Download or read book Environmental Influence on the Effect of a Single Overload on the Fatigue Crack Growth Behavior on a High Strength Aluminum Alloy written by J. de Fouquet and published by . This book was released on 1990 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The delaying effect of a single overload on the 2024 T351 aluminum alloy covering a wide ?K range has been studied in ambient air, secondary vacuum, and high purity nitrogen (N2). It is shown that for a given environment and an overload ratio, the delay behavior can be rationalized in terms of the peak stress intensity factor corresponding to the overload for the studied test conditions. At low ?K values, the overload effect is confined to a grain. The results obtained show that while the size of the overload affected zone is not affected by the environment, the number of delay cycles at an R ratio of 0.5 in vacuum can be ten times as high as that obtained in the two other environments. At an R ratio of 0.1, at low ?K levels, the delaying effects can be similar in vacuum and in air. The observed effects are explained on the basis of mechanisms governing constant-amplitude crack growth behavior of the studied alloy.
Download or read book Environmentally Assisted Cracking written by W. Barry Lisagor and published by ASTM International. This book was released on 1990 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Papers included topics of phenomena, basic mechanisms, modeling, test methodologies, materials performance, engineering applications and service experience and failures and reflects the current emphasis with regard to material/environment systems.
Download or read book Effects of Environment and Complex Load History on Fatigue Life written by American Society for Testing and Materials and published by ASTM International. This book was released on 1970 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Overload Effects in Aluminum Alloys written by A. Tougui and published by . This book was released on 2004 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents the behavior of selected aluminum alloys when subjected to a single overload, with an aim to highlight the effects of plasticity and environment. The delaying effect of a single overload is given in terms of number of delay cycles. The delay behavior is systematically compared with the constant amplitude crack growth resistance. It is shown that for most of the studied alloys, a strong parallel can be drawn between the constant amplitude crack growth behavior and the overload induced delay. Delay induced by an overload in vacuum is higher than that in air for the 7075 and the 2024 alloys, compatible with stronger constant amplitude crack growth resistance in vacuum. The influence of the elastic-plastic behavior is stronger in vacuum than in air. In the case of the Aluminum Lithium alloy, delay in air is higher than that in vacuum, which is opposite to the behavior under constant amplitude loading. The basic mechanisms governing crack growth in aluminum alloys and their influence on the delay induced by an overload are revealed. The experimental results are compared with a phenomenological model, taking into account the cyclic plastic behavior of materials.
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 Applied Mechanics Reviews written by and published by . This book was released on 1961 with total page 1096 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Overload and Underload Effects on the Fatigue Crack Growth Behavior of the 2024 T3 Aluminum Alloy written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-12-29 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth tests were conducted on 0.09 inch thick, 3.0 inch wide middle-crack tension specimens cut from sheets of 2024-T3 aluminum alloy. The tests were conducted using a load sequence that consisted of a single block of 2,500 cycles of constant amplitude loading followed by an overload/underload combination. The largest fatigue crack growth life occurred for the tests with the overload stress equal to 2 times the constant amplitude stress and the underload stress equal to the constant amplitude minimum stress. For the tests with compressive underloads, the fatigue crack growth life decreased with increasing compressive underload stress. Dawicke, David S. Langley Research Center NASA-CR-201668, NAS 1.26:201668 NAS1-96014; RTOP 538-02-10-01...
Download or read book The Influence of Hold Times on Fatigue Crack Growth of Aluminum Alloys written by H. L. Marcus and published by . This book was released on 1980 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of the research on fatigue crack growth in aluminum alloys are described in three general areas. The first relates the influence of hold time at an underload that follows an overload on the fatigue crack growth retardation behavior of the 7075 and 2219 aluminum alloys. A very distinct effect on retardation with hold time is observed. The effect is microstructure dependent with the time dependence behavior extending over a longer period for the high strength materials. This well-defined time dependence clearly shows that lifetime predictions based on accelerated short hold time tests could be very non-conservative. The influence of humidity was also determined using vacuum as a reference environment. The second aspect of the research investigated the nature of the residual displacement, d, that leads to the crack closure phenomena. The last major emphasis was to investigate how gaseous environments interact with fatigue crack growth in aluminum alloys. Combined AES/SIMS studies were made of fracture surfaces taken from fatigue crack growth specimens fatigued in vacuum and subsequently exposed to and fatigued in a range of environments.
Download or read book Environmental Corrosion fatigue Behavior of Aluminum Alloys written by D. N. Williams and published by . This book was released on 1970 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of environment on fatigue behavior are quite intimately related to such test variables as stress intensity, cyclic frequency, and temperature. The effect of these variables has been shown to be quite complex. However, a consistent pattern of behavior is beginning to emerge which, it is hoped, will lead to a considerably changed understanding of the corrosion-fatigue process. It is considered probable that an increased understanding of the corrosion-fatigue process will also contribute measureably to an improved understanding of general fatigue processes. Material variables such as composition, directionality of properties, and microstructure, have important effects on corrosion-fatigue behavior of aluminum alloys. However, it appears that these variables, at least in gaseous environments, may be important largely because of their effects on the mechanical behavior of aluminum alloys. On the other hand, studies in seawater suggest that these variables become increasingly important as the corrosive nature of the environment increases. This memorandum discusses in detail the effects of both test variables and material variables on corrosion fatigue. In addition, current theories of corrosion-fatigue mechanisms are outlined, and several methods of preventing corrosion fatigue are suggested. (Author).
Download or read book Effects of Underloads on Fatigue Crack Growth written by W. M. McGee and published by . This book was released on 1977 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of single overload-underload interaction on constant amplitude crack growth in 2219-T851 aluminum alloy are characterized in terms of delay cycles, affected zone sizes and overload shut-off ratios. Data are presented showing the effects of overload-underload/underload-overload sequences, overload magnitude, underload magnitude, and the constant amplitude maximum and minimum. The effects of hold periods in both tension and compression are also experimentally investigated. Delay cycle data are correlated with predictions from three different crack growth retardation models; namely the generalized Wheeler model, the generalized Willenborg model and the Grumman closure model. For each model, predictions are made using an assumed plastic zone radius and diameter for both plane stress and plane strain conditions and model comparisons are made. Correlations of measured affected zone sizes with the four different assumed plastic zone sizes are also presented. Sensitivities of the generalized Wheeler and generalized Willenborg models to overload shut- off ratio and threshold stress intensity factor are determined. Prediction sensitivity to three different crack growth equations for the 2219-T851 aluminum alloy is also evaluated. Recommendations for future work in development of crack growth retardation models are presented.
Download or read book Overload and Underload Effects on the Fatigue Crack Growth Behavior of the 2024 T3 Aluminum Alloy written by and published by . This book was released on 1997 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Microstructure on 7XXX Aluminum Alloy Fatigue Crack Growth Behavior Down to Near Threshold Rates written by and published by . This book was released on 1981 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation was undertaken to clarify the role of microstructure on steady state (constant load amplitude) and transient (single periodic overload) fatigue crack growth behavior in 7XXX aluminum alloys at low stress intensity factor ranges (delta K). These results were consolidated with data in the literature to obtain an understanding of microstructural effects on crack growth response over a broad delta K range. Constant load amplitude data show that there are significant differences in near-threshold FCG resistance among 7XXX alloys. Overaging to a T7 temper reduces low delta K FCG resistance greatly, whereas intermediate and high delta K FCG resistance is increased by overaging. In the presence of moisture at intermediate delta K levels, increasing Cu content from 1.0 to 2.3% increases crack growth resistance. However, there is no consistent effect of Cu content on near-threshold fatigue performance. Similarly, no clear influence of dispersoid type (Cr vs. Zr) on low delta K FCG resistance was detected. Increasing alloy purity (lowering Fe, Si content) enhances crack growth resistance at high delta K, but has no effect at near-threshold stress intensities. The importance of near-threshold FCG performance to alloy design and materials selection for fatigue resistance is discussed. Potential tradeoffs between design philosophies which emphasize damage tolerance characteristics vs. those which focus on improved life cycle economics are examined.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 1412 pages. Available in PDF, EPUB and Kindle. Book excerpt: NSA is a comprehensive collection of international nuclear science and technology literature for the period 1948 through 1976, pre-dating the prestigious INIS database, which began in 1970. NSA existed as a printed product (Volumes 1-33) initially, created by DOE's predecessor, the U.S. Atomic Energy Commission (AEC). NSA includes citations to scientific and technical reports from the AEC, the U.S. Energy Research and Development Administration and its contractors, plus other agencies and international organizations, universities, and industrial and research organizations. References to books, conference proceedings, papers, patents, dissertations, engineering drawings, and journal articles from worldwide sources are also included. Abstracts and full text are provided if available.
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 Concise Encyclopedia of Building and Construction Materials written by Fred Moavenzadeh and published by MIT Press. This book was released on 1990 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt: The building materials covered by the Concise Encyclopedia of Building and Construction Materials are classified in three groups: structural materials, semistructural materials, and auxiliary materials.
Download or read book Five year Index to ASTM Technical Papers and Reports written by American Society for Testing and Materials and published by . This book was released on 1976 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Constant Amplitude and Post overload Fatigue Crack Growth Behavior in PM Aluminum Alloy AA 8009 written by and published by . This book was released on 1991 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
