Download or read book Role of Crack Closure Mechanisms on Fatigue Crack Growth of Ti 62222 Under Constant Amplitude and Transient Loading at 54 25 and 175 C written by SG. Berge and published by . This book was released on 1999 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth behavior of Ti-62222 in sheet form was investigated at three temperatures under various load histories with a specific emphasis on crack opening measurements and mechanisms. Constant-amplitude R = 0.1 near-threshold results showed that based upon applied ?K, fatigue crack growth rates were lower at the two temperature extremes in comparison with those at room temperature. Based upon ?Keff, a moderate temperature effect was observed. The various shifts in the ?Keff curves were a result of different controlling crack closure mechanisms at each temperature. Single tensile overloads at 2.5 x Kmax produced a delay in fatigue crack growth and was most significant at -54°C. Remote crack opening measurements showed no appreciable change during the delay period due to the small region along the crack front that experienced crack closure. Near crack tip opening measured for various combinations of overloads, underloads, and constant ?K at 25°C revealed a general trend for higher near tip opening following a tensile overload. However, a sufficient number of measurements were inconsistent and thus only minimal confidence could be placed with the method. Scanning electron microscopy was used to evaluate surface fatigue crack growth profiles and fatigue crack growth fracture surface morphology.

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 Fatigue Testing and Analysis Under Variable Amplitude Loading Conditions written by Peter C. McKeighan and published by ASTM International. This book was released on 2005 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fatigue and Fracture Mechanics written by Walter G. Reuter and published by ASTM International. This book was released on 2002-12-31 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering the whole of Asia and the Pacific region, this text provides both an analytic overview and specific data for each of the 60 countries. Introductory chapters cover regional issues, including: a regional review with the year's trends, developments and key events' analysis of the threat of terrorism in the region; the effects of deflation on the economy; the water crisis and its impact on the poor; and the successes and failures of micro-credit in the region.

Download or read book Metal Fatigue in Engineering written by Ralph I. Stephens and published by John Wiley & Sons. This book was released on 2000-11-03 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Classic, comprehensive, and up-to-date Metal Fatigue in Engineering Second Edition For twenty years, Metal Fatigue in Engineering has served as an important textbook and reference for students and practicing engineers concerned with the design, development, and failure analysis of components, structures, and vehicles subjected to repeated loading. Now this generously revised and expanded edition retains the best features of the original while bringing it up to date with the latest developments in the field. As with the First Edition, this book focuses on applied engineering design, with a view to producing products that are safe, reliable, and economical. It offers in-depth coverage of today's most common analytical methods of fatigue design and fatigue life predictions/estimations for metals. Contents are arranged logically, moving from simple to more complex fatigue loading and conditions. Throughout the book, there is a full range of helpful learning aids, including worked examples and hundreds of problems, references, and figures as well as chapter summaries and "design do's and don'ts" sections to help speed and reinforce understanding of the material. The Second Edition contains a vast amount of new information, including: * Enhanced coverage of micro/macro fatigue mechanisms, notch strain analysis, fatigue crack growth at notches, residual stresses, digital prototyping, and fatigue design of weldments * Nonproportional loading and critical plane approaches for multiaxial fatigue * A new chapter on statistical aspects of fatigue

Download or read book Effect of Transient Loads on Fatigue Crack Growth in Mill Annealed Ti 62222 at 54 25 and 175 C written by RR. Stephens and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transient loads consisting of single tensile overloads and single tensile overloads followed by single compressive underloads were applied to Ti-62222 mill annealed titanium alloy at -54, 25, and 175°C. Tensile overload ratios were 2.0 and 2.5 and the compressive underload ratio was -0.5. Four reference steady-state ?KImp values, using constant ?K testing at R = 0.1, were investigated at each temperature. Cycles of delay, fatigue crack growth during delay, minimum fatigue crack growth rate, and crack extension during a transient load were obtained for all tests. Cycles of delay ranged from zero to crack arrest and mixed results often occurred making it difficult to draw many specific conclusions. Higher tensile overloads caused greater delay cycles and underloads were often detrimental compared to overloads only. Low temperature was mostly beneficial compared to room and high temperature that yielded similar delay. Crack growth delay distance was always greater than reversed plastic zone size. Macro- and microfractography revealed that surface crack closure, mode II displacements, crack tip blunting, branching, and tunneling, local state of stress, and residual compressive stresses contributed to the transient fatigue crack growth behavior.

Download or read book Effect of Transient Loads on Fatigue Crack Growth in Solution Treated and Aged Ti 62222 at 54 25 and 175 C written by RR. Stephens and published by . This book was released on 2004 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transient loads consisting of single tensile overloads and single tensile overloads followed by single compressive underloads were applied to Ti-62222 solution treated and aged titanium alloy at -54, 25, and 175°C. Tensile overload ratios were 2.0 and 2.5, and the compressive underload ratio was -0.5. Four reference steady state ?Kss values, using constant ?K testing at R = 0.1, were investigated at each temperature. Cycles of delay, fatigue crack growth during delay, and minimum fatigue crack growth rate during a transient load were obtained for all tests. Cycles of delay ranged from zero to crack arrest. Higher tensile overloads caused greater delay cycles, and underloads were often detrimental. Low and high temperatures were primarily beneficial to delay cycles relative to those at room temperature. Crack growth delay distance was always greater than the pertinent reversed plastic zone size. Fatigue crack growth life predictions were made using FASTRAN III and AFGROW computer programs and produced both conservative and non-conservative results with more than half the predictions being within ± 2 of the experimental results. Macro- and microfractography revealed surface crack closure, Mode II displacements, crack tip blunting, branching, and tunneling contributed to the transient fatigue crack growth behavior.

Download or read book Fatigue and Fracture Mechanics written by and published by . This book was released on 2001 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Transient Loads on Fatigue Crack Growth in Mill Annealed Ti 62222 at 540C 250C and 1750C written by Dwight Alan Schoenefeld and published by . This book was released on 1999 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 On the Role of Crack Closure Mechanisms in Influencing Fatigue Crack Growth Following Tensile Overloads in a Titanium Alloy written by CM. Ward-Close and published by . This book was released on 1988 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comparative study has been made of the transient fatigue crack growth rate behavior following tensile overloads at low (near-threshold) and high stress intensity ranges in an ?/?-type titanium alloy IMI 550, with specific emphasis of the role of crack closure mechanisms. After tensile overloads, fatigue cracks in both coarse-grained ?-annealed and fine-grained ?/? microstructures were observed initially to accelerate, followed by significant retardation, before growth rates returned to their baseline levels. The initial acceleration was attributed to an immediate reduction in near-tip closure, as indicated by metallographic sectioning, and a slight decrease in far-field closure, as measured by back-face compliance methods. Subsequent retardation was not associated with marked changes in far-field closure, although there were indications on compliance curves of a second "closure point" at a higher load, suggesting an approximate 50% increase in near-tip closure. Load interaction effects were found to be most severe where specific mechanisms of crack closure were prominant. Thus, the maximum post-overload retardations were seen in the coarse-grained ? microstructure, and when baseline stress intensity ranges were close to the threshold ?KTH, or when the maximum overload stress intensities approached the fracture toughness.

Download or read book Fatigue Crack Growth and Crack Closure Behavior of Ti 6Al 4V Alloy Under Variable Amplitude Loadings written by M. Jono and published by . This book was released on 1999 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth tests under constant-amplitude and repeated two-step loadings were carried out on a (? + ?) Ti-6Al-4V alloy which has duplex structure made up of equiaxed primary ?-phase grains with a discontinuous fine ?-phase dispersed in the boundaries. It was found that fatigue crack grew along ?-phase grain boundaries and that the fracture surface was very rough in the low stress intensity region under constant-amplitude loading. On the other hand, in the high region, transgranular crack growth was observed and the fracture surface was relatively smooth. The crack opening point, Kop, was affected by the amplitude of low-level load, ?KL, under repeated two-step loadings where the high-level load amplitude was kept constant. Kop was found to be higher than that predicted by Kop -- Kmax relationship under constant-amplitude loading and the fracture surface was rougher in comparison with that under constant-amplitude loading which has the identical stress intensity range. It was concluded that the crack opening point was controlled by both plasticity-induced crack closure in terms ofKmax and roughness-induced crack closure resulted from rougher surface in ?KL.

Download or read book Prediction of Fatigue crack Growth Under Variableamplitude and Spectrum Loading Using a Closure Model written by and published by . This book was released on 1981 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of Fatigue Crack Growth in Terms of Crack Closure and Energy written by N. Ranganathan and published by . This book was released on 1999 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fatigue crack growth behavior of the aluminum alloy 2024 is analyzed using the crack closure and an energy-based concept. The different test conditions studied include load ratio and environmental effects, crack growth retardation following a single overload, and crack propagation under block load tests. Crack opening loads using the compliance technique permit the effect of load ratio to be taken into account. After an overload, in the deceleration phase, the evolution of the crack opening load is not compatible with that of the crack growth rate. The measured crack opening levels under constant-amplitude loading conditions are comparable to those predicted under plane strain conditions for moderate ?K levels. It is shown that most of the effects usually attributed to closure can be successfully explained using energy concepts. In particular, it is shown that there exists a linear relationship between the crack growth rate and the energy dissipated per cycle at high growth rates, which is valid for both the environments studied, and it corresponds to a crack growth mechanism characterized by striation formation during each cycle. For lower growth rates a power law relationship can be proposed between these two parameters. The above-mentioned linear relationship holds also for the block loading conditions based on total energy dissipated per block. Certain experimental facts bring out the effect of closure on the energy dissipated. It is further shown that the possible existence of a mixed (Mode I and Mode II) mode crack opening at the crack tip has to be taken into account to correctly evaluate the energy dissipated near the crack tip.

Download or read book Measurement and Analysis of Critical Crack Tip Processes During Fatigue Crack Growth written by and published by . This book was released on 1985 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms Associated with Transient Fatigue Crack Growth Under Variable amplitude Loading written by C. M. Ward-Close and published by . This book was released on 1988 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Overload and Underload on Internal Strains stresses and Crack Closure During Fatigue crack Propagation written by Soo Yeol Lee and published by . This book was released on 2009 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overload and/or underload occurring during constant-amplitude fatiguecrack growth result in the retardation and/or acceleration in the crack-growth rate, making it difficult to predict the crack-propagation behavior and fatigue lifetime. Although there have been numerous investigations to account for these transient crackgrowth behavior, the phenomena are still not completely understood. Neutron and X-ray diffraction, and electric-potential measurements were employed to investigate these transient crack-growth micromechanisms; gain a thorough understanding of the crack-tip deformation and fracture behaviors under applied loads; and establish a quantitative relationship between the crack-tip-driving force and crack-growth behavior. Five different fatigue-crack-growth experiments (i.e., fatigued, tensile overloaded, compressive underloaded, tensile overloaded-compressive underloaded, and compressive underloaded-tensile overloaded) were performed to observe these transient crack-growth behaviors. The development of internal-strain distributions during variable-amplitude loadings, and the resultant residual-stress distributions around a crack tip were examined using neutron diffraction. The effects of a single tensile overload on fatigue-crack growth were focused on probing the crack-growth-retardation micromechanisms. Neutron diffraction and polychromatic X-ray microdiffraction showed high dislocation densities and considerable crystallographic tilts near the crack tip immediately after the overload. The interactions between the overload-induced plastic zone and newly-developed fatigue-plastic zone, and their influences on the evolution of residual-strain profiles are discussed. Neutron-diffraction and electric-potential measurements provide in-situ observation of the crack-opening/closing processes and internal-stress distributions in the vicinity of the crack tip during real-time fatigue-crack propagation following a tensile overload. Immediately after applying a tensile overload, the crack-tip became blunt and the large compressive residual stresses were developed around the crack tip. In the retardation period after the tensile overloading, the combined effects of the cracktip blunting at an overload point and compressive-residual stresses accompanying the crack closure induced the stress concentration at a blunting region until a maximum crack-arrest load was reached. Then, the stress concentration was transferred from the blunting region to actual crack-tip position with gradual crack opening, requiring a higher applied load. This observation of the stress-transfer phenomenon significantly promotes the fundamental understanding of overload-retardation phenomena. The postoverload crack-growth rates were normalized with the effective-stress-intensity-factor range, which suggests that it can be considered as the fatigue-crack-tip-driving force.