Multiaxial vibration fatigue—A theoretical and experimental comparison

Vibration fatigue using modal decomposition

The paper presents the procedure of estimation of fatigue life in the high-cycle fatigue regime under a multiaxial random loading using the spectral method. The procedure consists of application of the power spectral density function of the equivalent stress in the fatigue life assessment together with the known spectral method developed for the uniaxial stress state. The model proposed by Miles and Dirlik was presented as an example. Two groups of multiaxial fatigue failure criteria have been distinguished: the criteria based on the critical plane approach and the criteria using invariants of the stress state. Two sets of experimental data were used in order to compare the calculated and experimental fatigue lives. It has been shown that under the multiaxial random loading the results of fatigue life calculated according to the considered method are well correlated with the results of experiments if the multiaxial fatigue failure criterion is properly selected for mechanical parameters of the tested material.

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Comparison of some selected multiaxial fatigue failure criteria dedicated for spectral method

Some analytical expressions to measure the accuracy of the “equivalent von Mises stress” in vibration multiaxial fatigue

A review of past and recent developments in multiaxial excitation of linear and nonlinear structures is presented. The objective is to review some of the basic approaches used in the analytical and experimental methods for kinematic and dynamic analysis of flexible mechanical systems, and to identify future directions in this research area. In addition, comparison between uniaxial and multiaxial excitations and their impact on a structure’s life-cycles is provided. The importance of understanding failure mechanisms in complex structures has led to the development of a vast range of theoretical, numerical, and experimental techniques to address complex dynamical effects. Therefore, it is imperative to identify the failure mechanisms of structures through experimental and virtual failure assessment based on correctly identified dynamic loads. For that reason, techniques for mapping the dynamic loads to fatigue were provided. Future research areas in structural dynamics due to multiaxial excitation are identified as (i) effect of dynamic couplings, (ii) modal interaction, (iii) modal identification and experimental methods for flexible structures, and (iv) computational models for large deformation in response to multiaxial excitation.

/pdf/review-of-response-and-damage-of-linear-and-nonlinear-1ryp1m6xq6.pdf

Review of Response and Damage of Linear and Nonlinear Systems under Multiaxial Vibration

Determining the von Mises stress power spectral density for frequency domain fatigue analysis including out-of-phase stress components

A simulation method is presented for the fatigue analysis of automotive and other products that are subjected to multiple random excitations. The method is denoted as frequency domain stress-life fatigue analysis and was implemented in the automotive industry at DAF Trucks N.V. in Eindhoven, The Netherlands. As an example case, a chassis part is analysed. The results of the analysis are consistent with fatigue cracks encountered during testing, which illustrates the effectiveness of the adopted method in the automotive industry.

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R. Liebregts

Papers

Determining the von Mises stress power spectral density for frequency domain fatigue analysis including out-of-phase stress components

Prediction of mechanical fatigue caused by multiple random excitations