Author: J. TongPublisher:
ISBN:
Category : Materials
Languages : en
Pages :
Book Description
Effects of Frequency on Fatigue Crack Growth at Elevated Temperatures
Author: J. TongEffects of Frequency on Fatigue Crack Growth at Elevated Temperature
Author: J. TongFatigue Crack Growth Behavior of Ti-1100 at Elevated Temperature
Author: DC. MaxwellPublisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 14
Book Description
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.
Effects of Temperature and Frequency on the Fatigue Crack Growth Rate Properties of a 1950 Vintage CrMoV Rotor Material
Author: GA. ClarkePublisher:
ISBN:
Category : Crack propagation
Languages : en
Pages : 19
Book Description
Air environment fatigue crack growth rate data were developed for a 1950 vintage (air cast) chromium-molybdenum-vanadium (CrMoV) rotor steel at temperatures of 24, 121, 260, and 427°C (75, 250, 500, and 850°F) and loading frequencies of 0.0017, 0.017, 0.1, and 1.0 Hz. Results show that the room-temperature fatigue crack growth rate in the 1950 vintage material is on the order of two to eight times faster than that encountered in a more modern vacuum cast forging depending upon the ?K level of interest. Results also show that the effect of frequency on the fatigue crack growth rate varies with differing test temperatures. At room temperature as well as at 260 and 427°C (500 and 800°F), the rate of crack growth increases with decreasing frequency. At 121° (250°F), there is little effect of loading frequency on fatigue crack growth rate. This temperature dependent frequency effect is attributed to the different mechanisms interacted with fatigue at various temperatures. The effect of temperature on crack growth rates was also found to be frequency dependent with more pronounced temperature effects observed at lower frequencies. However, the general trend is the same for all values of frequency, that the rate of fatigue crack growth initially decreases before increasing at higher temperatures. The fact that fatigue crack growth rates do not increase monotonically with increasing temperature is attributed to the decrease in relative humidity of the test environment with increasing temperature.
The Effects of Frequency and Waveshape on the Fatigue Crack Growth of an Advanced Nickel Base Superalloy at Elevated Temperatures
Author: Sara DalbyNano and Microstructural Design of Advanced Materials
Author: M. A. MeyersPublisher: Elsevier
ISBN: 0080537235
Category : Technology & Engineering
Languages : en
Pages : 317
Book Description
The importance of the nanoscale effects has been recognized in materials research for over fifty years, but it is only recently that advanced characterization and fabrication methods are enabling scientists to build structures atom-by-atom or molecule-by molecule. The understanding and control of the nanostructure has been, to a large extent, made possible by new atomistic analysis and characterization methods pioneered by transmission electron microscopy. Nano and Microstructural Design of Advanced Materials focuses on the effective use of such advanced analysis and characterization techniques in the design of materials. - Teaches effective use of advanced analysis and characterization methods at an atomistic level - Contains many supporting examples of materials in which such design concepts have been successfully applied
Effect of Frequency on Fatigue Crack Growth Rate of Inconel 718 at High Temperature
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Fatigue crack growth was studied at 650 deg. C as a function of frequency for several ratios of minimum-to-maximum stress intensity, and for two values of maximum stress intensity factor. Crack lengths were monitored at low frequencies from compliance calculations based on crack mouth opening displacement measurements. At higher frequencies, crack length was measured using a d.c. electric potential system. It was found that fatigue crack growth rate can be characterized in three distinct frequency regions. These three regions represent fully cycle dependent, mixed, and fully time dependent crack growth behavior and each region can be modeled by a power law function. Observation of micro mechanisms support the existence of these three different regions of crack growth. Keywords: Fatigue crack growth, Time dependent growth, Cyclic-dependent growth, Nickel base superalloy, Crack growth rate model, Frequency effects.
Fatigue at Elevated Temperatures
Author: Publisher: ASTM International
ISBN:
Category : Metals
Languages : en
Pages : 804
Book Description
Effects of Environment, Loading Frequency, and Heat Treatment on Elevated Temperature Fatigue Crack Growth Rate of a Ni-Co-Fe Based Supperalloy
Author: Hua JiangElevated Temperature Effects on Fatigue and Fracture
Author: Robert S. PiascikPublisher: ASTM International
ISBN: 0803124139
Category : Aluminum alloys
Languages : en
Pages : 231
Book Description