Accession Number : ADA317845

Title :   In-Situ Measurement of Penetrator Erosion Rate and Dynamic Flow Stress During Long-Rod Penetration.

Descriptive Note : Final rept. Oct 92-Sep 94,

Corporate Author : ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s) : Chang, Albert L.

PDF Url : ADA317845

Report Date : AUG 1996

Pagination or Media Count : 56

Abstract : The penetration resistance of a given armor material against the long-rod projectile is primarily determined by its ability to erode away the projectile during the penetration process. Typically, high energy X-ray shadowgraphs were used to record projectile locations at different times after impact to calculate the projectile erosion rate. Due to the one-shot nature of the high energy X-ray equipment, this technique usually relies on combining multiple shadowgraphs taken from nominally 'identical' ballistic experiments at different times after impact, introducing considerable uncertainties in the calculated erosion rates. In the present report, we describe the development of a 94-GHz CW Doppler Radar Hyper-Velocimeter system for in-situ and continuous measurement of the projectile tail-end velocity history. This radar system is capable of measuring both the magnitude and the direction of the velocity of a moving object. Signal processing algorithms were developed to extract the high-resolution tail-end velocity history from the Doppler frequency data in the measured tail-end velocity history, several velocity-step changes are clearly visible. These velocity-step changes occur at specific times corresponding to stress wave reverberation along the projectile during the penetration process. Projectile length history (the erosion rate) was obtained by analyzing these velocity-step timing sequences. Tail-end position history was obtained by integrating the tail-end velocity history. Front-end position history was obtained through combination of the tail-end position history and the projectile length history. Dynamic flow stress of the projectile was obtained through the measurement of the size of the first velocity step in the tail-end velocity history.

Descriptors :   *TERMINAL BALLISTICS, *DYNAMIC TESTS, *SABOT PROJECTILES, ALGORITHMS, SIGNAL PROCESSING, ARMY RESEARCH, STRESS ANALYSIS, HYPERVELOCITY IMPACT, REACTION KINETICS, PROJECTILES, DOPPLER RADAR, IMPACT STRENGTH, EROSION, PENETRATION, YIELD STRENGTH, REVERBERATION, PROJECTILE TRAJECTORIES, STRESS WAVES, IMPACT POINT, LASER VELOCIMETERS, ARMOR PLATE, X RAY APPARATUS, BALLISTIC CAMERAS.

Subject Categories : Ballistics
      Armor

Distribution Statement : APPROVED FOR PUBLIC RELEASE