The machine works on the principle of energy transfer

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The machine works on the principle of energy transfer. The pendulum in the starting stationary position has potential energy. When released, the energy in the pendulum converts to kinetic energy that peaks at the bottom of the swing. At that time, some of the energy is transferred into the specimen. The hammer then continues to swing. Its height after impact is reduced from the original height, with the reduction being directly related to the energy absorbed. It may be said that the height after impact is inversely proportional to the energy absorbed. In such tests, a large part of the energy absorbed is taken up in a region at the notch, and a brittle type of fracture is often induced. It should be observed that these tests do not, and are not intended to, simulate shock loading in service; they simply give the resistance of a particular notched metallic specimen to fracture under a particular type of blow. It has been found that the results indicate differences in condition of a metal that are not indicated by other tests. Also these tests, when made on specimens at low temperatures, have proved useful in indicating whether or not adequate toughness is maintained at those temperatures. Tests of this sort find use as control tests of steels for special types of service. The impact values must be judged, however, in relation to a given type of steel and not by themselves. Impact tests are sensitive to variations in heat treatment, to alloy content, to sulfur or phosphorus content, and to environmental conditions. They are used considerably in some industries. See The Testing and Inspection of Engineering Materials, by Davis, Troxell, & Hauck for further information.
59 Impact Testing Machine: 1. Capacities 264 and 120 Foot-Pounds 7. Charpy Centering Tongs(not shown) 2. Indicating Scales 8. Tension Impact Support 3. Latching Device 9. Change-O-Matic Head 4. Izod Support Anvil 10. Electric Brake 5. Izod Setting Gage (not shown) 11. Not shown) 6. Charpy Support Anvil 12. Safety Latch Pendulum Height: a. Izod Position - 2.0 feet b. Charpy Position - 4.4 feet Test Range: a. Izod - 120 foot-pounds b. Charpy - 264 foot-pounds
60 Mountings for Charpy and Izod Specimens: Equipment and Materials Required 1. Tinius Olsen Charpy-Izod impact testing machine 2. Test specimens as provided by the instructor Procedure 1. Measure and record the dimensions of the specimens. 2. Fix pendulum latching device in the Charpy position. 3. Rotate hammer striking edges until Charpy position is obtained. 4. Lift pendulum until weight is supported by latching device. 5. Ensure that machine is plugged into 115 volt AC outlet. 6. Slide pointer on Charpy scale to full range of 264 ft-lb.
61 7. Release latch by lifting latch handle. Pointer should move to the zero position. If not, see your instructor.

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