Journal of the Association of Engineers, India

B. Karunes

Abstract

A metal, in its generally used form, is a compact aggregate of crystal grains with varying shapes and orientations, each grain having grown from separate nucleus in the original melt. The properties of this aggregate are not just the statistical averages of the properties of single crystals taken over all orientations as might apparently be expected, because the cementing layer of an amorphously distributed number of atoms at the crystal grain boundaries have properties quite different from those of the crystals themselves. The grain boundary properties combined with the crystal properties determine the properties of the metal. Thus to study the stress strain relation of a polycrystaline metal we cannot proceed from the study of perfect crystals of the metal directly, but have to depend on independant study of the aggregate itself.

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B. Karunes ¹

Affiliations
1 Calcutta University, IN

Abstract

This paper is to set a problem on the exact causes and process of buckling of columns and struts. The problem is of a theoretical nature and goes into the fundamentals of strength of materials and at the same time bears the great practical importance of being needed in almost every individual design of machines and structures.

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B. Karunes

Abstract

In recent years considerable amount of investigational and research work has been carried out on the theory of Plasticity and its application to the design of structures. The "Physical" theory of Plasticity has been a matter of study for a long time. Thus a knowledge of the mechanism of plastic flow and the behaviour of materials under straining in the plastic region was in possession of the engineers when they grew an interest to build up a theory suitable for application in the design of structures. This interest has arisen since they realised that the failure of a highly redundant steel structure, such as a welded rigid frame, does not take place when yield of the material is developed at some individual point or points but there is only a redistribution of the Bending Moments so that the structure absorbs energy in its other less stressed parts. With the realization of this feature, engineers started investigating, both theoretically and experimentally, what happens if designs could be made with yield stress as the working stress instead of the usual design methods taking working stress at about half the yield stress.

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