PSI - Issue 5

Chmelko Vladimír et al. / Procedia Structural Integrity 5 (2017) 825–831 Chmelko, V., Margetin, M./ Structural Integrity Procedia 00 (2017) 000 – 000

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these methods compared to the experimental results are reported by the authors for the area of deformations about 2%. The conservative results give the transformation hyperbole according the equation (3), as it leads to higher values of stresses and strains in the root of the notch, which in the subsequent calculations shortens the fatigue life. The differences of these transformation hyperboles grow with the increasing of the deformation magnitude. The open question remains, the deformation characteristic of material intersection determination with transformation hyperbole constructed for corresponding notch. For the time-varying loading, we cannot use neither the tensile curve of material, nor in case of the random character of loading process the Cyclic deflection curve, even nor in case of its modification in the form of the operational Cyclic deflection curve by Polák (1988).

Fig. 2. Comparison of transformation expressions Crews-Hardrath and Neuber for three chosen amplitude of nominal stress When observing the hysteresis loops during a random load process, it can be seen that the curvature of the loops in the non-linear region is not a constant (Fig. 3).

Fig. 3. The shape of tensile chosen parts of hysteresis curves for mentioned sequence of loading amplitudes