PSI - Issue 56

Vasilica Ioana Cimpoies et al. / Procedia Structural Integrity 56 (2024) 49–57 Author name / Structural Integrity Procedia 00 (2019) 000–000

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elements during experimental testing. The full-field in-plane displacements inside each sample have been obtained by quantitatively correlating the chosen set of points on each node, given by the group of pixels. The deformations have been identified by the software, in the next scenes, trough the displacement path of the pixels and reporting back the extent of deformation between each frame and the reference (Hursa, 2009), (Vanlanduit, 2009). The measured displacement of the pixels have been compared with the displacement of nodes from FEM simulations as shown in the Fig. 13.

Fig. 13. Displacements vectors of specific points obtained by DIC

Fig. 14. FEM results of a cell, highlighting the node’s displacement

3. Results In Table 1, a comparison between the compressive experimental testing and numerical analysis for all three models subjected to a load of 150 N is presented. The choice of a consistent load across all models allows for a comprehensive overview of their stiffness characteristics. Consequently, we were able to understand the changes in stiffness given by an increase in the number of cells. As illustrated in the graph (Fig. 15) is clear that having a greater number of cells in both directions results in a substantial reduction in stiffness. For instance, in a square pattern, the stiffness decreases by approximately 60% when compared to a single cell with similar dimensions and subjected to an identical load.

Table 1. The stiffness and strain comparison resulted from experimental testing and numerical analysis.

Experimental Testing

Numerical Analysis

Strain at a load of 150 N ( Δ L/L)

Stiffness

Strain at a load of 150 N ( Δ L/L)

Stiffness

Structure Type

%

(N/mm)

%

(N/mm)

M1X1 M1X1 M3X3

4.28 3.24 4.39

60.762 46.374 31.132

4.55

75.37 49.18 29.41

4.4 2.6

Fig. 15. Comparison of stiffness between the three structures