Study the fatigue behavior of AISI 1045 steel using ultrasonic fatigue test machine

Nowadays industrial developments and applying more dynamic loads on metals have made the issue of fatigue, which approximately cause 90% failure of the metal components to important problem. Some examples of such failures found in aircraft, automotive and high-speed trains and turbines. This resulted in design for industrial for special attention to the issue of fatigue. In the last two decades a new branch called very high cycle fatigue (VHCF) in fatigue life had attend for researchers. Access to this number of cycles (107) and above by using contemporary testing devices due to low frequency, is time-consuming and costly and thus has not been considered in the past. For a lot of material fatigue failure after 107 cycles have been reported, i.e. in the range of very high cycle fatigue. Very high cycle fatigue properties is significant issue for ensuring long life and reliability machines and structural components due to the growing demands of the industry. To achieve this number of cycles the fatigue testing machine with ultrasonic method in frequency about 20,000 Hz was used, and due to high-frequency, time reduction and achieving to high cycle is goal of using this device so can be used to study the properties of very high cycle fatigue. In this study, after describing the process theory, description of components and carry out the design for the vibration transducer and fatigue test specimen fatigue testing machine using ultrasonic method in frequency of about 20 kHz was made in laboratory and then the fatigue behavior of AISI 1045 steel using these device is studied and finally the stress-life curve for this steel was obtained to 108 cycle and The results show that the fatigue life of the steel decreased to 204 MPs. Finally, due to the fracture surfaces the failure of a samples is described.