Structural dynamics engineers are asked to make measurements for distinguishing differences between two structures. A frequent approach is to compare the modal parameters by change in Modal Assurance Criterion behaviour which focuses only on the Eigen values and Eigen vectors. A Graphical method of comparison was found for simple structures, which considers the spatial distribution of the entire frequency response spectrum. Point compliances represented by a color scale are measured at short intervals along reference line on a structural edge and the result is a three dimensional representation of dynamic behaviour. Experiments were conducted and MATLAB toolbox along with Graphical User Interface for compliance maps was built.
Contents
1 Notation
2 Introduction
3 Theory of Modal Analysis
3.1 Multiple Degrees of Freedom System
3.2 Frequency Response Measurements
3.2.1 Types of FRFs
3.2.2 The FRF Matrix Model
3.3 Modal Testing
3.3.1 Measuring FRF Matrix Rows or Columns
3.3.2 Exciting Modes with Impact Testing
3.4 Data Acquisition
3.5 Modal Parameter Extraction
3.6 Definitions of Waterfall Diagrams and compliance maps
3.6.1 Waterfall diagrams
3.6.2 Compliance maps
3.6.3 Waterfall diagrams Vs Compliance maps
4 Experimentation
4.1 Simulated Rectangular plate
4.2 Rectangular plate
4.4 Measurement preparations
4.4.1 Suspension of the structure
4.4.2 Selection of excitation points
4.4.3 Method to excite the structure
4.4.4 Method to excite the structure
4.4.5 Accelerometer considerations
4.4.5.1 Type of accelerometer
4.4.5.2 Mounting techniques
4.4.5.3 Accelerometer calibration
4.5 Experimental setup
4.6 Analysis
5 Results and Discussion
5.1 Results of Simulated rectangular plate
5.2 Results of rectangular plate
5.3 Results of Skis
6 Conclusion and Recommendations
7 References
A User’s Manual
1 Introduction
2 Window layouts of the GUI
3 Start and run the program at the first time
4 List of MATLAB® functions supplied by Saven Edutech
Author: Chandrasekhar Reddy Chinthalapalle, Haribabu Gorrepati
Source: Blekinge Institute of Technology
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