Problems of equivalent load amplitude in fatigue life calculations
This paper presents issues of fatigue life calculations in operational load conditions. The assumed runs were so processed as to get a set of sinusoidal cycles by using the following methods: full cycles counting method and rainflow counting method. On the basis of such sets of cycles of the varying parameters Sm i and Sa i were prepared block load spectra of equivalent amplitudes Saz , obtained with the use of an original method of these authors, in which two-parameter fatigue characteristics were applied. The work resulted in comparison of fatigue life results for load spectra determined by using the assumed cycles counting methods and the assumed two-parameter fatigue characteristics: the model IM, model II, model III and model IV, respectively
- 1. Bendat J.S., Pierdol A.G., Methods of analysis and measurement of random signals (in Polish), PWN, Warszawa, 1976.
- 2. Kocańda S., Szala J., Fundamentals of fatigue calculations (in Polish), PWN, Warszawa, 1997.
- 3. Norma ASTM, Standard practices for cycle counting in fatigue analysis, ASTM Designation: E 1049-85 (Reapproved 1990).
- 4. Ligaj B., Szala G., Experimental verification of twoparametric models of fatigue characteristics by using the tests of S355J0 steel as an example, Polish Maritime Research, No.1 (2010), pp. 39-50.
- 5. Szala J., Loads and fatigue life of machine elements (in Polish), University of Technology and Agriculture, Bydgoszcz 1989.
- 6. Szala G., Ligaj B., Description of cyclic properties of steel in variability conditions of mean values and amplitudes of loading cycles, Materials Science Forum, Fatigue Failure and Fracture Mechanics, Vol. 726, 2012, pp. 69-76.
- 7. Szala G., Theoretical and experimental analysis of twoparametric fatigue life characteristics of structural steels (in Polish), 1st part of the monograph titled: Twoparametric fatigue life characteristics of structural steels and their experimental verification, Publishing House of Operation Technology Institute , State Research Institute, Radom, 2011.
- 8. Szala G., Comments on linear summation hypothesis of fatigue failures, Polish Maritime Research, No.3 (2014), pp. 77-85.