Table 1. Impact treatments in this study

Impact height (m)	The number of impacts	Impact location	Impact energy (J)
Increasing impact height
0.25	1	-	0.86
0.5	1	-	1.72
0.75	1	-	2.57
Increasing the number of impacts and different impact locations
0.25	4	Same location	3.43
		Different locations	3.43