Development Of Domain Integral And Generalized Finite Element Methods For Three Dimensional Analysis Of Near Surface Cracking In Flexible Pavements
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Development Of Domain Integral And Generalized Finite Element Methods For Three Dimensional Analysis Of Near Surface Cracking In Flexible Pavements
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Author : Hasan Ozer
language : en
Publisher:
Release Date : 2011
Development Of Domain Integral And Generalized Finite Element Methods For Three Dimensional Analysis Of Near Surface Cracking In Flexible Pavements written by Hasan Ozer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Layered elastic theories and finite element method are among the most familiar and practiced mechanistic approaches. These approaches succeed to a certain extent in the analysis of classical bottom-up fatigue cracking of relatively thin flexible pavements, where tensile stresses and strains govern the behavior at the asphalt layer. However, elastic theories are incapable of predicting other pavement distresses, including near-surface cracking. Similarly, finite element method, which is equipped with fracture and continuum mechanics theories, also poses a significant challenge to the analysis of the near-surface cracking problem, where crack initiation and propagation planes are not easily predictable. Hence, the main objective of this study is to identify the effect of loading tire contact stresses on developing near-surface cracking potential. A numerical approach is chosen to analyze the problem, taking into account considering nonuniform tire-pavement contact stresses and multi-axial stress states in the proximity of tires. This study highlights the impact of novel computational methods, such as the Generalized Finite Element Method (GFEM), on the discovery and understanding of cracking mechanisms in pavements. GFEM allows for realistic modeling of complex phenomena that control fracture initiation and propagation. In this study, GFEM is adapted to analyze relatively thick flexible pavement structures to predict near-surface cracking. The three-dimensional (3-D) and highly multi-axial nature of the problem is successfully captured by this method, which is ideally designed for 3-D fracture problems for complex geometries and mixed loading conditions. This study proposes a high-order domain integral method for the computation of the crack front parameters such as energy release rate and stress intensity factors (SIFs). The method provides an approximation of the energy release rate function as a linear combination of Legendre polynomials. As a result, extracted functions are smoothly varying, which is crucial to obtain accurate crack propagation paths in 3-D for elastic or inelastic materials. Crack front directionality is captured by the proposed formulations and implementation using an energy release rate-based approach. The study also applies for the first time the domain integral techniques to pavement fracture problems utilizing the asphalt concrete viscoelastic characteristics. The GFEM, equipped with the tools developed in this study, is used as a computational platform to analyze near-surface cracking in relatively thick flexible pavement structures. Three-dimensional models of typical pavement structures are developed to analyze near-surface cracking and make predictions for potential critical locations for crack initiation and growth. Two potential scenarios become evident for crack growth in the vicinity of tires: Shear crack under compression and tensile crack. It is observed from the analysis that shear crack growth is the dominant mode of crack development due to loading in the proximity of tires, while tensile crack growth appears to develop within the pavement.
Generalized Finite Element Methods For Three Dimensional Crack Growth Simulations
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Author : Jeronymo P. Pereira
language : en
Publisher:
Release Date : 2010
Generalized Finite Element Methods For Three Dimensional Crack Growth Simulations written by Jeronymo P. Pereira and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
Three-dimensional (3-D) crack growth analysis is crucial for the assessment of structures such as aircrafts, rockets, engines and pressure vessels, which are subjected to extreme loading conditions. The analysis of 3-D arbitrary crack growth using the standard Finite Element Method (FEM) encounters several difficulties. The singularities at crack fronts require strongly refined finite element meshes that must fit the discontinuity surfaces while keeping the aspect ratio of the elements within acceptable bounds. Fully automatic generation of meshes in complex 3-D geometries satisfying these requirements is a daunting task. Partition-of-unity methods, such as the Generalized FEM (GFEM), are promising candidates to surmount the shortcomings of the standard FEM in crack growth simulations. These methods allow the representation of discontinuities and singularities in the solution via geometrical descriptions of crack surfaces, that are independent of the volume mesh, coupled with suitable enrichment functions. As a result, volume meshes need not fit crack surfaces. This work proposes an hp-version of the GFEM (hp-GFEM) for crack growth simulations. This method provides enough flexibility to build high-order discretizations for crack growth simulations. At each crack growth step, high-order approximations on locally refined meshes are automatically created in complex 3-D domains while preserving the aspect ratio of elements, regardless of crack geometry. The hp-GFEM uses explicit surface meshes composed of triangles to represent non-planar 3-D crack surfaces. By design, the proposed methodology allows the crack surface to be arbitrarily located within the GFEM mesh. To track the crack surface evolution, the proposed methodology considers an extension of the Face Offsetting Method (FOM). Based on the hp-GFEM solution, the FOM provides geometrically feasible crack front descriptions by updating the vertex positions and checking for self-intersections of the edges. The hp-GFEM with FOM allows the simulation of arbitrary crack growth independent of the volume mesh. Numerical simulations using the hp-GFEM coupled with the FOM are corroborated by experimental data and experimental observations. As an alternative to large-scale crack growth simulations, this work combines the proposed hp-GFEM with the generalized finite element method with global-local enrichment functions (GFEMgl). The proposed method allows crack growth simulations with arbitrary path in industrial level complexity problems while keeping the global mesh unchanged. Furthermore, this method allows crack growth simulations without solving the entire problem from scratch at each crack growth step. The GFEMgl for crack growth explores solutions from previous crack growth steps, hierarchical property of the enrichment functions as well as static condensation of the global-local degrees of freedom to expedite the solution process. Numerical examples demonstrate the robustness, efficiency and accuracy of the proposed GFEMgl for crack growth simulations.
Three Dimensional Numerical Analysis Of Reflective Cracks In Airfield Pavements
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Author :
language : en
Publisher:
Release Date : 2013
Three Dimensional Numerical Analysis Of Reflective Cracks In Airfield Pavements written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Three Dimensional Analysis Of Crack Growth
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Author : Yaoming Mi
language : en
Publisher: Computational Mechanics
Release Date : 1996
Three Dimensional Analysis Of Crack Growth written by Yaoming Mi and has been published by Computational Mechanics this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Nature categories.
Convergence Analysis Of The Generalized Finite Element Method With Global Local Enrichments
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Author : Varun Gupta
language : en
Publisher:
Release Date : 2010
Convergence Analysis Of The Generalized Finite Element Method With Global Local Enrichments written by Varun Gupta and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
The global-local analysis procedure in the Finite Element Method is broadly used in industry for the analysis of cracks or localized stress concentrations in large, complex, three-dimensional domains. However, the limitations of this technique are well-known. The global-local FEM (GL-FEM) involves two steps: First, the solution of the given problem is computed on a coarse, global, quasi-uniform mesh, in which the cracks or other local features need not be discretized. The solution of this problem is then used as boundary conditions to solve another Finite Element problem, which is basically a local sub-domain, comprised of localized features (like cracks), extracted from the global domain.The efficacy of the so-called Generalized Finite Element Method (GFEM) in solving such multi-scale problems has been quite well proven in past few years. Therefore, combining the two approaches, going one step further from Global-Local Finite Element Analysis, and using the local solution as an enrichment function for the global problem through the Partition of Unity framework of the Generalized Finite Element Method, gives rise to the Generalized Finite Element Method with global-local enrichments (or GFEMg-l). As these classes of methods are relatively new, there are many issues which need to be addressed to make these methods robust enough for their industrial applicability in a comprehensive manner. One of the issues surrounding this GFEMg-l approach concerns the domain size of the local problem containing the complex localized features of a structural problem, and the focus of this study is to provide guidance to address this issue. This study focuses on coming up with guidelines for selecting the size of the enrichment zone for three-dimensional fracture mechanics problems. A theoretical proof and rigorous convergence studies are presented here to provide the guidelines for selecting the size of enrichment zone for practical problems. The effect of inexact boundary conditions, applied to the local problem, on the solution is also investigated.
Applied Mechanics Reviews
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Author :
language : en
Publisher:
Release Date : 1989
Applied Mechanics Reviews written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Mechanics, Applied categories.
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Author :
language : en
Publisher:
Release Date : 1968
written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1968 with categories.
Three Dimensional Finite Element Analysis Of Cyclic Fatigue Crack Growth Of Multiple Surface Flaws
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Author : Corneliu Manu
language : en
Publisher:
Release Date : 1980
Three Dimensional Finite Element Analysis Of Cyclic Fatigue Crack Growth Of Multiple Surface Flaws written by Corneliu Manu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1980 with Finite element method categories.
Three Dimensional Crack Analysis By Finite Element Method With Boundary Integral Method At Crack Tip
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Author : Tae Moon Kim
language : en
Publisher:
Release Date : 1985
Three Dimensional Crack Analysis By Finite Element Method With Boundary Integral Method At Crack Tip written by Tae Moon Kim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with Cracking process categories.
A Generalized Finite Element Method For Three Dimensional Branched Cracks
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Author : Luziana Grillo Reno
language : en
Publisher:
Release Date : 2006
A Generalized Finite Element Method For Three Dimensional Branched Cracks written by Luziana Grillo Reno and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.