Cracks due to material fatigue are very dangerous for rotating machines. Early detection of any crack is therefore essential before permanent rupture and often fatal consequences can occur. The crack influences the vibration behaviour of the shaft by changing its rigidity. Using suitable analysis software, this change can be registered and inspection of the machine organised in good time.
In the experiment, the crack is simulated by an asymmetric flange joint. Variable tightening of the flange bolts produces a temporary gaping of the butt joint, which closely approximates to the behaviour of a crack.
The accessory setup includes two shafts of different lengths: one short and one long. The short shaft simulates a protruding shaft end, and is loaded with the PT 500.14 belt drive. The long shaft is used in conjunction with a safety bearing from PT 500.10 and an inertia disk from the base unit to investigate the effects of a crack in a shaft on the elastic rotor.
The accessory setup is mounted on the base plate of the machinery diagnostic base system PT 500.
To measure and evaluate the experiment, the computerised vibration analyser PT 500.04 is required. It includes all the necessary sensors, a measuring amplifier and analysis software to record the vibration phenomena.