A Rapid Throughput System for Shock and Impact Characterization: Design and Examples in Compaction, Spallation, and Impact Welding

Abstract

Many important physical phenomena are governed by intense mechanical shock and impulse. These can be used in material processing and manufacturing. Examples include the compaction or shearing of materials in ballistic, meteor, or other impacts, spallation in armor and impact to induce phase and residual stress changes. The traditional methods for measuring very high strain rate behavior usually include gas-guns that accelerate flyers up to km/s speeds over a distance of meters. The throughput of such experiments is usually limited to a few experiments per day and the equipment is usually large, requiring specialized laboratories. Here, a much more compact method based on the Vaporizing Foil Actuator (VFA) is used that can accelerate flyers to over 1 km/s over a few mm of travel is proposed for high throughput testing in a compact system. A system with this primary driver coupled with Photonic Doppler Velocimetry (PDV) is demonstrated to give insightful data in powder compaction allowing measurements of shock speed, spall testing giving fast and reasonable estimates of spall strength, and impact welding providing interface microstructure as a function of impact angle and speed. The essential features of the system are outlined, and it is noted that this approach can be extended to other dynamic tests as well.

High Strength and Fatigue Resistant Welds in NiTi and Brass by Impact Welding

“…1a), which will be vaporized after discharging the energy from the capacitor bank. This type of foil will generate an impact velocity of 600-700 m/s under an input energy of 12 kJ [15]. Two plastic standoff sheets with thickness of 2.4 mm and separation distance of 20 mm were used to provide the necessary acceleration distance and impact angle for achieving impact welds (Fig.…”

Impulse-Based Manufacturing Technologies

“…They use a vaporizing foil actuator to accelerate a projectile to velocities in the range of 300-400 m/s. The setup serves for impulse-based manufacturing, such as collision welding or powder compaction, as well as for characterizing, e.g., the spall strength of materials in shock physics [6].…”