Simulation Study On The Working Device Of Harvester

The harvester is an automated,efficient,versatile woodland harvesting device.Compared with traditional harvesting techniques,the harvester has unparalleled advantages in harvesting artificial forest.A harvester can do all the work instead of multiple machines,from harvesting,lopping,bucking,topping,to piling,saving the economic cost and improving the work efficiency.With the growing demand of domestic forest products,inventing a multifunctional,high efficient and adaptive harvester,in line with our national conditions,will become an important direction for the development of domestic forestry machinery.As important parts of harvester,the boom and head are the core technology of harvester,and the rationality of their design directly determines the efficiency of harvester and the performance of equipment.The main research contents of this paper are as follows:(1)Structural design: After studying the present situation and existing problems of the harvester at home and abroad,the whole structure of the working device of harvester is designed,and the operation process is determined.Moreover,the kinematic theory of the working device of harvester is calculated and analyzed.(2)To establish a virtual prototype: With powerful functions of Pro/ENGINEER Wildfire 5.0,i.e.,three-dimensional model,motion simulation and analysis of mechanisms,the virtual prototype of the working device of harvester is conducted,from modeling,assembling,to motion simulation.(3)Finite element analysis: As the main bearing part of the working device of harvester,the boom is carried out finite element analysis by ANSYS Workbench 14.0.The stress and displacement figures of the boom along the X,Y and Z axes under static load are obtained.As well as the equivalent stress,total displacement and equivalent strain figures are to check the boom in terms of strength and stiffness to meet the requirements.(4)Structural optimization: With the target-driven optimization method of ANSYS Workbench 14.0,the structural optimization of the boom is carried out.In addition,the objective function is the minimum mass of the boom,the design variable is the thickness of the multiple baffles,and the constraint is to meet the strength and stiffness requirements.The results were as follows:(1)A simple structure and reasonable working device of harvester was designed,fully meeting the requirements of cutting and thinning in artificial forest,and adapting to the present situation of forestry in China.The kinematics equation of the working device of harvester was established by D-H method,and its positive and inverse solutions were obtained,which provided the kinematic theory algorithm for similar mechanical research.(2)The whole process of the working device of harvester was conducted,from threedimensional designing,modeling,assembling,to motion simulation,and the movement trajectory,velocity and acceleration of the main points were obtained.Meanwhile the operational range of the boom,the movement envelope of the head,and other operating parameters were gained,indicating that the desired function could be achieved.(3)The maximum stress of the boom was 161.81 MPa less than the allowable stress of 181 MPa,the maximum displacement was 6.127 7 mm,and the maximum strain was 0.000 785 73,both within the allowable deformation range,indicating that the design of the boom met its strength and stiffness requirements.(4)Before the optimization,the quality of the boom was 1 073.1kg,while after the optimization,the quality of the boom was 958.93 kg,reducing the 10.64%.The final result has achieved light weight of the boom,saved the material,reduced the energy consumption and economic cost,and improved the product performance.