Experimental and numerical studies on the expanding fracture behavior of an explosively driven 1045 steel cylinder

Fragment velocity characteristics of warheads are key issues in the field of explosion technology and protection. However, the fragment velocity characteristics of a warhead with a hollow core under asymmetrical initiation are rarely touched. In this work, the effects of the diameter of the hollow core on the fragment velocities of warheads under asymmetrical initiation were investigated by experimentally verified numerical simulations. The results showed that the fragment velocity‐time curves exhibited a second time acceleration due to the collision of the shock/detonation wave and/or that of the detonation products. For warheads under symmetrical initiation, the second time acceleration becomes stronger, and then becomes slightly weaker with the increase of the diameter of the hollow core, due to the combined effects of bigger hollow core and less explosive charge mass. For warheads under asymmetrical initiation, the second time acceleration becomes more obvious with the increase of the diameter of the hollow core, because the larger shaped charge efficiency enhances the collision of the detonation products. A modified formula was proposed to predict the initial fragment velocity in the aiming direction of a warhead with a hollow core under asymmetrical initiation. Experimentally verified numerical simulations were then used to verify the formula and the results showed that the new formula could predict the velocity very well. This work could offer a good reference for the design of tunable effects warheads and aimable warheads.

Section: Validation Of Numerical Modelmentioning

confidence: 99%

“…The first warhead used to calibrate our numerical model came from Liu's experiments [20]. The explosive charge was JOB 9003 (1.834 g/cm 3 , detonation pressure 35.2 GPa, detonation velocity 8695 m/s), and the metallic casing was AISI 1045 steel (7.85 g/cm 3 ).…”

Section: Validation Of Numerical Modelmentioning

confidence: 99%

Fragment Velocity Characteristics of Warheads with a Hollow Core under Asymmetrical Initiation

Dong

Liu

2019

“…The first warhead [18] is charged by JOB 9003 explosive, with a density of 1.834 g/cm 3 and detonation velocity of 8695 m/s. The casing is made of steel 1045, with a density of 7.85 g/cm 3 .…”

Section: Velocity Formulas Correctionmentioning

confidence: 99%

“…The outer surface velocity of the middle cross section of the warhead casing was measured by the Photonic Doppler Velocimetry (PDV) technology. And it is proved in reference [18] that the middle part of the warhead cylinder can be considered as a twodimensional plane strain problem. Therefore, it's reasonable to valid our numerical model by the experimental velocity of the middle part of the warhead.…”

Section: Velocity Formulas Correctionmentioning

confidence: 99%

“…Therefore, it's reasonable to valid our numerical model by the experimental velocity of the middle part of the warhead. The material parameters using in the modelling are all adopted from reference [18] and the AUTODYN software's material database [17]. And in order to account for the casing fragmentation, a plastic failure strain of 0.65 and Mott's stochastic model with g ¼ 53:8 are set [2].…”

Section: Velocity Formulas Correctionmentioning

confidence: 99%

See 1 more Smart Citation

New Formula for Fragment Velocity in the Aiming Direction of an Asymmetrically Initiated Warhead

Xiong

et al. 2018

Fragment velocity is an important parameter for fragmentation warheads, but for an asymmetrically initiated warhead, formulas for calculating the fragment velocity in the aiming direction are rare. In this work, new formulas for calculating fragment velocities in the aiming direction and the initiation side of an asymmetrically initiated warhead were established by taking the long element from the warhead section and applying one‐dimensional gas dynamics. Accounting for the assumptions made during the formulas establishing, three experimentally verified warheads modelling of different charge ratios were used to verify the formulas. It is found that the velocity ratios of the modelling to the formulas’ calculations of different warheads are very similar. Hence the fitted curves for the velocity ratios versus the warhead charge ratios were used as correction factors for the established formulas. Finally experiments were designed and conducted to validate the revised formulas, which shows acceptable relative errors of 2.8 % and 9.9 %, better than already existing formulas. The established formulas could be a good reference for the damage evaluation of aimable warheads and for fragment velocity distribution research.

Fragment Velocity Formula for Reverse Detonation Driving with Opposite Initiation

Cheng

Wen

2020

In detonation driving problems, the explosive charge is typically initiated on one side of the charge and the fragment or plate is located on the other side. Many studies have been conducted on this driving style, which has numerous practical applications. However, few studies have been conducted on reverse detonation driving, wherein the initiation point is located on the same side as that of the fragment. Reverse detonation driving can lower the shock pressure in the fragment and solve the problem of spallation. In this study, the model of opposite initiation of cylindrical charge is used to investigate the reverse detonation driving style. A long element is considered along the direction of the initiation points and the warhead center, and a fragment velocity formula is established according to the one-dimensional gas dynamics. Then, based on the influences of the assumptions, such as the rigid constraint of the element, three experimentally verified numerical models are used to validate the established formula. The ratios of the formula computations and the corresponding modeling results exhibit similar trends. Therefore, these trends are fitted together and used as a correction factor for the established formula. The corrected formula is further validated through two-dimensional modeling with a different casing material model and three-dimensional modeling of the verified experimental configuration. The established formula can be used as a reference for the problem of reverse detonation driving.