Vibration-based Health Monitoring of Damaged Bevel Gears Using Adams

California Polytechnic State University uses Adams to simulate bevel gears in order to study power transmission systems
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Gear systems play an important role in power transmission systems. Bevel gears play important roles in vehicle differentials, where the direction of drive from the driving shaft must be turned 90 degrees to drive the wheels. The ability to detect gear system faults without disassembling it is highly desirable as undetected cracks on gear teeth are potential source of catastrophic failures in gear transmissions. Distinctive damage diagnostic measurements observable with vibration sensors are desirable in industrial application.

The purpose of the simulation was to model a gear system attempt match the predictions from a newly developed theory by General Electric called Sideband Energy Ratio (SER). In being able to match these predictions, it allows for the possibility to use Adams to further study the vibration signals from gear systems as well as try mimic real life operation. Preliminary models were performed and compared to theoretical mathematical models to validate the approach to simulating the bevel gear system. An actual 2:1 damaged bevel gear system was also tested to confirm the validity of SER.

With Adams Software, analysis on the contact forces between the bevel gears was performed. From the contact force, we were able to analyze vibrations signals from both an undamaged and a damaged bevel gear system. The signals from the contact forces were analyzed in frequency domain. The Adams Software was able to successfully show the theory of SER. The SERs calculated for our simulations had a mean of 0.970 for the undamaged gearing system, which is less than one as our predictions and theory would suggest. For the damaged system, the mean was 2.55 which is well over 1 and also matches our predictions and theory.

Adams Software with all its new updates will allow for more complex simulations to be performed. With ViewFlex, modeling flexible parts becomes much easier. It eliminates the need to use a FEA program to perform modal analysis on parts and then import a modal neutral file into Adams through Adams/Flex to change a rigid body into a flexible body. Adams/Machinery also provides a large library of gears and bearings that allow for quick modeling and significantly cuts down on time spent modeling in CAD programs. CAD models can take hours to make and import into Adams. When a small change is needed, the whole process would need to be redone.

Adams Software has allowed for analysis on gear systems that mathematical models could not provide due to the complexity and nonlinearity of gear contact.

Xi Wu PH.D., Brian Fang