Damage degree

Speed 1: 2 km∙h−1

Speed 2: 3 km∙h−1

Speed 3: 4.5 km∙h−1

1—No damage

6 AB

3 B

8 A

2—Peripheral damage

16 A

19 A

17 A

3—Cracking

15 A

17 A

15 A

4—Fragmentation

13 A

11 A

10 A