## 5 Conclusions  
The aim of this study was to assess the effect of antenna mounting on the occurrence of excessive deformations of a car roof. The methodology was designed based on data from the manufacturer, who used a Leica 3D scanning device to measure shape and geometry. A real roof model was used for numerical modelling. To validate the results of numerical modelling as well as the manufacturer's data, a tensometric measurement was performed on a painted and unpainted roof under operational load--antenna installation. Based on the analysis of the achieved results of numerical modelling and experimental measurements (3D scanning, tensometry), it was found that:  
Figure 16: The field of reduced stresses according to von Mises method in a selected roof part at unit loading (MPa). Figure 15: The field of resulting displacements in a selected roof part at unit loading (mm). * numerical modelling confirmed theoretical assumptions of the distribution of stress and strain fields,
* total displacements determined by 3D scanning after unmounting the antenna on the painted roof were higher in most of the examined places and the differences almost reached 18%,
* different values of deformations/stresses on the right and the left side of the roof determined by strain gauge measurements are directly related to the already deformed shape of the sheet,
* excessive deformation did not occur due to the antenna mounting as originally assumed,
* the antenna was mounted on a 0.8-mm thick roof plate, most likely already deformed due to previous technological operations (pressing, cutting out the mounting hole, painting). The mentioned methodology is also applicable for deformation-stress analysis in other stages of component production (in this case sheet metal roofs), but it is a question of finance and time. The identification of suitable measuring points and the application of strain gauges can be realized in the order of days. The largest item is not only the assessed part itself, but also the implementation of the experiment under operational load. It should be not forgotten that a series of measurements must be performed to obtain relevant results. In this case, there were two painted roofs and one unpainted. The presented paper describes the procedure of comparing relative deformations and stresses (FEM--transometry) and displacements (FEM--Leica). From the above-mentioned it is clear that although FEM analysis provides a great deal of information, numerical modelling is performed on an ideal model under boundary conditions, which may not correspond exactly to real bonds. The advantage of experimental methods is the determination of physical quantities under operating load, taking into account real bonds, material defects, residual stresses; however, they often only provide information about a certain quantity depending on the method used. The presented results can be used for a better understanding or interpretation of the displacement fields measured by Leica, or for adjusting the range of permissible deviations from the computer model in order to improve final products or minimize the error rate in production. Conceptualization, M.P. ([PERSON]) and J.Z. ; Methodology, M.P. ([PERSON]) and P.L. ; Software, P.L. ; Validation, M.P. ([PERSON]), M.P. ([PERSON]), J.Z. and P.L. ; Formal analysis, M.P. ([PERSON]) and P.L. ; Investigation, M.P. ([PERSON]), M.P. ([PERSON]), J.Z. and P.L. ; Resources, M.P. ([PERSON]); Writing--original draft preparation, M.P. ([PERSON]) and P.L. ; Visualization, M.P. ([PERSON]), P.L., M.P. ([PERSON]) and I.K. ; Project administration, M.P. ([PERSON]), J.Z., M.P. ([PERSON]) and I.K. All authors have read and agreed to the published version of the manuscript. This paper was developed within the projects implementation: VEGA Nr.