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CCCXVIII.

SOME TESTS OF THE STRENGTH OF CAST IRON MADE IN THE LABORATORY OF APPLIED MECHANICS OF THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY.

BY GAETANO LANZA.
(Member of the Society.)

WITH HEYWOOD COCHRAN, JOHN K. BURGESS, MAURICE A. VIELÉ, HENRY F. EASTMAN, AND WM. H. GERRISH.

THE object of this paper is to give a brief account of several sets of tests upon the strength and other resisting properties of cast iron, carried on in the laboratory of Applied Mechanics of the Massachusetts Institute of Technology, of which the results are, it is believed, of sufficient practical value to render them worthy of record.

The experiments referred to have formed the subjects of three graduating theses, viz. :

1st. An investigation upon the modulus of elasticity and some other properties of cast iron, by Heywood Cochran of the class

of 1885.

2d. An investigation of the tensile and the transverse strengths of cast iron, and a comparison of their respective moduli of elasticity, by John K. Burgess and Maurice A. Vielé, of the class of 1886.

3d. Experiments upon pulleys, keys and set screws, by Henry F. Eastman and William H. Gerrish, of the class of 1888.

The first portion of the work relates especially to the modulus of elasticity, and the limit of elasticity of common cast iron, and of gun iron, both planed and unplaned.

The main portion of the experiments, however, are upon the transverse strength of cast iron when used in the forms of window lintels and of pulleys.

The reason for undertaking these tests was, that it is well known that the modulus of rupture of cast iron varies greatly, according to the form of the casting, and the manner of using it; and it was

considered desirable to obtain some experimental results which should be applicable to the forms mentioned.

Some experiments were also made upon the strength of keys of cast iron, wrought iron, and steel, and upon the holding power of set screws, all of which are recorded here.

SUMMARY OF THE FIRST SET OF EXPERIMENTS—BY MR. HEYWOOD COCHRAN.

The object of the thesis was to determine the values of the modulus of elasticity, and of the limit of elasticity of certain kinds of common cast irou, and of gun iron, and the effect of re-testing the specimens.

The common iron consisted of a half-and-half mixture of Lake Superior magnetic and Harrington irons, the last being made from an English bog ore.

The gun iron consisted of a half-and-half mixture of Muirkirk, Md., and remelted Salisbury irons.

The chemical analyses as far as determined were as follows:

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The test specimens, all of which were cast at the South Boston Iron Foundry, were twenty-six inches long and square in section; those tested with the skin on being very nearly one inch square, and those tested with the skin removed being cast nearly one and onequarter inches square, and afterwards planed down to one inch square.

All were of the same section throughout their entire length.
The tables of tests will now be given:

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With a load of 11,000 lbs. the piece broke unexpectedly in the upper clamps, due to the fact that these clamps did not bind the piece as they should have done, but rather pinched it at its lower end. Then, too, the load was very suddenly applied. Upon re-testing, the piece broke with a load of 24,000 lbs., or 23,000 lbs. per square inch. A load of 6,500 lbs. was left on for seventeen hours and a half without producing any additional elongation. The position of the fracture was just outside the upper clamps.

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At the end of the test a load of 9,000 lbs. was left upon the

piece for seventy hours.

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The load of 5,500 lbs. was left upon the piece for two hours. At the end of this test a load of 12,000 lbs. was left upon the piece, this being above the limit of elasticity.

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