Identification of the scatter in high cycle fatigue from temperature measurements

Abstract

It is proposed to determine the scatter in a Wöhler diagram by analyzing temperature changes induced by microplasticity. A unified framework is introduced to study both phenomena. The identification procedure is applied to a dual-phase steel. c 2001 Académie des sciences/Éditions scientifiques et médicales Elsevier SAS Fatigue/ Microplasticity/ Poisson point process/ Weibull model Identification de la dispersion des limites d'enduranceà l'aide d'un essai d'échauffement Résumé.

Fast screening of the fatigue properties of thermoplastics reinforced with short carbon fibers based on thermal measurements

“…Since the pioneer studies [12,13], this technique has become of considerable interest over the last few years, on metallic materials for empirical approaches [14][15][16][17] or throughout constitutive modeling [18][19][20]. This is explained mainly by the considerable development of thermography devices and analysis [16,21,22].…”

“…A more interesting objective is to predict the fatigue mean curve. This approach relies on the use of an energy based fatigue criterion and could be determined either empirically [23,25,29], with the help of a constitutive model [18,30], or using additional microstructural measurements [31,32]. In all cases, it is necessary to check if the method can be applied, because a main difference of this approach compared to classic fatigue test is that it relates the response over a few initial cycles to the fatigue failure occurring after several days or weeks of testing.…”

“…An even more desirable objective is to predict the full fatigue curve including the fatigue scattering from the heat build-up curve. This has been proven to be possible on several metallic materials [18][19][20], by relating the dissipative energy to the damage mechanisms throughout a constitutive modeling including a probabilistic failure criterion. This last approach is clearly the most appealing but it faces several difficulties for short fibers reinforced composites.…”

Determination of an HCF criterion by thermal measurements under biaxial cyclic loading

“…Because fatigue data are usually scattered, classic identification techniques of fatigue properties (e.g., by using the staircase test [1]) are difficult and require the use of use many specimens. This is even more difficult if one wants to study HCF fatigue of materials under multiaxial Several authors have worked on a rapid estimation of the mean fatigue limit [2][3][4][5][6][7][8]. It is based upon temperature measurements of the studied specimen under mechanical cyclic loadings.…”

“…The results of so-called "heating tests" (i.e., thermal effects associated with cyclic loading) by plotting the change of the mean steady-state temperature with the stress amplitude applied to the specimen. A correlation is obtained between the fatigue limit of some materials and the stress level beyond which an increase in the specimen temperature can be observed by using thermocouples [7,8] or infrared (IR) cameras [2][3][4][5][6].…”