A fatigue life prediction model of welded joints under combined cyclic loading. / Um modelo para previsão de vida à fadiga de juntas soldadas submetidas a carregamentos combinados.
AUTOR(ES)
Keurrie Cipriano Goes
DATA DE PUBLICAÇÃO
2010
RESUMO
The main purpose of this work is to develop a practical and robust methodology to evaluate the fatigue life in seam weld joints fabricated with GMAW process when subjected to combine cyclic loading. The maximum linear stress at the typical crack initiation region, better known as hot spot stress, was used to calculate the fatigue life through high cycle fatigue method S x N (Stress x Life), widely used in design codes for the life assessment of welded structures. The Finite Element Method (FEM) was used to obtain the structural stresses distribution due the external loading and geometric discontinuities very common in seam weld joints. The fatigue analysis was conducted in virtual environment. The FEM stress results from each loading were imported to fatigue code FE-Fatigue and combined to perform the fatigue life prediction. The monotonic and cyclic properties of the joint materials were obtained in the literature and from the fatigue software database. These properties were adjusted based on laboratory fatigue tests in the investigated welded joints configurations. The measurement or modeling of the residual stresses resulted from the welded process is not part of this work. However, the thermal and metallurgical effects, like distortions and residual stresses, were considered indirectly through fatigue curves corrections in the samples investigated. A tube-plate specimen was submitted to combine cyclic loading (bending and torsion) with constant amplitude. The virtual durability analysis result was calibrated based on these laboratory tests and design codes such as BS7608 and Eurocode 3. The feasibility and application of the proposed numerical-experimental methodology and contributions for the welded joints structural integrity design are presented. The challenges and improvements are finally discussed.
ASSUNTO(S)
junta soldada hot spot elementos finitos structural integrity carregamento cíclico combinado integridade estrutural hot spot fatigue fadiga finite elements welded joint combined cyclic loading
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