scholarly journals Influence of Notch Sensitivity and Crack Initiation Site on Low Cycle Fatigue Life of Notched Components under Multiaxial Non-proportional Loading

2018 ◽  
Vol 13 (47) ◽  
pp. 126-140
Author(s):  
Stefano Bressan ◽  
Fumio Ogawa ◽  
Takamoto Itoh ◽  
Filippo Berto
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Initiation Site ◽  
Notch Sensitivity ◽  
Cycle Fatigue ◽  
Proportional Loading ◽  
Crack Initiation Site ◽  
Notched Components

Effect of Frequency on the Fatigue Behavior of IN718 Superalloy

2017 ◽  
Vol 1142 ◽  
pp. 23-30 ◽  
Author(s):  
Jin Hui Du ◽  
Xu Dong Lu ◽  
Qun Deng
Keyword(s):  
Grain Size ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Fatigue Cracks ◽  
Low Frequency ◽  
Initiation Site ◽  
Fatigue Properties ◽  
Crack Initiation Site

IN718 alloy possesses excellent mechanical properties at high temperatures, good process ability, therefore, it has been widely used in aero engine turbine disks, compressor disks, and power turbine shafts (i.e., rotating components). The fatigue properties of the alloy are a key factor that determines the safety and reliability of the engine. In this paper, the fatigue properties of IN718 alloy are investigated under low-and middle-frequency conditions at 600 °C and 455 °C, the initiation of fatigue cracks, and the relation between fatigue life and grain size are discussed. The results show that the carbides response as a crack initiation site at low-frequency fatigue condition (1 Hz), and string-type or heap-type carbides distribution promotes crack propagation and shortens fatigue life, the twin boundaries in large grains are act as a crack initiation site at middle-frequency fatigue condition (10 Hz). The grain size is smaller, and the low cycle fatigue properties of the alloy are better.

scholarly journals 104 Multiaxial Low Cycle Fatigue Life of Ti-6Al-4V under Non-proportional Loading

2009 ◽  
Vol 2009.46 (0) ◽  
pp. 7-8
Author(s):  
Yuuta SHIMIZU ◽  
Takamoto ITOH ◽  
Hiroshi NAKAMURA ◽  
Masahiro TAKANASHI
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Proportional Loading

Prediction of Low-Cycle Fatigue Life of Specimens With Fabrication Flaws

1968 ◽  
Vol 90 (4) ◽  
pp. 620-626 ◽  
Author(s):  
A. G. Pickett
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Low Cycle Fatigue ◽  
Small Specimen ◽  
Cycle Fatigue ◽  
Notch Stress ◽  
Weld Defect ◽  
Life Analysis ◽  
Fatigue Life Analysis ◽  
Crack Initiation Life

A modification of the notch stress procedure for fatigue-life analysis is presented. The importance of considering the mechanics of the specimen and the effects of the notch on specimen mechanics is illustrated by example. The procedure is applied to correlate the results of small specimen tests with large weld defect specimen tests. The significance of crack-initiation life and crack-propagation life and the dependence of these portions of total fatigue life on specimen geometry and loading is developed.

Factors Affecting the Low Cycle Fatigue Behavior around the Weak Axis of Welded I-Section Bracing Members

2006 ◽  
Vol 324-325 ◽  
pp. 959-962
Author(s):  
Yao Chun Zhang ◽  
Wei An Lian ◽  
Wen Yuan Zhang
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Crack Initiation ◽  
Surface Crack ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Cycle Fatigue ◽  
Loading History ◽  
Energy Dissipation Capacity ◽  
Surface Crack Initiation

The low cycle fatigue behavior and energy dissipation capacity around the weak axis of the welded I-section bracing members are investigated by 35 pinned-pinned bracing specimen tests under the axial cyclic loading with different characteristics. Particular attention is paid to the effects of loading amplitude, loading history and geometry properties of these members. It is found that the fatigue damage propagating to fracture in the flanges of the bracing members can be divided into 3 stages involving the macroscopic surface crack initiation, the penetrated crack formation and the penetrated crack propagation. Some empirical formulas to estimate the fatigue life and cyclic energy dissipation capacity of the bracing members are also presented based on the experimental data. The statistical analysis indicates that the fatigue life to surface crack initiation significantly depends on the inelastic local buckling and will increase with decreasing width-thickness ratio of the flanges and increasing slenderness ratios of the bracing members. Besides, it is found that the low cycle fatigue and energy dissipation of these members also depends on loading amplitude and loading history, and the effects of overloads and mean compression amplitude can improve the fatigue performance of bracing members. The test results show that the bracing members with better low-cycle fatigue resistance have the better energy dissipation capacities.

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