Modeling, Analysis And Optimization Of Natural Torsional Vibration Characteristics For The Powertrain Of Multi-axle Heavy-duty Special Automobile

In recent years, the demand for multi-axle heavy-duty special automobile has beenrapidly growing along with the sustained development of China’s economy andmilitary. This type of automobile has a complex powertrain containing onehigh-power diesel engine and multiple drive axles. When the frequency of enginetorque is accordant to the torsional vibration natural frequency of powertrain, severetorsional vibration would appear. Torsional vibration could increase the dynamic loadon powertrain, and even lead to bad damage of certain automotive components，such as driving shafts, gears, couplings, etc. In addition, the longitudinal vibration ofvehicle body resulting from torsional vibration would also have an adverse impact onthe cargo.However, the torsional vibration damper of automobile powertrain is so small that thenatural frequency is close to resonance frequency of powertrain. Therefore,modeling, analysis and optimization of the natural characteristic is an effectivemethod in the study on torsional vibration for the powertrain of multi-axle heavy-dutyspecial automobile.In this paper, the following work had been finished in order to reduce the torsionalvibration of a multi-axle heavy-duty special automobile powertrain:(1) According to the real structure and movement principles of the powertrain of themulti-axle heavy-duty special automobile, a mass-spring model for natural torsionalvibration characteristic of the powertrain was established.(2) Referring to the theoretical and empirical formulas in other papers, theparameters of the mass-spring model were calculated. And then, the parameterswhich have significant influences on natural torsional vibration characteristic of thepowertrain were also selected. What’s more, the multi-axle heavy-duty special automobile test for torsional vibration and parameter sensitivity analysis of naturaltorsional vibration frequency was conducted. Finally, a more precise calculation forthe parameters selected above was done.(3) A mass-spring model for the natural torsional vibration characteristic of themulti-axle heavy-duty special automobile powertrain was also established withANSYS, and the natural torsional vibration characteristic was obtained through themodal analysis. The effectiveness of this mass-spring model for natural torsionalvibration characteristic was validated with the data of real automobile test fortorsional vibration.(4) According to the theoretical analysis of the engine harmonic excitation, and basedon the data of the multi-axle heavy-duty special automobile powertrain test fortorsional vibration and common speed range of the engine on the automobile, thefrequency range of torsional vibration resonance was obtained. And then, thedangerous natural torsional vibration frequency of the powertrain was known with thenatural torsional vibration frequency taken into account. At last, a Finite Elementoptimization model was also established with ANSYS to complete the optimization ofnatural torsional vibration frequency for the automobile powertrain.(5) A program used for automatic modeling, analysis and optimization for naturaltorsional vibration characteristic of the multi-axle heavy-duty special automobilepowertrain was also introduced in the paper. This program was realized by theANSYS Parametric Design Language (APDL).