Journal of Theoretical
and Applied Mechanics

51, 1, pp. 3-13, Warsaw 2013

Least squares method modification applied to the NASGRO equation

Sylwester Kłysz, Janusz Lisiecki, Andrzej Leski, Tomasz Bąkowski
The paper has been intended to present some modification of Least Squares Method (LSM) as used for describing of experimentally gained fatigue crack propagation data by means of the NASGRO equation. In particular, the specific nature of the NASGRO equation and consequent difficulties with theoretical description of test data have been shown. An algorithm has been presented of how to find coefficients of the NASGRO equation for the modified LSM criterion. Computations have been performed for the aluminum alloy 2024 taken from the rotor blades of Mi-8 helicopter.
Keywords: fatigue crack propagation; NASGRO equation; method of least squares (LSM)