Abstract
Diaphragms made of stainless steel plates are widely used as switching parts in electrical devices. Since the cyclic loading is applied to these diaphragms by the repeated switching mode of on/off, the estimation of the fatigue life of diaphragms is very important. The fatigue characteristics of the diaphragm must be discussed considering the large scatter of material properties induced by the anisotropy. In this study, the tensile and the fatigue tests have been carried out for some specimens with a direction to cold rolling direction. A pulley driving system has been adopted as a fatigue testing apparatus because the load can be applied even when the thickness of the specimen is less than 0.1mm. From the experiment, it is recognized that the experimental data is scattered largely. In addition, the residual stress is generated by a press forming process and the stress acts on the diaphragm as a mean stress. In order to estimate the reliability of a diaphragm, therefore, the Goodman diagram with a design margin which can be considered the mean stress for fatigue can be obtained. We have proposed the method which can evaluate the reliability of a diaphragm to design life by Goodman diagram.
