This MDOF example can be viewed as the superposition of dynamic behavior of a number of SDOF systems .
An MDOF curve fitting algorithm based on least squares was used to account for the closed modes.
These include multishaker single-axis as well as multishaker multiaxis both for MDOF
single table tests and in cases where multiple shakers are directly attached to the unit under test.
Smallwood proposed control algorithms for MDOF random vibration as far back as the late 1970s, MDOF vibration was not formally recognized in the MIL-STD-810 until the 2008 release of MIL-STD-810G.
While modern MDOF excitation systems generally are designed to be multipurpose as discussed above, they are still found in various sizes ranging from table sizes of under 100 square inches with frequency response on the order of 5 khz to large earthquake systems capable of imparting motion on entire building assemblies with a frequency response generally below 100 hz.
Development of MDOF specific reference criteria and the inclusion of the MDOF criteria in military specifications are essential to the accuracy of an MDOF vibration test.
In this paper an original algorithm for automatic and robust identification of a linear SISO MDOF dynamic model of an experimental frequency response was presented.
Component, Kennedy-Pancu/Circle-Fitting ) Inverse Method (Bendent/Dobson F S I Method ) Ewins-Gleeson method  F M I Wavelet-based identification B M I methods [23-27] Method (versions and references) Highlights Linear Least Squares Method in No control on the nature of poles the Time Domain (Prony classical and zeros; ill conditioned and version ; ARMA / ARX/IIR+OE sensitive to noise; poor versions ) interpolation capabilities in the presence of MDOF systems.
The commercial analysis program SAP2000 was used to perform the Time-History Analysis (THA) of the MDOF system subject to all 14 records.
Since the Time-History records used to analyze an MDOF system are scaled to match the design response spectrum, a Single-Degree-Of-Freedom (SDOF) can be used for preliminary analysis [?
THA was performed using SAP2000 for three MDOF systems representing a typical seismic-isolated structure with a natural period of vibration equal to 2.
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