Mechanical Properties and Failure Criteria of DNP-based Melt-cast Explosives

doi:10.12382/bgxb.2023.0940

Abstract

Abstract:

3,4-dinitropyrazole (DNP)-based melt-cast explosive, characterized by its high energy content and enhanced safety, holds significant promise for applications in the field of energetic materials. Research into the mechanical properties and failure modes of this explosive under various stress conditions will provide essential theoretical and experimental support for its engineering applications. In this study, the quasi-static compressive mechanical properties, dynamic compressive mechanical properties, and quasi-static tensile mechanical properties of DNP-based melt-cast explosives are test using Instron 5965 universal materials testing machine and a split Hopkinson pressure bar. The influences of factors such as the content of additive (cellulose acetate butyrate) and strain rate on the mechanical properties are analyzed. The failure modes of DNP-based melt-cast explosives under quasi-static compression, dynamic compression, and quasi-static Brazilian splitting conditions are studied. The results demonstrate that the compressive strength of DNP-based melt-cast explosives generally increases with an increase in strain rate. The compressive strength decreases with an increase in the content of the additive under quasi-static loading, while it increases with an increase in the content of the additive underdynamic loading. A significant improvement in the tensile strength of melt-cast explosives is observed when the content of the additive reaches a certain threshold. Furthermore, the applicable strength failure criteria for DNP-based melt-cast explosives differ under different loading conditions, the quasi-static compression follows the maximum shear stress criterion, the dynamic compression adheres to the maximum tensile strain criterion, and the Brazilian disc test conforms to the maximum tensile stress criterion.

Key words: 3,4-dinitropyrazole, melt-cast explosive, mechanical property, additive, strength failure criterion

CLC Number:

O385
TJ012.4

XU Yueyue, ZHANG Xiangrong, GAO Jiale, LIU Zhanwei, MIAO Feichao, LIU Pan, ZHOU Lin. Mechanical Properties and Failure Criteria of DNP-based Melt-cast Explosives[J]. Acta Armamentarii, 2024, 45(9): 3114-3124.

Figures/Tables 25

Table 1 Comparison of DNP and TNT performances

炸药	密度/ (g·cm^-3)	熔点/℃	爆速/ (m·s^-1)	爆压/GPa
DNP	1.87	85	8104	29.4
TNT	1.65	81	6900	21.0

Table 2 Test formulation

配方	组分
1	DNP/HMX=40/60
2	DNP/HMX/功能助剂=39/60/1
3	DNP/HMX/功能助剂=37/60/3

Fig.1 Group mold mould

Table 3 Specifications of different formula grains

配方	编号	直径/ mm	高度/ mm	质量/ g	密度/ (g·cm^-3)	平均密度/ (g·cm^-3)
	1	10.06	9.98	1.43	1.80
1	2	10.05	10.03	1.43	1.80	1.81
	3	10.01	10.00	1.42	1.81
	4	10.02	10.00	1.43	1.81
	1	10.03	9.99	1.43	1.81
2	2	9.99	10.03	1.42	1.81	1.80
	3	9.99	5.07	0.71	1.80
	4	10.03	5.02	0.72	1.80
	1	10.01	9.97	1.41	1.80
3	2	10.01	10.07	1.42	1.80	1.80
	3	9.96	5.06	0.71	1.80
	4	10.00	5.10	0.72	1.81

Fig.2 Uniaxial compression and Brazilian disc test specimen

Fig.3 Uniaxial compression and Brazilian disc test specimen

Fig.4 SHPB test apparatus

Table 4 Bar parameters

杆件及子弹	长度/ mm	直径/ mm	密度/ (g·cm^-3)	弹性模量/GPa	波速/ (m·s^-1)
入射杆	1060
透射杆	1060	14.5	2.78	70	5018
阻尼杆	600
子弹	200

Fig.5 Collected waveform signals and stress equilibrium status

Fig.6 Brazilian disc test principle diagram

Fig.7 Quasi-static compressive stress-strain curve

Table 5 Comparison of strain rates at 10-4s-1

配方	抗压强度/MPa	失效应变	Δε_f/%	弹性模量/GPa
1	8.54	0.0121		1.02
2	6.51	0.0124	2.5	0.74
3	5.37	0.0139	15	0.44

Table 6 Comparison of strain rates at 10-2s-1

配方	抗压强度/MPa	失效应变	Δε_f/%	弹性模量/GPa
1	9.84	0.0116		0.98
2	7.45	0.0102	-12	1.00
3	6.11	0.0138	19	0.60

Fig.8 Crack morphologies of Formulations 1 and 2 after quasi-static compression

Fig.9 Microscopic morphologies of Formulations 1-3 after quasi-static compression (Both left and right are perpendicular to the cross-sectional view)

Fig.10 Dynamic mechanical test results at room temperature

Table 7 Comparison of strain rates at 70s-1

配方	抗压强度/MPa	失效应变	Δε_f/%	弹性模量/GPa
1	10.2	0.0043		3.40
2	13.5	0.0051	18.6	5.02
3	14.3	0.0057	32.6	5.46

Table 8 Comparison of strain rates at 180s-1

配方	抗压强度/MPa	失效应变	Δε_f/%	弹性模量/GPa
1	13.9	0.0056		5.71
2	20.2	0.0046	-17.9	6.96
3	25.7	0.0058	3.6	11.05

Table 9 Comparison of strain rates at 230s-1

配方	抗压强度/MPa	失效应变	Δε_f/%	弹性模量/GPa
1	17.1	0.0042		6.62
2	21.8	0.0058	38.1	6.27
3	23.1	0.0063	50.0	10.87

Fig.11 Fracture morphologies of Formulation 2 after compression at different strain rates

Fig.12 Damage levels of Formulations 1-3 at strain rates of 200-300s-1

Fig.13 Disc morphology after compression

Fig.14 Crack propagation process

Fig.15 Brazilian disc test load-displacement curve

Fig.16 Fracture surface morphologies of Formulations 1-3 in Brazilian disc test

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