Download or read book Three Dimensional Variable Constraint Effects in Fracture Initiation written by and published by . This book was released on 1991 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many naturally occurring cracks are three dimensional and cannot be evaluated using numerical techniques derived using two dimensional simplifications. The high stress and strain levels experienced in modern high toughness alloys prior to fracture require means to accurately simulate the nonlinear response of ductile materials in this regime. An accurate constitutive representation must be combined with a fracture criterion which is valid for the high strain regime to achieve accurate computerized simulations of fracture and near fracture behavior. In the current work, nonlinear numerical simulations are performed to determine the global and local responses of two surface cracked plates of HY-100 steel with varying crack propagation and crack depths. Failure is defined by a local fracture criterion using strain energy density. Differences in constraint along the crack perimeter are taken into account by recognizing the stress-strain history dependence of the critical strain energy density. Crack growth patterns determined from the numerical simulations accurately reflect experimental observations.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Constraint Effects in Fracture written by E. M. Hackett and published by ASTM International. This book was released on 1993 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers presented at the symposium on [title] held in Indianapolis, Indiana, May 1991, provide a framework for quantifying constraint effects in terms of both continuum mechanics and micro-mechanical modeling approaches. Such a framework is useful in establishing accurate predictions of the fracture
Download or read book Constraint Effect on Three dimensional Elastic plastic Fracture written by Yil Kim and published by . This book was released on 2003 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Constraint Based Fracture Mechanics written by Feizal Yusof and published by . This book was released on 2006 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Constraint Effects in Fracture Theory and Applications written by Mark Kirk and published by ASTM International. This book was released on 1995 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantification of Constraint in Three dimensional Fracture Mechanics written by Osama Abdulhamid Terfas and published by . This book was released on 2010 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Three Dimensional Effects in Fracture Mechanics written by CW. Smith and published by . This book was released on 1988 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: After citing several experimental methods used for measuring three-dimensional effects in opaque and transparent cracked bodies, an integrated optical method is focused upon for obtaining two independent estimates of fracture parameters associated with linear elastic fracture mechanics (LEFM). Results of the use of these methods to study the effect of free surfaces upon the stress singularity of cracks intersecting them are presented and a means of interpreting the results within the framework of LEFM is suggested.
Download or read book Mechanics of Fracture Initiation and Propagation written by George C. Sih and published by Springer. This book was released on 1991-04-30 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: The assessment of crack initiation and/or propagation has been the subject of many past discussions on fracture mechanics. Depending on how the chosen failure criterion is combined with the solution of a particular theory of continuum mechanics, the outcome could vary over a wide range. Mod elling of the material damage process could be elusive if the scale level of observation is left undefined. The specification of physical dimension alone is not sufficient because time and temperature also play an intimate role. It is only when the latter two variables are fixed that failure predictions can be simplified. The sudden fracture of material with a pre-existing crack is a case in point. Barring changes in the local temperature,* the energy released to create a unit surface area of an existing crack can be obtained by considering the change in elastic energy of the system before and after crack extension. Such a quantity has been referred to as the critical energy release rate, G e, or stress intensity factor, K Ie. Other parameters, such as the crack opening displacement (COD), path-independent J-integral, etc. , have been proposed; their relation to the fracture process is also based on the energy release concept. These one-parameter approaches, however, are unable simultaneously to account for the failure process of crack initiation, propagation and onset of rapid fracture. A review on the use of G, K I, COD, J, etc. , has been made by Sih [1,2].
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shallow Crack Fracture Mechanics Toughness Tests and Applications written by Gyoujin Cho and published by Elsevier. This book was released on 1992-01-01 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within the last decade there has been an increasing awareness that use of standards deeply notched fracture mechanics test specimens can result in substantial over-or-under-assessments of the real fracture toughness associated with shallow surface cracks.
Download or read book Variable order Singular Boundary Elements for Two and Three dimensional Stress Analysis with Applications in Fracture Mechanics written by Wei Zhou and published by . This book was released on 2002 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Effects in Nonlinear Fracture Explored with Interferometry written by Richard D. Pfaff and published by . This book was released on 1991 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling the Constraint Effects on Fracture Toughness of Materials written by Sunil Kumar Prakash and published by . This book was released on 2009 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Cleavage fracture has been a very important subject for engineers for a long time because of the catastrophic result it may cause. The experimental results of cleavage fracture exhibit a large amount of scatter and show significant constraint effect, which motivated the development of statistical and micromechanics based methods in order to deal with such problem. The Weibull stress model, which is based on the weakest link statistics, uses two parameters, m and [sigma]u?, to describe the inherent distribution of the micro-scale cracks once the plastic deformation has occurred and to define the relationship between the macro and micro-scale driving forces for cleavage fracture. In this paper we examine constraint effects on cleavage fracture toughness numerically using a constraint function g(M) derived from the Weibull stress model. The non-dimensional function g(M) describes the evolution of constraint loss effects on fracture toughness relative to reference plane-strain small scale yielding (SSY) condition (T-stress=0). We performed detailed finite element analyses of single-edge notched bending speciments and compute g(M) functions for them. The g-function varies with parameters of the Weibull stress model, material flow properties and speciment geometry but not with absolute specimen size. Knowing the g-function one can construct fracture driving force curves for each absolute size of interest."--Abstract.
Download or read book Fatigue and Fracture Mechanics written by Kenneth L. Jerina and published by ASTM International. This book was released on 2000 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contemporary Research in Engineering Science written by Romesh C. Batra and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue failures occur in aerospace,marine,nuclear structures and automobile com ponents from initiation and propagation of cracks from holes,scratches or defects in the material. To design against these failures, crack propagation life and fracture strength need to be accurately predicted. It is reported in the literature, that these failures often initiate as surface cracks, corner cracks and cracks emanating from fastner holes. Such cracks are with elliptic or nearly elliptic in shapes. The deviation from elliptic shape is due to varying constraint effect along the crack front. Even in situations, when the cracks are through the thickness of the material, there would be thicknesswise variation of constraint effects leading to three dimensional nature of crack growth. Accurate predictions of the crack growth in these cases by numerical methods can be made only by solving three-dimensional boundary value problems. Empirical relationships have been developed [1] based on Linear Elastic Fracture Mechanics over years describing fatigue crack growth response. Some of these empirical relationships required modifications in the later stages, to meet the design applications. The Crack closure phenomenon discovered by Elber[2, 3] during the crack growth phase is mainly attributed to the local material yielding near the crack tip and the consequent residual plastic wake behind the crack tip. It helped considerably in understanding several aspects of fatigue crack growth and rewrite these relations.
