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.
Download or read book Fatigue and Fracture Mechanices written by Steven R. Daniewicz and published by ASTM International. This book was released on 2005-09 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
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.
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).
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
Download or read book Advances in Fatigue Crack Closure Measurement and Analysis written by R. Craig McClung and published by ASTM International. This book was released on 1999 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three Dimensional Aspects of Fatigue Crack Closure written by A. F. Grandt and published by . This book was released on 1988 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final report summarizes progress on a basic research effort to determine three-dimensional aspects of the relationship between applied load and fatigue crack face separation. The research was motivated by the well known crack closure phenomenon, which indicates that naturally occurring fatigue cracks are physical held shut (or propped open) at zero load, so that crack surfaces do not separate in a linear elastic manner. Although prediction of fatigue crack opening behavior is of fundamental importance to many aspects of crack growth, relatively little is known about the three-dimensional character of closure. The research employed experimental and numerical procedures to develop predictive techniques for this important aspect of crack closure. Optical interference was used to measure crack opening in transparent polymer specimens, along with conventional crack opening and back face strain techniques for measuring crack closure. A numerical algorithm was developed to predict opening loads in surface flawed plates, and was compared with the experimental results. Keywords: Crack propagation, Cracking(Fracturing).
Download or read book Fracture Mechanics written by and published by ASTM International. This book was released on 1989 with total page 685 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
Download or read book A Practical Engineering Approach to Predicting Fatigue Crack Growth in Riveted Lap Joints written by C. E. Harris and published by . This book was released on 2000 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.
Download or read book Fatigue Crack Closure Outside a Small Scale Yielding Regime written by PL. Lalor and published by . This book was released on 1988 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: An elasto-plastic finite-element model has been developed to simulate fatigue crack growth and to establish crack opening levels in a notched member. Intermediate and high stress levels where small-scale yielding conditions no longer prevail were considered. Variations in crack opening and closure levels with crack length, stress state, R ratio, stress level, and degree of strain hardening were examined. Cracks were allowed to generate their own plastic wake upon advance from the notch surface. Restricting the development of a full plastic wake resulted in lower asymptotic closure levels for certain cases. Complete (R = -1) and partial (R = 0) closure of crack surfaces and the ensuing residual stresses in the crack wake were determined and linked to the crack length effect on closure. Two states of stress (plane strain and plane stress) were considered. Differences in closure levels between the two stress states developed as the crack grew from the notch.
Download or read book Small Fatigue Cracks written by K.S. Ravichandran and published by Elsevier. This book was released on 1999-09-30 with total page 511 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the fully peer-reviewed papers presented at the Third Engineering Foundation Conference on Small Fatigue Cracks, held under the chairmanship of K.S. Ravichandran and Y. Murakami during December 6-11, 1998, at the Turtle Bay Hilton, Oahu, Hawaii. This book presents a state-of-the-art description of the mechanics, mechanisms and applications of small fatigue cracks by most of the world's leading experts in this field. Topics ranging from the mechanisms of crack initiation, small crack behavior in metallic, intermetallic, ceramic and composite materials, experimental measurement, mechanistic and theoretical models, to the role of small cracks in fretting fatigue and the application of small crack results to the aging aircraft and high-cycle fatigue problems, are covered.
Download or read book Three dimensional Aspects of Plasticity induced Fatigue Crack Closure written by and published by . This book was released on 1988 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comprehensive Structural Integrity written by Ian Milne and published by Elsevier. This book was released on 2003-07-25 with total page 4647 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
