*3.3. Global Buckling Analysis*

In this section, the global buckling of 3D-TCP under different conditions shown in Figure 12 is analyzed. The opposite sides of the 2D-EPM are subjected to a linear load of 1 N/mm, whereas the opposite sides of the 3D-FEM are subjected to a uniform stress of 1/0.22 = 4.5455 MPa.

**Figure 12.** Boundary and load conditions used in bucking analysis. (**a**) Case 4; (**b**) Case 5; (**c**) Case 6; and (**d**) Case 7.

Table 8 lists the first six buckling modes and loads of 3D-TCP predicted by the two models under the conditions in Case 6. The first six buckling modes predicted by 3D-FEM and 2D-EPM are consistent, and the maximum error of buckling critical load in each buckling mode is only 2%. The calculation time of 2D-EPM in buckling analysis is about 18 times faster than 3D-FEM, verifying the effectiveness of 2D-EPM in global buckling analysis of 3D-TCP.

**Table 8.** Comparison of the buckling modes and critical loads (N) between 3D-FEM and 2D-EPM under the conditions in Case 6.

**Table 8.** *Cont.*

Table 9 lists the first buckling modes and critical loads predicted by the two models under the conditions in Case 4, Case 5 and Case 7. The first buckling modes predicted by the two models are nearly identical, and the maximum error of the buckling load is only 2.69%, which verifies the accuracy of 2D-EPM in buckling analysis of 3D-TCP under different conditions.

**Case 3D-FEM 2D-EPM Max. Error** Case 4 2.40% Case 5 2.09% Case 7 2.69%

**Table 9.** Comparison of the first buckling modes and critical loads (N) of 3D-TCP in different cases predicted by two models.
