User Defined Transient/SRS Control Modification
Use a synthetic pulse OR a user defined time history waveform as the starting point, then VibrationVIEW will continue to modify the wavelets which adjusts the time history waveform to meet the SRS demand.
- Minor Adjustments made to the original time history
- Meet or exceed RRS
- Control on SRS vs. UDT
- Adjusts wavelets to meet RRS
Commonly Used Seismic Test Specifications
Bellcore (Telcordia) GR-63
ICC-ES AC 156
Shock Response Spectrum (SRS)
Shock Response Spectrum is an accepted tool for developing laboratory shock tests. It was adopted by the military after Biot/MIT utilized SRS algorithms to develop qualification tests for Navy equipment. The SRS technique is a straightforward way to characterize a shock environment. It also supports defining a test with enveloped data from multiple shock events.
Time domain study of shock pulses is not sufficient. We need to convert from the time domain into the frequency domain to understand how energy is distributed across a frequency range and also how the product responds to those inputs across a frequency range. To move from the time domain to the frequency domain we have 2 possible solutions
- Fast Fourier Transform (FFT)
The FFT provides us the magnitude at various frequencies AND phase information at those frequencies. With this information it is possible to re-create the pulse.
SRS is slightly different in a few key ways:
- The SRS does not include any phase information, which means that the original pulse cannot be re-created. In fact, it means that many different pulses can result in the same or similar SRS.
- The amplitude is displayed vs. frequency. If we look at the FFT the magnitude values are displayed in G^2/Hz vs. frequency. In the SRS, we have Gpk vs. Frequency. That is SRS provides the peak response in each frequency window over a time interval. The averaging that applies to the FFT is not found in the SRS.
Using Data to Improve SRS Development
Shock Response Spectra (SRS) testing uses a synthesized pulse to drive a shaker, simulating a transient event. Originally developed to replicate Seismic shocks, the SRS approach is also widely used for defense and aerospace applications.
SRS allows engineers to better visualize the effects of a shock on a physical system. A designer can see the maximum dynamic load of various components or assemblies of a total system under test as a function of frequency. This can be correlated to the damage potential based on an input response. Although, the original pulse cannot be generated based on an SRS response the engineer does have the ability to know that the EFFECTS of a pulse are similar to those of the original recorded transient.
Does your vibration testing involve products containing electromagnetic relays or motor contactors? If so, there is the possibility that vibration events may cause chatter in your electromagnetic relay. Vibration Research Corporation’s VibrationVIEW software offers a chatter monitoring package that is capable of detecting and measuring chatter events.
So whether you are involved in seismic vibration testing of a product containing relays or motor contactors, concerned about possible discontinuities in your relays, or need to evaluate the acceptance criteria for your relays (IEEE 501; ANSI C37.98), Vibration Research’s chatter monitoring capabilities will serve you well.
Bellcore (Telcordia) GR-63-Core Application
Structures and equipment installed in data Centers located in seismically active regions must be designed to protect the operating equipment in the event of an earthquake. The VR9500 is capable of running a user-defined time transient which is also used to run earthquake tests with the standard Bellcore earthquake time transients. Users can run earthquake tests similar to the Bellcore standards along with any other earthquake time history.
Vibration Control Compatibility
VR’s vibration controller and vibration control software are comparable with any electrodynamic or servohydraulic shaker. Even better, our controller comes with a lifetime hardware warranty when your maintenance is current. Try one out for free with ALL software enabled today!
IEEE-344 Earthquake Control
- Input filtering for measurement of zero period acceleration (IEEE344-Annex A)
- Multiple damping plots (IEEE344-Annex A)
- Time interval waterfall PSDs (IEEE344 – Annex B)
- Sine Beat/Dwell/Sweep Fragility Testing (IEEE344 – Annex C)
- Peak stress cycle counting (IEEE344 – Annex D)
- Coherence Plots (IEEE344 – Annex E)
- Correlation Plots (IEEE344 – Annex E)
Servohydraulic Earthquake Testing
Data Acquisition & Analysis Applications Summary
- Event Triggering
- Transient Capture
- High Channel Count DAQ
- In-building Data Acquisition
- Video/Data Synchronization
- Order Tracking Analysis
- PSD Analysis
- FFT Analysis
- And more…
Vibration Control Applications Summary
- Nuclear Power
- Nuclear Quality Assurance
- Seismic Qualification
- Classical Shock Testing
- Uniform Building Code
- Pyrotechnic SRS Testing
- Structure Evaluation
- Component Durability & Fatigue
- Stress Screening
- And more…