Nouveau modele adimensionnel pour l'etude des assemblages boulonnes precontraints soumis a un chargement externe

Bolted joints have been widely used in various domains of the industry for many years. A great advantage of this type of fasteners consists in the ability to easily assemble and disassemble them, resulting in a faster maintenance operation. The application of an external force induces a force supplement in the bolt at which a moment supplement can be added in the case of an eccentric loading. Therefore, these supplements seen by the bolt will influence the bolt fatigue life. In spite of the simplicity of the parts in a preloaded bolted assembly, these supplements are much more complex to evaluate than it seems. The actual analytical models are not infallible when it comes to evaluate the force and moment supplements in the bolt, which results in an uncertain bolt fatigue life prediction. This shows that the actual models can still be improved.;This definition of bolted assemblies eliminates the influence that some parameters would have had on the response behaviour. Therefore, it is not necessary to define the bolt nominal diameter, the preload and the materials of the bolt and the parts to predict the dimensionless response behaviour of preloaded bolted joints submitted to an external loading. Indeed, it is the ratios between the dimensions and the bolt nominal diameter, the ratios between the forces and the preload and the ratio between the modulus of elasticity of the bolt and the parts that are the most important.;The independence of the dimensionless response behaviour over the preload has been proven with experimental results from Massol's [1] and Bahkiet's [2] work. The results from analytical and numerical models have been compared with the experimental results to show that the two models adequately represent the reality.;An example of application of the new approach demonstrates which advantages it brings up, i.e. a significant diminution of the number of analyses or experiments needed to predict the force and the moment supplements in the bolt. This will reduce the time spent on the search of the optimal combination of the geometric parameters of a bolted joint for a given design objective.;In order to regroup assemblies which have similar response behaviours, their geometry definition with their related parameters first need to be established. Thus, the dimensions of an assembly have been expressed in terms of its bolt nominal diameter instead of discrete dimensions. Then, the assembly proportions have a greater importance than its dimensions. Similarly, instead of plotting the supplements with respect to the external forces, the new dimensionless parameters have been favoured. This means that it is the force supplement to preload ratio (DeltaFb/Q) and the moment supplement to bolt nominal diameter times preload ratio (DeltaMb/(d nomQ)) that have been plotted with respect to the external force to preload ratio (Fe/Q).;The new dimensionless parameters from this new approach have been implemented in the actual analytical models, from which a new one has been proposed. This new model better evaluates the position of the equivalent contact force than the actual models while keeping an adequate evaluation of the force and moment supplements.