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

Nagaraja, SR and Prasad, JK and Jagadeesh, G (2012) Theoretical-experimental study of shock wave-assisted metal forming process using a diaphragmless shock tube. In: PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING, 226 (G12). pp. 1534-1543.

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Abstract

The use of high-velocity sheet-forming techniques where the strain rates are in excess of 10(2)/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.

Item Type:	Journal Article
Publication:	PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING
Publisher:	SAGE PUBLICATIONS LTD
Additional Information:	Copyright for this article belongs to SAGE PUBLICATIONS LTD, ENGLAND
Keywords:	high-velocity metal forming;shock waves;explicit dynamic analysis;FEM diaphragmless shock tube
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	04 Jan 2013 06:05
Last Modified:	04 Jan 2013 06:05
URI:	http://eprints.iisc.ac.in/id/eprint/45623

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