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 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 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 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 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 Load Interaction Effects in Ti 62222 at 540C and 1750C for Near threshold and Paris Regime Fatigue Crack Growth written by Shannon Charles Berge and published by . This book was released on 2003 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Geometry and Load History on Fatigue Crack Growth in Ti 62222 written by RR. Stephens and published by . This book was released on 2000 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fatigue crack growth behavior of Ti-62222 mill-annealed material in sheet form was examined as a function of specimen geometry. The geometries investigated were the eccentrically loaded single edge-notch tension (ESE(T)), the compact tension (C(T)), and the middle tension (M(T)). Tests were conducted at room temperature at two load ratios (R=0.1 and 0.7) and covered a broad range of crack growth rates ranging from 10-7 to 10-2 mm/cycle. The same precracking and threshold test procedures were used for all geometries as each threshold test was started at the same crack length and continuous load shedding was applied at a K-gradient of C=-0.08 mm-1. As a result, the same stress intensity-crack length (K-a) history was maintained throughout all of the threshold tests. Experimental results showed differences in fatigue crack growth behavior at the lowest crack growth rates while higher crack growth rates were similar. Surface roughness differences at lower crack growth rates were observed at the same nominal ?K for the three geometries, suggesting differing crack growth mechanisms. Discrepancies observed in specimen behavior are assessed in terms of the crack tip stress field distribution which include both y-direction and T-stresses. In addition, supplemental fatigue crack growth tests showed a dependence on crack length and load reduction procedure.

Download or read book Load Interaction Effects on Fatigue Crack Growth in Ti 6Al 4V Alloy written by Robert Peh-ying Wei and published by . This book was released on 1973 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of delay, retardation in the rate of fatigue crack growth, produced by load interactions in variable amplitude loading, on the accurate prediction of fatigue lives of engineering structures is discussed. The effects of a broad range of loading variables on delay in fatigue crack growth at room temperature are examined for a mill annealed Ti-6Al-4V alloy. The results are used to estimate crack growth behavior under programmed loads.

Download or read book Fatigue Crack Growth Under Spectrum Loads written by Ralph Ivan Stephens and published by ASTM International. This book was released on 1976 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effects of Different Load Schemes on the Fatigue Crack Growth Rate written by P. Ljustell and published by . This book was released on 2006 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted on a nickel-based super alloy, Inconel 718, at an elevated temperature of +400°C. The basic question was how to conduct the experiments in order to obtain fatigue crack growth data as free from load history effects as possible in the stage II region. This was investigated by use of four different load sequences. An important question was to investigate if the so called constant KI,max-method provides an upper bound of the fatigue crack growth rate in the stage II region. The results indicate that the constant KI,max-method gives an upper bound in fatigue crack growth rate in the current measuring range but also gives a statistically significant lower exponent of the crack growth equation. A more reliable method to establish the fatigue crack growth parameters is to propagate the crack under constant stress-intensity factor range. This should be done at two different stress-intensity factor ranges for a few millimetres at each range. Also, ?K-reducing procedure should not be used, when performing fatigue crack growth testing in the stage II region, in order to minimize the risk of transient crack closure effects.

Download or read book Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6 2 2 2 2 written by and published by . This book was released on 2001 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Underloads on Fatigue Crack Growth of Titanium 17 written by Stephan M. Russ and published by . This book was released on 2003 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fatigue Crack Growth Behavior of Ti 1100 at Elevated Temperature written by DC. Maxwell and published by . This book was released on 1995 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effects of temperature, frequency, and cycles with superimposed hold times are evaluated in Ti-1100 in order to study the complex creep-fatigue-environment interactions in this material. Crack growth rate tests conducted at a cyclic loading frequency of 1.0 Hz show that raising the temperature from 593 to 650°C has only a slightly detrimental effect on crack growth rate, although these temperatures produce growth rates significantly higher than at room temperature. From constant ?K tests, the effects of temperature at constant frequency show a minimum crack growth rate at 250°C. From the minimum crack growth rate at 250°C, the crack growth rate increases linearly with temperature. Increases in frequency at constant temperatures of 593 and 650°C produce a continuous decrease in growth rate in going from 0.001 to 1.0 Hz, although the behavior is primarily cycle dependent in this region. Tests at 1.0 Hz with superimposed hold times from 1 to 1000 s are used to evaluate creep-fatigue-environment interactions. Hold times at maximum load are found to initially decrease and then increase the cyclic crack growth rate with increasing duration. This is attributed to crack-tip blunting during short hold times and environmental degradation at long hold times. Hold times at minimum load show no change in growth rates, indicating that there is no net environmental degradation to the bulk material beyond that experienced during the baseline 1 Hz cycling.

Download or read book On Transient Effects in Fatigue Crack Growth written by Zhaoxiong Yang and published by . This book was released on 1987 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Threshold Fatigue Crack Growth in Ti 6Al 2Sn 4Zr 6Mo written by Dale A. Nagy and published by . This book was released on 1987 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to examine the effects of different loading histories, closure loads, and stress ratios on the near-threshold crack growth rate of a Titanium-Aluminum alloy. Two different test types were conducted on four separate specimens to determine the threshold stress intensity of the material. The first test type maintained a constant maximum stress intensity factor, K(max) on a specimen with a growing crack. As the crack grew, the minimum stress intensity factor was increased until the crack growth rate reached the threshold level. The second test type also maintained a constant K(max). For this test a block of cycles was applied to the specimen and if the crack growth rate for the block of cycles was below the threshold level then K(min) was decreased by a small amount and another block of cycles was applied. This process was continued until the crack growth rate reached the threshold level. Once the threshold stress intensity was determined the cracks were grown under constant maximum load and stress ratio (R) to measure the threshold crack growth rate. Both test types were conducted over a wide range of stress ratios to investigate the effects of varying closure loads.

Download or read book The Effect of Compressive Loads on Fatigue Crack Growth Behavior written by Pete Au and published by . This book was released on 1982 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Load and Environment Interactions in Fatigue Crack Growth written by T. T. Shih and published by . This book was released on 1974 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influences of environment on delay and on fatigue crack growth under programmed loading were examined for a mill annealed Ti-6Al-4V alloy. Test environments included dehumidified argon, air (with 30-60% relative humidity), distilled water, and 3.5% NaCl solution. The effects of load sequence and block size on fatigue under programmed loads were investigated also. Experimental results show that the mildly aggressive environments (atmospheric moisture and distilled water) have little effect on delay. Salt solution, on the other hand, has a significant effect on delay and on crack growth under programmed loading; the effect on delay being dependent on frequency or hold-time. Both load sequence and block size can significantly alter fatigue life under programmed loading. The need for further fundamental understanding of load and environment interactions in fatigue is discussed. (Modified author abstract).