Analysis Of The Natural Torsional Vibration Characteristics And Its Randomness For The Powertrain Of Multi-axle Driving Automobile

At this stage, the demand and application of multi-axle driving automobiles areincreasing in the fields of military and economy along with the rapid development ofChina. The high-power engines are usually installed in multi-axle driving automobiles,and there are high possibility of torsional resonance and strong harm for multi-axledriving automobiles because of the structural complexity and particularity of theengines. It’s required to do the analysis of the natural torsional vibrationcharacteristics for the powertrain of multi-axle driving automobile. In addition, theparameters of powertrain material and size will change owing to the error of materialinhomogeneity, manufacturing, assembly, installation and parts wear etc, and therandomness of the natural torsional vibration characteristics will appear. For thesereasons, it’s necessary to analyze the natural torsional vibration characteristics andits randomness for the powertrain of multi-axle driving automobile.Currently, the research on the natural torsional vibration characteristics for thepowertrain of multi-axle driving automobile is weak and further study is necessary.Road test of automobile torsional vibration is less, and the test method needs moreattention. The research and application of the randomness for automotive powertraintorsional natural vibration characteristics have not been carried out and they need tostrengthen.Based on the analysis above and the military cooperation projects, the analysis ofthe natural torsional vibration characteristics and its randomness for the powertrainof multi-axle driving automobile are done and the following work had been finished.(1) Study of the torsional natural vibration characteristics model for powertrain ofmulti-axle driving automobile and the parameter determination methodBased on the structural analysis along with the principles of modeling and mechanics theory, the models of the components of the multi-axle driving automobile powertrainwere established. The moment of inertia and torsional stiffness of the rotating partshad been obtained rapidly. Some parameters were provided by the company, andsome were calculated by the theoretical formula and empirical formula. The torsionalvibration parameters were normalized as the crankshaft speed based on theprinciple of normalization, and the normalized model of natural torsional vibrationcharacteristic for the powertrain of multi-axle driving automobile was established.(2) Analysis of the natural torsional vibration characteristics for the powertrain ofmulti-axle driving automobileThe finite element simulation method of the natural torsional vibration characteristicsfor the powertrain of multi-axle driving automobile was established based on ANSYS,and the test method was proposed based on the actual road test. Both the twomethods were used to analyze the natural torsional vibration characteristics for thepowertrain of multi-axle driving automobile. The rationality and effectiveness of thefinite element model were verified by comparing the simulation and test results, andthe use of speed fluted disc in road tests was proved to be rational. The position withrelatively large torsional vibration amplitude was found in the powertrain.(3) Analysis of the natural torsional vibration characteristics randomness for thepowertrain of multi-axle driving automobileThe powertrain of multi-axle driving automobile was considered as the system withrandom parameters, and the analysis method of natural torsional vibrationcharacteristics randomness for the powertrain of multi-axle driving automobile wasexplored by PDS (Probabilistic Design System) of ANSYS. The moment of inertiaand torsional stiffness were considered as the input random variables, and thenatural frequency was regarded as the output random variable. The randomness ofthe natural torsional vibration characteristics for the multi-axle driving automobilepowertrain was analyzed based on Probabilistic FEM. The statistical properties ofnatural torsional vibration frequency were acquired such as mean value, standarddeviation and the coefficient of variation etc. The important parameters with greatinfluence were determined by the sensitivity analysis. In order to meet the localization demand, the influence of the torsional vibration parameters of thehydraulic transmission gear to the natural torsional vibration characteristics of thepowertrain was analyzed, and the hydraulic transmission gear consists of torqueconverter and gearbox. Based on the analysis, the theory and method support wereprovided for the powertrain localization.