# Quality Analysis of Bonded Joints in the Renovation of Plastic Automotive Parts
## 1 Introduction
Also, the effect of the applied adhesion thickness did not have a significant variation on the bond strength for the CFRP/HS materials, and similarly, increasing the adhesion thickness to CFRP (i.e., from 1.2 mm to 2.1 mm) did not support a significant increase in the bond strength. The use of adhesives on aluminium joints for the automotive industry was investigated by author [PERSON] [21], who examined in more detail the influence of water, corrosive ions, and external stresses on the properties of adhesively bonded joining structures. In her research, she clarified the presence of ionic modes that, together with a high moisture content, can lead to substrate corrosion, with adhesive joints being particularly sensitive to filament corrosion. As a result of the study, the presence of dynamic or static stresses was accelerated by the action of water or corrosive ions. The fatigue strength using epoxy adhesive for PMMA material in combination with aluminium joints was similarly investigated by [PERSON] et al. [22]. They found that bonded joints on a PMMA-aluminium material combination were more sensitive to temperature compared to PMMA-PMMA joints, and for both types, the applied stress had a higher effect than the frequency. Authors [PERSON] and [PERSON] [23] discussed non-conventional ways of joining composites and metals in the context of reducing the weight of car bodies. In their research, they used epoxy-based adhesives that were applied using hand lamination technology with vacuum-assisted suction. As a result, it was found that the best-bonded joint was achieved with the composite-galvanized sheet combination, where the highest values of shear stress--18.69676 MPa and maximum force--5842 N for grooved processed samples were achieved. Author [PERSON] [24] applied the bonding technology to ductile aluminium alloys, where he investigated the mechanical behaviour of the joints under impact loading, focusing on the thickness of the adhesive layer. The results were that higher joint strength can be achieved under an impact loading compared to static conditions and that relatively thin adhesive layers are advantageous compared to thick layers, which also exhibit higher failure loads. The best results in impact were obtained using an adhesive layer with a thickness of 0.2 mm. The evaluation of the bonded joint using aluminium alloy materials (AA5083 H11, Aalco Metals Limited, Wednesbury, England) with two-phase HSS steel (DP780) used in the automotive industry was addressed by the author [PERSON] [25] who analysed the tensile strength of similar and dissimilar joints. He also discussed the lap length of the joints and the thickness of the adhesion layer. As a result, it was found that for DP steel, a 22% higher strength was obtained when the overlap length was increased from 10 mm to 15 mm, but there was a 20% increase in strength when the change from 45 mm to 15 mm was made. Similar results were obtained for Al alloy, where a 26% higher strength was obtained for the overlap length from 10 mm to 15 mm, however, when the change from 42 mm to 15 mm an increase of 25% was obtained, and when the length was varied from 35 mm to 20 mm, about a 25% strength was obtained. The study of adhesive joints and their applications in hybrid composite structures was addressed by [PERSON] [26] who focused his research on surface treatment, joint configuration, material properties, as well as geometric parameters that affect the properties of bonded joints. The choice of these materials was related to their application in automotive manufacturing. Environmental factors, such as humidity and temperature prior to the formation of the bonded joint and the method of adhesive application, were also addressed.