Laser Generated Crack-Like Features Developed for Assessment of Fatigue Threshold Behavior

2010 ◽  
pp. 592-592-14
Author(s):  
Aaron T. Nardi ◽  
Stephen L. Smith
Keyword(s):  
Fatigue Threshold ◽  
Threshold Behavior

Fatigue Threshold Behavior of Stainless Steel in High Temperature Air and Water

2016 ◽  
Author(s):  
Elaine West ◽  
Heather Mohr ◽  
Erik Lord
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Crack Closure ◽  
Austenitic Stainless Steels ◽  
Fatigue Threshold ◽  
Threshold Behavior ◽  
Load History ◽  
History Effects ◽  
Stress Ratios ◽  
Type 304

The fatigue threshold behavior of stainless steel was assessed in high temperature air and hydrogenated deaerated water environments as a function of stress ratio (R). Fatigue threshold experiments were conducted on four different heats of type 304, 304/304L, and 308L austenitic stainless steels in 250°C air and water environments at stress ratios ranging from 0.1 to 0.8. Air and water experiments showed that operational threshold ΔK (ΔKTH) values ranged from 4.3–6.0 and 3.9–5.3 MPa√m, respectively. ΔKTH values were observed to generally decrease with increasing R which is attributable to crack closure effects. The water ΔKTH measurements were either consistent with or lower than air threshold measurements, and the potential roles of the competing effects of crack closure and hydrogen enhanced planar slip will be discussed in the context of these results. Load history effects in the form of overloads and underloads were shown to significantly impact ΔKTH measurements and these results motivated testing aimed at characterizing material property based intrinsic ΔK threshold (ΔKTH*) values. The ΔKTH* values for stainless steel fatigue crack growth in 250–288°C air and water environments are estimated to be 3 and 2 MPa√m, respectively.

Laser Generated Crack-Like Features Developed for Assessment of Fatigue Threshold Behavior

2008 ◽  
Vol 5 (7) ◽  
pp. 101557
Author(s):  
Aaron T. Nardi ◽  
Stephen L. Smith ◽  
R. Neu ◽  
K. Wallin ◽  
S. R. Thompson ◽  
...  
Keyword(s):  
Fatigue Threshold ◽  
Threshold Behavior

Fatigue threshold behavior of adhesive joints

2010 ◽  
Vol 30 (3) ◽  
pp. 145-159 ◽  
Author(s):  
S. Azari ◽  
M. Papini ◽  
J.A. Schroeder ◽  
J.K. Spelt
Keyword(s):  
Adhesive Joints ◽  
Fatigue Threshold ◽  
Threshold Behavior

scholarly journals Modelling the Variability and the Anisotropic Behaviour of Crack Growth in SLM Ti-6Al-4V

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1400
Author(s):  
Rhys Jones ◽  
Calvin Rans ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos ◽  
Nam Phan ◽  
...  
Keyword(s):  
Crack Growth ◽  
The United States ◽  
Fatigue Threshold ◽  
Growth Equation ◽  
Single Edge ◽  
Test Program ◽  
Large Variability ◽  
Single Edge Notch ◽  
Anisotropic Behaviour ◽  
Edge Notch

The United States Air Force (USAF) Guidelines for the Durability and Damage Tolerance (DADT) certification of Additive Manufactured (AM) parts states that the most difficult challenge for the certification of an AM part is to establish an accurate prediction of its DADT. How to address this challenge is the focus of the present paper. To this end this paper examines the variability in crack growth in tests on additively manufactured (AM) Ti-6Al-4V specimens built using selective layer melting (SLM). One series of tests analysed involves thirty single edge notch tension specimens with five build orientations and two different post heat treatments. The other test program analysed involved ASTM standard single edge notch specimens with three different build directions. The results of this study highlight the ability of the Hartman–Schijve crack growth equation to capture the variability and the anisotropic behaviour of crack growth in SLM Ti-6Al-4V. It is thus shown that, despite the large variability in crack growth, the intrinsic crack growth equation remains unchanged and that the variability and the anisotropic nature of crack growth in this test program is captured by allowing for changes in both the fatigue threshold and the cyclic fracture toughness.

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