13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- Open marks indicate the data in the surface initiated fracture, while solid marks give those data in the interior inclusion initiated fracture. In order to complete a series of fatigue tests to obtain all the data in Fig.1, it takes several years for one kind of metallic material. This circumstance introduces a serious difficulty to every researcher in the area of “Metal Fatigue” from technological and economical backgrounds. If the high loading frequency such as ultrasonic fatigue test was accepted to save the testing time, temperature raising of the specimen due to the internal friction would take place and some cooling system or intermittent loading system should be furnished to examine the original fatigue property[9-12]. Thus, the acceleration fatigue test by ultrasonic technology would cause new difficult subjects as the fatigue testing method to obtain the fatigue property at the usual frequency. In order to overcome these difficulties, authors have developed special types of fatigue testing machines in rotating bending, in which four specimens can be tested simultaneously[13,14]. Thus a series of fatigue tests even in gigacycle regime can be carried out within a reasonable time period. Based on this advantageous performance, the name of “GIGA QUAD” was accepted for this new machine. By using this machine of GIGA QUAD, fatigue tests can be performed much quickly comparing with the conventional testing machines, even if it is used with various environment options. Accordingly, this machine is useful to file up a number of fatigue test data in gigacycle regime for various kinds of metallic materials, and such databases can provide the fundamental design data for mechanical structures in the wide variety of the engineering application. 2. DUAL-SPINDLE ROTATING BENDING FATIGUE TESTING MACHINE This machine has two spindles and two specimens can be mounted at both ends of each spindle as indicated in Fig.2 and Fig.3. Each spindle is driven by an electric motor via a V belt and the number of revolution is counted by means of photo-sensor. Thus, this machine can perform fatigue tests for 4 specimens simultaneously. In order to apply the testing load, the corresponding weight is suspended through a helical spring attached to the outer bearing block. The rotating speed of the spindle, that is, the testing speed is 3,150rpm (52.5Hz) GIGA QUAD has two types of ‘YRB200’ and ‘YRB200L’ according to the loading capacity (Maximum load). The maximum load of YRB200 is 20kg, whereas the load of YRB200L is 80kg. Table 1. Specification of the Device YRB200 YRB200L Motor 0.2kw-4P 0.4kw-4p Capacitance 380V 380V Collet Chuck φ2.5～13 φ2.5～20 Max Load 20kg x 4 80kg x 4 Spindle Speed 3,150rpm 3,150rpm Weight 140kg 170kg Size 470x400x1050 800x660x1100 Spindle Number 2 2
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