## 3 Results  
### FEM Analysis Results  
The finite element method simulates a physical part or assembly's behavior by dividing the geometry of the part into a number of elements of standard shapes, applying loads and constrains, then calculating variables of interest [37; 38; 39; 40]. Numerical methods, such as the finite element method, have been applied in various researches in order of achieving such a spring design that eliminates the limitations of the theoretical and experimental methods in the calculation and measurement of the maximum stress in the different sections of the spring [41]. Springs IICAD modules support the FEM analysis. With the purposely made buttons, the user can easily access FEM analysis files of the computed/ designed spring. Boundary conditions of the compression spring FEM models are predefined in the CATIA software, with a clamp applied on the bottom surface of the spring and user defined restrain which simulates only the vertical spring movement. This way, the spring housing is simulated. For the torsion spring, similarly, one of the free ends is clamped, while the other end is loaded with the distributive force. The parametric approach of 3D modeling was interlinked with the Springs IICAD system, so with an input of any geometric parameter, material property and force, changes are made in the specific files. When input parameters are set in the Springs IICAD system and the calculation button is activated, spring geometry is updated in the 3D model file, based on the input of geometric parameters. An FEM analysis file follows these geometric updates and includes a specified load and material property defined in the Spring IICAD system. This way, a spring FEM model is processed where it originates from its initial state, and under specified force, geometry and mechanical properties, a load state occurs followed with the stress and deflection images. Meshing is performed via a uniform grid with the parabolic tetrahedron finite elements (TE10) since they are more accommodating for the curved surfaces. The mesh size and absolute sag, for both types of springs, amount to 0.2 mm and 0.1 mm, respectively. The number of finite elements and nodes used for discretization of a spring model depends on the spring parameters, since the parametric approach can result in many design solutions. Table 2 shows the number of finite elements and nodes generated for specific spring design, with the following sizes for the compression spring: number of revolutions--10, pitch--4 mm, mean coil diameter--20 mm, wire diameter--2 mm; and for the torsion spring: number of revolutions--25, pitch--2 mm, mean coil diameter--28 mm, wire diameter--1.8 mm, and length of free ends--50 mm. Figure 7 shows the Von Mises stress distribution and displacement for the specific set of parameters of a compression spring. Maximum Von Mises stress according to colormap shown in Figure 7 is located at the \"crossing zone\" between the plain end and the first coil of the spring. This stress spike is caused with the stress concentration. However, maximum working stresses occur on the inner side of the spring coil, which is a result of the uneven stress distribution due to a wire twist. The maximum deflection of a compression spring is located at the top coil, i.e., the load zone of the spring. Figure 8 shows the Von Mises stress distribution and displacement for the specific set of parameters of a torsion spring. Maximum Von Mises stress is located at the fixed end of the torsion spring. This stress is also caused with the stress concentration. Maximum working stresses occur in a different location of a spring wire due to complex stress conditions, i.e., the simultaneous effect of the bending moment and the spring wind. Maximum deflection is located at the loaded end of the spring. Alongside the fast manipulation of geometric parameters and easy insight into stress and deflection conditions, the significance of FEM analysis is best reflected in the