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This paper proposes a mixed hardware and software solution to impose different controlled dynamic load patterns to a bladed disk using non-intrusive acoustic excitation. The test bench is coupled to an autonomous measurement system consisting of an infrared Laser Doppler Vibrometer (LDV) placed on a robotic arm. The development of the test bench is described from the definition of the requirements up to the calibration of the different components (acoustic excitation devices, power amplifiers, LDV positioning, etc.). The relation between the supplied voltage and the resulting pressure acting on the blade is also assessed. The main application of the developed test bench consists in the imposition of Standing or Traveling Waves Excitation in order to appropriate a given nodal diameter content and experimentally study the response to typical excitation pattern encountered when integrated on motor. Another application consists in the experimental mistuning measurement through modal analysis and the use of the Inverse Component Mode Mistuning method.

This paper introduces an improvement of the stress calibration methodology of stator blades to consider a nodal diameter of interest of the structure. The proposed calibration procedure and the search for optimal excitation set-up are detailed. To this purpose, the following points are addressed. Experimental modal analyses are performed using both accelerometers and strain gages. Post-processing techniques are developed to determine the nodal diameters of the identified modes. SAFE (Singh’s Advanced Frequency Evaluation) diagrams are computed from the experimental data and compared with the diagrams obtained numerically by finite elements computations. Multiple excitations are used to appropriate the targeted modes. A comparative study of different shaker types, of the number of excitation points and of their location is performed. Calibration is achieved by comparing strain measurements taken on one gage installed on the engine and velocities measured using laser vibrometers. It allows reducing the impact of the instrumentation on the modal content. The calibration factors obtained by the novel proposed procedure are compared to the ones given by the currently used methodology.