From f836847451286879f7b09e7fa244dcc9d38550d4 Mon Sep 17 00:00:00 2001 From: "E. Cheynet" Date: Thu, 14 May 2020 16:50:46 +0200 Subject: [PATCH] Update README.md --- README.md | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/README.md b/README.md index 9800ad6..92d3d75 100644 --- a/README.md +++ b/README.md @@ -1 +1,24 @@ -# OMA_1SDOF \ No newline at end of file +# OMA_1SDOF + + +## Summary +If the free-decay response (FDR) of a SDOF is not directly available, it is possible to use ambient vibrations data yo estimate the modal damping ratio. Here, the Random Decrement Technique (RDT) [1], as well as the Natural Excitation Technique (NExT) [2], are used. First, the response of a SDOF to white noise is simulated in the time domain using [3]. Then the IRF is computed using the RDT or NExT. Finally, and an exponential decay is fitted to the envelop of the IRF to obtain the modal damping ratio. + +## Content + +The present submission contains: +- a function RDT.,m that implements to Random Decrement Technique (RDT) +- a function NExT that implements the Natural Excitation Technique (NExT) +- a function expoFit that determine the modal damping ratio by fitting an exponential decay to the envelope of the IRF. +- a function CentDiff used to simulate the response to a white noise load of a SDOF in the time domain. +- An example file Example.m + +Any question, comment or suggestion is welcomed. + +## References + +[1] Ibrahim, S. R. (1977). Random decrement technique for modal identification of structures. Journal of Spacecraft and Rockets, 14(11), 696-700. + +[2] James III, O. H., & Came, T. G. (1995). The natural excitation technique (next) for modal parameter extraction from operating structures. + +[3] http://www.mathworks.com/matlabcentral/fileexchange/53854-harmonic-excitation-of-a-sdof