Using mechanoluminescence as a low-cost, non-destructive diagnostic method for transient polymer impact processes

Abstract

At ballistic velocities, certain polymers such as nylon and polyethylene have been shown to exhibit mechanoluminescence (ML) upon impact. This ML event results in the emission of photons in the visible wavelength spectrum and may occur on transient timescales as short as a sub-microsecond. In this study, we take advantage of this ML phenomenon to design a low-cost diagnostic tool by recording the ML emissions. The design consists of photodiodes of spectral range in the near-infrared to visible spectrum located radially in order to record the luminescence emissions around the circumference of the ML footprint during impact. Ultra-high-molecular-weight polyethylene rods were fired at velocities between 200 and 450 m/s as preliminary proof of concept experiments. Recorded signals were post-processed to yield information such as the projectile’s time-of-arrival, approximate impact location, and approximate attitude during initial impact. The experimental setup, measurement and post-processing techniques, and reconstruction results are detailed and discussed in this work.