Virtual Crack Extension Method for Calculating Rates of Energy Release Rate and Numerical Simulation of Crack Growth in Two and Three Dimensions PDF Download

Author: Changyu Hwang
Publisher:
ISBN:
Category :
Languages : en
Pages : 628

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Author: I. Milne
Publisher: Elsevier
ISBN: 0080437494
Category :
Languages : en
Pages : 749

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Author: Brett Richard Davis
Publisher:
ISBN:
Category :
Languages : en
Pages : 328

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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: Ian Milne
Publisher: Elsevier
ISBN: 0080490735
Category : Business & Economics
Languages : en
Pages : 4647

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The aim of this major reference work is to provide a first point of entry to the literature for the researchers in any field relating to structural integrity in the form of a definitive research/reference tool which links the various sub-disciplines that comprise the whole of structural integrity. Special emphasis will be given to the interaction between mechanics and materials and structural integrity applications. Because of the interdisciplinary and applied nature of the work, it will be of interest to mechanical engineers and materials scientists from both academic and industrial backgrounds including bioengineering, interface engineering and nanotechnology. The scope of this work encompasses, but is not restricted to: fracture mechanics, fatigue, creep, materials, dynamics, environmental degradation, numerical methods, failure mechanisms and damage mechanics, interfacial fracture and nano-technology, structural analysis, surface behaviour and heart valves. The structures under consideration include: pressure vessels and piping, off-shore structures, gas installations and pipelines, chemical plants, aircraft, railways, bridges, plates and shells, electronic circuits, interfaces, nanotechnology, artificial organs, biomaterial prostheses, cast structures, mining... and more. Case studies will form an integral part of the work.

Author: Ronald Krueger
Publisher:
ISBN:
Category :
Languages : en
Pages : 66

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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: Jay Carroll
Publisher: Springer
ISBN: 3319069772
Category : Science
Languages : en
Pages : 249

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Fracture, Fatigue, Failure and Damage Evolution, Volume 5: Proceedings of the 2014 Annual Conference on Experimental and Applied Mechanics, the fifth volume of eight from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on a wide range of areas, including: Mixed Mode Fracture I: Emphasis on Modeling Mixed Mode Fracture II: Emphasis on Experimental Measurements Full-Field Measurements of Fracture Microscale & Microstructural Effects on Mechanical Behavior I: Nanoscale Effects Microscale & Microstructural Effects on Mechanical Behavior II: MEMS Microscale & Microstructural Effects on Mechanical Behavior III: Microstructure Microscale & Microstructural Effects on Mechanical Behavior IV: Shape Memory Alloys Fracture & Fatigue of Composites Fracture & Fatigue for Engineering Applications Wave-Based Techniques in Fracture & Fatigue I Wave-Based Techniques in Fracture & Fatigue II: Acoustic Emissions

Author: Sashi Kanta Panigrahi
Publisher: CRC Press
ISBN: 1000806677
Category : Science
Languages : en
Pages : 133

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This book provides up-to-date information relevant to the analysis and design of adhesively bonded joints made up of fiber-reinforced polymer (FRP) composites using functionally graded adhesive (FGA). Damage behaviors in adhesively bonded joints of laminated FRP composites have been addressed, and joint configurations have been modeled using special finite elements (FEs) and multipoint constraint elements to simulate the contact behavior. Detailed 3D finite element analyses (FEAs) have been presented for different adhesively bonded joint structures along with guidelines for effective design philosophy of adhesively bonded joints in laminated FRP structures using FGA. Features: Provides a thorough and systematic discussion on the functionally graded adhesive and its joints. Discusses analytical modeling and numerical analyses of the joints. Details 3D stress and failure delamination analysis for composite analyses of functionally graded out-of-plane joints under various combinations of loading. Illustrates FE modeling and simulation of interfacial failure and damage propagation in out-of-plane joints. Includes the effect of various gradation function profiles on damage growth driving forces (SERR). This book is aimed at researchers, professionals and graduate students in composites, infrastructure engineering, bonding technology and mechanical/aerospace engineering.

Author:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 784

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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 882

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In nonlinear applications of computational fracture mechanics, energy release rate techniques are used increasingly for computing stress intensity parameters of crack configurations. Recently, deLorenzi used the virtual-crack-extension method to derive an analytical expression for the energy release rate that is better suited for three-dimensional calculations than the well-known J-integral. Certain studies of fracture phenomena, such as pressurized-thermal-shock of cracked structures, require that crack tip parameters be determined for combined thermal and mechanical loads. A method is proposed here that modifies the isothermal formulation of deLorenzi to account for thermal strains in cracked bodies. This combined thermo-mechanical formulation of the energy release rate is valid for general fracture, including nonplanar fracture, and applies to thermo-elastic as well as deformation plasticity material models. Two applications of the technique are described here. In the first, semi-elliptical surface cracks in an experimental test vessel are analyzed under elastic-plastic conditions using the finite element method. The second application is a thick-walled test vessel subjected to combined pressure and thermal shock loadings.