13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- By means of this unit, a variety of environment varying cycles such as dried and humid environment after dropping the corrosive solution can be created easily. Figure 6. High temperature environmental testing unit 3.4. 2-step variable loading unit A special loading unit has been developed to perform the rotating bending fatigue test under the condition of 2-step variable loading. Stress applied to the specimen is provided by suspending the appropriate weight in the structure of the machine. In this unit, 2-step loading is applied by lifting a part of weight with air cylinder periodically in testing. By setting any value of the weight and the lifting period, one can perform fatigue tests in a wide variety of the testing environments close to real machines in the practical use. 3.5. Fracture alarm unit A fracture alarm unit which can detect fracture of specimen and inform the fracture to researchers via e-mail has been developed. In the case of fatigue test to obtain the S-N property, the test is repeatedly conducted by using a lot of specimens. In some cases, stress is changed with a definite time span in order to simulate the actual service loading. Since the fatigue life of each specimen has a distinct scatter, it is impossible to know the fatigue life exactly before the fatigue test. Due to this difficulty, every researcher has to come to the testing machine to confirm whether the specimen has failed or not. If the person does not notice the fracture of the specimen, he/she wastes much time to find the fatigue failure even though the number of cycles to failure is recorded. In order to prevent such a time consumption, this unit was originally developed here. Adopting this unit, the researcher can get the prompt information on the failure immediately after the specimen has failed. Thus, the next fatigue test can be started soon and the above time consumption can be effectively solved. In addition to this advantage, researchers’ mental stress to check the fatigue failure can be also reduced.
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