Experiment on Dynamic Mechanical Characteristics and Damage Fractal Law of Crack in Decoupled Charge Scratch Blasting

doi:10.12382/bgxb.2022.1270

Abstract

Abstract:

In order to study the dynamic mechanical characteristics and damage law of crack in decoupled charge structure scratch blasting, the dynamic mechanical characteristics of PMMA explosive crack propagation with the decoupled coefficients of 1.00, 1.33, 1.67 and 2.00 are studied by appling the dynamic caustics experimental technology. The damage variable and fractal dimension after blasting are calculated by fractal dimension theory. The results show that, for R_d<1.67, the damage variables of the partitions around a blasthole are larger, and there are more secondary cracks in the non-scratched direction of the blasthole. For R_d=1.67, the dynamic mechanical behaviors of the left and right cracks on the blasthole are similar, and the damage variables and fractal dimension are the smallest. With the increase of the decoupled coefficient, the length of the main crack decreases, the propagation speed of the main crack, the stress intensity factor and the dynamic energy release rate decreases, but the crack propagation time increases and the quasi-static effect of the explosive gas is prolonged. The dynamic mechanical characteristics of reactivation, initiation, propagation and stop of crack under the action of explosive gas have realized the quantitative analysis of dynamic and static separations to a certain extent. The relationship between the damage variable and fractal dimension of PMMA decoupled charge structure scratch blasting under free boundary conditions is ω=0.00175D^9.04.

Key words: decoupled charge structure, scratch blasting, dynamic caustics, damage variable, fractal dimension

CLC Number:

TD235

MA Jun, WANG Xuguang, LI Xianglong, WANG Jianguo. Experiment on Dynamic Mechanical Characteristics and Damage Fractal Law of Crack in Decoupled Charge Scratch Blasting[J]. Acta Armamentarii, 2023, 44(12): 3676-3686.

Figures/Tables 18

References 21

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炮孔直径/mm	药卷直径/mm	不耦合系数R_d	药量/mg
6	6	1.00	60
8	6	1.33	60
10	6	1.67	60
12	6	2.00	60

炮孔直径/mm	药卷直径/mm	不耦合系数R_d	药量/mg
6	6	1.00	60
8	6	1.33	60
10	6	1.67	60
12	6	2.00	60

R_d	主裂纹长度/mm			次裂纹长度/ mm	裂纹总长度/ mm	炮孔周围裂纹数量
R_d	左侧	右侧	差值	次裂纹长度/ mm	裂纹总长度/ mm	炮孔周围裂纹数量
1.00	89.76	92.16	2.40	39.95	221.87	5
1.33	57.30	64.50	7.20	21.11	142.91	4
1.67	60.04	60.15	0.11	0	120.19	2
2.00	38.78	37.81	0.97	0	76.59	2

R_d	主裂纹长度/mm			次裂纹长度/ mm	裂纹总长度/ mm	炮孔周围裂纹数量
R_d	左侧	右侧	差值	次裂纹长度/ mm	裂纹总长度/ mm	炮孔周围裂纹数量
1.00	89.76	92.16	2.40	39.95	221.87	5
1.33	57.30	64.50	7.20	21.11	142.91	4
1.67	60.04	60.15	0.11	0	120.19	2
2.00	38.78	37.81	0.97	0	76.59	2

R_d	分区	1	2	3	4	5	6	7	8	9	10
	A	0	0	0	0	0.0026	0	0	0	0	0
1.00	B	0.0044	0.0370	0.0566	0.0586	0.2316	0.0319	0.0158	0.0135	0.0331	0.0042
	C	0	0	0	0	0.1374	0	0	0	0	0
	A	0	0	0	0	0	0	0	0	0	0
1.33	B	0	0.0141	0.0493	0.0570	0.2673	0.0445	0.0453	0.0168	0	0
	C	0	0	0	0	0.0347	0	0	0	0	0
	A	0	0	0	0	0	0	0	0	0	0
1.67	B	0	0	0.0351	0.0400	0.2058	0.0441	0.0252	0.0126	0	0
	C	0	0	0	0	0	0	0	0	0	0
	A	0	0	0	0	0	0	0	0	0	0
2.00	B	0	0	0	0.0135	0.1752	0.0672	0.0085	0	0	0
	C	0	0	0	0	0.0073	0	0	0	0	0