Download or read book Evaluation of the Adjusted Compliance Ratio Technique for Measuring Crack Closure in Ti 6A1 4V written by SM. Graham and published by . This book was released on 1999 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Standard fatigue crack growth rate tests within the upper threshold and Paris Law regions were conducted on specimens from three large, standard-grade Ti-6Al-4V forgings in order to evaluate the adjusted compliance ratio (ACR) method for closure correction. Constant R-ratio tests were conducted to generate data containing crack-tip closure, and constant Kmax tests were performed to produce high R ratio, and hence closure-free, data in the threshold and upper threshold regimes. Direct comparisons are made of the closure corrected data generated using the current ASTM slope offset method and the ACR method. While it is clear that the ACR technique is easier to implement and will always lead to less closure correction than the slope offset technique, it is not clear which is more accurate. It appears that the slope offset method may be overcorrecting for closure effects and the ACR method may be undercorrecting.
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 An Evaluation of the Plasticity Induced Crack Closure Concept and Measurement Methods written by James C. Newman (Jr.) and published by . This book was released on 1998 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Special Applications and Advanced Techniques for Crack Size Determination written by John J. Ruschau and published by ASTM International. This book was released on 1995 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprises ten papers discussing topics including methods for the measurement of surface crack size, multiple site cracking, and cracking under nonisothermal conditions using AC potential difference procedures; influences of crack deflection and crack splitting on DC potential calibrations; complianc
Download or read book Journal of Testing and Evaluation written by and published by . This book was released on 2006 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crack Wake Influence Theory and Elastic Crack Closure Measurement written by H. Tada and published by . This book was released on 2000 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental and analytical evidence indicates that "closure" or interference of crack faces does not entirely isolate the crack tip from damaging strains. To account for the contribution of the cyclic crack tip strain below the opening load, a new analysis technique has been developed for estimating ?Keff. This technique is based on crack wake influence theory (the relationship between the effect of crack wake interference on a displacement or strain measurement location and the corresponding effect at the crack tip). Solving the distribution and position functions provides a method of equating remote compliance measurements to reduction in crack tip elastic strain. The experimental method involves determining the ratio of the compliance of the shielded crack to that of the fully open crack (CR). This relationship remains elusive until it is recognized that 1 -- CR is directly related to the influence of the closure mechanism on both the measurement location and the crack tip. The verification of this method includes experimental measurements of a large center crack panel with multiple displacement and strain gage measurement locations. The standard crack has been replaced with a milled slot, allowing precision blocks to be inserted at specific positions to simulate crack wake interference. Finite element analysis and theory of elasticity are linked to the experiment to better understand the measurement requirements for crack tip closure. The estimation of ?Keff using the ratio of influences from the theory of elasticity can be directly compared with other approximation techniques such as the adjusted compliance ratio or opening load.
Download or read book Results of the Second Round Robin on Opening load Measurement Conducted by ASTM Task Group E24 04 04 on Crack Closure Measurement and Analysis written by E. P. Phillips and published by . This book was released on 1993 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: A second experimental Round Robin on the measurement of the crack opening load in fatigue crack growth tests has been completed by the ASTM Task Group E24.04.04 on Crack Closure Measurement and Analysis. Fourteen laboratories participated in the testing of aluminum alloy compact tension specimens. Opening-load measurements were made at three crack lengths during constant Delta K, constant stress ratio tests by most of the participants. Four participants made opening-load measurements during threshold tests. All opening-load measurements were based on the analysis of specimens compliance behavior, where the displacement/strain was measured either at the crack mouth or the mid-height back face location. The Round Robin data were analyzed for opening load using two non-subjective analysis methods: the compliance offset and the correlation coefficient methods. The scatter in the opening load results was significantly reduced when some of the results were excluded from the analysis population based on an accept/reject criterion for raw data quality. The compliance offset and correlation coefficient opening load analysis methods produced similar results for data populations that had been screened to eliminate poor quality data.
Download or read book Fatigue and Fracture Mechanices written by Steven R. Daniewicz and published by ASTM International. This book was released on 2005-09 with total page 591 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Results of the Second Round Robin on Opening Load Measurement Conducted by ASTM Task Group E24 04 04 on Crack Closure Measurement and Analysis written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: A second experimental Round Robin on the measurement of the crack opening load in fatigue crack growth tests has been completed by the ASTM Task Group E24.04.04 on Crack Closure Measurement and Analysis. Fourteen laboratories participated in the testing of aluminum alloy compact tension specimens. Opening-load measurements were made at three crack lengths during constant Delta K, constant stress ratio tests by most of the participants. Four participants made opening-load measurements during threshold tests. All opening-load measurements were based on the analysis of specimens compliance behavior, where the displacement/strain was measured either at the crack mouth or the mid-height back face location. The Round Robin data were analyzed for opening load using two non-subjective analysis methods: the compliance offset and the correlation coefficient methods. The scatter in the opening load results was significantly reduced when some of the results were excluded from the analysis population based on an accept/reject criterion for raw data quality. The compliance offset and correlation coefficient opening load analysis methods produced similar results for data populations that had been screened to eliminate poor quality data. Phillips, E. P. Langley Research Center RTOP 50-63-50-04...
Download or read book Results of the Round Robin on Opening Load Measurement Conducted by ASTM Task Group E24 04 04 on Crack Closure Measurement and Analysis written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental Round Robin on the measurement of the opening load in fatigue crack growth tests was conducted on Crack Closure Measurement and Analysis. The Round Robin evaluated the current level of consistency of opening load measurements among laboratories and to identify causes for observed inconsistency. Eleven laboratories participated in the testing of compact and middle-crack specimens. Opening-load measurements were made for crack growth at two stress-intensity factor levels, three crack lengths, and following an overload. All opening-load measurements were based on the analysis of specimen compliance data. When all of the results reported (from all participants, all measurement methods, and all data analysis methods) for a given test condition were pooled, the range of opening loads was very large--typically spanning the lower half of the fatigue loading cycle. Part of the large scatter in the reported opening-load results was ascribed to consistent differences in results produced by the various methods used to measure specimen compliance and to evaluate the opening load from the compliance data. Another significant portion of the scatter was ascribed to lab-to-lab differences in producing the compliance data when using nominally the same method of measurement. Phillips, Edward P. Langley Research Center RTOP 505-63-01-05...
Download or read book A New Method for Opening Load Determination from Compliance Measurements written by D. Kujawski and published by . This book was released on 2005 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: A brief review of the most popular compliance based methods for determination of the crack opening load is included in the introduction. This review reveals the demand for a noise resistant method that is especially needed in the near-threshold region where a partial crack closure prevails and the existing ASTM method does not calculate the correct opening load. With this in mind, a new technique was developed ('Q' method). It uses integration instead of differentiation of the compliance data. It also accounts for the partial crack closure situations. The derivation of the Q method is discussed together with its relation to the ASTM procedure, and both methods were used to analyze experimental data of 2324-T39 and 7475-T7351 Al alloys tested at 0.1 and 0.9 load ratios. On average, the crack opening load values from the Q method are smaller by the factor of about 2/? in comparison to those obtained from the ASTM procedure.
Download or read book Experimental Determination of Crack Closure by the Cut Compliance Technique written by H-J Schindler and published by . This book was released on 1999 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cut compliance method was developed to measure residual stress profiles. Its idea is to release them by introducing progressively a cut into the considered body. From the strain change due to progressive cutting it is possible to calculate the distribution of the released stresses. Since the method uses fracture mechanics principles the stress intensity factor due to residual stresses is delivered as well. Being a special type of residual stresses, the distribution of the contact stresses of fatigue crack closure and the corresponding closure stress intensity factors can be suitably determined by this method. Furthermore, it enables the residual stresses in front of the crack tip to be determined, which in crack retardation play a role as important as the closure effects. The basic theoretical relations for some frequently used fatigue specimens are analytically derived. They also can serve to evaluate the contact stresses from the commonly used unloading compliance technique, which is often used to identify crack closure effects. Some preliminary examples demonstrate the capability of the suggested method.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1976 with total page 984 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 1044 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 Applied Mechanics Reviews written by and published by . This book was released on 1994 with total page 1036 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 1995 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:
