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Abstract: Largely used as main material in railway riveted bridges during the second half of the nineteenth century, the puddled iron characterizes for having an anisotropic behaviour due to the large amount of non metallic inclusions that it posses. Its mechanical characterization is thus difficult. Since these ancient structures have supported variable cyclic loadings at least for a century, the determination of the puddled iron's fatigue properties becomes crucial to their maintenance. The self-heating method is proposed in this paper to accomplish this task. The obtained experimental self-heating curves show dispersion non observed in homogeneous materials, this phenomenon is explained by the lack of determination of the representative elementary volume of the puddled iron. However, this data gives us important information such as the minimum and maximum boundaries of the mean fatigue limit for several orientations. A two-scale probabilistic model for high cycle fatigue is also used to represent the dispersion on the experimental data by using Weibull's distribution law to describe several characteristics of each site where the microplasticity occurs. The influence of such parameters and the limitations of the model are also studied. [Copyright &y& Elsevier]

This paper is focused on variable amplitude loading spectra applied in the automotive industry, more specifically for the chassis system parts with respect to high cycle fatigue design. A first analytical model referred to as Heuler's model is considered. It is of the simplest use, with one parameter to be identified. A whole identification process, based on road measurement realized on carmaker's proving ground with instrumented vehicles, is developed and discussed. Once the model is identified, the cycles influence on damage production is also investigated. In the light of the obtained results with this model, a second one, noted modified Heuler's model, is introduced and investigated. This model, similar to the first, requires the identification of two parameters. Once again, the whole model identification process is applied, and the lifetime accuracy is assessed. A new tool is presented, enabling the visualisation on the loading spectrum representation of the most and less damaging cycles. Hence, a methodology is set to legitimize a gate implementation when studying a variable amplitude loading spectrum. [ABSTRACT FROM AUTHOR]