Topic
Vibration fatigue
About: Vibration fatigue is a research topic. Over the lifetime, 3460 publications have been published within this topic receiving 46297 citations.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: This research develops a new topological optimization (TO) method to assess dynamic fatigue failure in the frequency domain for random excitation forces and performs an adjoint sensitivity analysis with fatigue assessment methods.
Abstract: This research develops a new topological optimization (TO) method to assess dynamic fatigue failure in the frequency domain for random excitation forces. Besides static failure, fatigue life (or fatigue failure) is an important design criterion for the safety of mechanical and building structures. Therefore, many assessment theories and computational approaches have been proposed, and they can be divided into two categories: time domain and frequency domain. Although both approaches have been successfully applied for engineering purposes, they are rarely considered in structural TO. To consider fatigue failure caused by stochastic mechanical loads in structural TO, this research adopts fatigue assessment approaches in the frequency domain, such as narrow band solution, the Wirsching and Light method, the Ortiz and Chen method, and Dirlik method. For TO, we perform an adjoint sensitivity analysis with those fatigue assessment methods. We consider some two-dimensional benchmark problems and show that the present design method successfully constrains fatigue.
19 citations
••
TL;DR: In this article, a parametric optimization of structures subjected to multiaxial high-cycle fatigue is proposed to reduce the mass of the studied structure while maintaining its fatigue durability on an established level.
19 citations
••
TL;DR: In this paper, a non-isothermal continuum damage model is identified for a widely used hot work tool steel AISI H11 (X38CrMoV5) with a nominal hardness of 47 HRc.
Abstract: High temperature operational conditions of hot work tool steels induce several thermomechanical loads. Depending on the processes, (i.e: forging, die casting or extrusion), stress, strain, strain rate and temperature levels applied on the material are nevertheless very different. Thus, lifetime prediction models need to be able to take into account a broad range of working conditions. In this paper, a non-isothermal continuum damage model is identified for a widely used hot work tool steel AISI H11 (X38CrMoV5) with a nominal hardness of 47 HRc. This investigation is based on an extensive high temperature low cycle fatigue data base performed under strain rate controlled conditions with and without dwell times in the temperature range 300 • C-600 • C. As analysis of experimental results does not reveal significant time dependent damage mechanisms, only a fatigue damage component was activated in the model formulation. After normalization, all fatigue results are defined on a master Woehler curve defined by a non-linear damage model, which allows the parameter identification. Last, a validation stage of the model is performed from thermomechanical fatigue tests. Keywords continuum damage mechanics; tempered martensitic steels; Woehler curve; fatigue life prediction; high temperature fatigue.
19 citations
01 Aug 1995
TL;DR: In this paper, an extension to the equivalent load range method is defined, where the mean level of the load cycles is taken into account, and the fatigue stress reserve factor is defined as the factor by which the prevailing fatigue stress has to be multiplied in order that the calculated fatigue lifetime equals the design lifetime.
Abstract: Fatigue is the main design driver for the calculation of the structural integrity of wind turbine components. In the JOULE II project `Load and Power Measurement Programme on Wind Turbines Operating in Complex Mountainous Regions` and in several other research projects there is a need to compare different fatigue load spectrums on a quantitative basis. A common way to compare two or more fatigue load spectrums is the use of an equivalent load range. The calculation of the equivalent load range is easy to perform. The fatigue behaviour of the material is formulated with a straight S-N curve on log-log scale. Different material behaviour may be characterised with different slopes of the S-N curve. A disadvantage of the above method is the neglecting of the mean level of a load cycle. In case of glass-polyester, glass-epoxy, cast steel, carbon epoxy, or wood laminates the mean level of the cycle effects the fatigue life. This could be avoided by calculating the fatigue stress reserve factor. This factor is defined as the factor by which the prevailing fatigue stress has to be multiplied in order that the calculated fatigue lifetime equals the design lifetime. The disadvantages of the fatigue stress reserve method are the need of detailed cross sectional data, the need of the specific fatigue formulae of the materials, the iterative calculation of the factor, and the fact that the results are not easy to generalize for other materials than considered. In this document an extension to the equivalent load range method is defined. With the extension the mean level of the load cycles is taken into account. The method is easy to apply and fully consistent with the equivalent load range method. In chapter 2 the formulae for calculating the equivalent load range are given. In chapter 3 the formulae for the equivalent load cycle method are given. An example is presented in chapter 4. Some conclusions are given in chapter 5. 2 figs., 3 tabs.
19 citations
•
TL;DR: In this paper, a mechanistic model for predicting performance of asphalt mixtures in terms of crack propagation rate, fatigue life assessment, and permanent deformation characteristics is presented, based on stress evaluation by the finite element method and on a comprehensive viscoelastoplastic material law.
Abstract: A mechanistic model for predicting performance of asphalt mixtures in terms of crack propagation rate, fatigue life assessment, and permanent deformation characteristics is presented. The model is based on stress evaluation by the finite element method and on a comprehensive viscoelastoplastic material law. A critical octahedral shear strain is assumed to be the failure criterion. A computer simulation of the resilient and residual deflections of uncracked beams as well as a fatigue crack growth simulation of an initially cracked beam are performed. These results are then compared with laboratory tests performed at various load levels with varying periods of loading and unloading. The agreement between the predicted and the measured performance of the sand-asphalt mixture in terms of residual and resilient deflection, crack length versus number of load applications, and rest period effect on fatigue life is found to be quite good. The simulation is then applied to predict rutting parameters, fatigue life curves, and crack propagation rate versus stress intensity factor for the sand-asphalt mixture.
19 citations