Advancing Mistuning Identification and Dynamic Modeling of Blisks Through Blade Detuning Tests

Abstract

Blisks extensively used in advanced aeroengines are vulnerable to vibration problems due to the high sensitivity of the blisk’s forced response to blade mistuning. This paper proposes an emerging mistuning identification technique based on blade detuning tests (BDTID) for predictive dynamic modeling of blisks. The conventional frequency-mistuning modeling approaches relying on blade mistuning identification by reduced-order model techniques and modal test data of the full blisk are also adopted to construct different mistuned models of a blisk test piece for comparison purposes. A complete assessment of these blisk models is achieved through the forced response tests in a stationary traveling wave excitation test rig. The BDTID consists of blade-detuning tests followed by a correction procedure. The detuning tests enable us to approximately evaluate the “blade-alone” frequencies through blade-by-blade impact testing in combination with a mass detuning mechanism. The correction procedure is able to evaluate the detuning test quality by the quantification of the residual interblade coupling due to mass detuning. More importantly, a robustness investigation demonstrates that this procedure is able to capture the “true” blade mistuning even in cases of poor blade detuning test quality. The resultant mistuned blisk model exhibits high accuracy in the modal correlation and forced response validation results. Compared with conventional methods, BDTID takes advantage of easy implementation with less experimental effort and has proven robust performance. It is therefore recommended for blade mistuning identification and predictive blisk dynamic modeling in a wide variety of scenarios.