To further improve the strike accuracy and penetration power of explosively-formed projectile (EFP) after long-distance flight, a polygonal charge capable of forming EFP with tail fins was designed during the study. A model for calculating the EFP velocity was derived from the effective charge and detonation projection theories with the integration of calculus. The circumferential velocity distributions of EFP formed using polygonal charges were obtained using this model, and the mechanisms underlying the formation of tail fins were elucidated. The feasibility of using this polygonal charge to form tail fin EFP was verified by conducting multi-media soft recovery tests and numerical simulations. Furthermore, the feasibility of forming tail fin EFP using polygonal charges with different numbers of sides and the effects of the structural parameters of a hexagonal charge on the formation of tail fin EFP were investigated by simulation. The ranges of optimal values for the structural parameters of a hexagonal charge capable of forming high-performance tail fin EFPs were determined.

Limited initiation energy or external stimulation may cause incomplete detonation in a warhead. At present, there is no quantitative method to characterize the energy release of a warhead charge for incomplete detonation such as explosion and deflagration. We propose a method based on average fragment quality to characterize the energy released by a warhead charge. The theoretical study shows that the average fragment quality after warhead initiation is inversely proportional to the initial fragment velocity. The relationship between the average fragment quality and explosive energy release is established and verified by experiment. This relation can be used to determine the charge energy released after warhead initiation. It provides a theoretical basis for optimizing efficiency of charge energy use in high-energy conventional damage technology and warhead design, and provides a quantitative method for evaluating insensitive ammunition.

The radius of jetting projectile charge (JPC) varies significantly from the head to the tail, resulting in the crater formed with a large and uniform radius when penetrating steel target. Current methods for calculating crater radius typically use the average radius without considering JPC radius distribution, leading to large errors in the calculation. Therefore, it is necessary to introduce JPC radius distribution when predicting JPC penetration and cratering. By incorporating the radius distribution in the calculation of JPC break-up time, the modified break-up time model was used to obtain the prediction model for penetration depth. Based on the current jet (JET) cratering theory, JPC radius distribution was introduced to derive the prediction model for crater radius of JPC penetration. The X-ray tests and numerical simulations were used to obtain the radius and velocity distribution of JPC. Finally, the prediction model was verified using data from static penetration tests and literature. The results show that the penetration depth calculated using the modified model had a small error compared to the test results, therefore, the modified model could predict the variation of the crater radius with the penetration depth. And the variation of crater radius was in good agreement with the tests, and accorded with the characteristics of uniform crater radius of JPC penetration. The findings have important guiding significance for JPC design and evaluation.

This study presents a systematic investigation into the mechanical responses of two tungsten-based alloys—84W–11.2Ni–4.8Fe and 88W–8.4Ni–3.6Fe—fabricated via selective laser melting (SLM). Quasi-static compression tests using a universal testing machine and dynamic impact experiments employing a split Hopkinson pressure bar (SHPB) were conducted over a temperature range of 298–598 K and strain rates spanning from 1 × 10⁻³ s⁻¹ to 2.3 × 10³ s⁻¹. Both alloys exhibited significant strain-rate hardening and thermal softening effects. Based on the experimental data, a Johnson–Cook (J–C) constitutive model was established. The fidelity of the calibrated model for the 84W alloy was rigorously validated through pulsed X-ray radiography and static armor penetration tests. The SLM-fabricated 84W-shaped charge liner produced a well-collimated jet with a tip velocity of 5101.5 m/s and achieved a penetration depth of 87 mm into rolled homogeneous armor (RHA)-equivalent steel targets. Numerical simulations using the developed J–C model showed close agreement with experimental measurements, with a maximum discrepancy of only 9.19%, thereby confirming the predictive capability of the constitutive model. These results demonstrate that the proposed J–C model can reliably characterize the large-deformation behavior of SLM-processed 84W and 88W liners under the extreme thermomechanical conditions characteristic of shaped charge jet formation—namely high temperature, high pressure, and ultra-high strain rate. Collectively, this work establishes a foundational framework for the application of SLM technology to shaped charge liner design and provides a critical basis for further research into jet formation physics and penetration mechanics of tungsten-based alloys.

The point load test (PLT) has been widely used to estimate the strength of rock materials in the laboratory due to its convenience and applicability. While most of the traditional methods count on empirical formulas for prediction, the empirical factors have different values for different rocks so the applicability of those empirical formulas is limited. The dynamic compressive strength has been considered as a crucial parameter for rock dynamic mechanical properties. The split Hopkinson pressure bar (SHPB) developed by Kolsky is a common apparatus to perform dynamic rock tests to obtain the dynamic compressive strength. This study proposed a numerical-experiment integration technique for the prediction of dynamic strength from PLT. Using the idea of digital twins, the rock parameters were calibrated to minimize the difference between the experimental curves from PLT and the numerical curves. Then, the calibrated parameters could be employed to reproduce the rock dynamic test numerically to estimate the dynamic compressive strength. The result showed that the proposed method has an acceptable accuracy in estimating the dynamic compressive strength of rocks compared with the SHPB, and the variation of dynamic increase factor (DIF) on strain rates was consistent with the experimental results. Our work provided the feasibility of the numerical-experiment integration approach for estimating other mechanical parameters of rock such as the dynamic compressive strength of rock.