ANALYSIS OF VIBRATION MODES OF SEMI-TRAILER AXLE AND their effects on FATIGUE LIFE

Abstract

During the operation of the axle, the load acting on the axle housing in the vertical direction has a significant effect on the fatigue life of the components. Cracks are caused by a constant stress concentration in the axle housing, resulting in fatigue at the concentration point. If the load exceeds a certain threshold, microscopic cracks will begin to form at the stress concentration point. Later, the cracks grow due to the cyclic load of fatigue. Eventually, the cracks reach a critical limit and then the structure suddenly breaks. Axle housing failures are also affected by factors such as uneven load effect, housing slope, and eccentricity. The paper presents an analysis of reliability and damage to the rear axle of a truck semi-trailer caused by natural vibrations. For this purpose, finite element analysis where conducted, preceded by a theoretical introduction. Several vibration modes were considered in order to determine the most likely point of damage initiation to the semitrailer axle. Comparing the test results with the observations, it was found that natural vibrations in the range of 53-533 Hz may be the cause of the limited fatigue life of the main tube. Due to the greatest deformation of the central part of the axis during vibrations, the greatest stresses in the critical zone will occur for mode 8 at a frequency of about 533 Hz which also means many fatigue load cycles.