抄録
Fatigue strength in steel wire has recently been more emphasized than ever as an important requirement for wire ropes in general use, as well as for pre-stressed concrete wires. Many of the fatigue testing machines for wire rod in practical use are of the rotating bending type. For example, fatigue testing machines of the Haigh-Robertoson type, the Hunter type and the Schwining & Dorgerloh type are most commonly used as fatigue testing machines for wire rod. But their behavior leaves something to be desired. The designing of a testing machine which would give accurate results of the experiments and which is of simple construction has long been anticipated. In this paper the outline of a newly designed fatigue testing machine is described.
Requirements for the design of the fatigue testing machine are listed as follows:
1) The testing machine should be of the constant-load type in which the load is kept constant during the test.
2) The testing machine should be of the uniform bending type, the specimen being held as a simple beam.
3) The testing machine should be of simple design and of low cost and should be capable of measuring the bending moment with great accuracy.
4) Fatigue tests, not only at room temperature but also at high or low temperature, ought to be carried out by using simple apparatuses for heating or cooling.
The newly designed testing machine is designed so as to satisfy these conditions so far as possible. By using this fatigue testing machine specimens of various sizes of diameter from 2mm to 8mm can be tested. The revolutions of the motor for this machine are variable, ranging from 500rpm to 10000rpm without step.
From the results of experiments and consideration it is concluded that the newly designed fatigue testing machine is quite excellent as a fatigue testing machine for wire rod. The main advantages of this testing machine consist in its simplicity of design, its low cost, the accuracy with which the bending moment can be measured and its high speed of operation.
