*3.2. Numerical Analysis*

The 3D numerical model of the experiment was run in ABAQUS software [21]. In numerical estimations, the structure was built in simplified way, as was described in detail in Section 2.4 (screws as tie connections between two nodes, no holes, profiles with sharp corners, only increasing force considered). As a result, the numerical stiffness was greater than experimental stiffness and the effect of primary/secondary stiffness (which arises from, among others, hole elongation, natural spacing between assembled element—parameters not mapped in the numerical simulations) was not captured. However, other selected results—displacements in the direction perpendicular to the panel and stress

map in the direction perpendicular to the corrugation (the direction of the strain gauges SG1 and SG5)—are presented in Figure 11. The results confirmed the dominant character of profile distortion (shape of the profile deformation, stress distribution in the area of the support, opposite signs of the stresses on both sides of the sheeting). The shapes of profile deformation are compared in Figure 12. The results in the area of screw fasteners are compared in Figure 13.

**Figure 11.** Selected results of the numerical analysis: (**a**) displacements in the direction perpendicular to the panel [mm]; (**b**) stresses in the direction perpendicular to the corrugation [MPa].

**Figure 12.** The comparison of the shape of the profile deformation: (**a**) test, (**b**) numerical model.

**Figure 13.** The comparison of the results in the area of self-drilling screw: (**a**) test, (**b**) numerical model (stresses in the direction parallel to the corrugation [MPa]).
