- Design the most advantageous crowning for pinion gear teeth to minimize stress by increasing contact area and decreasing average contact stress.
- The engineers at Nabtesco used Abaqus finite element analysis (FEA) software to calculate the contact area and stress of various pinion gear designs. With the help of their own subroutine, the engineers were able to model both contact area and stress history for easier design evaluation. Isight was also utilized for post-processing automation and design optimization.
- Abaqus allowed the Nabtesco engineers to maximize gear contact area, while minimizing average stress contact. This resulted in a significantly more durable gear design that led to decreased maintenance and cost without requiring numerous physical experiments. With Isight, the design time was reduced drastically.
Gearing up for large wind turbines
Precision yaw and pitch drives for robotic reduction gears are a specialty of Nabtesco Corporation of Japan, known worldwide for unique technology that allows those components to be smaller and lighter than many conventional robotic drives. But when the company expanded into energy harvesting equipment, such as wind turbines and solar energy collector trackers, they realized that ‘smaller and lighter’ have their limits in large industrial structures. “Particularly in the wind industry, our biggest challenges are ensuring sufficient gear strength and long-term endurance in gusty conditions,” says Kazuhiko Yokoji, CAE manager, CAE & material department, whose team provides computer-aided engineering (CAE) services for the entire Nabtesco group. “Our reduction gears are made up of a lot of very complicated assemblies, with many parts that come in contact with one another. For each wind turbine configuration, we have to provide our customers with the best possible design that minimizes overall stress while maintaining durability.”
Every yaw and pitch drive in a wind turbine engages with a pinion gear, made from specialized treated steel, that transmits power from the drive to the nacelle or blade. In a huge wind turbine, the rotation angle between drive and pinion gear teeth is particularly small, so repeated contact over time—particularly under the ‘routine’ stresses of high winds and tower vibration—has the potential to damage tooth surfaces and cause assembly breakdowns.
Our CAE workflow now enables us to optimize crowning of pinion gear teeth designs accurately and with far less manpower than before. This method reduces design times dramatically.
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