The Time domain decomposition (TDD)  is an output only method to extract mode shapes of a structure. Here, the modal damping ratios are in addition extracted by using the functions presented in . The TDD is based on a more famous technique called Frequency domain method (FDD) that was introduced by [2,3]. An Awesome example of FDD already exists on matlab File Exchange . In a previous version the present submission contained a function for the FDD. This function has been modified and moved to a new submission .
This script contains:
- The function TDD.m : function to apply the TDD method.
- An example file Example1.m
- Acceleration data beamData.m (4 Mb)
Comments, suggestions for improvements and questions are welcome. All the credits for the theory go to  and .
 Byeong Hwa Kim, Norris Stubbs, Taehyo Park, A new method to extract modal parameters using output-only responses, Journal of Sound and Vibration, Volume 282, Issues 1–2, 6 April 2005, Pages 215-230, ISSN 0022-460X, http://dx.doi.org/10.1016/j.jsv.2004.02.026.
 Brincker, R.; Zhang, L.; Andersen, P. (2001). "Modal identification of output-only systems using frequency domain decomposition". Smart Materials and Structures 10 (3): 441. doi:10.1088/0964-1726/10/3/303.
 BRINCKER, Rune, ZHANG, Lingmi, et ANDERSEN, P. Modal identification from ambient responses using frequency domain decomposition. In : Proc. of the 18*‘International Modal Analysis Conference (IMAC), San Antonio, Texas. 2000
Example file contains one more figure
Major changes: The example file and TDD.m function are simplified. The modal damping ratio are now calculated. The code for FDD has been moved to File ID: #57153
MathWorks update: Added Live Script.
-typo + picture
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