sine sweep vibration testing primer
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DESCRIPTIONSine Sweep Vibration Testing Primer. Eric Sauther OPT521 Optomechanics Fall 2013. Why do we do a Sine Sweep Vibration Test?. Part Responses to a Sine Wave Input are important to characterize a part/assembly for several reasons: Characterize Model Response Endurance Limits of Part(s) - PowerPoint PPT Presentation
Sine Sweep Vibration Testing
Sine Sweep Vibration Testing PrimerEric Sauther OPT521 Optomechanics Fall 2013Why do we do a Sine Sweep Vibration Test?Part Responses to a Sine Wave Input are important to characterize a part/assembly for several reasons:Characterize Model Response Endurance Limits of Part(s)Actual characterized response under test, instead of CalculatedCharacterize response of Test Equipment so it can be backed out of the performance dataGeneral Investigation. If we dont understand how a part will perform, or life of the part (related to Endurance) we can characterize it. A more well Known Phrase would be Destructive Testing
What is Sine Sweep Vibration?Wikipedia describes vibration as a Oscillatory motion about an equilibrium point.For a Sine Sweep Vibration it is a movement back in forth usually in one DOF. The movement is in a controlled oscillatory motion that can be defined as a sinusoidal function. The Sine Wave Amplitude, and rate at which you wish to Sweep through the range of frequencies of interest are programmed inputs into the Vibration Table youll be using for testing.
A Sine Sweep Signal InputTypes of Sine SweepsTypical Sine Sweep is a linear input
A Sine Sweep Signal InputFor a test engineer the parameters for a Sine Sweep input are already provided to you by an Analyst or exists as an industry standard input profile. Some materials, Parts, and Environments have been already well characterizedIt is Relevant to have an understanding that Displacement, Velocity, and Acceleration are related due to first Order Harmonic Oscillation in a Single DOF
Sine Sweep Signal InputIn a single DOF we can derive the relationships to find our test parameters for Displacement, Velocity and Acceleration at any given frequency input.
Sine Sweep Signal Input
Displacement, Velocity, Help define your input signal normally shown as AccelerationSine Sweep Signal Response from Force InputAs weve investigated through SolidWorks in HW 8 for class we found that there is a complex motion response of a part in all Degrees of freedom with a directed input at a coordinate axes.
Sine Sweep Signal ResponseCalculated Response (Transmissibility) Relative to Q factorSine Sweep Signal ResponseDigging further we know that Part under test will have a response through a range of frequencies through the Transmissibility relationship
Sine Sweep Signal Input (Actual)
Previously we showed the way the Ramping of acceleration is determined.The area of inspection for the expected response about resonance is found In the Dwell areaDwell AreaRamping of AccelerationMAX G Allowed Sine Sweep Signal ResponseTest Response of Two metal bars at different LengthsKnowing this we can set a pre-determined Sine Sweep signal Input to the part under test. We Plateau the area of interest in order to better further investigate the response area, and to have a Factor of Safety for the Acceleration input.
LET US NOT BREAK OUR PART Response at ResonanceSine Sweep Product Response
Vibration Test Set-Slip TableOne Example of Vibration table offering a Single DOF vibration AxisVibration Test Set-Slip TableExample of a Slip TableThings to note in Table setupControl accel should be on the farthest edge of the table and as close as possible to the product.Multiple Control Accels can be used and Averaged.Accel should be Tri-axial in configurationTable should already be characterized with support fixture
Vibration Test Set-Control Accel
Warning LimitsAbort Limits+/- 30% of Expected Response+/- 40% of Expected ResponseSoftware by Unholtz-Dickie Corporation VWINIIVibration Control & Analysis System
Vibration Test Set-Control Accel
VibrationTest Set-Measurement AccelsParameters for individual Accel performance
VibrationTest Set-Measurement Accels
Additional HomeworkThe audience should take note that this is the simplest of vibration tests. It is worth your energy to dig further in and understand how other tests are performed and why.One in particular is called Random Testing. This is more representative of what the product will see In the real environment.ReferencesKevin Napolitano, and Daniel Linehan [Multiple Sine Sweep Excitation for Ground Vibration Tests], Proceedings of the IMAC-XXVII Society for Experimental Mechanics Inc, February 9-12, (2009).Connection Technology Center Learn Basic Vibration Monitoring with CTCs Vibration University, (2012). Dr. Paul Ibanez ANCO Engineers, Inc., "An Introduction to Shake Tables for Seismic Testing of Equipment And Glossary of Vibration Terminology," ancoengineers.com, October 1st,(2008).http://shodhganga.inflibnet.ac.in/bitstream/10603/2274/11/11_chapter%203.pdf, ch.3 Page 54Unholtz-Dickie Corporation, Fixture Design NotesUnholtz-Dickie Corporation, VWIN II / VWIN XL / VWIN VIBRATION CONTROLLER OPERATING MANUALTom Irvine, http://www.vibrationdata.com/tutorials.htmAuxiliary Slides
Auxiliary Slides-Sine Sweep EquationsTable 1 Sine Sweep Rate Parameters
Auxiliary Plot Units/Slope
Simply an Octave is a doubling of the Frequency limits (think musical instruments). Auxiliary Plot Response Example -Acceleration
Auxiliary Plot Response Example-Dislacement