VISUAL ENGINEERING SERIES

Tools for Solving Noise & Vibration Problems

• ODS Analysis • Modal Analysis

• Acoustic Analysis • MIMO Simulation
• Structural Modifications • Experimental FEA
What is ME’scopeVES? Direct Data Acquisition
ME’scopeVES (Visual Engineering Series) is a series The optional Acquisition window in ME scopeVES can
of software packages designed to make it easier for you to directly control a broad range of multi-channel data acquisi-
observe and analyze a variety of noise & vibration problems tion hardware front-ends. The User Interface is the same,
in machinery and structures. ME’scopeVES is used for regardless of the acquisition hardware used.
operating deflection shape (ODS) analysis, modal analysis,
The User Interface is designed specifically for structural
acoustic analysis, MIMO modeling & simulation, and
testing. It consists of an Acquisition window connected
structural modifications.
to a Structure window, where the next measurement
ME’scopeVES is used to display and analyze experimental location is depicted, and a Data Block window where
multi-channel time or frequency domain data, acquired measurements are accumulated.
during the operation of a machine, or forced vibration of
The Acquisition window acquires time domain data from
a structure. With it, you can interactively display ODS's,
the front-end hardware and performs signal processing on
mode shapes, acoustic shapes, or engineering data shapes
the data, including time domain windowing, spectrum
directly from experimental data.
averaging, and calculation of Auto & Cross Spectra, FRFs,
By animating the spatial response of a structure in slow Coherences, etc.
motion, you can view a structure’s overall motion, and the
motion of one part relative to another. Locations of excessive Interactive 3D Modeling
vibration are easily identified. You can also view mode A 3D model of the test structure must be built or imported
shapes, which give you a better understanding of trouble- in order to display shapes in animation. ME’scopeVES
some resonant vibration problems, so that structural contains a variety of drawing tools to assist you in building
modifications can be made to control or isolate them. 3D models. Models can be drawn interactively by dragging
objects on the screen, or by editing their properties in
With interactive sweep animation, you can animate a
spreadsheets. Objects can also be cut, copied, and pasted
structure model by sweeping through a set of time histories,
between drawings.
and observe its overall response; whether it be sinusoidal,
random, transient, linear or non-linear, stationary or non- ME’scopeVES also contains a Drawing Assistant that
stationary. With interactive dwell animation, you can rapidly generates 3D models using substructures. Complex
dwell at a specific time or frequency in a set of response structure models are created by merging together several
data, and display shapes statically or with sinusoidal substructures with simple geometries. The Drawing
animation. Assistant contains a substructure browser from which you
can select pre-defined substructures for building the model.
The Drawing Assistant also contains powerful
In addition to its interactive animated display, ME’scopeVES Revolve and Extrude commands which
contains state-of-the-art tools for Experimental Modal Analysis can be used to create 3D models from 2D
(EMA), Multiple-input Multiple-output (MIMO) modeling & profiles. 2D profiles can be drawn freehand,
simulation, Structural Dynamics Modification (SDM) and or traced from digital pictures or drawings
experimental Finite Element Analysis (FEA). using the picture tracing capabilities in
ME’scopeVES or third party software.

Importing Measured Data Measurements in Local Directions

When making vibration measurements, it is usually easiest
ME’scopeVES has file translators for importing data from
to attach the transducers directly to the surface of the test
a wide variety of disk data files. File formats used by all
structure. If the surface is curved, each transducer will
popular multi-channel data acquisition systems, analyzers,
sense motion in a different local direction.
recorders, and data collectors are supported.
In ME’scopeVES, each point on a 3D structure model has Resonances and Mode Shapes
its own local measurement axes which can be graphically Modes of vibration are used to characterize all vibration
oriented to coincide with the transducer measurement in mechanical structures. All vibration can be characterized
directions. This feature gives you the freedom to mount as a summation of contributions from rigid body modes
transducers directly on curved surfaces. Tri-axial and radial and elastic modes. An elastic mode characterizes a structural
measurements are easily defined on the 3D test model resonance. If a structural resonance is excited, the structure
using this feature. will readily absorb energy and resonate at levels that can
far exceed deflections due to static loading. These excessive
Interpolation for Unmeasured Points
vibration levels can also create excessive noise, and can
Vibration measurements are usually made at relatively few
cause material fatigue and premature failure.
points on a test article. On the other hand, the 3D model
of the test article will typically require more points to give Each resonance has a specific “natural” or modal fre-
it a realistic appearance. ME’scopeVES contains a unique quency, a modal damping value, and a mode shape.
spatial interpolation feature which calculates shape These three properties of a mode will not change unless
values for all unmeasured points based on the shape values one of the physical properties or the boundary conditions
at neighboring measured points. With interpolation turned (e.g. supports) of the structure changes.
on, a more realistic animated shape is displayed from
Under the proper conditions, a structure will readily absorb
relatively few measurements.
energy and resonate if excited at or near one of its modal
Interactive Shape Animation frequencies. Modal damping is a measure of how quickly
the resonant vibration will decay when all forces are re-
An Operating Deflection Shape (ODS) is the simplest way
moved from the structure. The mode shape defines the
to see how a machine or structure moves during its opera-
spatial deformation of the structure due to the resonance.
tion; at a specific frequency or moment in time. An ODS
contains the overall dynamic response of a structure due If one of the resonances of a structure is excited, its deflec-
to forced and resonant excitation. tion shape will often be dominated by the mode shape
associated with the resonance. By observing ODS’s in
With sweep animation, Time-Based ODS s are displayed
animation, ME’scopeVES helps you determine whether
by sweeping through a set of time histories describing
or not a resonance is being excited.
motions at multiple points and directions on a test article.
You can stop the animation, back it up, and play it forward Documentation with Digital Movies™
to observe in slow motion phenomena that may have taken With our unique Digital Movies™ feature, you can save
place very quickly in real time. You can use sweep animation any ME’scopeVES animation sequence in a Microsoft AVI
to analyze the run up, coast down, or other transient be- file. The AVI file can be played back and the animation
havior of a machine. viewed just as it appeared when the movie was made.
With dwell animation, you can observe the Frequency- Digital Movies can be embedded in Microsoft PowerPoint
Based ODS of a structure at a single frequency. You simply presentations, Word documents, or Web pages, and played
move the cursor to a frequency of interest in your test by simply clicking on them. Digital Movies can also be
data, and the animated display will display the ODS for that played on Macintosh, Linux, or Unix computers.
frequency. A frequency-based ODS can also help you de-
termine whether or not a resonance is being excited, or Packages & Options
whether the vibration is an order related forced vibration. ME’scopeVES can be purchased in a variety of different
packages. The basic Visual ODS“ package contains all
of the features for interactively drawing 3D models,
Interactive Shape Animation allows you to view importing multi-channel measurement data, and inter-
shapes directly from your experimental data actively displaying shapes in animation. All of the other
without curve fitting or any other processing. advanced packages consist of the Visual ODS“ package
with options added to it. (See the back cover).
Acquisition Options to vibration data. It allows you to analyze vibro-acoustic
ME’scopeVES can be ordered with Acquisition options problems, by displaying both vibration and acoustic data
that allow you to setup, control, and directly acquire data. together in the same animated picture. Vibration data is
Most popular multi-channel data acquisition systems, displayed on the 3D test model, while acoustic data is
analyzers, recorders and collectors are supported. The displayed on an acoustic surface.
Acquisition window is particularly useful for Impact Acoustic Intensity is measured with a two or four channel
Testing, where user interaction with data acquisition acoustic probe and a multi-channel acquisition system.
and post-processing is essential. Each Intensity measurement is made in a direction at each
This option adds an Acquisition window to ME’scopeVES point in a point grid. Intensity is usually measured either
that contains all of the controls necessary for acquiring, normal to the acoustic grid or surface, or in three directions
calculating, displaying, and saving multi-channel data. The (tri-axially) at each grid point.
Acquisition window calculates a variety of frequency Sound Power flow though an acoustic surface can be
domain measurements, including Auto & Cross Spectra, calculated from Intensity data. Sound power is calculated
FRFs, Coherences, ODS FRFs, etc. using the surface area surrounding each test point and the
Impact testing (with force and exponential windowing), surface normal at each test point. Sound power is then
and tests using ambient, pure random, and sine excitation displayed on the acoustic surface using a color map.
methods are supported. Shaker signal generation using Interactive Source Ranking allows you to graphically
random, burst random, chirp and burst chirp are also document the breakdown of acoustic energy measured
supported with hardware front-ends that have signal out- from various components of a test article. Acoustic sources
put capability. can be ranked according to their percentage of the total
Connected Windows power, in dB units or watts.
The Acquisition window is connected to a Structure
window with a 3D test structure model in it, and a Data
Signal Processing Option
Block window where measurements are accumulated. This option includes FFT commands that simultaneously
Using these three connected windows, you can select transform all measurements in a Data Block window
measurement points & directions on a 3D model, acquire between the time and frequency domains. This allows you
measurements, and view ODS’s or mode shapes in to conveniently analyze data and display shapes from either
animation, even before all measurements have been time or frequency data.
acquired.
With only a few measurements, you can begin to see how The prime factor FFT transforms any
a structure is deforming. As more measurements are ac- number of samples, not just a powers-of-2,
quired, the shapes will gain more definition. thus providing more flexibility for working
Measurement Sets with your data.
Measurement sets are used in the Acquisition window
to designate each set of simultaneously acquired data. Each You can cut, copy, and paste data, or portions of data be-
measurement set contains the measurement DOFs and tween one Data Block and another. When measurements
all front end channel setup parameters for acquiring data. with dissimilar time or frequency axes are pasted together,
All measurement sets for an entire test are saved in an interpolation between samples is used so that the pasted
Acquisition file, so the test can be repeated using the data matches the time or frequency axis of the destination
same parameters. Data Block.This allows you to combine measure-ments
acquired with different hardware front ends into a common
Acoustics Option
Data Block.
This option post-processes and displays Acoustic Intensity,
Sound Pressure Level (SPL), and Sound Power in addition
Vibration data can be measured with a variety of trans- Elements of the FRF matrix can be measured or synthesized
ducers, including accelerometers, proximity probes, lasers, from modal parameters.
photonic sensors, etc. However, the question, How much
MIMO response waveforms caused by multiple forces
is the machine or structure actually moving? is
are calculated using the MIMO model. FRFs defining the
usually answered with displacement values.
dynamics of the structure between the ap-
propriate excitation and response DOFs are
With the signal processing option, you can integrate or required, plus time or frequency waveforms
differentiate time or frequency waveforms or shapes between of the excitation forces. MIMO modeling is also
accelerations, velocities, and displacements. used to calculate and display ODS’s due to
multiple sinusoidal forces at a single frequency.
The MIMO force waveforms required to cause multiple
Notch or band pass windows can be used for removing
structural responses are also calculated using the MIMO
unwanted portions of your data such as noise or DC offsets.
model. This capability is useful for Force Path Analysis.
The exponential window can also be used for removing
The FRFs and response waveforms required for this cal-
noise. This window adds a specific amount of damping to
culation can be measured or synthesized in ME’scopeVES.
each mode, which is automatically removed from the modal
damping estimates obtained during curve fitting. MIMO FRFs
MIMO FRFs can be calculated from multiple excitation
ODS FRFs
force and response time waveforms, or from Auto &
When the excitation forces cannot be measured, and
Cross Spectra. If time waveforms are used, time domain
therefore a set of FRFs cannot be calculated, a set of ODS
windowing (Rectangular, Hanning, or Flat Top), linear or
FRFs is calculated instead. An ODS FRF measurement is
peak hold spectrum averaging, triggering, and overlap
calculated from operating (or response only) data.
processing can be applied during the FRF calculations.
ODS’s can be displayed in animation directly from a set of Ordinary Coherences are calculated for single input forces,
ODS FRFs. ODS FRFs have peaks at resonant frequencies, and Multiple & Partial Coherences are calculated for
thus making it easier to locate resonances. Operating multiple input forces.
mode shapes can also be obtained by curve fitting a set
of ODS FRFs. Modal Analysis Option
Modal analysis is used to analyze resonant vibration in a
Order Tracked ODS’s
structure. Modal parameter estimation (or curve fitting)
An Order Tracked ODS provides a picture of a rotating
is used to estimate the modal parameters of a structure
machine’s deformation as a function of one of its rotational
from a set of FRF data. Each mode is defined by its modal
orders. With the Signal Processing option, you can import
frequency, modal damping, and mode shape.
and process multi-channel order tracked peak & phase
response data. Order Tracked ODS’s can then be displayed This option includes SDOF (one mode at a time), MDOF
in animation directly from the ordered tracked operating (multiple modes at a time), and Global (multiple measure-
data. ments at a time) curve fitting methods for estimating modal
parameters. SDOF curve fitting is fast and easy to use,
MIMO Modeling & Simulation Option and is useful for quickly obtaining mode shapes so that
This option uses a Multiple Input Multiple Output (MIMO) they can be displayed in animation.
FRF matrix model to calculate structural responses, FRFs,
MDOF curve fitting is more powerful, and simultaneously
or excitation forces. Each part of the model can be cal-
estimates modal parameters for two or more modes at a
culated from the other two. Excitation force and response
time. It is useful for curve fitting FRFs with high modal
waveforms can either be obtained experimentally or
density (many modes in a small frequency band).
synthesized in ME’scopeVES.
Global curve fitting is better for obtaining parameter Polynomial method, thus allowing it to also estimate the
estimates of local modes, that is modes that are confined parameters of a large number of modes. Because all three
to local regions of a structure. of these methods can estimate the parameters of a large
number of modes at a time, they are used with a Stability
diagram for best results.
The Modal Analysis option also contains a
Quick Fit command that performs curve fitting Stability Diagram
The Stability diagram is very useful for obtaining modal
in one operation. All of the curve fitting methods
frequency & damping estimates from data with closely
can be used on selected measurements, and coupled modes (two or more modes represented by
in user-controlled cursor bands. a single resonance peak), or repeated roots (two or
more modes at the same frequency but with different
mode shapes).
Mode Indicator
The first step of curve fitting is to determine how many The Stability diagram displays frequency & damping
modes are contained in a set of measurements. Resonances estimates for a range of model sizes, from 1 to several
are indicated by peaks in FRF measurements. This option hundred. Modal parameters are said to be “stable” when
contains a Count Peaks command that calculates a Mode estimates from successive model sizes yield values within
Indicator function from the FRFs, and counts its peaks user-specified tolerances. Stable frequency & damping
above a user-defined threshold. estimates are saved directly from the Stability diagram.
Polynomial Curve Fitting MIMO Curve Fitting
The Polynomial method uses a least squared error curve For structures that have closely coupled or repeated
fitting algorithm to estimate the numerator and denominator roots, a set of MIMO FRFs must be measured to insure
polynomial coefficients of an analytical FRF model from that all modes are correctly identified. A set of MIMO FRFs
experimental data. The numerator and denominator co- is measured in a MIMO modal test.
efficients are then processed to obtain modal parameters. In a MIMO shaker test, the structure is simultaneously
This method also uses extra numerator polynomial excited from two or more exciter locations. In a roving
terms to compensate for the residual effects of out-of-band exciter MIMO test, two or more fixed response transducers
modes in the curve fitting frequency band. With residual are used. A set of MIMO FRFs corresponds to FRFs from
compensation, curve fitting can be done in narrow fre- two or more rows or columns of the MIMO matrix model.
quency bands without incurring errors due to out-of-
band modes. The Advanced Modal Analysis option also contains two
additional Mode Indicator functions, the Complex Mode
Advanced Modal Analysis Option Indicator Function (CMIF) and the Multivariate Mode
This option contains additional curve fitting methods that Indicator Function (MMIF), that are helpful for finding
will assist you in estimating modal parameters under more closely coupled modes and repeated roots from a set of
difficult conditions. It contains the Complex Exponential, MIMO FRFs.
Z-Polynomial, and ERA curve fitting methods. Modal Assurance Criterion (MAC)
The Complex Exponential method curve fits a set of The MAC calculation is useful for numerically comparing
time domain Impulse Response Functions (inverse FFT’s two different ODS’s or mode shapes. A MAC value of 1
of FRFs) using a least squared error algorithm. The ERA means that the two shapes are identical. A MAC value
method, developed by NASA for use with large scale mo- greater than 0.9 means that the two shapes are similar,
dal tests on spacecraft structures, also curve fits a set of and a value less than 0.9 means that they are different.
IRF data. MAC values are displayed in either a spreadsheet or a 3D
Bar chart.
The Z-Polynomial method uses the Z-transform to
significantly enhance the numerical stability of the
Structural Modifications Option in order to preserve the mass and elastic properties of
If any of the physical properties of a structure (its geometry, the structure. A set of scaled mode shapes is called a
density, elasticity, or boundary conditions) is changed, or modal model.
if brackets, stiffeners, tuned absorbers, or other types of This option contains a unique mode shape scaling command
modifications are added to the structure, its modes will so that any set of mode shapes, including operating mode
change and it will vibrate differently. If a noise or vibration shapes, can be properly scaled for use as a modal model.
problem is due to the excitation of a resonance, the structure
must either be isolated from the excitation source or Advanced Modifications Option
physically modified in order to reduce its vibration levels. With this option, you can construct a Finite Element
The Structural Dynamics Modification (SDM) algorithm model of your test structure and solve for its analytical
allows you to calculate the effects of structural modifications mode shapes. Experimental FEA allows you to investigate
on the modes of a structure. Structural modifications are a much wider variety of structural modifications than with
modeled using industry standard Finite Elements. The the SDM method alone.
Finite Element library includes springs, masses, and This option includes both a normal mode “band” solver
dampers, as well as higher order elements such as rods and a complex mode solver that includes modal damping.
(with axial stiffness), bars (with axial, shear, and bending The normal mode solver can solve for the modes of FE
stiffness), triangular and quadrilateral plate elements, and models with up to 20,000 DOFs, and the complex mode
solid elements such as tetrahedra, prisms and bricks. solver can solve for the modes of models with up to
2000 DOFs.
FEA Assistant
All modification elements are displayed on the 3D structure The FEA Assistant allows you to easily pop-
model. Each element type has its own spreadsheet, where its ulate a 3D geometric model with finite
properties (thickness, density, elasticity, etc.), can be edited. elements.You can start by populating your
3D test model with finite elements, or mesh
it to add more elements for improved
SDM converts all structural modifications into mass, stiffness accuracy. The FEA Assistant uses built-in materials and
and damping changes. These changes, together with the properties lists from which you can select pre-specified
modes of the unmodified structure, are used to calculate physical properties for the finite elements before adding
the new modes of the modified structure. The new mode them to the model.
shapes can be viewed in animation, compared with the
Modal Test Planning
modes of the unmodified structure, used to synthesize
With the Advanced Modifications option, you can simulate
FRFs for comparison with measured FRFs, or used in
an entire modal test using analytical modes and MIMO
MIMO simulations.
simulation. This is very helpful for planning transducer
SDM can be used with either experimental or analytical and excitation locations prior to the actual test. Following
mode shapes. Analytical mode shapes can be calculated the test, you can conveniently compare experimental
with the Advanced Modifications option, or imported from modes with analytical modes, thus validating both your
most popular Finite Element Analysis (FEA) packages. finite element model and your experimental results.
Once an FEA model has been validated, its analytical modes
The FE model can also be used to expand ODS’s or mode
can then be used with SDM to quickly investigate many
shapes to include deflections for all unmeasured DOFs of
modification possibilities.
the model. This unique Shape Expansion capability
Scaling Operating Modes uses the FE model to calculate shapes with many DOFs in
In order to be used for modeling purposes (SDM, MIMO them using experimental data that was acquired at only a
or FRF Synthesis), mode shapes must be properly scaled few DOFs.
3D Modeling & Display Measurement Display
• Quad View (front/back, top/bottom, left/right, and • Displays time or frequency domain measurements.
3D views).
• Imports PC disk files saved by popular multi-channel data
• Interactive rotation & elevation in the 3D view. acquisition systems, analyzers, recorders & collectors.
• Auto rotation in the 3D View. • Imports & exports UFF, ASCII Spreadsheet, MATLAB,
• Interactive zoom, pan, rotation, and perspective distance. DADiSP & MS WAV file formats.
• Surfaces with color fill, transparency, and surface textures. • Displays up to 100 measurements in Row/Column, 10 in
Strip Chart, an unlimited number in Overlay, Cascade, &
• Surface textures imported from digital photographs. Color Map formats.
• Lighted surfaces. • Real, Imaginary, Magnitude (Linear, Log, dB), Phase, CoQuad
(Real & Imaginary), Bode (Magnitude & Phase), Nyquist
• Drawing Assistant for rapidly building structure models (Real vs. Imaginary).
using rectangular, cylindrical & spherical coordinates.
Includes sizing, no. of points, positioning, revolve, extrude, • Horizontal & vertical zoom with scrolling.
and a substructure palette with pre-defined substructures.
• Line, Peak & Band Cursors.
• Interactive drawing tools. Select & drag objects on screen,
resize, rotate, and stretch objects to rapidly build a • Grid lines, labels, DOFs, units & cursor values displayed on
structure model. each measurement.
• Cut, Copy & Paste of drawing objects. • Spreadsheet for editing measurement properties (select,
show/hide, color, line types, DOFs, units, labels, etc.)
• Spreadsheets for editing properties of drawing objects.
• Play button, plays the sound of each measurement.
• Measurement Axes (rectangular, cylindrical, spherical &
machine), graphically oriented at each point. • Measurement statistics.
• Interactive point numbering. • Auto, relative & fixed vertical axis scaling.
• Measurements displayed on the model. • Maximize vertical axis display.
• Imports structure models from UFF, AutoCAD (DXF), STL, • Linear & Log horizontal axis.
FEMAP, NASTRAN & ANSYS files. • Print & Copy to Clipboard.
Shape Animation • Text font, window, background, fill, text color & line type.
• Interactive shape animation directly from time or frequency Direct Data Acquisition
domain measurements, using a line, peak, or band cursor.
• Connects to most popular multi-channel acquisition
• Interactive shape animation directly from a Shape Table. front ends.
• Interpolation of shape data for unmeasured points using • Front end sampling, triggering, sources & measurements
data from neighboring measured points. selected from tabs.
• Animation in Quad view or a Single view. • Front end channel parameters, windowing, etc. setup in a
• Display of two shapes (side-by-side & overlaid) from two spreadsheet.
sources (Data Blocks or Shape Tables). • Displays both acquired time domain and calculated
• Shape contour colors (including nodal lines). frequency domain waveforms.
• Shape animation of scalars or vectors (translations & • Scope mode for looking at front end time domain
rotations). waveforms.
• Deformed & un-deformed structure displayed together. • Displays un-windowed and windowed front end waveforms.
• Speed & amplitude controls. • Impact force & exponential windows.
• Display of maximum deflection points & shape values. • Accept/reject controls for impact testing.
• Display of shape values at selected (monitored) points. • Outputs multiple shaker random (burst random), chirp
(burst chirp) signals for selected front end hardware.
• Animation using arrows.
• Calculates MIMO FRFs, Multiple & Partial Coherences,
• Animation with persistence. Auto & Cross Spectra, ODS FRFs.
• Auto, relative & fixed shape scaling. • Measurement points & directions graphically indicated on
a connected structure model.
• Animation in selected directions.
• Measurements accumulated into a connected Data Block.
• Animation from selected references in multiple
reference data. Acoustics
• Print & Copy to Clipboard. • Animated display of vibro-acoustic (acoustic & vibration)
data.
• Digital Movies, documents animation as an AVI file.
• Displays narrow band or 1/1, 1/3rd, 1/12th, 1/24th octave
band measurements.
 • Displays measurements in Linear, Log, dB, dB Reference. • Multiple Reference curve fitting.
• Acoustic Intensity calculated from Cross Spectrum or time • Stability diagram. Graphical display of frequencies &
domain data. damping for a range of curve fitting model sizes.
• Sound Power through a surface calculated from • CMIF (Complex Mode Indicator Function), indicates closely
Intensity data. coupled modes & repeated roots.
• Converts narrow band measurements to octave band. • MMIF (Multivariate Mode Indicator Function), indicates
closely coupled modes & repeated roots.
• A, B & C weighting of narrow band or octave band
measurements. • Modal Assurance Criterion (MAC), numerical shape
comparison.
• Noise source ranking based on percentage, dB, or watts.
• Shape Complexity plot.
• Magnitude & phase tone calibration.
• Shape component Magnitude ranking.
Signal Processing
• Simultaneous FFT & IFFT on all measurements in a Data MIMO Modeling & Simulation
Block. (Not restricted to powers-of-2 number of samples.) • MIMO Forced Response. Calculates multiple response time
or frequency waveforms from FRFs (or modes) and multiple
• Integration & differentiation of time or frequency signals. excitation force waveforms.
• Waveform Cut, Copy & Paste. • MIMO Sinusoidal Forced Response. Calculates and
• Notch & Band windows for removing unwanted data. displays response shapes due to multiple sinusoidal
excitation forces.
• Exponential window for removing noise or sharpening
resonance peaks. • MIMO Forces. Calculates multiple excitation force time or
frequency waveforms from FRFs (or modes) and multiple
• Calculates Fourier Spectra,Auto Spectra, PSDs & ODS FRFs response waveforms.
from time domain operating data, using Hanning, Flat Top,
or Rectangular windows, triggering, linear or peak spectrum • Calculates MIMO FRFs or Transfer Functions, and Ordinary
averaging, overlap processing. or Multiple & Partial Coherences from multiple excitation
& response time waveforms, using Hanning, Flat Top, or
• Calculates ODS FRFs from Auto & Cross Spectra. Rectangular windows, triggering, linear or peak averaging,
• Displays Order Tracked ODS’s from multi-channel Order overlap processing.
Tracked response data. • Calculates MIMO FRFs,Transfer Functions, and Coherences
• Block Math functions (scale, add, multiply, conjugate, etc.) from Auto & Cross Spectra.
• Linear (RMS) to Power (MS) units conversion. Structural Modifications
• Peak, Peak to Peak, RMS scaling. • Interactive graphical addition of modification elements to
a structure model.
Modal Analysis • Displays modification elements on the structure model.
• SDOF Co-Quad & Peak curve fitting.
• Point mass, linear spring & linear damper elements.
• MDOF Polynomial curve fitting, with compensation for
out-of-band modes. • Rod & beam elements.
• Local or Global curve fitting. • Triangular & quadrilateral plate elements.
• Quick Fit command, one step curve fitting with minimum • Tetrahedron, prism & brick solid elements.
user interaction. • Spreadsheets for finite element properties.
• Interactive curve fitting using selected measurements and • Modal sensitivity analysis.
a band cursor.
• Substructuring (connecting together two or more structures
• Mode Indicator functions with resonance peak counter. using finite elements).
• Frequency & damping estimates overlaid on Mode Indicator • Tuned absorber (mass, spring, damper element).
graph.
• Scaling of operating modes.
• FRFs synthesized from modal parameters.
Advanced Modifications
• All curve fitting functions and modal parameters saved
with each measurement. • FEA Assistant. Populates a geometric model with finite
elements. Includes material & geometric property lists.
• Imports & exports modal parameters in UFF format
• Calculates Normal Modes for up to 20,000 DOFs.
Advanced Modal Analysis
• Calculates Complex Modes (with damping) for up to 2000
• MDOF Z-Polynomial curve fitting. DOFs.
• MDOF Complex Exponential curve fitting. • Shape Expansion. Calculates unmeasured shape DOFs
• MDOF ERA (Eigenvalue Realization Algorithm) curve fitting. using FE model and response measurements at a few DOFs.