| Minimizing weight is a primary objective in every system design in the aerospace and automotive industry. Therefore, the use of composite materials has become an integral part of the design of mechanical components. However, in composite structure design, their complexity normally makes it impossible to design them as a single part. This leads to the necessity of using joints. Sadly, these joints introduce discontinuities in the stress distribution within the components and are often the sites of stress concentration. Therefore, they may limit the performance of a structure, in addition to increasing the overall mass significantly due to the use of mechanical fasteners such as bolts and rivets. This is why bonded joints are increasingly popular. They are much lighter than bolted or riveted joints and are often more rigid. Unfortunately, it is very difficult to inspect a bonded joint for defects since the presence of cracks in the adhesive cannot be observed with the naked eye.;The main objective of this work is to propose a new design methodology for hybrid joints. To accomplish this, it is necessary to establish reliable analysis tools to improve our understanding of the behavior of these joints when subjected to an external force. A better understanding of the interactions between the parameters is also required.;To improve our knowledge on the subject, a literature review was conducted. This review was structured as to emphasize on the behavior of hybrid single lap joints when subjected to an external force in tension. Following this literature review, an analysis of the stress distribution within the joint was carried out using a finite element model. The model and the results were compared with those from two papers in order to validate the quality of representation. Subsequently, a modification was made to an existing analytical model in order to add the bolts' preload as a parameter. These two models, namely the finite element model and the analytical model, were then used for a sensitivity study using a design of experiments. To perform this analysis, a kriging model was used to reduce the computing time. Finally, the hybrid single lap joint was analyzed using axiomatic design in order to propose new approach to design these joints.;The results of this work can be divided into three parts. First, an analytical model identified in the literature review has been improved to take into account the bolts' preload. The results are satisfactory within the limitations of the original model. It must be pointed out that this model does not consider the non-linear behavior of materials used in the joint, which can lead to poor reliability when highly non-linear materials are used. The sensitivity analysis carried out using the analytical model and the finite element model identified the influence of the parameters on the mechanical performances of the joint. It should be noted that the width of the joint is one of the most important parameter, as well as the thickness of the adherents. The sensitivity analysis also identified the notable effect of the radial clearance of the bolt shank. This parameter should be minimized in order to maximize performances. Finally, the geometry obtained with the axiomatic design and through physical integration reduced the maximum peel stress considerably. The use of washers based on Belleville springs allowed to significantly increase the area affected by the bolts' preload. Therefore, this final geometry should significantly increase the maximum external load that can be supported by the joint and increase its fatigue life.;Finally, an improved geometry was proposed using the theory of axiomatic design. The use of chamfers at the ends of the adherents, the addition of modified washers and the use of a stiffer adhesive between the two bolts have significantly reduced the maximum peel stress in the adhesive layer. These changes have also increased the rigidity of the joint. However, analyzes have not demonstrated a decrease in the maximum shear stress inside the adhesive. Therefore, further work should be considered to assess the effect of some parameters of the improved joint on the distribution of shear stress in the adhesive layer. Among the parameters to consider, the ratio between the surfaces bonded by each of the two adhesives and the dimensions of the chamfers and the modified washers should be analyzed. (Abstract shortened by UMI.). |
