<p>In the first step of this study a rotating beam fatigue test setup is designed and constructed where two main bearings serve as fixed supports, while symmetric&#xa0;dead-weights are applied to the load bearings. Rotating steel beams are tested using the constructed test setup and following standard procedures. According to classical theory the fatigue failures of the test specimen are caused by the reverse bending moment induced by these dead-weights and of course the marine factors have influence on fatigue life. However, primary analysis indicates that the reverse bending stress in all cases is well below the endurance strength of the specimen material. Consequently, the specimens are not expected to experience fatigue failure. However, all the specimens fail after a specific time span, rendering the assumption of classical approach inaccurate and indicating some other factors (other than marine factors) must be considered for predicting fatigue life of those rotating steel beams. The main objective of this work is to trace/ find out the dominating factors. One important factor might be the vibration transmitted from the test setup to the rotating steel beams, which influences the fatigue life and is considered in the current study. The constructed rotating beam fatigue test setup is operated by a motor, which is directly coupled to the rotating beam specimen through a fixture. Thus, the rotation of motor serves as the primary source of vibration of the test setup. Therefore, the secondary step of this study was to characterize the test setup in terms of vibration. For this purpose, each bearing of the test setup was equipped with a MEMS-based accelerometer, specifically the ADXL345. Exhaustive analyses (based on Statistics and FFT) of the acceleration data reveals significant random vibration along multiple axes, indicating vibration transmission from the test setup to the test specimens must be considered in predicting fatigue life of the rotating steel beams.</p>