Experimental Investigations on Microshock Waves and Contact Surfaces

Abstract

The present work reports on progress in the research of a microshock wave. Because of the lack of a good understanding of the propagation mechanism of the microshock flow system (shock wave, contact surface, and boundary layer), the current work concentrates on measuring microshock flows with special attention paid to the contact surface. A novel setup involving a glass capillary (with a 200 or 300 μm hydraulic diameter D) and a high-speed magnetic valve is applied to generate a shock wave with a maximum initial Mach number of 1.3. The current work applies a laser differential interferometer to perform noncontact measurements of the microshock flow's trajectory, velocity, and density. The current work presents microscale measurements of the shock-contact distance L that solves the problem of calculating the scaling factor Sc=Re×D/(4L) (introduced by Brouillette), which is a parameter characterizing the scaling effects of shock waves. The results show that in contrast to macroscopic shock waves, shock waves at the microscale have a different propagation or attenuation mechanism (key issue of this Letter) which cannot be described by the conventional "leaky piston" model. The main attenuation mechanism of microshock flow may be the ever slower moving contact surface, which drives the shock wave. Different from other measurements using pressure transducers, the current setup for density measurements resolves the whole microshock flow system.

Graphene-Like Nanoflakes for Shock Absorption Applications

“…For plastic deformation, V s is computed using , where ε L is the elastic strain limit (∼1.5 × 10 6 for the GNF). A decrease in the velocity is indicative of a decrease in the work-hardening rate in the GNF as it shatters. , …”

“…A decrease in the velocity is indicative of a decrease in the work-hardening rate in the GNF as it shatters. 22,23 An ideal shock-wave profile exhibits a discontinuity at the front, a plateau at the top, and a gradual arrival to zero pressure, schematically shown in the inset in Figure 3. However, real shock waves imprint a number of peculiarities that are pressure-and material-dependent.…”

Surface Interactions of Transonic Shock Waves with Graphene-Like Nanoribbons

“…Among them, SHPB is an inexpensive, time-effective, safe measurement route to generate shock waves to realize an explosion scenario off the field [10]. Mechanical parameters of aluminum alloys were investigated, both at room [11] and high temperature [12] using the SHPB technique. Furthermore, tensile, force-displacement behavior, and compressive strength data were analyzed for shock mitigation in carbon nanotube/polymer composites [13][14][15].…”