Estimating the Median Fatigue Limit for Very Small Up-and-Down Quantal Response Tests and for

2009 ◽  
pp. 29-29-14 ◽  
Author(s):  
RE Little
Keyword(s):  
Fatigue Limit ◽  
Quantal Response

THE INFLUENCE OF SMALL DEFECTS ON THE FATIGUE LIMIT OF 1045 STEEL

2019 ◽  
Author(s):  
Daniel Oliveira ◽  
Artur Dias ◽  
Cainã Bemfica de Barros ◽  
Fábio Castro ◽  
Roberto Costa
Keyword(s):  
Fatigue Limit ◽  
1045 Steel

Theoretical justifi cation for use of combined methods for hardening of surfaces of machine parts in order to control their fretting resistance

2020 ◽  
pp. 339-342
Author(s):  
V.F. Bez’yazychny ◽  
M.V. Timofeev ◽  
R.V. Lyubimov ◽  
E.V. Kiselev
Keyword(s):  
Surface Layer ◽  
Fatigue Limit ◽  
Surface Hardening ◽  
Theoretical Justification ◽  
Hardening Process ◽  
Subsequent Application ◽  
Machine Parts ◽  
Combined Methods

The theoretical justification for the hardening process of the surface layer of machine parts for combined methods of surface hardening with subsequent application of strengthening coatings, as well as reducing or increasing the fatigue limit due to the fretting process is presented.

scholarly journals Effect of micro-notches on fatigue strength of electrodeposited nanocrystalline nickel thin films

2018 ◽  
Vol 165 ◽  
pp. 04011
Author(s):  
Keisuke Tanaka ◽  
Yuta Murase ◽  
Hirohisa Kimachi
Keyword(s):  
Thin Films ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Stress Ratio ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Fine Grained ◽  
Nickel Thin Films ◽  
Nano Crystalline ◽  
Fictitious Crack

The effect of micro-notches on the fatigue strength of nickel thin films was studied. Two types of thin films with 10 μm thickness were produced by electrodeposition using sulfamate solution without and with brightener: ultra-fine grained film (UFG) with the grain size of 384 nm and nano-crystalline grained film (NCG) with that of 17 nm. Micro-sized notches introduced by FIB had the width of 2 μm and various depths from 8 to 150μm. Fatigue tests were conducted under the stress ratio of 0.1. The fatigue strength decreased with increasing depth of notches. NCG had much higher strength than UFG compared at the same notch depth. Notches as small as 8μm did reduce the fatigue strength of both UFG and NCG. The fatigue limit was controlled by the initiation of cracks and no non-propagating crack was observed in specimens fatigued below the fatigue limit. A model of fictitious crack successfully predicted the reduction of the fatigue limit due to micro-notches. The characteristic crack length of NCG was much smaller than the UFG, while the fatigue strength of defect-free NCG was larger than that of UFG. SEM observation of fracture surfaces was conducted to reveal micromechanisms of fatigue crack initiation.

Origins of heart rate variability: relationship of heart rate burst morphology to work duration and load

1999 ◽  
Vol 277 (4) ◽  
pp. H1491-H1497
Author(s):  
Daniel Roach ◽  
Robert Haennel ◽  
Mary Lou Koshman ◽  
Robert Sheldon
Keyword(s):  
Heart Rate ◽  
Burst Duration ◽  
Heart Period ◽  
Quantal Response ◽  
Ambulatory Ecg ◽  
Work Duration ◽  
Baroreceptor Activation ◽  
Relationship Of ◽  
Electrocardiogram Ecg ◽  
The Impact

We are developing a lexicon of specific heart period changes, or lexons, that recur frequently and whose physiological meaning can be read into ambulatory electrocardiogram (ECG). The transient, reversible “burst” of tachycardia induced by exercise initiation can also be seen on ambulatory ECG. We hypothesized that burst morphology depended on the work that preceded it and on baroreceptor activation. Ten subjects with mean age 38 yr (range 17–69 yr) underwent two protocols of semisupine cycling in which load and duration were varied. Burst duration increased with longer cycling times (median values of 18.0, 25.5, and 23.7 s with 1, 3, and 5 s of cycling, respectively; P= 0.033). Burst shape as assessed by heart period exponential decay constant and burst magnitude did not change. To assess the impact of workload, subjects cycled for 5 s at loads of 0, 25, 50, and 75 W. No significant differences were seen in burst duration, burst magnitude, or burst shape. Tachycardia preceded hypotension by 4.6 ± 2.2 s, which is inconsistent with baroreceptor involvement in the onset of burst tachycardia. Because burst morphology is a nearly quantal response to the initiation of exercise, the presence of a burst on an ambulatory ECG implies the onset of exercise.

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