Dynamic gearbox simulation for fault diagnostics using a torque transducer

Christopher Jon Bruns, Purdue University

Abstract

Gears are common mechanical components used to transfer torque. A gear train consists of multiple gears on multiple gear shafts with the purpose of producing an output torque or speed proportional to an input torque or speed. Gear trains are usually housed in a gearbox, which contains the gears, gear shafts, bearings, and some sort of lubrication. Gearboxes are found in many applications including automotive transmissions, wind turbines, helicopter engines, and geared motors. Essentially anywhere a rotational motion is produced, gears can be used to transfer that motion using a constant of proportionality to the output torque and speed. Gearboxes are prone to mechanical failure due to the surface contact between and fluctuating stresses on the gear teeth. Fatigue cracks, pitting, wear, and lubrication degradation are common precursors to severe failure such as chipped or missing gear teeth, which could have catastrophic effects on the gearbox and surrounding mechanical components. Gearbox diagnostic methods could allow for the detection of deterioration in the health of the gear train. The use of a torque transducer on a gear shaft to measure the torsional vibrations of the gear train has the potential to detect gearbox faults. Such a detection system could make the user of a gearbox aware of the need for repair or replacement of gearbox components before more serious failure occurs. This research presents techniques that are used to mathematically model a gearbox and faults within the gearbox in order to predict the capabilities of the torque transducer to detect gear failure. The effects of gear failure and deterioration on the torsional vibrations of the gearbox are also analyzed. Data collected during experimentation with a gearbox fitted with a torque transducer is presented and compared to the analytical model. The modeling techniques accurately calculated the gear mesh stiffness properties for a wide range of gear tooth health conditions. Then, the same modeling techniques within a simulation environment were able to show the effects of gear damage on the dynamic response of the system measured by a torque transducer. The simulation results correlated well with the experimental data, but due to the lightly loaded nature of the test gearbox, the dynamic effects of the included faults were not as clear in the experimental results as in the simulation results where the load was increased.

Degree

M.S.M.E.

Advisors

Adams, Purdue University.

Subject Area

Mechanical engineering

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