Table 1 Stress distribution of each group under 500 N load (Gpa)

1

0.29 (0.10)

0.29 (0.13)

0.945

2

0.66 (0.07)

0.67 (0.05)

0.793

3

0.70 (0.11)

0.66 (0.16)

0.606

4

1.26 (0.31)

1.28 (0.16)

0.906

5

2.00 (0.24)

1.92 (0.23)

0.535

6

1.24 (0.37)

1.22 (0.19)

0.915

7

1.41 (0.34)

1.41 (0.24)

0.972

8

2.80 (0.27)

2.76 (0.52)

0.874

9

0.63 (0.04)

0.62 (0.05)

0.721

10

0.6 (0.04)

0.55 (0.07)

0.136

11

2.12 (0.34)

2.00 (0.38)

0.541

12

2.20 (0.23)

2.14 (0.35)

0.722

13

4.83 (0.64)

4.74 (0.35)

0.764

14

4.57 (0.54)

4.63 (0.47)

0.835

15

5.79 (0.57)

5.89 (0.51)

0.716

16

5.88 (0.42)

6.08 (0.65)

0.502