Deceleration time of projectile penetration/perforation into a concrete target: Experiment and discussions

Abstract

Deceleration time histories of the 25.3 mm diameter, 428 g projectile penetration/perforation into 41 MPa reinforced concrete slabs with thicknesses of 100, 200, and 300 mm, are discussed. An ultra-high g small-caliber deceleration data recorder with a diameter of 18 mm is employed to digitize and record the acceleration during launch in the barrel, as well as the deceleration during penetration or perforation into targets. The accelerometer mounted in the data recorder measures rigid-body projectile deceleration as well as structural vibrations. To validate these complex signals, a validation approach for the accuracy of the recorded deceleration time data is proposed based on frequency characteristic analyses and signal integrations, and three sets of whole-range deceleration time data are validated. As the deceleration of the rigid-body projectile is the main concern, a signal processing approach is further given to obtain the rigid-body deceleration data, that is, using a low-pass filter to remove the high-frequency responses associated with vibrations of the projectile case and the internal supporting structure. The first valley frequency from the spectrum analysis is determined to be the critical cutoff frequency. To verify the accuracies of the theoretical model and the numerical simulation in predicting projectile motion time histories, theoretical projectile penetration/perforation deceleration time models are given and numerical simulations are performed. The predicted projectile time histories consist well with the validated deceleration time test data, as do their corresponding velocity and displacement time curves.