# Quality Analysis of Bonded Joints in the Renovation of Plastic Automotive Parts
## 1 Introduction
The evaluation of the mechanical properties of plastics is becoming more and more widespread also for polymers, whose macromolecular properties change due to radiation crosslinking. In his research, the author dealt with the influence of radiation dose on the mechanical properties of material properties, specifically, PP filled with a 15% mineral filler [10]. Nowadays, when several types of adhesives can be used for different purposes, it is necessary to specify and clarify their relevance for a particular purpose. One of the areas is the ability to select the appropriate type of adhesive and understand its impact on the mechanical properties of parts that may be used in automotive renovation. Just these findings of which type of adhesive is suitable for which purpose provides us with the ability to not only properly understand the importance of the adhesive for the area, but also its properties in terms of the strength achieved or resistance with respect to the environment to which they are exposed. Thanks to this line of knowledge, it is possible to determine which type of adhesive is suitable for which purpose. \begin{table}
\begin{tabular}{l l} \hline \hline \multicolumn{1}{c}{**Advantages of Bonded Joints**} & \multicolumn{1}{c}{**Disadvantages of Bonded Joints**} \\ \hline Weight reduction, joint tightness. & Full strength is achieved only after curing. \\ Different materials can be bonded together. & Low resistance to increased temperature. \\ Smooth exterior surfaces. & Requirement of surface treatment before bonding. \\ Possibility of joining large areas. & Curing agents are required. \\ Bond is permanent, making the bond more consistent & Long curing times. \\ with stress distribution across the bonded surface. & High requirements for flatness and surface finish of the surface \\ Possibility to bond very thin materials. & of the bonded parts. \\ Most adhesives have good mechanical & Load possibility of the bonded joint only after a defined period \\ absorption properties (noise reduction, vibration reduction). & of time. \\ High bond strength, especially at & \\ shear and impact strength. & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The advantages and disadvantages of bonded joints. Currently, we are confronted with a shortage of standardized procedures that characterize adhesive joints. For this technology, we need to think about the standardization of testing protocols, advanced numerical techniques, and adhesives designed for specific special applications, as well as the integration of non-destructive evaluation techniques [11]. The characterization of the flexural strength for similar and dissimilar carbon-fibre-reinforced polymer/aluminium single-lap adhesive joints used for the automotive industry was investigated by [PERSON] [12], who focused his work on three-point experiments on the flexural strength and failure mechanisms of dissimilar single lap joints. The individual bonded joints were made from carbon-fibre-reinforced polymer (CFRP) and aluminium substrates bonded with Araldite 2015 adhesive. The results show that the CFRP/CFRP one-piece bonded joint shows a much higher bond strength when compared to the aluminium/aluminium one-piece bonded joint at three-point bending. Another author, who analysed strength in bolted and bolted-bonded joints, single lap joints, and metal/composite plates used in the automotive industry was [PERSON] [13], where he used acrylic glue (Acrytron 1E1, Pulsar Chemistry, Ankara, Turkey) for the experiment. As a result of the tensile test, it was found that the highest maximum tensile stresses occurred in the AZ91-CF bolted specimens. No delamination effect or plastic deformation was observed on the bonded surfaces in the tensile specimens in all groups. Similarly, author [PERSON] [14], in his research, dealt with a method of joining high-strength steel plates with local preheating using clinching technology, which is often used for joining materials of different grades and thicknesses in the automotive industry.