derived from Efthymiou's analytical equations for the stress concentration factor, combined with the stresses superposition. The fatigue damage evaluation is calculated through the simplified fatigue analysis proposed by DNV (2019). The results showed greater conservatism in the IIW (2016) recommendations in comparison to the numerical and analytical methods presented in DNV (2019). Regarding the influence of the weld on the solid model, due to the simplifications adopted, a modest variation in the stresses was observed, which did not imply significant changes due to the consideration of the weld geometry.