Download or read book The Effect of Periodic Overloads on Flight by flight Fatigue Crack Growth Rates written by Margery A. Dean and published by . This book was released on 1983 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: The life prediction of aerospace structures subjected to service loading conditions can be complex and expensive. Fortunately, many flight-by- flight loadings can be analyzed as constant amplitude loading if the variability in crack growth rate is low. A test program was designed such that the stress intensity factor (Kmax) was held constant by uniformly reducing the load as the fatigue crack grew. With a constant Kmax, the crack growth rate remains constant throughout the life of the test. The baseline fatigue crack growth rate variability was established for the 7075-T6 center-cracked panels under a flight-by-flight load history. The effect of introducing overloads to the baseline flight history on the crack growth rate variability was reported. The results indicate that the delay region for the applied 114% overloads was predicted by Irwin's plastic zone model and was equal to 0.0382 inches which was equal to 225 flights. The delay behavior was consistent for the several overload conditions that were studied. When the occurrence of overload increased, the fatigue crack growth decreased. The standard error of estimate remained relatively constant, suggesting that a block approach to life prediction is feasible for flight-by-flight load history.
Download or read book The Effect of Periodic Overloads on Flight by flight Fatigue Crack Growth Rates written by Margery A. Dean and published by . This book was released on 1983 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The life prediction of aerospace structures subjected to service loading conditions can be complex and expensive. Fortunately, many flight-by- flight loadings can be analyzed as constant amplitude loading if the variability in crack growth rate is low. A test program was designed such that the stress intensity factor (Kmax) was held constant by uniformly reducing the load as the fatigue crack grew. With a constant Kmax, the crack growth rate remains constant throughout the life of the test. The baseline fatigue crack growth rate variability was established for the 7075-T6 center-cracked panels under a flight-by-flight load history. The effect of introducing overloads to the baseline flight history on the crack growth rate variability was reported. The results indicate that the delay region for the applied 114% overloads was predicted by Irwin's plastic zone model and was equal to 0.0382 inches which was equal to 225 flights. The delay behavior was consistent for the several overload conditions that were studied. When the occurrence of overload increased, the fatigue crack growth decreased. The standard error of estimate remained relatively constant, suggesting that a block approach to life prediction is feasible for flight-by-flight load history.
Download or read book The Effect of Periodic Overloads on Flight by flight Fatigue Crack Growth Rates written by Margery A. Dean and published by . This book was released on 1983 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Load Variables on Fatigue Crack Initiation and Propagation written by D. F. Bryan and published by ASTM International. This book was released on 1980 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Mission Overloads on Fatigue Crack Growth in Ti 6Al 2Sn 4Zr 2Mo written by Daniel Maurice Solomon and published by . This book was released on 2018 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft turbine engines, especially military engines, experience variable amplitude loading (mission loading) during operation. Predicting the impact of overloads in turbine engines is key in interpreting fatigue damage and assessing the reliable lifetime of components. The objective of this study was to understand the effects of single and repeated overloads during fatigue crack growth in Ti-6Al-2Sn-4Zr-2Mo used in aircraft turbine engine rotor components. Experiments were conducted using compact tension specimens in a servo-hydraulic testing machine to measure the fatigue crack growth rates during the application of single overloads under stress intensity factor and load control. Additional experiments were conducted having, variable amplitude loading consisting of a controlled number of constant amplitude baseline cycles between periodic overloads. Single overload experiments revealed crack growth acceleration and not the classic retardation typically expected. Repeated overloads experiments demonstrated that Miner's rule accurately predicted realistic overload behavior. Overall, the crack growth rates during single overload or repeated overloads resulted in consistent behavior, and significant crack growth retardation was not observed throughout testing in this material. In addition, crack growth rates were similar for overload and underload block fatigue conditions. The understanding of this behavior and the impact on aircraft turbine engine life tracking using Total Accumulated Cycles (TACs) was discussed. It appeared that minor cycles were generally more damaging than currently accounted for in military turbine engine life tracking.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1984 with total page 1278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Proceedings of the Society for Experimental Stress Analysis written by Society for Experimental Stress Analysis and published by . This book was released on 1977 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vol. 1, no. 1 contains Proceedings of the 17th (or the last) Eastern Photoelasticity Conference.
Download or read book Advances in Fracture Research written by K. Salama and published by Elsevier. This book was released on 2013-10-22 with total page 3063 pages. Available in PDF, EPUB and Kindle. Book excerpt: Held every four years, the International Congress on Fracture is the premier international forum for the exchange of ideas between scientists and engineers involved in producing and using materials resistant to fracture and fatigue. This major six-volume work which forms the proceedings of the Seventh International Congress on Fracture therefore provides the most comprehensive account available of the current status of research into fracture and fatigue, and the application of this knowledge to the design, fabrication and operation of materials and structures. As such, it will be an essential reference for materials scientists and mechanical, structural, aeronautical and design engineers with an interest in fracture and its prevention.
Download or read book Cyclic Stress strain Behavior analysis Experimentation and Failure Prediction written by and published by ASTM International. This book was released on 1971 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Compressive Loads on Spectrum Fatigue Crack Growth Rate written by TM. Hsu and published by . This book was released on 1980 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A procedure, which allows flight-simulation profiles to be applied under stress intensity factor control, was used to study effects of compressive-compressive load cycles on spectrum fatigue crack growth rate. This approach eliminates the maximum stress-intensity factor, Kmax, and its associated plastic-zone size as a variable within a given test, and allows a small amount of crack growth representing instantaneous conditions in conventional load control tests. Tests were performed on center-cracked 7075-T651 aluminum alloy specimens subjected to typical flight-spectra, simulating both transport and bomber airplanes. The results indicated that the number of compressive-compressive cycles has little effect on spectrum-crack-growth rate and that essentially the same results were produced by a single compressive load. It was also found that the crack growth rate was relatively insensitive to the magnitude of the compressive load. A saturated condition was reached at a fairly low load level. The sequence of overload-comprensive load was also evaluated. For low stress intensity factor, the crack growth rate obtained was slightly higher when the application of compressive loads preceded an overload. However, the opposite occurred when the stress intensity factor was larger.
Download or read book Advances in Intelligent Systems Computer Science and Digital Economics written by Zhengbing Hu and published by Springer Nature. This book was released on 2020-01-23 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book comprises high-quality, refereed research papers presented at the 2019 International Symposium on Computer Science, Digital Economy and Intelligent Systems (CSDEIS2019): The symposium, held in Moscow, Russia, on 4–6 October 2019, was organized jointly by Moscow State Technical University and the International Research Association of Modern Education and Computer Science. The book discusses the state of the art in areas such as computer science and its technological applications; intelligent systems and intellectual approaches; and digital economics and methodological approaches. It is an excellent reference resource for researchers, undergraduate and graduate students, engineers, and management practitioners interested in computer science and its applications in engineering and management.
Download or read book Basic Questions in Fatigue written by Jeffrey T. Fong and published by ASTM International. This book was released on 1988 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced High Pressure O2 H2 Technology written by S. F. Morea and published by . This book was released on 1985 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metals Abstracts written by and published by . This book was released on 1993 with total page 1220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
