Static and vibration analyses of the blade disc system were then performed to obtain CCF test conditions and identify LCF load and HCF vibration frequency that produced maximum stress in the blade hazardous location.
The blade disc system, i.e., the compressor rotor system, connects the blades to the disc through pins, with the blades distributed around the edge of the disc.
During operation, the blade disc system is affected by unbalanced excitation causing the blade to vibrate.
The dangerous blade disc resonance speed was identified as 8425.51 rpm, and the first order bending vibration state (567.29 Hz) from static analysis is shown in Figure 5.
Single-blade vibration characteristics are meaningless and should not be used as the basis for HCF vibration conditions because practical situations almost invariably incorporate multiple coupled blade disc systems.
Vibration analysis of the blade disc system showed it was prone to first-order resonance and the sinusoidal excitation signal frequency [f.sub.H] = 251.68 Hz.
Caption: Figure 5: Static analysis of the blade disc system.
The company's Hucknall plant in Nottinghamshire makes a type of casing and combustion chambers, while its Annesley works, also in Nottinghamshire, makes blade discs
, or high-tech fan blades, known as blisks