Multi-Sine Vibration Testing for Aircraft Structures
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Solution Overview
Problem
Current vibration testing methods for aircraft structures are inefficient, as multi-reference random excitation methods suffer from low signal-to-noise ratios, while sinusoidal sweep methods require multiple runs and prolong testing time due to their single-reference nature.
Innovation Solution
A multi-sine vibration testing method is employed, where multiple independent sinusoidal waveforms with different frequencies sweep continuously through a range of frequencies simultaneously, allowing for simultaneous excitation and measurement of frequency response functions, reducing testing time while maintaining data quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-reference random excitation methods are used, then all frequency response functions can be measured simultaneously reducing data collection time, but the signal-to-noise ratio becomes relatively low leading to unsatisfactory FRF results
Solution Approach 1:
The patent segments the excitation signal into multiple independent sinusoidal waveforms, each targeting specific frequency ranges or mode types (symmetric/antisymmetric). This segmentation allows simultaneous excitation of multiple references while maintaining the high signal-to-noise ratio of sinusoidal methods, resolving the contradiction between fast data collection and measurement precision
Solution Approach 2:
The patent creates a multi-functional excitation system where a single test run simultaneously performs multiple functions: exciting symmetric modes, exciting antisymmetric modes, and measuring all frequency response functions across the frequency range. This multi-functionality eliminates the need for separate test runs while maintaining data quality
2Measurement precision
If sinusoidal sweep methods are used, then higher RMS input loads and cleaner FRF results are achieved, but multiple sequential runs are required prolonging overall testing time
Solution Approach 1:
The patent merges multiple sinusoidal sweep excitations into a single simultaneous excitation signal. By combining multiple independent sinusoidal waveforms with different frequency characteristics into one composite excitation signal applied to multiple references at once, the system achieves both high FRF result quality and reduced testing time
Solution Approach 2:
The patent implements continuous useful action by maintaining simultaneous sinusoidal excitation across all references throughout the entire frequency sweep range. The multi-sine signal continuously excites multiple modes and references in parallel, eliminating idle time between sequential test runs and maximizing productivity while preserving measurement precision
Data Source
AI summary
A multi-sine vibration testing method includes coupling a vibratory excitation source and a sensor to a test structure, then providing a reference signal to the excitation source, wherein the reference signal comprises a first sinusoidal waveform having a first frequency and a second sinusoidal waveform having a second frequency different from the first frequency. The first frequency and the second frequency each sweep between a corresponding start value and a corresponding end value, and the frequency response is measured from each of the sensors while providing the reference signal.