Welcome to Vibrationdata
Modal Testing & Statistical Energy Analysis Page

 Dear Guest,
Writing tutorials and maintaining a website are expensive endeavors. I need your help to continue this effort. Your subscription will allow me to continue this site and to add new materials.

The software and tutorials require a username and password which are given by subscription. The subscription instructions are given below.
The subscription entitles the user to download all of the items on this page, as well as other Vibrationdata pages.


Thank you for your support.
Sincerely, Tom Irvine
Email: tomirvine@aol.com

MODAL TESTING
An Introduction to Frequency Response Functions:  frf.pdf
The Impulse Response Function: impulse_response_function.pdf
Response of a Single-degree-of-freedom System Subjected to an Impulse Force: force_impulse.pdf

The Impulse Response Function for Base Excitation:  impulse_response_function_base.pdf
Nyquist and Nichols Plots: Nyquist_plot.pdf

The Steady-State Frequency Response Function of a Multi-degree-of-freedom System Subjected to Harmonic Base Excitation: mdof_FRF_base.pdf
Structural Dynamics Testing using an Impulse Force:  structd.pdf
This tutorial also covers use of the exponential window.

Exponential Windows: expw.pdf. Guest tutorial submitted by
G. Weber.

Effective Modal Mass & Modal Participation Factors: ModalMass.pdf

The Fundamentals of Modal Testing: modal_fund.pdf

Frequency Response Function Measurements: FRF_measurements.pdf


Kijewski and Kareem, Analysis of full-scale data from a tall building in Boston: damping estimates: boston.pdf

Richardson, Derivation of Mass, Stiffness and Damping Parameters From Experimental Modal Data: derivation_modal.pdf

Okuma, Heylen, Sas, Identification of Rigid Body Properties of 3-D Frame Structure by MCK Identification Method:  ident_MCK.pdf

See also:  Transfer_Functions

MODAL DENSITY
Modal Density:  mdens.pdf
Matlab Script: modal_density.m
STATISTICAL ENERGY ANALYSIS
Radiation & Driving Point Impedance of a Thin, Isotropic Plate: dp_impedance.pdf
Vibroacoustic Critical and Coincidence Frequencies of Structures: critical_frequency.pdf
Vibration Response of a Thin Cylindrical Shell to External Acoustic Pressure via Statistical Energy Analysis: SEA_cylindrical_shell.pdf
Matlab Scripts:
SEA_cylinder.m
SEA_plot.m
progressbar.m
Transmission loss through a single partition: single_partition.m
Transmission loss through a single partition using the plane wave method: single_partition_plane_wave.m
Fill factor for a payload fairing
fill_factor.m
octaves.m
Vibration Power Measurement using a Plate as a Reverberant Structure: VPthesis.pdf
Byam & Radcliffe, Statistical Energy Analysis Model and Connectors for Automotive Vibration Isolation Mounts: IsolMount.pdf
See also: Vibroacoustics
 Bruel & Kjaer Booklets
Structural Testing 1: Mobility Measurement
Structural Testing 2: Modal Testing

Software

Executable

Source

Digital filtering using a Butterworth 6th order filter. The user must supply an input time history file. Both lowpass and highpass options are available.
filter.exe
filter.cpp
Fast Fourier transform (FFT) of a time history. The transform operates on a time series with 2^n points, where n is an integer.
Also, corresponding inverse FFT.
fft.exe

invfft.exe
fft.cpp

invfft.cpp
Conventional Fourier transform of a time series with an arbitrary number of points.
fourier.exe
fourier.cpp
Zoom FFT of a time series.
zoomFFT.exe
zoomFFT.cpp
Cross-spectrum of two time histories. The output files may be used for modal test data analysis.
cross_spectrum.exe
cross_spectrum.cpp
Cross-spectrum of two time histories. The program generates H1 and H2 frequency response functions (FRFs), the coherence function, and the corresponding impulse response functions.
cross_spectrum_modal.exe
cross_spectrum_modal.cpp
This program generates a power transmissibility function for a single-degree-of-freedom subjected to a force input.
The transmissibility dimension is: ( accel^2 / force^2 )
 force_trans_modal.exe
 force_trans_modal.cpp
This program performs a curve-fit on an acceleration spectral function resulting from an applied force.

The main purpose is to determine the damping ratio.

The spectral function may be:
1. acceleration PSD
2. acceleration Fourier magnitude
3. transfer function magnitude (accel/force)
 
 bandwidth_damp.exe
 
bandwidth_damp.cpp
Driving point impedance of a thin plate, bending waves
dp_impedance.exe
-
Driving point impedance of a beam, longitudinal waves
dpi_beam.exe
-
Critical and Ring Frequencies of a Cylinder.
SEA_cylinder_parameters
-

Matlab Script
Calculate frequency & impulse response functions from an input force and response amplitude time history. frf_from_th.m

Supporting Functions:

fix_size.m

frf_median_filter.m
 Recommended Books
1. D.J. Ewins, Modal Testing: Theory and Practice
2. Lyon and Dejong, Theory and Application of Statistical Energy Analysis
3. L. Cremer and M. Heckl, Structure-Borne Sound
Please recommend this site by clicking on the Google +1 Button.
____________________________________________________________________________________

Other Vibrationdata Pages:    
Home | Software | SRS | References | Animation | Videos