SteBLife – A new short-time procedure for the calculation of S-N curves and failure probabilities

Characterization of the fatigue behaviour and lifetime evaluation of metallic materials based on thermographic NDT-methods

“…Test data published in [18][19][20] have been used along with new test results, which were obtained from the same batch of specimens. These data were used to examine the former work of Risitano et.…”

“…The change in temperature, commonly used in the PHYBALLSV related experiments [18] and the SteBLife-method [19,20], which is calculated by the formula = 1 − ( 2 + 3 )/2, are further corrected by subtracting the very first value from every test, in order to make sure, that all the tests start with = 0. [18,19] When not only taking the change in temperature into account, but also considering thermodynamics, it is meaningful to calculate the area of the region enclosing the -curve, which represents the dissipated energy during the fatigue process [17,29].…”

“…The fatigue tests were performed until failure or to a maximum number of cycles = 2 · 10 6 . During the tests, temperature measurement areas on the specimen are defined with the same method as described in [18][19][20] …”

“…Since Reifsnider and Williams applied an IR-camera in this field for the first time [7], there is an increasing number of publications dealing with similar methods [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Among these different activities having been published, the parameters commonly used to describe the change in temperature of defined measurement areas are [3,4,6], [5] or [12], which are given different physical meanings by different authors while the symbols being similar.…”

“…al. [2,19,20] use to represent the temperature difference calculated by the formula = 1 − ( 2 + 3 )/2, where 1 is the surface temperature in the middle of the specimen's gauge length and 2 as well as 3 are the surface temperatures of both gauge length-shaft transitions having a significant thicker diameter, where only elastic deformations appear. Ummenhofer [11] derives a non-linear temperature amplitude with NUC (non-uniformity-correction)-method.…”