Authors

Abstract

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.

Abstract in Chinese

清选筛箱是实现联合收获机清选功能的关键部件，其使用寿命直接影响整机可靠性。针对清选筛箱质量大，工作时承受往复周期性载荷，易造成疲劳损伤且影响使用寿命，本文提出一种基于试验台架的清选筛箱疲劳耐久分析方法。首先，通过模态和动力学仿真，分析筛箱的变形、应力分布情况，识别筛箱疲劳损伤热点区域。在此基础上，设计并搭建筛箱试验台架以采集筛箱载荷信号，基于仿真结果优化传感器测点布置，并通过信号处理分析筛箱受力特性。结合多测点载荷信号，采用nCode软件编制疲劳载荷谱，并基于Miner疲劳损伤理论，对筛箱疲劳寿命进行预测。研究结果表明，筛箱内部抖动板、鱼鳞筛等零部件与筛框侧壁连接区域出现多处应力集中区域，为其结构的疲劳损伤危险区域，其中尾筛连接区域应力值最大。整体而言，筛箱前半部分的疲劳寿命普遍高于后半部分，筛框两侧侧壁与尾筛的连接区域为筛箱结构中疲劳耐久薄弱区域，其疲劳寿命分别为5.829×106、5.591×106循环次数。该研究为清选筛箱结构设计和优化提供了一定参考依据。