## 4 Conclusions  
The behavior of single-lap adhesive joints used in the automotive and aerospace industry was investigated under three-point bending loading conditions. Various combinations of adherend such as aluminum/aluminum, CFRP/CFRP, and aluminum/CFRP were studied. The parameters of overlap length, adhesive thickness, and the distance between loading points were constants during the bending tests. The main conclusions are as follows:  
Figure 11: Bending moment at the edge of the overlap at the point of failure for the different adherend combinations in the single-lap adhesive joints during three-point bending.  
1. The strength of single-lap joints under three-point bending was related to the type of adherend materials, so that the materials with lower stiffness (polymeric composites) provide better joint strength compared with materials of greater stiffness (metallic materials).
2. A CFRP/CFRP single-lap adhesive joint exhibits significantly higher joint strength in comparison to an aluminum/aluminum single-lap adhesive joint under three-point bending. This distinction highlights the superior performance and load-bearing capacity of the CFRP/CFRP joint configuration, making it an advantageous choice for applications requiring robust structural integrity and durability.
3. In the context of a single-lap adhesive joint under three-point bending, it is important to note that the regions located below the neutral axis are subjected to tensile stress. Conversely, the areas situated above the neutral axis experience compressive stress. This stress distribution is a critical consideration in the analysis of joint behavior under three-point bending loading conditions, as it directly influences the structural response and integrity of the adhesive bond.
4. The strength of dissimilar CFRP/aluminum single-lap joints is usually linked to the placement of the adherends, whether they are positioned at the top or bottom of the joint structure. Notably, when the CFRP adherent is situated at the bottom, it imparts significantly greater joint strength and deformation compared to situations where the aluminum adherend is placed at the bottom. This observation underscores the critical role that adherend positioning plays in determining the overall load-bearing capacity and performance of these joints under three-point bending.
5. In addition to its superior bending strength, the CFRP/CFRP joint configuration also displayed the largest displacement at failure, surpassing the aluminum/aluminum single-lap adhesive joints by 16%.  
Conceptualization, J.B. and A.A.-S.; methodology, J.B.; software, J.B. and A.A.-S.; validation, J.B., A.A.-S. and H.S.G.; formal analysis, J.B.; investigation, J.B.; resources, J.B.; data curation, J.B.; writing--original draft preparation, J.B. and R.J.C.C.; writing--review and editing, J.B., H.S.G., A.A.-S. and L.F.M.d.S.; visualization, J.B.; supervision, H.S.G. and R.J.C.C.; project administration, H.S.G. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
Data Availability Statement: Data are contained within the article.  
The authors declare no conflict of interest.