scholarly journals Load history effects on fatigue crack propagation: Its effect on the R-curve for threshold

2015 ◽  
Vol 9 (33) ◽  
pp. 209-214 ◽  
Author(s):  
X. Zhou ◽  
A. Hohenwarter ◽  
T. Leitner ◽  
H.P. Gänser ◽  
R. Pippan
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Load History ◽  
History Effects

A New Stochastic Model for Prediction of Fatigue Crack Propagation

2005 ◽  
Vol 297-300 ◽  
pp. 1764-1769
Author(s):  
Khalil Farhangdoost ◽  
E. Pooladi B.
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Stochastic Model ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Nonstationary Process ◽  
Total Probability ◽  
Load History ◽  
Generating Series ◽  
Process Effects

Fatigue damage plays a significant role in fatigue life of structures and mechanical parts. Characterizing crack length as a random process in fatigue life, is a matter of controversy which is the first step of this new stochastic model for prediction of fatigue crack propagation. Minimum uncertainties and capability of using closure load are the model advantages. Generating series of a nonstationary process, effects of load history in immediate last step of crack propagation using Total Probability Theory (TPT) are some assumptions of this model. The model results have been compared with actual test results of Ti-6Al-4V CT specimens.

High Cycle Fatigue and Fatigue Crack Propagation Behaviors of Modified A7075-T73 Alloy

2014 ◽  
Vol 52 (4) ◽  
pp. 283-291 ◽  
Author(s):  
Gwan Yeong Kim ◽  
Kyu Sik Kim ◽  
Joong Cheol Park ◽  
Shae Kwang Kim ◽  
Young Ok Yoon ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
High Cycle Fatigue ◽  
Cycle Fatigue

scholarly journals Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 4: sporadic fatigue crack propagation

2020 ◽  
Vol 92 (9) ◽  
pp. 1521-1536
Author(s):  
Clive Bucknall ◽  
Volker Altstädt ◽  
Dietmar Auhl ◽  
Paul Buckley ◽  
Dirk Dijkstra ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
High Molecular Weight ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Individual Growth ◽  
Paris Equation ◽  
Number Of Cycles ◽  
Ultra High Molecular Weight

AbstractFatigue tests were carried out on compression mouldings supplied by a leading polymer manufacturer. They were made from three batches of ultra-high molecular weight polyethylene (UHMWPE) with weight-average relative molar masses, ${\overline{M}}_{\mathrm{W}}$, of about 0.6 × 106, 5 × 106 and 9 × 106. In 10 mm thick compact tension specimens, crack propagation was so erratic that it was impossible to follow standard procedure, where crack-tip stress intensity amplitude, ΔK, is raised incrementally, and the resulting crack propagation rate, da/dN, increases, following the Paris equation, where a is crack length and N is number of cycles. Instead, most of the tests were conducted at fixed high values of ΔK. Typically, da/dN then started at a high level, but decreased irregularly during the test. Micrographs of fracture surfaces showed that crack propagation was sporadic in these specimens. In one test, at ΔK = 2.3 MPa m0.5, there were crack-arrest marks at intervals Δa of about 2 μm, while the number of cycles between individual growth steps increased from 1 to more than 1000 and the fracture surface showed increasing evidence of plastic deformation. It is concluded that sporadic crack propagation was caused by energy-dissipating crazing, which was initiated close to the crack tip under plane strain conditions in mouldings that were not fully consolidated. By contrast, fatigue crack propagation in 4 mm thick specimens followed the Paris equation approximately. The results from all four reports on this project are reviewed, and the possibility of using fatigue testing as a quality assurance procedure for melt-processed UHMWPE is discussed.

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