## 3 Results  
Simulations and various types of analyses are currently part of modern Cax systems. The importance of 3D models is primarily confirmed during the pre-production stage of concept creation or experimental testing, where various production options and methods can be verified on individual 3D parts or the entire virtual assembly. Based on the visualization of the proposed procedures, the weak points can be relatively quickly evaluated and subsequently eliminated without the need for significant interventions. Cost savings can be achieved through the use of 3D models in these stages of the production process. The finite element method (FEM) will be used to simulate the development of stresses caused by thermal expansion of the combustion chamber shell. In practice, the FEM method is frequently used to simulate stress curves, heat flow, fluids, and deformations of the selected construction component or created set of parts. The main idea is to use finite nodal points to replace the continuous volume of the model. Individual node points represent the detected parameters of the component. The mentioned method can be used to determine the critical zones of the component or to check the designed parts. Thermal analysis deals with the effect of heat flows and thermal fields on the mechanical properties of selected structural elements. One of the main aspects of the calculation is dilation and thermal stress, either at the level of the selected part or the entire assembly. It is imperative to note that the computation of steady heat flow or transient heat flow accompanied by time-varying boundary conditions is of utmost significance in various domains. These analyses are particularly useful in instances where internal stresses and deformations arise in the casting or mold. The analysis of the selected structural element was performed utilizing the CAx HyperMesh 10 system. Based on the creation of a 3D model of the combustion chamber shell in the Rapidform XOR environment, the geometry of the entire batch can be continuously transferred to the HyperMesh working environment (Figure 6). It is also possible to use other simulation systems to evaluate the designed structural element due to the possibility of exporting the entire batch to *IGS and *STP formats. Before the actual transformation of the selected CAD model, it is advisable to modify this model to simplify tasks, shorten the length of the solution, etc. The methods of simplifying the CAD model include the suppression of geometry elements, geometry cleaning, and geometry idealization. Figure 6: Simplification of the combustion chamber 3D model. The mesh of the selected group is generated by subdividing it into a finite number of small elements. The finer the subdivision, the more detailed the description of the actual structural component. When a mesh is established on the investigated part, the process involves the generation of nodes and elements. This operation is carried out through systems known as mesh generators. In contemporary FEM software, the creation of a mesh on the construction part can be automated. The advantage of automatic mesh creation lies in being liberated from the arduous task of manually adapting the mesh to the part's geometry. However, the drawback of employing this tool is the absence of direct control over the mesh creation process in the area of interest. This also encompasses the method of free meshing. The utilization of this mesh generation method is applicable to geometrically irregular shapes. The generation of a mesh through this method is straightforward and expeditious, albeit the ensuing calculations entail a considerable amount of time, given the creation of a substantial number of elements. Another method is denoted as mapped meshing. In terms of computational efficiency, this method proves to be faster due to the reduced number of elements on the structural component, but this method is incapable of generating meshes on geometrically irregular shapes.