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Bu Wer

FIG. 5.

314 wer

Fig. 6.

metrical on each side of the neck. This should be noted on the report.

VI. Report. Report consists in filling out the blank form supplied for the test (except as indicated by the instructor.)

TENSION TEST WITH HENNING POCKET RECORDER.

Object.-To determine the properties of material from load-elongation diagram drawn by apparatus.

Preparation.— Ascertain magnification of the lever in the apparatus. Set the lever stop with a clearance of 0.03 inches. Measure and lay off specimen as for a regular tension experiment. Place the test bar in the wedges of the machine and adjust the apparatus under the direction of the instructor. Wedges must be blocked to prevent their flying out upon rupture of the specimen.

Experiment.-Run out the poise by steps of 4,000 pounds and allow the apparatus to draw a scale of loads on the card up to 50,000 pounds. Apply the load with the intermediate speed, keeping the beam floating until the specimen is broken. Note the load in pounds at the yield limit and the maximum limit.

Computation. The card is completed by drawing the elongation axis through the zero of loads and at right angles to the load axis, and also a straight line from the rupture point perpendicular to the elongation axis.

The load at yield limit and maximum limit are scaled from the card and checked by observations taken during the test. The per cent. of elongation obtained by the measurements on the fractured specimen is to be checked by scaling from the card. The work of deformation up to any point may be obtained from the area in square inches under the curve up to the point in question by multiplying this area by the scale value in inch-pounds of each square inch of card. This product divided by the volume of the specimen between the gauge points will be the “rupture-work” in inch-pounds per cubic inch.

Compare the value of resilience by the card with the values as obtained from the following formulæ:

T?
Elastic Resilience

2E

per cent. elongation (T" + 2T') Rupture-work=

300 Where T" and T' equal the stress in pounds per square inch at elastic limit and maximum load respectively, and E is the modulus of elasticity, E cannot generally be accurately determined from the card. (See instructor for assumed value.)

N. B.-Be sure to record on the data sheet the serial number of the specimen before placing it in the wedges of the machine. Make sure that the magnification of the lever is taken account of in all measurements involving this magnification. The beam must be kept floating throughout the experiment even after the maximum load has been reached.

TENSION TEST WITH EXTENSOMETER.

Object. In this experiment the elastic properties of metals in tension are determined.

Method.-Carefully measure and prepare each specimen as for regular tension test (note the serial number on the specimen). Grip the piece in the wedges by

metrical on each side of the neck. This should be noted on the report.

VI. Report.

Report consists in filling out the blank form supplied for the test (except as indicated by the instructor.)

TENSION TEST WITH HENNING POCKET RECORDER.

Object.-To determine the properties of material from load-elongation diagram drawn by apparatus.

Preparation.— Ascertain magnification of the lever in the apparatus. Set the lever stop with a clearance of 0.03 inches. Measure and lay off specimen as for a regular tension experiment. Place the test bar in the wedges of the machine and adjust the apparatus under the direction of the instructor. Wedges must be blocked to prevent their flying out upon rupture of the specimen.

Experiment.-- Run out the poise by steps of 4,000 pounds and allow the apparatus to draw a scale of loads on the card up to 50,000 pounds. Apply the load with the intermediate speed, keeping the beam floating until the specimen is broken. Note the load in pounds at the yield limit and the maximum limit.

Computation.— The card is completed by drawing the elongation axis through the zero of loads and at right angles to the load axis, and also a straight line from the rupture point perpendicular to the elongation axis.

The load at yield limit and maximum limit are scaled from the card and checked by observations taken during the test. The per cent. of elongation obtained by the measurements on the fractured specimen is to be checked by scaling from the card. The work of deformation up to any point may be obtained from the area in square inches under the curve up to the point in question by multiplying this area by the scale value in inch-pounds of each square inch of card. This product divided by the volume of the specimen between the gauge points will be the “rupture-work” in inch-pounds per cubic inch.

Compare the value of resilience by the card with the values as obtained from the following formulæ:

T?
Elastic Resilience

2E

per cent. elongation (T" + 2T') Rupture-work

300 Where T" and T' equal the stress in pounds per square inch at elastic limit and maximum load respectively, and E is the modulus of elasticity, E cannot generally be accurately determined from the card. (See instructor for assumed value.)

N. B.-Be sure to record on the data sheet the serial number of the specimen before placing it in the wedges of the machine. Make sure that the magnification of the lever is taken account of in all measurements involving this magnification. The beam must be kept floating throughout the experiment even after the maximum load has been reached.

TENSION TEST WITH EXTENSOMETER. Object. In this experiment the elastic properties of metals in tension are determined.

Method.- Carefully measure and prepare each specimen as for regular tension test (note the serial number on the specimen). Grip the piece in the wedges by

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