XIX Reunión de Usuarios de SIMULIA Stress Intensity Factors Calculation of Cracks in Bolted Joints with XFEM Romero Menéndez María <[email protected]> Martínez González Álvaro José <[email protected]> ICEMM S.L, Parque Científico Universidad Carlos III de Madrid, 28918 Leganés, Spain, www.icemm.es RESUMEN Un tema de especial interés para la industria aeroespacial es el análisis de la propagación de grietas. Especial atención se presta a la propagación de grietas en uniones atornilladas, debido a su amplia presencia en las estructuras aeronáuticas. Punto clave en los análisis de propagación de grietas es el cálculo del Factor de Intensidad de Tensiones (SIF). Existen diferentes técnicas disponibles en Abaqus para este tipo de análisis, como el método de la Integral de Contorno y XFEM. Un breve repaso de ambas técnicas se lleva a cabo en este trabajo, mediante la validación de los resultados obtenidos con técnicas analíticas. Se estudia también la variación del SIF a través del espesor, fenómeno que no es posible analizar con modelos en 2D. Finalmente, el trabajo se centra en el análisis del SIF de una grieta de borde de agujero en un modelo 3D de una unión atornillada. En este tipo de análisis, a pesar de estar sometido a tensión axial, debido a las excentricidades presentes en el problema, existe flexión secundaria, que afecta el cálculo del SIF. Para estudiar la influencia de este efecto en la propagación de grietas, se compararán resultados obtenidos mediante modelos 3D y 2D (sin flexión secundaria). ABSTRACT Crack growth analysis is of major interest for the aerospace industry. Special focus is put on cracks in bolted joints connections, due to its large presence in aircraft structure. Key issue in crack growth analysis is the calculation of Stress Intensity Factor (SIF). Different techniques are available in Abaqus for this type of analysis, such as Contour Integral approach and XFEM. A brief review of both techniques is done in the present work and results obtained for simple geometries are validated with analytical solutions. It is also studied the SIF variation in the through thickness direction due to the local constraint variation along the crack front which cannot be captured with 2D models. Finally, the work is focused in SIF analysis for a crack growing from bolt hole in a 3D bolted joint model. In this type of analysis, despite the fact that the joint is only subjected to tension stress, due to the eccentricities of the problem, secondary bending is also present, affecting SIF calculation. In order to study the influence of secondary bending in through crack propagation, SIF obtained for 2D models (without secondary bending) and 3D models are compared. 1 INTRODUCTION Bolted joints are very common connections in aerospace industry. One of the main problems of this type of structures is the initiation of damage due to fatigue, since bolt holes are stress concentration areas.
Stress Intensity Factors Calculation of Cracks in Bolted Joints with XFEM
May 30, 2023
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