Experimental Study on Vibration Characteristics of Bolt Joint of Combine Harvester under Multi-source Excitation

Various components of combine harvester are connected by bolts and their connectors, which affect and excite each other during working process, and have severe impacts, wear, and unbalanced collisions．Degree of looseness and main vibration at bolt connections was studied, time-domain characteristics of main working components of combine harvester during working process were extracted, and main frequency and harmonics response of bolts and their connections were analyzed．Results indicated that during normal operation, time-domain characteristic values of edge bolts of vibrating screen were at extremely high levels, and frequency components were also relatively complex．Main frequency of other measurement points was 34.7195 Hz, and there was no obvious sideband generated in frequency doubling．However, vibration screen bolts were not affected by engine rotation frequency and its doubling frequency, except for their own main frequency of 2.302 Hz and its high doubling frequency．It could be concluded that bolt connection of vibrating screen was subjected to the most severe and complex load, laying foundation for online monitoring of bolt and connector loosening and failure at vibrating screen．