FATIGUE LIFE ANALYSIS FOR THE CLEANING SIEVE BOX OF A COMBINE HARVESTER BASED ON MEASURED LOADS

The cleaning sieve box is a key component to achieve the cleaning of a combine harvester, and its service life directly affects the reliability of the entire machine. Aiming at the high quality of the cleaning sieve box and the cyclic loading during operation (which can easily cause fatigue damage and affect its service life), a fatigue durability analysis method for the cleaning sieve box based on a test bench is proposed. First, the deformation and stress distribution of the sieve box are analyzed through modal and dynamic simulation to identify the hotspots of fatigue damage in the sieve box. On this basis, a sieve box test bench was designed and built to collect load signals of the sieve box. The layout of sensor measuring points was optimized based on simulation results and the force characteristics of the sieve box was analyzed through signal processing. Then based on the load signals from multiple measuring points, a fatigue load spectrum was developed using nCode software, and the fatigue life of the sieve box was predicted using Miner's fatigue damage theory. The results indicated that there are multiple stress concentration areas in the connection area between the shaking plate, fish scale screen and the side wall of the screen frame of the sieve box, which are the fatigue damage risk areas. The stress value in the connection area of the tail screen is the highest. Overall, the fatigue life of the front half of the sieve box is generally higher than that of the rear half. The connection area between the side walls of the screen frame and the tail screen is the weak fatigue durability area, with fatigue lives of 5.829 × 106 and 5.591 × 106 cycles, respectively. This study provides a certain basis for the design and optimization of the cleaning sieve box structure.