Dynamic Analysis, Dynamic Stress Simulation Research On Loading Equipment Of Backhoe Loader And Topological Optimization On Lift-arm

Backhoe loaders are high-tech product and have two capacities of excavating and loading.They were designed and produced in developed countries in the eighties of the twentiethcentury. They have broad purpose and are fit for municipal constructions, especially for diggingand laying pipelines. Equipments of backhoe loaders are various except for buckets and dredgebuckets, example for grab bucket, agitator, lifting fork, hydraulic hammer and so on. So theyplay important role in constructing roads, capital construction, mine, oil fields, irrigation works,loading materials etc.Backhoe loaders developed very late and were being lagging state. The velocity ofdeveloping is very slow. At present research on special eight bars mechanism of loadingequipment is little at home. Research on dynamic performance of the mechanism is not enoughand optimization is so little. Such as lift arm, the shape is still designed on trial and errormethod and lacks theoretical foundations.This dissertation researched dynamic characteristic, dynamic stress and topologicaloptimization of lift-arm based on the project—"Research and Development on different typesof linkage mechanism of loader equipment". The dynamic characteristic was analyzed based oncoupling hydraulic systems and multi-body mechanical systems;dynamic stress of engineeringmechanism was researched by way of combining multi-body systems and finite elementmethod based on ADAMS(Automatic Dynamic Analysis of Mechanical Systems) andANSYS;topological structure of lift-arm was optimized based on BESO(BidirectionalEvolutionary Structure Optimization).The main contents and research methods are presented in the following text.1. These theories of multi-body systems in ADAMS was expatiated systematically.Methods of building and solving the Lagrange's equation in multi-body systemswere presented in detail;Methods and theory of building the elastic bodies wereanalyzed;finally discussed the combining of multi-body systems and finiteelement methods.2. For the first time multi-body mechanical systems model and hydraulic systemsmodel of backhoe loader were built in ADAMS and coupling simulation wasachieved. Interactive actions in all working situation were analyzed includingscooping, lifting and unloading. This section paid attention to analyzing ontranslation, constraint force of joint and the pressure of head end and rod end ofactuator. The multi-body mechanical models of backhoe loader were built inCATIA then transferred into ADAMS and constricted;the hydraulic systemsmodels were built in ADAMS/Hydraulics and coupling simulation was achievedby actuators.3. Modal analysis of elastic body of loading equipment such as lift arm, drag bar androcker were completed in ANSYS, and then the MNF files were produced byspecial interface with ADAMS. Working equipment models of Rigid-elasticcoupling bodies were completed in ADAMS and laid a foundation for dynamicstress simulation.4. For the first time dynamic stress of working equipment was researched in allworking conditions including scooping, lifting and so on. And the dynamic stressdistribution characteristics of elastic components in time domain are obtained afterdynamic simulation. Thus the results laid a foundation for fatigue analysis and lifeestimate.5. Theories of ESO(Evolutionary Structural Optimization)were expatiated in detailThis method was achieved by secondary development in ANSYS and the APDL(ANSYS Parametric Design Language)was used. Validity and practicability ofESO method were testified by a simple example.6. Topological optimization on lift-arm of working equipment was implemented forthe first time. Firstly, the finite element models were built in ANSYS, and thenlift-arm of loading equipment is analyzed by BESO(Bidirectional EvolutionaryStructure Optimization)method under multiple loads and the results shows thatthis developed method was efficient and practicability. The method can be used intopological optimization without any limit.The meanings of this dissertation are presented in the following text.1. The meaning of dynamic analysis of equipment: mechanical analysis methods ofloading equipment had been static condition analysis and the dynamic analysis ofmain components was under scooping condition on the ground. The weight ofworking equipment is heavy so oscillating was produced on it under initialaccelerate and final decelerate and subsidiary loads came into being. So the dynamicanalysis had important meaning on loading equipment.2. The meaning of mechanical systems and hydraulic systems coupling simulation:Backhoe loaders are driven by hydraulic systems. Usually the dynamic analysishadn't considered the influence of hydraulic systems. This paper the models ofmulti-body mechanical systems and models of hydraulic systems were built and thencoupling simulation was implemented. Finally the dynamic performances ofequipment on hydraulic driving were obtained and modeling the interaction betweenthe hydraulic system and multi-body dynamics models. This method is suitable forany mechanical systems driven by hydraulic systems.3. The meaning of dynamic stress of loading equipment: This method makes dynamicstress of loading equipment obtain in design phrase and laid a foundation for fatigueanalysis and life estimate. Thus can shorten designing time , save cost and enhancingthe market compete capacity. This method can be used to aviation, transportationmobiles on the land or on the sea and so on.4. The meaning of lift-arm structural topological optimization: The lift-arm topologicalstructure had even stress distribution and smaller maximal stress by the BESOmethod. And had important meaning of shorten structural weight and heighteningworking efficiency. This method can be extended to optimize engineering structureor complicated continuum structure.In a word, this dissertation researched loading equipment of the backhoe loaderthoroughly and there were innovative achievements in dynamic stress and lift-arm topologicaloptimization. Thus results supplied warrant for designing and improving product. At the sametime, these methods can be used to other domains for dynamic analysis, dynamic stress andtopological optimization.