Session: 30-07 Mistuning

Paper Number: 82173

82173 - Blisk With Small Geometry Mistuning and Blend Repair: As-Measured FE Model and Experimental Verification 

Bladed integrated disks (blisks) are subjected in service to inevitable blade damages like foreign object damages or loss of small parts of material due to wear.  The “blend repair”, as a cost-effective routine repair path for blisks, allows to remove the minor damages on the blade maintaining its functionality as much as possible. Predicting the influence of the blend repair on the dynamics of a blisk is relevant in order to  avoid  possible failures not foreseen at the repair stage. Building a blended blisk model could be very challenging since small-sized blends may in fact alter both the blade frequencies and the mode shapes, inducing further mistuning in the blisk.

This paper presents an ‘as-measured model’ of a blended blisk, built after the detection of the true geometry of the blisk by a 3D optical scanning system. An improved mesh deforming method was developed to adapt the mesh on the as-measured geometry. As a result, the blisk model explicitly represents the geometric features of the blades in the presence of both small blade-to-blade geometry deviations and blends repairs.

The capability of the as-measured model to represent the dynamics of the realistic blended blisk will be experimentally verified by blade detuning tests. The Blade detuning test consists of blade-by-blade impact testing on the blisk where detuning masses are purposefully attached on all the blades except the one currently under test. Due to the quite simple test setup and implementation, the detuning test enables to estimate the blade frequency mistuning pattern of the blisk with low experimental effort. However, it was proved that non-negligible residual inter-blade coupling is responsible for an inaccurate identification of the truly ‘blade-alone’ mistuning pattern from the blade detuning test results. Therefore, a novel mistuning identification method, recently developed by the authors, will be employed in order to improve the accuracy of the estimated mistuning pattern. Comparison of the experimentally derived mistuning pattern against the numerical counterpart will be fully addressed.

Presenting Author: Biao Zhou Nanjing University of Aeronautics and Astronautics

Presenting Author Biography: Dr. Biao Zhou obtained a degree of PhD in 2013 in Mechanical Engineering in &#201;cole Centrale de Lyon, France. Since <br/>2015 he has been associate Professor in structural dynamics in Nanjing University of Aeronautics and Astronautics, China. Currently he is working as Marie Skłodowska-Curie Individual Fellow in Politecnico di Torino, Italy during 2021~2023. His research interests focus on structural dynamics of bladed disks and dynamic testing.

Authors:

Biao Zhou Nanjing University of Aeronautics and Astronautics
Jingchao Zhao Nanjing University of Aeronautics and Astronautics
Nan Ye Nanjing University of Aeronautics and Astronautics
Teresa Berruti Dipartimento di Ingegneria Meccanica e Aerospaziale, Politecnico di Torino