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Author : Ani Ural
Publisher :
ISBN 13 :
Total Pages : 344 pages
Book Rating : 4.E/5 ( download)
Download or read book Advanced Three-dimensional Simulations and Cohesive Modeling of Fatigue Crack Growth written by Ani Ural and published by . This book was released on 2004 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Xiao Li
Publisher : Cuvillier Verlag
ISBN 13 : 373698619X
Total Pages : 140 pages
Book Rating : 4.7/5 (369 download)
Download or read book Investigation of Cohesive Zone Models for Three-Dimensional Fatigue Crack Propagation in Engineering Metals written by Xiao Li and published by Cuvillier Verlag. This book was released on 2017-09-12 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the development of technology, damage tolerance design becomes compulsory and fatigue crack propagation life is a necessary design case, e.g. in aerospace industry. For low cycle fatigue problems, the failure process is generally ductile which cannot be described by the known Paris' law properly. Predicting elastoplastic fatigue crack growth life remains one of the most challenging problems in fracture mechanics. Cohesive zone modeling provides an alternative way to predict crack growth in ductile materials under elastoplastic loading conditions. The investigations of constraint effects have confirmed that cracking depends on the applied load intensity and the load configuration. Present dissertation concerns the constraint effect on the cohesive zone model and the application of the cohesive zone model for three-dimensional low cycle fatigue crack growth predictions. - A new stress-triaxiality-dependent cohesive zone model is proposed to describe 3D elastoplastic fracture process. - A new cyclic cohesive zone model is proposed to describe the fatigue crack growth with both low and high growth rates. - A new stress-triaxiality-dependent cyclic cohesive zone model is proposed and the stress-state affects both the cohesive law and the damage evolution equation.
Author : Stephen G. Cupschalk
Publisher :
ISBN 13 :
Total Pages : 64 pages
Book Rating : 4.:/5 (244 download)
Download or read book Three-dimensional Finite-element Simulation of Fatigue-crack Growth and Closure written by Stephen G. Cupschalk and published by . This book was released on 1987 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 18 pages
Book Rating : 4.:/5 (317 download)
Download or read book Three-Dimensional Gear Crack Propagation Studies written by and published by . This book was released on 1998 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three-dimensional crack growth simulation was performed on a split-tooth gear design using boundary element modeling and linear elastic fracture mechanics. Initial cracks in the fillet of the teeth produced stress intensity factors of greater magnitude (and thus, greater crack growth rates) than those in the root or groove areas of the teeth. Crack growth simulation was performed on a case study to evaluate crack propagation paths. Tooth fracture was predicted from the crack growth simulation for an initial crack in the tooth fillet region. Tooth loads on the uncracked mesh of the split-tooth design were up to five times greater than those on the cracked mesh if equal deflections of the cracked and uncracked teeth were considered. Predicted crack shapes as well as crack propagation life are presented based on calculated stress intensity factors, mixed-mode crack propagation trajectory theories, and fatigue crack growth theories.
Author :
Publisher :
ISBN 13 :
Total Pages : 60 pages
Book Rating : 4.:/5 (946 download)
Download or read book Simulations of Failure Via Three-Dimensional Cracking in Fuel Cladding for Advanced Nuclear Fuels written by and published by . This book was released on 2014 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Enhancing performance of fuel cladding and duct alloys is a key means of increasing fuel burnup. This project will address the failure of fuel cladding via three-dimensional cracking models. Researchers will develop a simulation code for the failure of the fuel cladding and validate the code through experiments. The objective is to develop an algorithm to determine the failure of fuel cladding in the form of three-dimensional cracking due to prolonged exposure under varying conditions of pressure, temperature, chemical environment, and irradiation. This project encompasses the following tasks: 1. Simulate 3D crack initiation and growth under instantaneous and/or fatigue loads using a new variant of the material point method (MPM); 2. Simulate debonding of the materials in the crack path using cohesive elements, considering normal and shear traction separation laws; 3. Determine the crack propagation path, considering damage of the materials incorporated in the cohesive elements to allow the energy release rate to be minimized; 4. Simulate the three-dimensional fatigue crack growth as a function of loading histories; 5. Verify the simulation code by comparing results to theoretical and numerical studies available in the literature; 6. Conduct experiments to observe the crack path and surface profile in unused fuel cladding and validate against simulation results; and 7. Expand the adaptive mesh refinement infrastructure parallel processing environment to allow adaptive mesh refinement at the 3D crack fronts and adaptive mesh merging in the wake of cracks. Fuel cladding is made of materials such as stainless steels and ferritic steels with added alloying elements, which increase stability and durability under irradiation. As fuel cladding is subjected to water, chemicals, fission gas, pressure, high temperatures, and irradiation while in service, understanding performance is essential. In the fast fuel used in advanced burner reactors, simulations of the nuclear fuels are critical to understand the burnup, and thus the fuel efficiency.
Author : Amir R. Khoei
Publisher : John Wiley & Sons
ISBN 13 : 1118457684
Total Pages : 600 pages
Book Rating : 4.1/5 (184 download)
Download or read book Extended Finite Element Method written by Amir R. Khoei and published by John Wiley & Sons. This book was released on 2015-02-23 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduces the theory and applications of the extended finite element method (XFEM) in the linear and nonlinear problems of continua, structures and geomechanics Explores the concept of partition of unity, various enrichment functions, and fundamentals of XFEM formulation. Covers numerous applications of XFEM including fracture mechanics, large deformation, plasticity, multiphase flow, hydraulic fracturing and contact problems Accompanied by a website hosting source code and examples
Author : T. A. Cruse
Publisher :
ISBN 13 :
Total Pages : 107 pages
Book Rating : 4.:/5 (227 download)
Download or read book Advanced Modeling for Fatigue Growth of Small Surface Cracks written by T. A. Cruse and published by . This book was released on 1988 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary result of the sponsored research is the development and application of the boundary element method for two- and three-dimensional fatigue crack growth analysis. The two-dimensional formulation developed previously (AFOSR Contract No. F49620-84-C-0042) was extended to investigate the crack tip behavior of long and short cracks under cyclic loading. The influence of residual plasticity on stress intensity factor was used to obtain an unambiguous estimate of the plastic zone size. It was demonstrated that the effect of the plastic wake on the stress intensity factor for crack opening (closure) and the effect of the residual stress on the retardation are identical manifestations of the same plasticity process. The boundary integral equations also provide insight to the mathematical equivalence of these two effects. Keywords: Fracture mechanics, Fatigue crack growth, Crack retardation, Crack closure, Crack opening displacement, Boundary element method. (jes).
Author : John Edward Pope
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (256 download)
Download or read book A Three-dimensional Model of Fatigue Crack Growth Incorporating Crack Closure written by John Edward Pope and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : American Society for Testing and Materials
Publisher : ASTM International
ISBN 13 :
Total Pages : 260 pages
Book Rating : 4./5 ( download)
Download or read book Damage Tolerance in Aircraft Structures written by American Society for Testing and Materials and published by ASTM International. This book was released on 1971 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Brett Richard Davis
Publisher :
ISBN 13 :
Total Pages : 328 pages
Book Rating : 4.:/5 (9 download)
Download or read book Three-dimensional Simulation of Arbitrary Crack Growth written by Brett Richard Davis and published by . This book was released on 2014 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: A finite-element-based simulation technique is developed in Chapter 1 to predict arbitrary shape evolution of 3-D, geometrically explicit cracks under stable growth conditions. Point-by-point extensions along a crack front are predicted using a new, energy-based growth formulation that relies on a first-order expansion of the energy release rate. The key term in this expansion is the variation of energy release rate, made readily available via the virtual crack extension (VCE) method. The variation of energy release rate acts as an influence function relating changes in applied load to geometry changes along the crack front. The crack-growth formulation is incorporated into an incremental-iterative solution procedure that continually updates the crack configuration by re-meshing. The numerical technique allows crack shapes to evolve according to energy-based mechanics, while reducing the effects of computational artifacts, e.g. mesh bias. Chapter 1 offers three simulations of mode I, planar crack growth as proof-of-concept of the new technique. To extend the simulation approach to more general crack growth situations, Chapter 2 presents a new implementation for decomposing 3-D mixed-mode energy release rates using the VCE method. The technique uses a symmetric/anti-symmetric approach to decompose local crack-front displacements that are substituted into the global VCE energy release rate form. The subsequent expansion leads to the mixedmode energy release rate expressions. As a result of the expansion, previously unaddressed modal-interaction coupling terms are found to impact the mixed-mode energy release rates. Five numerical examples are presented as verification of the implementation. This development expands the VCE method's advantages over similar procedures when simulating arbitrary crack growth. The energy-based growth formulation and accompanying simulation technique is generalized in Chapter 3 to predict arbitrary, mixed-mode, non-planar crack evolution. The implementation uses a novel basis-function approach to generate a crack extension expression, rather than relying on the local, point-by-point approach described in Chapter 1. The basis-function expression dampens the effect of numerical noise on crack growth predictions that could otherwise produce unstable simulation results. Two simulations are presented to demonstrate the technique's ability to capture both general non-planar behavior, as well as local mixed-mode phenomena, e.g. "factory-roof" formation, along the crack front.
Author : Yaoming Mi
Publisher : Computational Mechanics
ISBN 13 : 9781853124457
Total Pages : 184 pages
Book Rating : 4.1/5 (244 download)
Download or read book Three-dimensional Analysis of Crack Growth written by Yaoming Mi and published by Computational Mechanics. This book was released on 1996 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: The engineering applications presented in this text concentrate on the simulation and analysis of general mixed mode crack growth in three dimensions.
Author : Jeronymo P. Pereira
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (774 download)
Download or read book Generalized Finite Element Methods for Three-dimensional Crack Growth Simulations written by Jeronymo P. Pereira and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author : Ronald Krueger
Publisher :
ISBN 13 :
Total Pages : 66 pages
Book Rating : 4.:/5 (317 download)
Download or read book The Virtual Crack Closure Technique: History, Approach and Applications written by Ronald Krueger and published by . This book was released on 2002 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview of the virtual crack closure technique is presented. The approach used is discussed, the history summarized, and insight into its applications provided. Equations for two-dimensional quadrilateral elements with linear and quadratic shape functions are given. Formula for applying the technique in conjuction with three-dimensional solid elements as well as plate/shell elements are also provided. Necessary modifications for the use of the method with geometrically nonlinear finite element analysis and corrections required for elements at the crack tip with different lengths and widths are discussed. The problems associated with cracks or delaminations propagating between different materials are mentioned briefly, as well as a strategy to minimize these problems. Due to an increased interest in using a fracture mechanics based approach to assess the damage tolerance of composite structures in the design phase and during certification, the engineering problems selected as examples and given as references focus on the application of the technique to components made of composite materials.
Author :
Publisher :
ISBN 13 :
Total Pages : 18 pages
Book Rating : 4.:/5 (317 download)
Download or read book Prediction of Fatigue Crack-growth Patterns and Lives in Three-dimensional Cracked Bodies written by and published by . This book was released on 1984 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Hans Albert Richard
Publisher : Springer
ISBN 13 : 3319325345
Total Pages : 305 pages
Book Rating : 4.3/5 (193 download)
Download or read book Fatigue Crack Growth written by Hans Albert Richard and published by Springer. This book was released on 2016-06-13 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a concise introduction to fatigue crack growth, based on practical examples. It discusses the essential concepts of fracture mechanics, fatigue crack growth under constant and variable amplitude loading and the determination of the fracture-mechanical material parameters. The book also introduces the analytical and numerical simulation of fatigue crack growth as well as crack initiation. It concludes with a detailed description of several practical case studies and some exercises. The target group includes graduate students, researchers at universities and practicing engineers.
Author : TA. Cruse
Publisher :
ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.:/5 (125 download)
Download or read book Three-Dimensional Elastic Surface Cracks written by TA. Cruse and published by . This book was released on 1988 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses a variety of issues associated with the elastic fracture mechanics modeling of surface cracks; both analytical and experimental issues are addressed. The primary analytical focus is on the use of the boundary integral equation method for elastic fracture mechanics analysis. An advanced code is highlighted. A new formulation for three-dimensional crack-surface integral equations is presented with some new analytical results associated with the free-surface singularity. Essential agreements with the results of Benthem are obtained. Fatigue crack growth results for surface cracks in tension and bending are compared with analytical solutions. It is shown that surface cracks in tension grow essentially in accord with an elastic fracture mechanics prediction, whereas surface cracks in bending do not conform to the elastic prediction, based on surface values of the elastic stress-intensity factor. Some thoughts for further research are given.
Author : RH. Dodds
Publisher :
ISBN 13 :
Total Pages : 19 pages
Book Rating : 4.:/5 (125 download)
Download or read book Modeling of Three-Dimensional Effects on Fatigue Crack Closure Processes in Small-Scale Yielding written by RH. Dodds and published by . This book was released on 2005 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: In ductile metals, plasticity-induced closure of fatigue cracks often retards significantly measured crack growth rates in the Paris regime and contributes strongly to the observed R-ratio effect in experimental data. This work describes a similarity scaling relationship based on the 3D small-scale yielding framework wherein the thickness, B, defines the only geometric length-scale of the model. Dimensional analysis suggests a scaling relationship for the crack opening loads relative to the maximum cyclic loads (Kop/Kmax) governed by the non-dimensional load parameter ̄K=Kmax/?0 ?B, i.e., a measure of the in-plane plastic zone size normalized by the thickness. Both Kop and Kmax refer to remotely applied values of the mode I stress-intensity factor. Large-scale, 3D finite element analyses described here demonstrate that Kop/Kmax values vary strongly across the crack front in thin sheets but remain unchanged when Kmax, B, and ?0 vary to maintain ̄K = constant. The paper also includes results to demonstrate that the scaling relationship holds for non-zero values of the T-stress (which affect the Kop/Kmax values) and for an overload interspersed in the otherwise constant amplitude cycles. The present results focus on R = Kmin/Kmax = 0 loading, although the scaling relationship has been demonstrated to hold for other R > 0 loadings as well. The new similarity scaling relationship makes possible more realistic estimates of crack closure loads for a very wide range of practical conditions from just a few analyses of the type described here.
