Dynamic Analysis And Strength Research On Tree-pushing Device Based On Bulldozer Chassis

Bulldozer is modified into treedozer to adapt the forest logging. Comb-teeth blade is a new type of tree-pushing device of bulldozer. It is mainly used to reclaim wasteland and clear shrubs. Changing the traditional blade into the comb-teeth style makes it much more efficient because the comb-teeth blade can hold the shrubs in it while eliminating the soil. This paper primarily focused on rigid flexible coupling analysis for the two important components of comb-teeth blade: comb-tooth and launching bridge. Then fatigue simulation analysis was done for the comb-tooth. Stress distribution and fatigue damage distribution of comb-teeth and launching bridge were got and fatigue life of the tooth was evaluated. The main contents of the paper are as follows:1. Based on the relevant domestic and foreign documents, the development of bulldozer and application status in logging industry was summarized. Several kinds of logging bulldozers were briefly introduced. Structure characteristics of comb-teeth blade were analyzed and research objectives and contents were raised.2. The resistance strength model of comb-teeth blade was built based on the properties of operation object and characteristics of mechanical structure. The resistance faced by the blade includes both roots of shrubs and soil. The shear strength model of soil-root system was built based on Coulomb Law and Wu-Waldron Model. The loads on comb teeth blade were mainly from the digging, holding and raising stages. Both normal loads and ultimate impact loads were analyzed for each stage. The comb-teeth blade consists of 15 teeth and 2 side-teeth. In one case, the loads were distributed equally to the teeth which reflected the normal working situation. In another case, the loads were imposed on one tooth only which reflected the maximum loads to a tooth in all the possible impact cases.3. The strength of tooth and launching bridge were analyzed through ADAMS and ANSYS co-simulation. Because the 15 teeth are same, only one was chosen as the target and was made into a flexible body. As a result, the ultimate stress appeared in the holding stage when the tooth was attacked by imposed loads. The stress was smaller than the yield limit which proved that the tooth could fulfill the strength requirement. The load on launching bridge was influenced by the position of impact load. In the simulation of launching bridge, the impact load imposed on the middle, right and left site of the blade respectively. The result of each situation was analyzed and none of them exceeded the yield limit.4. Fatigue life of the tooth was predicted with the fatigue analysis software MSC.Fatigue. The result file(.rst format file) and the load file(.dac format file) had been gained from the achievement of former work. After they were input into the software, some necessary arrangements were settled. Fatigue life was evaluated with the life repeats map and damage map of the structure.