Gear tooth root fatigue test monitoring with continuous acoustic emission

A test rig is used to load an individual gear tooth in static bending fatigue. The two gears are meshed together, with the lower (fully restrained, rotation prevented) gear attached to a fixed shaft whilst the upper (free) gear is mounted on a shaft held in bearings. A torque is applied to this shaft using a compression testing machine via a loading arm. Acoustic Emission signals were collected by a Pancom P15 sensor (50 – 500 kHz) coupled to the free gear adjacent to the tooth under test using cyanoacrylate adhesive. The data was recorded by a MISTRAS group PCI 2 data acquisition system. Complete wavestreams were captured over one loading cycle. These wavestreams capture the sensor output without any interpretation by the data acquisition system, and are independent of threshold. Each wavestream was collected every 10 cycles, sampled at 2MHz, 16-bit resolution and a duration of 1s, which covers one complete tooth loading cycle.