342 Effect of Contact Pressure on Crack Initiation Life in Fretting Fatigue of High Strength Steel

2000 ◽  
Vol 2000.8 (0) ◽  
pp. 293-294
Author(s):  
Kozo NAKAZAWA ◽  
Norio MARUYAMA ◽  
Takao HANAWA
Keyword(s):  
Crack Initiation ◽  
Contact Pressure ◽  
High Strength Steel ◽  
High Strength ◽  
Fretting Fatigue ◽  
Crack Initiation Life

scholarly journals Finite Element Analysis of Fretting Fatigue Fracture in Lug Joints Made of High Strength Steel

2018 ◽  
Vol 165 ◽  
pp. 11005
Author(s):  
Reza Hojjati Talemi ◽  
Jie Zhang ◽  
Stijn Hertelé ◽  
Wim De Waele
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Crack Propagation ◽  
High Strength Steel ◽  
Fatigue Crack Initiation ◽  
High Strength ◽  
Fretting Fatigue ◽  
Contact Interface ◽  
Structural Applications

Many structural applications are aiming for weight reduction by using high strength steel. In a lug joint the load is transmitted by a pin, which leads to a pressure distribution on the hole in the lug. When a lug joint is subjected to axial cyclic loading conditions, the stress distribution becomes multiaxial, i.e. a combination of normal and tangential stresses. In such loading case, a fretting crack initiates at the contact interface between the pin/lug connection which is followed by a fatigue crack propagation up to the final rupture of the lug. In this study, the fretting fatigue crack initiation and propagation in a pin/lug joint are simulated using multiaxial fatigue criterion and fracture mechanics, respectively. To do so, first a 2D finite element model is developed for obtaining stresses and strains at the contact interface in a pin/lug joint. Using the extracted data, fretting fatigue failure parameters are analysed. Next, the obtained stresses and strains are used to estimate the crack initiation lifetime using a fatigue multiaxial critical plane model. A 3D model is set-up to simulate the crack propagation using eXtended Finite Element Method (XFEM). Eventually, the predicted total fatigue lifetimes are compared against experimental observations taken from literature.

scholarly journals Crack Initiation and Propagation Fatigue Life of Ultra High-Strength Steel Butt Joints

2019 ◽  
Vol 9 (21) ◽  
pp. 4590 ◽  
Author(s):  
Markus J. Ottersböck ◽  
Martin Leitner ◽  
Michael Stoschka ◽  
Wilhelm Maurer
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Welded Joints ◽  
High Strength Steel ◽  
High Strength ◽  
Crack Initiation And Propagation ◽  
Butt Joints ◽  
Fatigue Assessment ◽  
Initiation And Propagation ◽  
Ultra High Strength Steel

The division of the total fatigue life into different stages such as crack initiation and propagation is an important issue in regard to an improved fatigue assessment especially for high-strength welded joints. The transition between these stages is fluent, whereas the threshold between the two phases is referred to as technical crack initiation. This work presents a procedure to track crack initiation and propagation during fatigue tests of ultra high-strength steel welded joints. The method utilizes digital image correlation to calculate a distortion field of the specimens’ surface enabling the identification and measurement of cracks along the weld toe arising during the fatigue test. Hence, technical crack initiation of each specimen can be derived. An evaluation for ten ultra high-strength steel butt joints reveals, that for this superior strength steel grade more than 50% of fatigue life is spent up to a crack depth of 0.5 mm, which can be defined as initial crack. Furthermore, a notch-stress based fatigue assessment of these specimens considering the actual weld topography and crack initiation and propagation phase is performed. The results point out that two phase models considering both phases enable an increased accuracy of service life assessment.

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