Fatigue Analysis Of Key Component Of Double Bundled Rope

The burning of straw in rural areas has become one of the culprits of polluting the atmosphere.Straw burning will produce smoke containing aerosol particles,which therefore leads to haze.In order to find a sustainable and economical comprehensive utilization of straw,local governments vigorously promote the straw baler.As the core parts of the baler,rope device completes the knot on the compressed straw.It need to complete a series of actions including sending,twining,knocking and backing away the rope for a total of 1 second.What's more,since the working environment is bad,the knitting period is short and the impact load is large,these conditions result in the key components hug line arm,olecranon,tooth plate,frame and other parts easy to wear,or even fracture.Therefore,fatigue analysis for the key components of the rope device has important practical significance.This thesis studies the rope device on the pick-up baler as the research object.Then it predicts the fatigue life of the rope device through the combination of the experimental analysis,the finite element analysis,the dynamic simulation and the fatigue analysis,which provides the basis for the optimization and improvement of the agricultural machines.The specific work as follows:First,the knotting test of the rope device is obtained by studying the construction and working process of the rope device and referring to the international and industry standard.Naturally,it is reasonable to get the performance index of the rope device and position the points of easy wear and fracture using relative analysis and derivation.The stress-strain of each mode and dangerous part are obtained in series of methods such as the metallographic microscopy and hardness test,obtaining the material properties of the steel heat treatment manual,dividing the hexahedral mesh produced by the finite element analysis software and carrying out the modal analysis and static analysis.Then,the rope device is used as the rigid body and the rigid-flexible coupling kinetic simulation to obtain the working spectrum of the rope device as the rigid body and as the flexible body,and the load spectrum is compiled by the rain flow counting method,which lays the foundation for the fatigue analysis.Secondly,according to the problems in the process of modeling for irregular components,the thesis adopts to point cloud extraction for these irregular components through the 3D scanner and three coordinate measuring machine and conducts 3D model building based on reverse engineering.Using a series of methods such as metallographic analysis and hardness test,comparing the steel heat treatment manual to get material properties,divided by a hexahedral mesh using the finite element analysis software and modal analysis and static analysis,then it is feasible to obtain each order modal vibration mode and stress – strain of dangerous parts.Then through establishing rope devices as analysis of rigid body and rigid flexible coupling dynamics simulation,obtained as a rigid body and rope as rigid-flexible coupling work spectrum,and Based on the rain flow counting method for load spectrum compiling,lay the foundation for fatigue analysis.Thirdly,the S-N curve of the material is calculated by the empirical formula of fatigue limit and strength.The S-N curve,the fatigue load spectrum,and the analysis of stress-strain progress import the fatigue software to analyze stress fatigue of key parts based on the Nominal Stress Method,and compare the analyses above with calculated results of fatigue life when the rope device is considered as rigid body and flexible body respectively.Then this thesis compares the simulation and calculation results with those of practical experiments.At least,the key components are optimized according to the results of experiment and fatigue analysis.The feasibility of the optimization is verified by comparing the fatigue life analysis before and after optimization.In addition,a series of methods in this thesis can predict the fatigue life period of key parts and life cycle in the stage of product development by fatigue analysis of key components of rope devices.As a result,we can reduce the huge development costs of the manufacturing physical prototype and conducting durability test.In a word,the research method of this thesis has practical value.