Aerodynamic/Structural Mistuning Technologies for Assessing IBR/Blisk Repairs

Blade-to-blade variations in frequencies lead to the phenomenon of mistuning. Even very small amounts of mistuning can cause some blades to vibrate much more than others. Mistuning can cause an amplification of resonant response by up to 400 percent, and has been identified as a primary factor in HCF failures. One issue in setting blend limits is whether or not the blending operation will exacerbate mistuning so that the Blisk will have significantly higher vibratory response and fail from HCF. It is proposed in this STTR that BDC’s mistuning technology be extended to assess the effect of blending on structural mistuning. The inspection machine could be used during the repair process to determine if blending produces mistuning that significantly increases the risk of failure from high vibratory response. Also, BDC will develop new technologies to assess how blending affects aerodynamic mistuning and to integrate these technologies with BDC’s Mistuning Inspection Machine. These new technologies will be developed using the combined strengths of Blade Diagnostics Corporation and Duke University. The technology is also applicable to other Blisk repair techniques that may result in non-standard blade geometries. Also, the latest models of commercial aircraft engines are also using IBRs/Blisks.