Theoretical–experimental study of shock wave-assisted metal forming process using a diaphragmless shock tube

Abstract

The use of high-velocity sheet-forming techniques where the strain rates are in excess of 102/s can help us solve many problems that are difficult to overcome with traditional metal-forming techniques. In this investigation, thin metallic plates/foils were subjected to shock wave loading in the newly developed diaphragmless shock tube. The conventional shock tube used in the aerodynamic applications uses a metal diaphragm for generating shock waves. This method of operation has its own disadvantages including the problems associated with repeatable and reliable generation of shock waves. Moreover, in industrial scenario, changing metal diaphragms after every shot is not desirable. Hence, a diaphragmless shock tube is calibrated and used in this study. Shock Mach numbers up to 3 can be generated with a high degree of repeatability (±4 per cent) for the pressure jumps across the primary shock wave. The shock Mach number scatter is within ±1.5 per cent. Copper, brass, and aluminium plates of diameter 60 mm and thickness varying from 0.1 to 1 mm are used. The plate peak over-pressures ranging from 1 to 10 bar are used. The midpoint deflection, circumferential, radial, and thickness strains are measured and using these, the Von Mises strain is also calculated. The experimental results are compared with the numerical values obtained using finite element analysis. The experimental results match well with the numerical values. The plastic hinge effect was also observed in the finite element simulations. Analysis of the failed specimens shows that aluminium plates had mode I failure, whereas copper plates had mode II failure.

Deformation of Stacked Metallic Sheets by Shock Wave Loading

“…Their investigations were focused on the use of one explosive drive shock tube (EDST) and achieved results from a series of tests using EDST were discussed [12]. Nagaraja et al [13] studied the deformation of thin metallic plates/foils, which were subjected to shock wave loading in the newly developed diaphragm-less shock tube. Aluminum, copper and brass plates of 60-mm diameter with different thicknesses and pressures were tested [13].…”

“…Nagaraja et al [13] studied the deformation of thin metallic plates/foils, which were subjected to shock wave loading in the newly developed diaphragm-less shock tube. Aluminum, copper and brass plates of 60-mm diameter with different thicknesses and pressures were tested [13].…”

Shock Tube as an Impulsive Application Device

“…Shock tube, driven with explosives, has also been employed as a device to create a shock loading [13]. Diaphragmless shock tube was considered to study the response of the copper, brass, and aluminum plates [14]. Kumar et al [15] implemented shock tube as the experimental set-up to study the effect of aluminum panel curvature on blast response where in-plane strain is measured on the back face of the panels.…”

Design and Fabrication of hand operated mini Shock Tube

“…Florence [6] has used shock waves generated by explosives to deform aluminium and steel plates of thickness 6.25 mm. Nagaraja S R et al [7] have fabricated a diaphragm-less shock tube and have used it for metal forming applications. Experiments were conducted on metallic plates of thickness ranging from 0.1 mm to 1 mm.…”