Compressor blade failure

Objectives

• To determine the primary and secondary causes of compressor failure.
• To determine the crack growth history using materials characterisation, fracture mechanics techniques and component modelling.

Approach

• Blades, airfoils and platforms from several stages of the rotors and stators were extensively examined to identify the principal fracture mechanisms.
• Fractures in the compressor disc rim dovetail slots were also examined as a result of finding no evidence of primary failure in the blades.
• Materials characterisation of the blades and disc material in order to confirm that the material met specification requirements. The generation of crack propagation rate data for the disc material in order to carry out crack growth prediction studies.
• Component modelling and fracture mechanics to determine the stress conditions in the disc rim dovetail slots and the life to failure of cracks.

Benefits

• Confirmation of likely failure modes. (HCF cracking within the compressor disc dovetail slots)
• Elimination of foreign object damage, blade cracking and material properties as primary causes of failure.
• Increased knowledge of possible failure modes and optimisation of inspection requirements and scheduling.

Conclusion

The investigation confirmed that there was no evidence, on the damaged components supplied, of foreign object damage or compressor blade fatigue failure. The investigation confirmed the existence of high cycle fatigue cracking, initiating in the dovetail slots, in the rim of a compressor disc.

For more information please email contactus@twi.co.uk.