Ernest L. Baker

Study of Detonation and Cylinder Velocities for Aluminized Explosives

The detonation properties of aluminized explosives have been studied using experimental data and EXP‐6 thermo‐chemical potential calculations with the JAGUAR computer program. It has been found that the observed detonation velocity behavior for aluminized explosives can be accurately represented by a reaction zone model in which unreacted aluminum is initially in equilibrium with H‐C‐N‐O compounds. The JAGUAR procedures have been modified to represent the reaction zone behavior and to enable specified temperature differences between the gas and aluminum particles in the initial portion of this reaction zone. The modified procedures enable isentropic expansion for incomplete or complete aluminum reaction in the zone, and result in close agreement with experimental cylinder test data.

EIGENVALUE DETONATION OF COMBINED EFFECTS ALUMINIZED EXPLOSIVES

Theory and performance for recently developed combined—effects aluminized explosives are presented. Our recently developed combined‐effects aluminized explosives (PAX‐29C, PAX‐30, PAX‐42) are capable of achieving excellent metal pushing, as well as high blast energies. Metal pushing capability refers to the early volume expansion work produced during the first few volume expansions associated with cylinder and wall velocities and Gurney energies. Eigenvalue detonation explains the observed detonation states achieved by these combined effects explosives. Cylinder expansion data and thermochemical calculations (JAGUAR and CHEETAH) verify the eigenvalue detonation behavior.

Detonation energies of explosives by optimized JCZ3 procedures

Procedures for the detonation properties of explosives have been extended for the calculation of detonation energies at adiabatic expansion conditions. The use of the JCZ3 equation of state with optimized Exp-6 potential parameters leads to lower errors in comparison to JWL detonation energies than for other methods tested.

Optimized JCZ3 procedures for detonation properties at highly overdriven conditions

Optimized extended JCZ3 procedures which have been implemented through the “JAGUAR” computer routines result in accurate detonation properties for wide ranges of conditions including the C-J state and high volume expansions. In order to obtain improved results at highly overdriven conditions, optimized EXP-6 parameters have been established for formic acid by the use of experimental Hugoniot data for PBX-9501. The procedures of this study enable the highly accurate calculation of detonation properties of explosives for a very wide range of volumes.

JAGUAR PROCEDURES FOR DETONATION BEHAVIOR OF SILICON CONTAINING EXPLOSIVES

Improved relationships were developed in this study for the thermodynamic properties of solid and liquid silicon and silicon dioxide for use with JAGUAR thermo‐chemical equation of state routines. Analyses of experimental melting temperature curves for silicon and silicon dioxide indicated complex phase behavior and that improved coefficients were required for solid and liquid thermodynamic properties. Advanced optimization routines were utilized in conjunction with the experimental melting point data to establish volumetric coefficients for these substances. The new property libraries resulted in agreement with available experimental values, including Hugoniot data at elevated pressures.

Jaguar Analyses of Experimental Detonation Values for Aluminized Explosives

Comparisons of JAGUAR C‐J velocities with experimental detonation values for a number of explosives indicate that only slight, if any, aluminum reaction occurs at the detonation front even if small or sub‐micron particles are utilized. For sub‐micron particles, it is important to account for the presence of aluminum oxide in the explosive formulation. The agreement with the calculated JAGUAR values for zero aluminum reaction is within 2% for most experimental detonation velocities considered. Comparisons of experimental cylinder velocities by JAGUAR analytical procedures indicate that with small aluminum particles substantial aluminum reaction occurs at low values of the radial expansion, even though little reaction is observed at the detonation front.

Accuracy and Calibration of High Explosive Thermodynamic Equations of State

The Jones-Wilkins-Lee-Baker (JWLB) equation of state (EOS) was developed to more accurately describe overdriven detonation while maintaining an accurate description of high explosive products expansion work output. The increased mathematical complexity of the JWLB high explosive equations of state provides increased accuracy for practical problems of interest. Increased numbers of parameters are often justified based on improved physics descriptions but can also mean increased calibration complexity. A generalized extent of aluminum reaction Jones-Wilkins-Lee (JWL)-based EOS was developed in order to more accurately describe the observed behavior of aluminized explosives detonation products expansion. A calibration method was developed to describe the unreacted, partially reacted, and completely reacted explosive using nonlinear optimization. A reasonable calibration of a generalized extent of aluminum reaction JWLB EOS as a function of aluminum reaction fraction has not yet been achieved due to the increased mathematical complexity of the JWLB form.

JAGUAR Procedures for Detonation Behavior of Explosives Containing Boron

The Jaguar product library was expanded to include boron and boron containing products by analysis of Available Hugoniot and static volumetric data to obtain constants of the Murnaghan relationships for the components. Experimental melting points were also utilized to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX—boron mixtures calculated with these relationships using Jaguar are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that the boron does not react near the detonation front or that boron mixtures exhibit eigenvalue detonation behavior (as shown by some aluminized explosives), with higher detonation velocities at the initial points. Analyses of calorimetric measurements for RDX—boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the detonation properties of the formulation.The Jaguar product library was expanded to include boron and boron containing products by analysis of Available Hugoniot and static volumetric data to obtain constants of the Murnaghan relationships for the components. Experimental melting points were also utilized to obtain the constants of the volumetric relationships for liquid boron and boron oxide. Detonation velocities for HMX—boron mixtures calculated with these relationships using Jaguar are in closer agreement with literature values at high initial densities for inert (unreacted) boron than with the completely reacted metal. These results indicate that the boron does not react near the detonation front or that boron mixtures exhibit eigenvalue detonation behavior (as shown by some aluminized explosives), with higher detonation velocities at the initial points. Analyses of calorimetric measurements for RDX—boron mixtures indicate that at high boron contents the formation of side products, including boron nitride and boron carbide, inhibits the det...

Optimization of parameters for JCZ3 equation of state

Individual parameters for HCNO explosive product species were optimized with available Hugoniot pressure-density data. Large improvement in the agreement with the Hugoniot data resulted for most of the species considered. C-J velocities and pressures for explosives calculated with new analytical procedures and the optimized parameter set demonstrate improved agreement with the experimental values.

Gun Testing Ballistics Issues for Insensitive Munitions Fragment Impact Testing

The STANAG 4496 Ed. 1 Fragment Impact, Munitions Test Procedure is normally conducted by gun launching a projectile for attack against a munition. The purpose of this test is to assess the reaction of a munition impacted by a fragment. The test specifies a standardized projectile (fragment) with a standard test velocity of 2530±90 m/s. The standard test velocity can be challenging to achieve and has several loosely defined and undefined characteristics that can affect the test item response. MSIAC performed and international review of the STANAG 4496 related to the fragment impact test. To perform the review, MSIAC created a questionnaire in conjunction with the custodian of this STANAG and sent it to test centers. Fragment velocity variation, projectile tilt upon impact, aim point variation and projectile material were identified as observed gun testing issues. These, as well as other gun testing issues, have significant implications to resulting IM response.The STANAG 4496 Ed. 1 Fragment Impact, Munitions Test Procedure is normally conducted by gun launching a projectile for attack against a munition. The purpose of this test is to assess the reaction of a munition impacted by a fragment. The test specifies a standardized projectile (fragment) with a standard test velocity of 2530±90 m/s. The standard test velocity can be challenging to achieve and has several loosely defined and undefined characteristics that can affect the test item response. MSIAC performed and international review of the STANAG 4496 related to the fragment impact test. To perform the review, MSIAC created a questionnaire in conjunction with the custodian of this STANAG and sent it to test centers. Fragment velocity variation, projectile tilt upon impact, aim point variation and projectile material were identified as observed gun testing issues. These, as well as other gun testing issues, have significant implications to resulting IM response.