Abstract
Novel accelerated random vibration fatigue test methodology and strategy are proposed, which can generate a design of the experimental test plan significantly reducing the test time and the sample size. Based on theoretical analysis and fatigue damage model, several groups of random vibration fatigue tests were designed and conducted with the aim of investigating effects of both Gaussian and non-Gaussian random excitation on the vibration fatigue. First, stress responses at a weak point of a notched specimen structure were measured under different base random excitations. According to the measured stress responses, the structural fatigue lives corresponding to the different vibrational excitations were predicted by using the WAFO simulation technique. Second, a couple of destructive vibration fatigue tests were carried out to validate the accuracy of the WAFO fatigue life prediction method. After applying the proposed experimental and numerical simulation methods, various factors that affect the vibration fatigue life of structures were systematically studied, including root mean squares of acceleration, power spectral density, power spectral bandwidth, and kurtosis. The feasibility of WAFO for non-Gaussian vibration fatigue life prediction and the use of non-Gaussian vibration excitation for accelerated fatigue testing were experimentally verified.
Highlights
Many engineering structures usually undergo vibration loading
The objectives of this study are as follows: (1) develop a hybrid test strategy for the accelerated random vibration fatigue test, which can generate a design of the experimental test plan, significantly reduce test times and costs, and avoid complex finite element modeling and verification process and the risk of inaccuracies caused by modeling; (2) verify the feasibility of WAFO for non-Gaussian vibration fatigue life prediction; (3) experimentally and numerically investigate all the factors affecting the structure random vibration fatigue life; (4) explore the possibility of non-Gaussian vibration for accelerated fatigue testing
From the test results of Group A, though root mean square (RMS) values and bandwidths of A1, A2, and A3 are different, there is no significant difference between the test result Te and the simulation result Tp due to the same power spectral density (PSD) magnitude designated at first-order natural frequency of the structure
Summary
Many engineering structures usually undergo vibration loading. To ensure the reliability and safety of structures during the operation, we need timely validation of long-term durability of engineering structures under their service vibration environment. This is usually done by the laboratory vibration tests. Operational life under normal vibration conditions could be too long that the laboratory vibration tests at those levels would not be possible for many structures and materials. It is necessary to perform accelerated vibration testing in a laboratory environment, which in terms of loading is considerably more severe than the operative one. The operative life duration is estimated by relating the structural fatigue life tested in the laboratory condition by a proper scaling factor
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