A tunable modified-Hopkinson impact fatigue device.

This paper presents a novel, tunable impact fatigue device that can be configured to apply compressive strikes on a variety of materials and geometries at low to intermediate strain rates, and the ability to compliment the investigations using full-field quantitative visualization of material deformation and failure properties. The device ranges in velocities between 0.5 and 4.6 (±0.1) m/s at frequencies between 0.05 and 0.25 Hz using a modified-Hopkinson pressure bar design. The corresponding control and actuation system runs autonomously and can be programmed for 10⁵ cycles at either a constant velocity, pre-entered velocity profiles with changing parameters, or a completely random velocity profile during testing. The device capabilities are demonstrated on 2.38 mm thick polycarbonate plates under low cycle fatigue at velocities of 1 and 2 m/s and impact energies of 0.15 and 0.60 J, highlighting different visible damage mechanisms present under different loading profiles. [ABSTRACT FROM AUTHOR]