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

K Sajun Prasad,Anupam Vivek,Glenn S Daehn,Stephen R Niezgoda,Yu Mao

doi:10.3390/jmmp4040116

K Sajun Prasad, Anupam Vivek + Show 3 more

Open Access

https://doi.org/10.3390/jmmp4040116

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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.

Highlights

Equation of state (EOS) describes the states and thermodynamic properties of the material, and its measurement is of immediate interest in military, automobile, aerospace, and other several manufacturing applications [1]
Numerous approaches have been developed for obtaining the EOS of a variety of materials through dynamic shock wave compression [2], static compression [3] and static coupled with dynamic compression techniques [4]
The experiment is further identified with shock arrival time measurements on the sample impact and rear surfaces using velocity interferometry (VISAR) probes to obtain an accurate measurement of shock velocity and, determine the EOS or shock Hugoniot state

Summary

Introduction

Equation of state (EOS) describes the states and thermodynamic properties of the material, and its measurement is of immediate interest in military, automobile, aerospace, and other several manufacturing applications [1]. Vivek et al [11] have developed the Vaporizing Foil Actuator (VFA) technique for many impulse and impact processes, such as impact welding [12,13], forming and embossing [14], shearing [15], and high-energy rate metalworking [16] In this method, the pressure created from the electrically driven rapid vaporization of a thin aluminum (Al) foil is used to generate an immense transient pressure that can be used to launch projectiles to velocities well in excess of 1 km/s. Three critical dynamic material phenomena are shown as examples of the utility of this system: powder compaction, spallation, and impact welding. The voltage and current traces from the corresponding experiments were collected using a 1000:1 BK PR28A voltage divider and a 50 kA: 1 V Rogowski

RReessuulltt and Discussions

Findings

Spallation in Copper