Design of Accelerated Life Test for Sleeve Bearing of Construction Equipment Based on Wear Prediction

Joint bearings of attachments play a key role in the reliability of construction equipment. These joint bearings operate in very harsh environments with strongly varying dynamic impact loads and oscillating under low sliding speeds. The bearings therefore operate in boundary lubrication, which means that direct metal-to-metal contact inevitably renders the sleeve bearing highly prone to wear. The assessment of durability for sleeve bearings is carried out using a test bench with oscillatory motion. However, estimating a quantitative accelerated factor considering the actual operating conditions is limited. The aim of this work is to determine the experimental conditions of the accelerated life test and to analyze the quantitative accelerated factor considering the wear limits of bearings. The wear limits are determined by the analysis of dimensional management that simulates the dispersion of a bucket end position by using 3DCS dedicated software. The accelerated factor is obtained by the comparing the times required to reach the wear limits. This test duration is calculated by the prediction methodology of wear depth based on the correlation between wear rate and film parameter. After the wear tests are performed using a test bench with actual bearings, the wear depth is measured to verify the estimated bearings. The proposed methodology is useful to design an accelerated life test under periodically changed lubrication condition caused by oscillatory motion.