不耦合装药刻痕爆破裂纹的动态力学特征及损伤分形规律实验

doi:10.12382/bgxb.2022.1270

摘要/Abstract

摘要：

为探究不耦合装药刻痕爆破裂纹的动态力学特征和损伤规律,采用动态焦散线实验技术研究不耦合系数R_d为1.00、1.33、1.67和2.00时聚甲基丙烯酸甲酯(PMMA)的爆炸裂纹扩展的动态力学特征,结合分形维数理论计算爆后损伤变量和分形维数。研究结果表明:R_d<1.67时,炮孔周围分区的损伤变量都较大,且在炮孔非刻痕方向形成了较多次生裂纹;R_d=1.67时,炮孔左、右裂纹的动态力学行为相似,爆后损伤变量和分形维数最小;随着R_d的增大,爆炸主裂纹长度减小,主裂纹扩展的速度、应力强度因子和动态能量释放率减小,但裂纹扩展时间增加,爆生气体的准静态作用延长,爆生气体作用对裂纹的再次激活、起裂、扩展和止裂的动态力学行为影响,在一定程度上实现了动、静作用分离的量化分析;自由边界条件下PMMA不耦合装药刻痕爆破的损伤变量ω与分形维数D关系为ω=0.00175D^9.04。

关键词: 不耦合装药, 刻痕爆破, 动态焦散线, 损伤变量, 分形维数

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

中图分类号:

TD235

马军, 汪旭光, 李祥龙, 王建国. 不耦合装药刻痕爆破裂纹的动态力学特征及损伤分形规律实验[J]. 兵工学报, 2023, 44(12): 3676-3686.

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.

图/表 18

图1 刻痕爆破示意图

Fig.1 Schema ticdiagram of cratch blasting

表1 PMMA材料动态力学参数

Table 1 Dynamic mechanical parameters of PMMA materials

E_d/GPa	C_p/(m·s^-1)	C_s/(m·s^-1)	υ_d	C_t/(m²·N^-1)
6.1	2.32×10³	1.26×10³	0.32	0.88×10^-10

表2 叠氮化铅爆炸性能参数

Table 2 Explosion performance parameters of lead azide

密度/ (g·cm^-3)	爆容/ (L·kg^-1)	爆热/ (kJ·kg^-1)	爆温/℃	爆速/ (m·s^-1)
1.29	308	1524	3050	5644

表3 实验方案

Table 3 Experimental scheme

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

图2 动态焦散线试验系统

Fig.2 Dynamic caustics test system

图3 爆后试件照片

Fig.3 Post-blast specimen photos

表4 爆后裂纹扩展长度

Table 4 Crack propagation length after blasting

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

图4 Rd=1.67时裂纹尖端焦散斑系列图像

Fig.4 Series images of crack tip caustic speckle for Rd=1.67

图5 Rd=2.00时裂纹尖端焦散斑系列图像

Fig.5 Crack tip caustic speckle series images when Rd=2.00

图6 裂纹尖端位移曲线

Fig.6 Displacement curves of crack tips

图7 裂纹尖端扩展速度曲线

Fig.7 Expansion speed curves of crack tips

图8 裂纹尖端动态应力强度因子曲线

Fig.8 Dynamic stress intensity factor curveof crack tips

图9 裂纹尖端动态能量释放率曲线

Fig.9 Dynamic energy release rate curves of crack tips

图10 损伤分区

Fig.10 Damage partitions

表5 各分区损伤变量

Table 5 Damage variables of partition

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

图11 整体损伤分形维数

Fig.11 Overall damage fractal dimension

图12 Rd=1.00和Rd=1.67分区分形维数

Fig.12 Partition fractal dimensions for Rd=1.00 and 1.67

图13 损伤变量与分形维数关系

Fig.13 Relationship between damage variable and fractal dimension

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