In this paper, the Theory of Critical Distances (TCD) is reformulated to be employed to estimate random vibration fatigue lifetime of notched components. Using the Point Method argument, the response stress at the critical distance from the notch root is taken as the damage parameter and then used to perform the vibration fatigue life analysis in the presence of geometrical features. First, the finite element simulation is conducted to obtain the response Mises stress power spectrum at the critical distance under the load excitation being investigated. Subsequently, the probability density distribution of the stress amplitude at this position is calculated. Finally, fatigue lifetime is predicted via the parent material S–N curve. In order to check the accuracy of the proposed reformulation of the TCD, a series of random vibration fatigue results were generated by testing notched aluminum alloy specimens under load spectra covering the first‐, second‐, and third‐order natural frequencies. The results from the vibration fatigue tests being performed are seen to be in sound agreement with the predicted lifetimes. This strongly support the idea that the TCD is successful also in predicting random vibration fatigue lifetime of notched components.
In order to reduce the vibration fatigue test time of aeronautical engineering components made of aluminum alloy, a random vibration fatigue acceleration model under narrow-band excitation is proposed in this paper. A threeparameter S-N curve is adopted to consider the effect of small stress response, while a scale factor α is introduced to consider the effect of stress distribution. The random vibration fatigue tests of 2024-T3 and 7075-T6 aluminum alloy specimens with elliptical holes are performed, where the vibration fatigue lives of load spectra with the same bandwidth and different excitation acceleration levels are obtained. The test results show that the proposed model is in sound agreement with the test results.
In order to reduce the vibration fatigue test time of aeronautical
engineering components made of aluminum-alloy, a random vibration
fatigue acceleration model under narrow-band excitation is proposed in
this paper. A three-parameter S- N curve is adopted to
consider the effect of small stress response, while a scale factor
α is introduced to consider the effect of stress distribution.
The random vibration fatigue tests of 2024-T3 and 7075-T6 aluminum-alloy
specimens with elliptical holes are performed, where the vibration
fatigue lives of load spectra with the same bandwidth and different
excitation acceleration levels are obtained. The test results show that
the proposed model is in sound agreement with the test results.
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