Download or read book Fatigue Crack growth and Crack Closure Behavior of Aluminum Alloy 7050 and 9310 Steel Over a Wide Range in Load Ratios Using Compression Pre cracking Test Methods written by Talal Mehdi Senhaji and published by . This book was released on 2016 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue-crack-growth-rate tests were conducted on compact tension specimens made of 7050-T7451 aluminum alloy and 9310 steel. Compact tension specimens were tested over a wide range of load ratios (0.1 ≤ R ≤ 0.9) to generate crack-growth-rate data from threshold to near fracture. Three methods were used to generate near threshold data. A crack-closure analysis was performed on both materials using the FASTRAN crack-closure model. The crack-growth-rate data for each material correlated very well and each collapsed onto a nearly unique curve in the low- and mid-rate regimes using the strip-yield model in the FASTRAN life-prediction code. For the 7050 alloy, a constraint factor of a = 1.8 was required, while for the 9310 steel a = 2.5 worked very well in correlating the test data over a very wide range in R values and rates from threshold to near fracture.
Download or read book Crack Closure Behavior of 7050 Aluminum Alloy Near Threshold Conditions for Wide Range in Load Ratios and Constant Kmax Tests written by J. C. Newman and published by . This book was released on 2010 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Through the thickness Fatigue Crack Closure Behavior in an Aluminum Alloy written by and published by . This book was released on 1990 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Compression Precracking to Generate Near Threshold Fatigue Crack Growth Rates in an Aluminum and Titanium Alloy written by John J. Ruschau and published by . This book was released on 2008 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The scope of this paper is to determine the fatigue-crack growth rates in the near-threshold regime for both an aluminum and titanium alloy using the compression precracking constant-amplitude (CPCA) test method on compact specimens. Tests were conducted over a wide range of stress ratios (R=Pmin/Pmax=0.1 to 0.9). Results were compared with threshold and near-threshold data generated on the same materials using the ASTM E647, "Standard Test Method for Measurement of Fatigue Crack Growth Rates," load-shedding test procedure. On the 7075-T651 alloy, very little difference was observed in threshold values between the load-shedding and CPCA test methods. In contrast, the titanium alloy (Ti-6Al-4V) showed very large differences between the CPCA and load-shedding test results in the near-threshold and threshold regimes for the low stress ratios. Results under high R conditions (R>=0.7) agreed well between the two-threshold test methods for both materials. On the titanium alloy, the load-shedding test method also produced a specimen width effect on near-threshold behavior, whereas the CPCA test method produced results that were independent of specimen width and produced "steady-state" constant-amplitude data in the near-threshold regime, after the crack had grown several compressive plastic-zone sizes.
Download or read book Effects of Thickness on Plasticity Induced Fatigue Crack Closure written by KK. Chan and published by . This book was released on 1999 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The crack-opening stress was measured using a strain gage technique on 7050 aluminum alloy, under constant amplitude and repeated overload. The behavior of crack-opening stress predicted by Newman's FASTRAN-II is consistent with the experimental results for repeated overload. It is also found that the FASTRAN-II program is capable of predicting crack growth on the 7050-T76 aluminum plate and 7050-T7452 aluminum hand forging under complex simulated flight loading which contains a significant number of compression cycles.
Download or read book Fatigue Life and Crack Growth Prediction Methodology written by J. C. Newman (Jr) and published by . This book was released on 1993 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue and Crack growth in 7050 T7451 Aluminum Alloy Under Constant and Variable amplitude Loading written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue and crack-growth tests were conducted on 7050-T7451 aluminum alloy under a wide range of loading conditions. Crack-growth tests were conducted on compact, C(T), specimens under constant-amplitude loading, single-spike overloads, and a simulated aircraft spectrum loading. Fatigue tests were also conducted on single-edgenotch bend, SEN(B), specimens under constant-amplitude loading and three aircraft load spectra. The FASTRAN, life-prediction code, was used to make crack-growth predictions on the C(T) specimens; and to make fatigue-life calculations using a 12- micrometer initial flaw size at the center of the edge-notch on the SEN(B) specimens. The predictions agreed fairly well with most of the tests, except the model was unconservative on the single-spike overload tests and the severe spectrum Mini-TWIST+ Level 1 tests. The discrepancy was suspected to be caused by a low constraint factor and/or crack paths meandering around overload plastic zones. A roughness- and plasticity-induced crack-closure model would be needed to improve the model.
Download or read book Fatigue Crack Growth with Negative Stress Ratio Following Single Overloads in 2024 T3 and 7075 T6 Aluminum Alloys written by DK. Chen and published by . This book was released on 1976 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modified pre-cracked compact specimens of 2024-T3 and 7075-T6 aluminum alloys were subjected to four different overload patterns followed by subsequent constant-amplitude steady-state loading with R=Plmin/lmax equal to 0, -1/2, -1, and -2. The overload patterns were tension, compression-tension, tension-compression, and compression. Cyclic loading with negative stress ratio, R, drastically reduced crack-growth retardation. The higher the negative R ratio the greater the reduction in retardation. Overload ratios, OLR =Phmax/Plmax, ranging from 2.0 to 3.0 were used. For compression overloads, the OLR ranged from -2.0 to -4.0. High compression overloading was detrimental and dependent upon subsequent R ratio loading. Substantial fracture surface abrasion near the mid-thickness occurred for higher negative R ratios. Striations were not readily found in this region, however, they were quite evident near the edges, which indicated crack closure was greater near the mid-thickness. The 2024-T3 gave better crack growth life than 7075-T6 in some loading conditions, while the opposite was true for other loadings. The results indicate negative R ratio must be considered in retardation models and that retardation life cannot be modeled based solely on overload plastic zone sizes.
Download or read book Effects of Bonding Temperatures on Fatigue Crack Growth written by Rodney L. Wilkinson and published by . This book was released on 1983 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Changes in the crack growth behavior of 7075-T651 aluminum specimens which has been exposed to temperatures between 150 degrees and 355 degrees F (66 deg and 179 deg C) were evaluated. Specimens were fatigue tested at room temperature under flight-by-flight loading conditions. Results from these tests were then compared with data from the baseline (as received) material. Exposure to 250 deg F (121 deg C) or more produced a definite increase in speciment life, apparently due to a decrease in crack growth rates.
Download or read book Stress Ratio Effects on Crack Opening Loads and Crack Growth Rates in Aluminum Alloy 2024 written by William T. Riddell and published by . This book was released on 1998 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of Crack Closure on Fatigue Crack Growth Thresholds in 2024 T3 Aluminum Alloy written by EP. Phillips and published by . This book was released on 1988 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crack opening loads were determined in load-shedding fatigue crack growth threshold tests on 2024-T3 aluminum alloy at stress ratios R of -2, -1, 0, 0.33, 0.5, and 0.7. The effects of load-shedding procedure and rate were investigated. Values of threshold ?K were found to vary significantly with R, whereas values of threshold effective ?K did not. That is, the variation of threshold ?K with R was almost completely explained by accounting for the measured variation in crack opening load behavior with R. The load-shedding guidelines of ASTM Test Method for Measurement of Fatigue Crack Growth (E 647) produced a threshold ?K value for R = 0.7 that was in agreement with the value determined using a procedure that should minimize closure effects (constant-Kmax, increasing-Kmin test). At both R = 0 and R = 0.7, high load-shedding rates produced high values of threshold ?K caused by large closure effects.
Download or read book An Investigation of Fatigue Crack Growth Behavior in Cast Particulate Reinforced Aluminum Alloys written by Anthony George Keslinke and published by . This book was released on 1990 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fatigue Crack Growth Behavior of 7XXX Aluminum Alloys Under Simple Variable Amplitude Loading written by PE. Bretz and published by . This book was released on 1984 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This investigation examines the influence of temper and purity on the fatigue crack growth (FCG) behavior of four 7XXX aluminum alloys (7075-T6, 7075-T7, 7050-T6, 7050-T7) tested using a periodic single overload spectrum at low stresses. The loading sequence consists of a periodic single overload spike occurring once every 8000 constant amplitude cycles; the overload spike is 1.8 times the constant amplitude load peak. All tests have been performed in high humidity (>90% relative humidity) air at a frequency of 20 Hz and a constant amplitude load ratio of R = 0.33. The observed microstructural effects on transient (that is, spectrum) FCG behavior are contrasted with those for steady-state (constant load amplitude) fatigue performance.
Download or read book Fatigue Crack Growth Behavior of the 7050 T73511 Aluminum Alloy in the Presence of Bonded Reinforcement written by Karthik Kumar Krishnakumar and published by . This book was released on 2001 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of Fatigue Crack Closure with the Extension of Long and Short Cracks in Aluminum Alloy 2124 written by AF. Blom and published by . This book was released on 1988 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of crack closure during the extension of long and short fatigue cracks has been investigated in a 2124 aluminum alloy using both experimental and numerical procedures. Specifically, the growth rate and closure behavior of long (~17 to 38 mm) cracks in compact C(T) specimens and through-thickness physically-short (~50 to 40 ?m) cracks in single-edge-notched SEN(B) bend specimens have been examined experimentally from threshold levels to instability (over the range ~10-12 to 10-7 m/cycle), and results compared with those predicted numerically using an elastic-plastic finite-element analysis of fatigue crack advance in plane strain. It is shown that the numerical analysis consistently underpredicts the magnitude of crack closure for both long and short cracks, particularly at near-threshold levels; an observation attributed to the fact that the numerical procedures can only model contributions to closure from cyclic plasticity, whereas, in reality, significant additional closure arises from the wedging action of fracture surface asperities and corrosion debris. Such closure is shown to provide the predominant mechanism for rationalizing differences in the growth rate behavior between long and physically short cracks, although other factors, such as the nature of the singularity and the extent of local plasticity, are deemed potentially to be important.
Download or read book Prediction of Fatigue crack Growth in a High strength Aluminum Alloy Under Variable amplitude Loading written by J. C. Newman (Jr) and published by . This book was released on 1989 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization and Predition of Fatigue Crack Formation and Fatigue Crack Growth Behavior of the 7050 T73511 Aluminum Alloy Using Strain life and Linear Elastic Fracture Mechanics Techniques written by Claire Louise Stroede and published by . This book was released on 1998 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
