The Influence of Geometrical Correlation in Modal Validation Using Automated 3D Metrology
Structural analysis is a major part of all manufacturing and testing industries. The need for high level accuracy of the results in the testing field has increased progressively, resulting in development of advanced state of art techniques. In order to acquire the vibrational characteristics of a structure, a detailed Finite Element Analysis (FEA) modelling is performed. Also, Experimental Modal Analysis (EMA) is conducted to extract the dynamic characteristics of a structure. The results obtained from both the processes are correlated for validation purposes. Based on the correlation (good or bad) the structural analysis is validated. In most cases the correlation is not satisfactory; it is mainly because of the boundary conditions that differ in FE and EMA.
This research study explains in detail how important the boundary conditions are for modal validation. But the most imperative part, as the first step of correlation, is the geometry analysis. If the geometrical correlation is not accurate, the later part of correlation will turn out to be an assumption based on inaccuracies. Assumption of a geometrical correlation, without being sure of the differences, will lead to inaccurate results for validation.
A reference plate is tested and simulated by using EMA and FEA techniques respectively. EMA is conducted by using a 3D SLDV for measuring the output response and the input force of excitation is induced by a Scalable Automatic Modal hammer (SAM). This plate is then scanned using ATOS Triple Scan II GOM 3D geometry scanner. The scanned results are compared with the FE model of the reference plate.
The results presented show the importance of geometrical correlation for modal validation and provide results of deviations that were observed on a reference plate. With these conclusions, working on modal validation can be developed by reducing the inaccuracies for the presentation of correlation.
KeywordsExperimental modal analysis Impact modal testing Validation Geometrical correlation 3D geometry scanner FE Non-mass loaded impact
Computer Aided Design
Experimental Modal Analysis
Finite Element Analysis
Scalable Automatic Modal Hammer
- 3D SLDV
3D Scanning Laser Doppler Vibrometer
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