Evaluation of SCS
Evaluation Method
We evaluated the stiffness of the SCS by conducting a three-point bending test. Figure 8a presents a schematic of the test. We used a tension and compression testing machine (Shimadzu, AG-50kNX) to conduct the test for both ends supported with a concentrated load. The test conditions were as follows: the displacement speed was set at 5.00 mm/min, the load was applied until the stroke reached 30 mm, and the data were recorded with a sampling period of one point per second. Twelve types of SCSs with n = 4, 6, 8, and 10 and L = 5 mm, 10 mm, and 15 mm were tested. A load bar was attached to the testing machine, such that the load could be applied only to the center of the SCS (Figure 8a(i)). A wooden board was placed, such that the distance between fulcrums was 280 mm, and the SCS was fixed by pins inserted into the valley folds (Figure 8a(ii)). Figure 8a(iii) presents a photograph of the actual test. The valley fold was not formed at one end of the SCS (Figure 8a(iv)). Figure 9 presents a movie of the actual test.
Figure 8a(v) presents the beams in a three-point bending test of both ends supported with a concentrated load. The relationship between the load P and deflection δ is expressed as the following equation: