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Negative Shrinkage of Thin-walled Investment Brass Castings

Roy Soumyajit, Pramanick A. K., Datta P. K.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 1

17--24

EN

Dhokra or Dokra casting is a sophisticated cast metal craft tradition of the Indian subcontinent. It has been practiced by the countryfolk now since the Copper Age. It is a lost wax casting process in the hot clay mold. The technology is such sophisticated that it can produce up to 400 μm thin-walled hollow cast products with complicated and intricate shapes using Brass, Bronze, Copper, and other copper alloys. The investigation was for engraving Brass (2% lead) which is used by Dhokra artisans nowadays. In a field visit during dimensional analysis, one discrepancy was identified. The metal thicknesses of hollow castings are thicker than the thickness of the wax pattern. This cast metal dilation phenomenon is unusual. Shrinkage of metals compared to the pattern dimension is familiar in the casting world. The same abnormalities in the repeated investigation at different sites were observed. All the studies and experiments were organized to explain the reason hidden behind the phenomenon.

2

Elastic stability of square stiffened plates with cutouts under biaxial loading

Srivastava A. K. L., Datta P. K.

International Journal of Applied Mechanics and Engineering

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2006

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Vol. 11, no 2

421-433

EN

A finite element method for the buckling loads on a longitudinally square stiffened plate with square cutouts is investigated under various combinations of biaxial loading at the plate boundary. The forces are assumed to act in the plane of the undeformed middle surface of the plate. The characteristic equations for the natural frequencies, buckling loads and their corresponding mode shapes are obtained from the equation of motion. The buckling load parameter for various modes of the stiffened plate with square cutouts subjected to in-plane biaxial loads, has been determined for various edge conditions. Numerical results are presented for a range of hole to plate size from 0 to 0.8. In the structural modeling, the plate and the stiffeners are treated as separate elements where the compatibility between these two types of elements is maintained. The present approach is more flexible than any other finite element modeling in that the mesh division is independent of the location of the stiffeners.

3

Parametric instability of stiffened plates

Srivastava A. K. L., Datta P. K., Sheikh A. H.

International Journal of Applied Mechanics and Engineering

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2004

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Vol. 9, no 1

169-180

EN

The parametric instability behavior of a stiffened plate subjected to uniform in-plane edge loading is studied using the finite element analysis. The method of Hill's infinite determinants is applied to analyze the dynamic instability regions. Numerical results are presented to demonstrate the effects of various parameters, such as the aspect ratio, boundary condition, stiffening scheme, on the dynamic stability of stiffened plates. The results show that the location, size and number of stiffeners have a significant effect on the location of the boundaries of the principal instability regions when compared with those of a flat unstiffened plate.