Jets from point-initiated hemispherical-lined shaped charges

The capacity of analytical models to accurately represent real-world phenomena is critical to the study of jet formation physics. Shaped charge performance can be influenced by the detonation wave geometry as it interacts with the liner, making accurate representation of the wavefront essential when evaluating hemispherical liners. Previous work established an analytic foundation for predicting jet characteristics of plane-wave-initiated, hemispherical-lined charges. Extending this framework, the present study introduces a modified set of analytic equations describing the collapse and jet formation of constant-wall-thickness, hemispherical-lined shaped charges initiated on or off the axis of symmetry. The proposed model is first evaluated against experimental data from two on-axis-initiated charges. Agreement between experiments and continuum-based simulations establishes a basis for further assessment, after which model predictions are also compared with simulations of identical configurations. The model is then examined across a matrix of simulations spanning variations in charge geometry and both on- and off-axis initiation locations. Although further research is warranted to identify more appropriate methods for describing collapse velocity profiles, the analytic framework predicts jet characteristics with sufficient accuracy relative to simulations that neglect liner material strength when a well-characterized profile is used as input. For the copper-lined, LX-14 simulation cases neglecting liner material strength and having an explosive-to-liner mass-per-unit-area ratio less than 17.20, the model yields an average coefficient of determination of 0.91 and an average mean absolute error of \(\pm ~0.23\) km/s. These matrix results, together with the close agreement obtained for simulations of the two experimental configurations neglecting liner material strength, support the validity of the proposed point-initiation model across the configurations evaluated in this study. Comparisons with the experimental data and additional simulations incorporating liner material strength, however, indicate that further refinement is needed to more fully account for material strength effects beyond those represented by the simple empirical jet-tip-truncation approach. Despite this, the present framework provides an efficient and practical method for predicting jet characteristics of point-initiated, hemispherical-lined shaped charges.