Geometric Optimization of Ultrasonic Fatigue Test Specimens Based on Thermo-Elastic Behavior

Nowadays, the number of oscillations applied to some parts reaches the range of 107 and higher. Recently, researchers have used ultrasonic fatigue tests to study the fatigue behavior in these parts. This device is considered because of the high frequency of loading and as a result, achieving a higher number of oscillations in a shorter time. There is no universally accepted standard for this test, therefore, one of the geometries that are often used as a sample in this test is the geometry in the form of an hourglass In this research, while investigating this geometry in order to achieve optimal geometry or achieve maximum stress, the effect of geometric parameters on temperature increase during high-frequency vibration or the thermoelastic effect, which is known as one of the disadvantages of ultrasonic fatigue testing, has been investigated. This effect should also be minimized. For this purpose, the dimensions of the hourglass geometry were defined as parameters and its changes were investigated using the simulation. The results showed by decreasing the radius of curvature, along with the stability of the middle diameter and the diameter of the cylindrical part, the amount of stress increases and also the amount of temperature changes decreases. On the other hand, the diameter of the cylindrical part increases, while the middle diameter and the amount If the curvature is constant, it will increase the amount of stress and temperature. The above results were evaluated using the experimental arrangement and a good match was observed in them.