High speed vibration analysis systemVIC-3D High-Speed FFT

Non contact full field ODS working deformation and strain measurement systemNon-Contact Full-Field ODS and Strain Measurement System

Technical OverviewTechnology Overview

The VIC-3D HS FFT system is a measurement solution newly added to the VIC-3D product line by CSI, which can view, measure, and analyze in a full field 3D manner in steady-state orTransient eventThe entire venueWork Deformation (ODS)information The system'sNano level precisionEasy to implement frequency domain based viewing and analysis of work deformation ODS. The system provides 3D displacement, strain, velocity, and acceleration measurements at any frequencyThousands of data pointsThe results are not only visual, but users can also export data for finite element analysis and validation.

The VIC-3D HS FFT System by Correlated Solutions, Inc. is a new addition to the Vic-3D product line of measurement solutions which enables full-field 3D viewing, measurement, and analysis offull-fieldoperational deflection shapes (ODS’s)which occur fromtransientevents.ODS’sin the frequency domain can easily be viewed and analyzed with levels of accuracy in thenanometerrange.Three-dimensional displacements, strains, velocities, and accelerations are all computed forthousands of data points for any given frequency.The result is not only visual, but users can export the data for FEA analysis and validation.

Application CasesApplication Example

Here is an example of a measurement result from the system. A 8 "x 10" thin aluminum plate suspended by rubber bands is hammered from the back with a small hammer. The impact generated the following vibration modes:
An example of the system’s results are seen below. An thin 8″ x 10″ aluminum plate suspended with rubber bands was tapped from behind with a small hammer. The impact produced the following shapes:

All ODS SS

To see another test, you can check out the brake rotor example on our Applications Page.

Comparison with traditional measurement techniquesVs.traditional measurement techniques

  • Non contact measurementDue to the fact that the VIC-3D HS FFT system provides non-contact full field vibration analysis of specimens under dynamic or transient loads, this method avoids the problems of traditional sensors, such as sensor debonding or damage during the experimental process (especially transient and impact loading), the influence of sensor quality on specimens, and noise and cable management issues.
  • Full field dataThere is no need to analyze and select measurement points in advance! All point information can be easily discovered and displayed for recognition through post-processing. This means that there is no longer a need for extensive pre testing work to ensure the reliability of the results.
  • 3D data resultsDue to the VIC-3D HS FFT system always measuring data on all X/Y/Z axes, there is no need to use a large number of single axis accelerometers or expensive dual axis or three-axis accelerometers.
  • Comprehensive strain and displacement dataThe system automatically generates full field strain, deformation, and mode information, accompanied by all frequency and amplitude data.
  • No need for window functionThe windowing process has been described by ODS experts as a 'necessary evil' in this field. Through the HSVA system, there is no need to add a window function, and ODS analysts do not need to consider the occurrence of spectral energy leakage.​(Note: During data collection, the use of rectangular windows to truncate the time history of signals results in sidelobe leakage of spectral energy. Using other window functions can improve the leakage of spectral energy, such as using Hanning and Hamming windows for random signals, and exponential windows for attenuated signals
  • Non-contact measurements– Since the VIC-3D HS FFT System provides non-contact full-field vibration analysis of components under dynamic or transient load, it circumvents the problems associated with the conventional sensors such as debonding or becoming damaged during the event (especially transient and shock loading), sensors adding mass to the test component, noise, and cable management.
  • Full-field data– Point selection can be overlooked completely! Unknown nodes are easily discovered and displayed during post-processing. This means that no pretesting is necessary to ensure reliable results.
  • 3D Results– Since the VIC-3D HS FFT system always measures in all three axes, orienting multiple single axis accelerometers or using pricey bi-axial or tri-axial accelerometers are no longer required.
  • Integrated strain and displacement data–Full-field strain, deformation, and shape variables are automatically produced along with frequency and amplitude data.
  • No Windows– The windowing processing has been described as a “necessary evil” by ODS experts in the field. With the HSVA system, no windows are used, giving the ODS analyst confidence that leakage has not occurred.

Using the VIC-3D HS FFT system, detailed ODS results can be obtained without the need for adhesives, wires, signal analyzers, power amplifiers, or load sensors. Measuring ODS data for small, complex structures or very large-scale structures is faster and easier than replacing a pair of lenses.

With the VIC-3D HS FFT system, there are no adhesives, wires, signal analyzers, power amplifiers, or load cells necessary for detailed ODS results. Obtaining data for a tiny, complex structure or a very large one is faster and easier than changing a pair of lenses.

New Vic-3D HS FFT Window Function Options New Vic-3D HS FFT Windowing Options

Recently, the software team of CSI company developed and implemented a new method for post-processing FFT data obtained from the VIC-3D HS FFT system. This method can apply Hann and Hamming window functions to FFT data to obtain clearer working deformation ODS information. These window functions are useful for noise measurements that require better frequency resolution but have no problem with moderate sidelobes.

Recently, our software team has developed and implemented a new way to post-process FFT data obtained with the VIC-3D HS FFT System. The Hann and Hamming window functions can now be applied to the FFT data to produce clearer operational deflection shapes. These window functions are useful for noise measurements where better frequency resolution is wanted but moderate side lobes do not present a problem.

All ODS SS

The Hann window function has good frequency resolution and reduces spectral leakage. If you don't know the properties of the signal but want to apply a smoothing window, start with the Hann window. Usually, this compromise results in a slight decrease in frequency resolution, but it greatly reduces aliasing.
The Hann window function has good frequency resolution and reduced spectral leakage. If you do not know the nature of the signal but you want to apply a smoothing window, start with the Hann window. Generally, it produces greatly reduced aliasing, though the trade-off is a slight decrease in frequency resolution.
The Hamming window function performs better in eliminating the nearest sidelobes, but performs poorly in eliminating other sidelobes. Although both ends of the Hann window touch zero, eliminating all discontinuities, the Hamming window has not yet reached zero, so there is still a slight discontinuity in the signal, which is about one-fifth the height of the Hann window.
The Hamming window function does a better job of cancelling the nearest side lobe but a poorer job of canceling any others. While the Hann window touches zero at both ends eliminating all discontinuity, the Hamming window doesn’t quite reach zero and thus still has a slight discontinuity in the signal, giving it a height of about one-fifth that of the Hann window.
Here is an intuitive view of how these different windows affect FFT data:
Below is a good visual representation of how these different windows can affect the FFT data:

All ODS SS

ODS measurement using window function Operational Deflection Shapes Analyzed with Window Function

The VIC-3D HS FFT system enables full field 3D observation, measurement, and analysis of the working deformation (ODS) generated by transient events. ODS in the frequency domain can be easily observed and analyzed with an accuracy in the nanometer range. It can provide thousands of data points for 3D displacement, strain, velocity, and acceleration at any specific frequency. The results are not only visually intuitive, but can also be exported as finite element analysis and validation data.

The VIC-3D HS FFT system by Correlated Solutions enables full-field 3D viewing, measurement, and analysis of full-field operational deflection shapes (ODS) which occur from transient events. ODS in the frequency domain can easily be viewed and analyzed with levels of accuracy in the nanometer range. Three-dimensional displacements, strains, velocities, and accelerations are all computed for thousands of data points for any given frequency. The results are not only visual, but can be exported as data for FEA analysis and validation.

Comparison with single point laser vibrometerVs. single pointlaser vibrometers

  • 3D data resultsDue to the VIC-3D HS FFT system always measuring all information of the X/Y/Z axes, the measurement always obtains 3D results.
  • The measurement process is simple-Even very large structures can be measured in a single transient test. The camera does not need to be moved or repositioned to obtain more data from the sampled data.
  • Faster collection speed-Using the VIC-3D HS FFT system, the amplitude does not affect the acquisition time. Even on ultra large structures with very large amplitudes, the full field data acquisition time only takes a few seconds.
  • Comprehensive strain and displacement dataFull field strain, deformation, and shape variables are automatically generated along with frequency and amplitude data.
  • 3D Results– Since the VIC-3D HS FFT system always measures in all three axes, 3D results are obtained with each test.
  • Simple procedures– Very large structures can be measured in only a single transient test. The cameras do not need to be moved or repositioned at all to acquire additional data from the specimen.
  • Faster acquisition– With the VIC-3D HS FFT system, amplitude does not affect acquisition time. Even on very large structures with very large amplitudes, full-field data acquisition time requires only seconds.
  • Integrated strain and displacementdata–Full-field strain, deformation, and shape variables are automatically produced along with frequency and amplitude data.

The VIC-3D HS FFT system has stronger robustness and stability than a single point laser vibrometer. Full field 3D data can be obtained very quickly with minimal setup and testing time.

Single point laser vibrometers are not as robust as the VIC-3D HS FFT system. Full-field 3D data can be acquired very quickly and with very little setup and testing time.

Comparison with scanning laser vibrometerVs.scanning laser vibrometers

  • Smaller device sizeThe camera used for the VIC-3D HS FFT system can be mounted on a single tripod, making the system very portable. The measurement conversion of your 3D vibration measurement system between laboratory or laboratory to field has never been so simple.
  • Lower economic investmentEven the most expensive VIC-3D HS FFT system is only a small part of the price of a 3D laser scanning vibrometer system.
  • Faster collection speedWhen using the VIC-3D HS FFT system, the amplitude does not affect the acquisition time. Even on ultra large structures with very large amplitudes, the full field data acquisition time only takes a few seconds.
  • Comprehensive strain and displacement dataFull field strain, deformation, and shape variables are automatically generated along with frequency and amplitude data.
  • Smaller equipment– The cameras used for the VIC-3D HS FFT system fit on a single tripod, which makes the system quite portable. Moving your 3D vibration measurement system from lab to lab or out to the field for testing has never been easier.
  • Smaller price– Even the most expensive VIC-3D HS FFT system will be a fraction of the price of a 3D laser scanning vibrometer system.
  • Faster acquisition– With the VIC-3D HS FFT system, amplitude does not affect acquisition time. Even on very large structures with very large amplitudes, full-field data acquisition time requires only seconds.
  • Integrated strain and displacementdata–Full-field strain, deformation, and shape variables are automatically produced along with frequency and amplitude data.

Laser scanning vibrometers can provide three-dimensional vibration measurement data, but they are bulky and very expensive. Analogous to the same measurement application, using the VIC-3D HS FFT system, you can obtain a more compact device at a more favorable price.

Scanninglaser vibrometers provide measurements in 3D,but are quite bulky and very expensive. When compared to acquiring measurements with DIC, you can look forward to more compact equipment at a smaller price.

System characteristicsSystem Features

  • Can view, compare, extract and export data in the form of animation and graphics, facilitating finite element comparative analysis
  • 3D full field measurement, working deformation analysis with nanoscale resolution at high frequencies (supporting up to 50kHz)
  • Extremely low amplitude measurement under extremely high acceleration conditions
  • Measurement of Maximum Amplitude under Low Acceleration Conditions
  • Simultaneously providing full field strain, deformation, and deformation information
  • A simple measurement process can obtain high-precision results
  • User friendly interface
  • The investment only requires a fraction of the price of the laser vibrometer system
  • View, compare, animate, graph, extract, and export data for easy FEA comparison
  • Measure 3D full-field, high frequency (50kHz max) operational deflection shapes with nanometer resolution
  • Measure extremely low amplitudes with extremely high accelerations
  • Measure extremelyhighamplitudes withlowaccelerations
  • Full-field strain, deformation, and shape variables are still available
  • Easy procedures, accurate results
  • User friendly interface
  • Only a fraction of the price of a laser vibrometer system

Other specific applications of VIC-3D HS FFT system包括 Other practical applications for the VIC-3D HS FFT System include:

  • Explosive Testing
  • Door Slams door closing test
  • Engine running Run ups/Run downs
  • Shake Testing
  • Drop Testing