Download or read book Three Dimensional Aspects of Fatigue Crack Closure in Surface Flaws in Polymethylmethacrylate Material written by AF. Grandt and published by . This book was released on 1988 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation using a Newton interference method with a transparent polymethylmethacrylate (PMMA) to measure crack opening displacement and closure on surface flaw crack growth is described. Fatigue crack growth tests are conducted on rectangular plates loaded in bending using optical interferometry measurements to map the crack surface opening displacement profiles and define crack opening loads. Results are presented for an experiment of constant applied stress intensity factor along the crack face free surface. The crack opening displacement patterns and measured closure loads are found to be strongly influenced by the formation of a void internal to the crack surfaces.
Download or read book Mechanics of Fatigue Crack Closure written by Wolf Elber and published by ASTM International. This book was released on 1988 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Fatigue Crack Closure on the Growth Rate of Surface Flaws written by and published by . This book was released on 1994 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inconsistent experimental results of fatigue crack closure studies over the past 15 years have caused recent investigators to conclude that the fundamental phenomena controlling the crack driving mechanisms are not understood. A major contributor to this misunderstanding is an inadequate understanding of the complex three-dimensional nature of closure. This is true for two-dimensional thru-the-thickness cracks as well as for three-dimensional part-thru surface cracks. To assess the three-dimensional influences of fatigue crack closure on the growth rate of surface flaws, an experimental investigation was conducted using a rectangular plate of polymethylmethacrylate (PMMA) material loaded in four-point bending. The use of transparent PMMA material and a Newton optical interferometer system with a laser light source provided the capability to simultaneously measure three-dimensional crack opening displacement (COD) profiles and closure loads (Pc1).
Download or read book Observations of Three Dimensional Surface Flaw Geometries During Fatigue Crack Growth in PMMA written by AF. Grandt and published by . This book was released on 1990 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of fatigue crack growth experiments was conducted on a transparent polymer (PMMA) using a surface flaw geometry in bending. A Newton interferometric technique was used to measure crack opening displacements and closure for four different loading histories. Results are presented for conditions of constant applied stress-intensity factor along the crack face free surface, at the crack tip in the depth direction, for constant applied load range, and for a block loading sequence.
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 Surface crack Growth written by Walter G. Reuter and published by ASTM International. This book was released on 1990 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the symposium (on title) held in Sparks, Nevada, April 1988. Twenty-two peer-reviewed papers are divided into sections on models and experiments (monotonic loading), and fatigue crack growth. Areas addressed include the differences in constraint for 2-D through-thickness cracks and 3-D surface
Download or read book The Effects of Slip Character and Crack Closure on the Growth of Small Fatigue Cracks in Titanium aluminium Alloys written by James M. Larsen and published by . This book was released on 1990 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was performed to study the effects of slip character and crack closure on the propagation of small fatigue cracks in titanium- aluminum alloys. The materials examined were solution-treated Ti-4Al and Ti-8Al, as well as aged Ti-8Al. The propagation of naturally initiated surface cracks of depths as small as 25 micrometers was compared with the behavior of large through-thickness cracks. An extensometer was used to monitor crack closure throughout the large crack tests, and the closure behavior of the small cracks was measured using a computerized laser interferometric displacement gage having a displacement resolution of 0.01 micrometer. The measurements of crack closure were used to compute an effective stress intensity factor range. In all three alloys and for all test conditions, which included a range of stress levels and stress ratios, small cracks propagated faster than large cracks subjected to an equivalent Delta K, and the small cracks propagated under conditions that were significantly below the large-crack threshold, Delta K(th). Although the character and distribution of slip in Ti-Al alloys may have a dramatic influence on fatigue crack initiation and on the propagation of large cracks, this effect was minimal for small cracks.
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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Study of Fatigue Crack Propagation and Retardation Using Polymethylmethacrylate written by Francis J. Pitoniak and published by . This book was released on 1972 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue cracks were grown in compact tension specimens of polymethylmethacrylate, a transparent polymer which was used as a model for metals. Various peak overloads applied to the constant DeltaK baselines used produced changes in the baseline load crack growth rates. A study of the monochromatic light interference fringe patterns emanating from the fatigue cracks at zero load indicated that the crack surface were closed along the saw cut edge and on the free surface of the specimens. The crack surfaces were displaced in the interior of the specimen at zero load. Measurement of the crack opening displacements from the fringe patterns indicated that the crack surfaces opened on the free surface at approximately half the baseline load level for a stress ratio of approximately zero. This is in agreement with the Elber crack closure concept.
Download or read book A Three dimensional Investigation of Steady state Fatigue Crack Closure Behavior for Through thickness and Part through Flaws written by Suvendoo Kumar Ray 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 Cyclic Deformation Fracture and Nondestructive Evaluation of Advanced Materials written by Michael R. Mitchell and published by ASTM International. This book was released on 1994 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: Examines the initiation and growth of fatigue cracks and the fracture toughness of advanced materials such as silicon nitride, special alloys and steels, thermoplastics, and graphite-epoxy composites; and explains several non-destructive techniques to evaluate such materials for manufacturing defect
Download or read book Metals Abstracts written by and published by . This book was released on 1996 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 International Aerospace Abstracts written by and published by . This book was released on 1993 with total page 1146 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:
