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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ME'scope and Solidworks
Registered Member I had an epiphany! I can realign the complete imported structure to conform to the Z axis being vertical simply by using the "X" and "Z" spin boxes. By doing this, I don’t have to re-orient vibrant’s supplied sub-structures and I can continue to use the axis orientation I am used to using. Let the dog wag the tail. Another hint for more accurate graphics is to use polygons to create round objects. They are imported more accurately than round objects. By using an even number of faces, you can... [ more ]
Registered Member I have several machines with common problems. Instead of creating a Structure file for each, I add the structure to the same folder as the other sub-structures supplied by Vibrant. This way you can multiply the time savings for individual parts that can be reused. Another trick that is simple to do is to zero the entire structure vertically and horizontally. This is done by: 1. going to the points view of the machine and selecting the point that you would like to zero the machine on. 2. [ more ]
Registered Member .STL type files can be imported from Solidworks into ME’scope. Only the triangular surfaces and points are imported. Lines are not. All the surfaces are imported with their color black. This can be changed to a more useful color by selecting "Surface Triangles", double clicking on the spreadsheet column heading "color" and clicking on the color you would like. In Solidworks, use the command “File/Save As”, “As file type”, STL. In the dialog box, click the options button and change the... [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
problem on testing steering column resonating
Registered Member I am not familiar with the MBBM. I would guess the following is the answer based on equipment I am familiar with. Did you check to see if the bias was steady on the new MBBM. If the bias voltage is fluctuating, you will get different results. It also sounds like you changed the response on the MBBM’s accelerometer when you dropped it. It should be recalibrated and the bias voltage adjusted to the level required. Maybe someone with knowledge of the MBBM can do better at helping. [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ODS SIMULATOR
Registered Member The MeScope software from Vibrant Technology will allow you to create a "Shape Table" and then type in your phase and amplitude that you have collected with your analyzer. [ more ]
Registered Member Bubble charts are a way to go. Before getting a good animation program, this was the tool I used. In order to use the 2120 or 2130 to collect the phase data, a DLP will have to be purchased. Otherwise, you will have to manually record the data. On the thread Aubrey references, Tony gives good advice. [ more ]
Registered Member Here is a link to a "Poor Man's ODS" thread here on the site: Poor Man's ODS Aubrey [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ODS WOW What a new task
Registered Member Was there a question? [ more ]
Registered Member Thanks for the advise. Question about transfering to RBM WARE from ME/SCOPE. [ more ]
Registered Member 1x vibration, Welcome to ODS/Modal Analysis. I agree with Walt. I am surprised you didn’t come away from a three day course in ODS without an outline you can use to give you direction. Personally, I feel your first requisite is a thorough understanding of your data collector. Collecting data for Cross Channel phase, Coherence, and Resonance Detection are subjects you should have focused on. Your three day class should have deepened your understanding of these subjects. If you have been... [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Paper machine calender stack ODS.
Registered Member Sorry for the delay, again, Mike. The phase relationship between the transducers is averaged and the result should be pretty accurate and taken care of automatically. No effort on your part. The amplitudes are individual and each is averaged. The only thing you need to worry about is the position of the roving transducer. You must keep it in the same relationship. If you can't, then you must tell the software. On my advanced two channel software, this is done by placing a minus sign in front... [ more ]
Registered Member Thanks again Jon. I am still struggling a little with this, forgive me if my questions are a bit basic. This ODS is still relatively new to me. Do you have to trim the data you import as a data block so it all starts with the same phase relationship to the fixed transducer, or does the software do that automatically? For example concidering a single freq, Say your data block waveform for point 1 starts at the waveform peak, and for point 2 it starts in the trough, even though these are in... [ more ]
Registered Member Successful ODS and Modal analysis data collections are done with 2 channel analyzers. The best way to collect the data is using a fixed and a roving transducer. The data you are collecting is repeatable, not transient, so the phase relationship should be close enough that simultaneous data collection isn’t necessary from roving location to roving location. Since the readings are averaged, transient data disappears. Make a drawing with a small enough grid to capture mode shapes in the... [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Accelerometer setup
Registered Member Hi Kiai, Yes, you can use different sensor sensitivitys. In your sensor setup, you select the parameters for whatever individual sensors you are using. What units you use depends on the frequency of concern. I normally use displacement since I am moslty concerned about low frequency problems. [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Turbo Generator set ODS
Registered Member Hi Planty, Sorry for the delay. I've been off for several days. The structure file wasn't that important. It was just support for the animation I posted. You should be able to easily recreate it using your select tools. As you may have already discovered, Me'scope is based on the points. To make sub-groups, you "display/points", use the alt key and left key to select the points in a particular part of the machine. Use your "ctrl" key to select individual points you can't get using the "alt"... [ more ]
Registered Member Thank Jon, The structure file wont open in my version of ME scope ( V 2.0.0.24) Neither would it open in word or excel. Maybe the newer programs have more import file formats? Can you please send as a standard tab delimited file, if possible. If I group the structure into components does that prevent interpolation of non connected components. This has been something I have had to manually fix in some models. Points seem to be interpolated to measured points depending on how close they are... [ more ]
Registered Member Here is the modified structure file [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ANSYS
Registered Member Shebbirao The Ansys trhough CAD perform calculations of natural frequencies and Vibration Modes, by an theorical way. ODS, E-Shape and others measures of actual vibration mode of structures and machines. Ricardo Góz from Brazil [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ODS Model Measurement Points
Registered Member Thanks Aubrey, I have noticed that he has many posts on these forums. Glen [ more ]
Registered Member It may get an answer quicker if you sent an email straight to one of the "go to" guys on the board. If they are not too swamped they will answer you back with a great answer. Tony Dematteo, tony.dematteo@4Xdiagnostics.com" has helped me out on a couple of occasions. Aubrey [ more ]
Registered Member Thanks for the starting tips Tom. The project on the fans which was given to me has never been attempted here before (Me'Scope was purchased for it) and issues with IT has left little time for completion before my placement terminates so I need all the help I can get. I have access to our vibration data so will be able to find the dominant frequencies. At the moment I think they are around 22Hz (From mills) and running speed of about 25Hz. I will be using a triax and speedvue for phase. How... [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ODS data
Registered Member Hi Jon Thanks for the info. [ more ]
Registered Member Depends on what method you use to collect the Phase/Amplitude data you are animating. You will be looking at a single frequency, but if you have collected a spectrum of data, you can move the frequency you are looking at. If you manually imput a single phase/amplitude at a specific frequency, then that's all you can animate. [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Mass and stiffness from compliance plots
Registered Member Both Dan Ambre and Tony DeMatteo have demonstrated what you are asking about. Send an e-mail to Tony for a duplicate application he provides in his class. Dan had an article published in Uptime Magazine, Nov/Dec 2008 that covered his diagnosis of a vertical pump issue. Link to some of Dan's information [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
SKF Machine ODS
Registered Member My understanding is that MEScope will run on most box's. Which is good. [ more ]
Registered Member Hi Aubrey, The SKF Machine ODS software is actually MESCope V4.XX with specific drivers for the older CMVA series of data collectors. The software is now running at V5.XX and the drivers have been removed. However the CMXA series of data collectors (Microlog GX and AX) run a specific module for Modal and ODS readings and the data is directly imported into V5. In addition to this if you have a Microlog AX with the recorder module you can not only do ODS measurements in the frequency domain... [ more ]
Registered Member Thanks Dave, That is the direction I hope we go. Aubrey [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Why this thread is needed?
Registered Member Excellent replies guys. We have used modal analysis several times to identify problems with large fans. It really helps people understand how a total system comes together to make a reliable asset. [ more ]
Registered Member There are methods of determining resonance that could be discussed. Examples: Impact testing Modal hammers Problems with balancing Programs used to animate ODS and Modal data like ME-Scope [ more ]
Registered Member Josh, The answer is yes and yes. Modal analysis can be used as follows: 1) in the design phase to verify analytical model 2) in the manufacture phase to verify or prove there are no resonant structure problems or interval faults (cracks or voids) 3) in the installation phase to verify structural response or to diagnose high vibrations 4) to assist in diagnosis and correction of high vibrations found by Simple survey. Modal analysis and the related Structure test methods are essential for... [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Clamped vs. free beam modal analysis
Registered Member I should mention that the motivation for viewing modeshapes as a sum of traveling waves is simply to understand the resonant frequencies as was first mentioned by Amar. If we look at the pinned/pinned case, we can see that the wave travels twice the length of the beam in one cycle. We conclude that the resonant frequency is F = c / (2*L) where c is the speed of the wave in the beam, which is a constant (characteristic of the beam material and cross section). If we look at the pseudo... [ more ]
Registered Member Thanks Walt. The pinned/pinned diagram shows a decomposition of a standing wave ("Total") into the sum of a forward-travelling wave and backward travelling wave. The total (purple curve) does in fact have 0 displacement at each boundary as required by the pinned/pinned boundary condition. The forward and reverse travelling waves at each boundary have non-zero magnitude of equal magnitude and opposite sign (which of course sums to 0). This corresponds to a reflection with inversion at the... [ more ]
Registered Member El'Pete, Why does the Pinned/Pinned modes (above 1st mode) have displacements at the beam ends if they are pinned and restricted from motion? I am very impressed with your animation! Walt [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ODS DATA - TURBINE/GENERATOR SHAFTS
Registered Member Hi Tony, Thanks for taking time to get me up to speed on ME'Scope utilizing Bently Nevada prox probes. This opens up a whole new world for me. It's amazing to view the orbits through the frequency ranges. I am just experimenting on my BN rotor kit - Looking forward to getting out in the field and doing some actual turbine/generator shafts. Again, Thanks and Happy New Year! - Mike (Data Dog) [ more ]
Registered Member Hello Data Dog In ME'scope... Create your shaft. It can be a line connecting two points or a cylinder. Either way, keep the coordinates RECTANGULAR. By default, "Z" will be vertical and "X" or "Y" will be horizontal (depending on your view of the shaft). You can change the software to make "X" or Y" vertical if you wist. I wouldn't bother. Assign the data from one of the two prox probes on a bearing to the "Z" and the other prox data to "X" or "Y". If the probes are 45 degrees from vertical,... [ more ]
Registered Member Steve, Thanks for the feedback. Tony, Your turbine/generator shaft(s)ODS is exactly what I am trying to duplicate. In the ME'Scope Software - Measurement Axes (Rectangle, Cylindrical , Spherical, Machine -??). Also, how do you set up the 90 degree (45 Left - 45 Right) to include polarity? I am having difficulty in getting the orbital pattern. Thanks for sharing your animation - nice job. -Mike [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Blower Data
Registered Member Thanks, Tony. Here is a picture of the machine xRacer is concerned about. [ more ]
Registered Member I agree that it may be a weak frame. Anytime a structure looks bent or twisted in ODS animation the problem is either weakness or resonance. One way to tell for sure is to test for resonance (measure phase and magnitude during run-up or coast-down, negative averaging, peak hold bump test single channel or dual channel impact testing). Another way to tell if the ODS animation indicates resonance vs. weakness is to look at the animation of another frequency (if available in the test data). If... [ more ]
Registered Member I would check your blower pulley for eccentricity and runout. The frame is weak because there is no corner bracing. This may be the reason for the possible misalignment of the pulleys. Check the frame for a resonance in the "Y" direction (note the possible mode shape through 1,2,3,4,5) and the blower support around 26 and 27 in the vertical "Z" direction with bump tests. [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Motor Resonance Revisited
Registered Member Backside Quad View with contours. [ more ]
Registered Member Here is the backside view with contours. [ more ]
Registered Member Hi Steve, There is a bolt head between the feet of the fan support. Is this what holds the base to the main structure? The main movement looks like it is on the other side of the base and looks like a second mode shape. Turning on the "animate/contours/fill" would show where the maximum movement was taking place and turning on "animate/contours/values" would quantify the movements. Also, rotating the 3d view to the other side would give a better view of the problem area. Here is my... [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Recommended Transducer & Mounting
Registered Member Hi Walt, I normally use a single accelerometer, but there are times when you can't get a reading without adding another surface. I use my "cube" on long rails where I am taking an axial reading and there isn't a surface to collect the data from. Before I modified the "cube", I would omit the data in that axis. [ more ]
Registered Member I assume that adding a triaxial base with 3-magnets to a triazial accelerometer is an attempt to keep the accelerometer orientation consistent with the structure's coordinates for any/all measurement points. While I assume that this configuration can or has worked for some situations, I do not like it for the following reasons: 1) May be too heavy for some structures 2) May affect frequency response for tests at higher frequencies 3) It may not accomodate mounting on all measurement surfaces... [ more ]
Registered Member We have the 3143D1 permanently installed on a number of motors. The selection of that transducer was before my time here. At this time, we are just trying to stay consistent. It's much easier to get an accelerometer from our stock than trying to get a purchase requisition fulfilled. The 3063B is a bigger (twice the size) of the 3143D1. Steve [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Examples
Registered Member Walt - I agree with your concern and will attempt to recollect the data and pay close attention to sensor orientation. In regards to using a tri-axial as described in the other thread, I'm having a hard time seeing how to get data in 3 directions at some measurement points. How do you do it with a single axis transducer? Another question: We are coming out of an outage, and the sister pump is now in service. Is it worthwhile to collect modal data with the other pump in service? My only other... [ more ]
Registered Member Hi Steve, I would like to discuss this privately using an e-mail if you're willing. Your animation shows horizontal radial being in the "Y" direction. Your Vertical is the "Z" direction. Your Axial is in the "X" direction. This is why I have been asking for you to look in the "Y" axis data. I don't know if you reviewed this thread, but here is a tidbit I learned the hard way: Accelerometer Orientation [ more ]
Registered Member Steve, I question the polarity (phase) of your measurement points on motor. It shows the motor case to be distorting, and I doudt this is occuring. Points 59 & 60 horizontal motion should be outward when base points 73 & 74 vertical motion is upward. We discussed triaxial accelerometer mounting issues in the previously mentioned Link. It is difficult to keep the accelerometer axis (data channels) and their polarity properly matched to the structures coordinate system (+X, +Y, +Z). I... [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
Hoffman Type Blower Problem
Registered Member Hi John, In this case, I used the same values for the feet, instead of getting discrete readings for each of the 4 corners. To clarify, the front left foot used the reading for #5, the rear left foot used reading #6, the right rear used the reading for #7 and the right front foot used the reading for #8. That is why there is no distortion to any of the motor feet. Access to all four corners of each foot was not possible. If the feet were moving out of sync with the base, I would be checking... [ more ]
Registered Member Hi Joh, I notice you have a constraints problem with the motor feet and the plate they attach to. (The feet rise above and fall below the plate.) I have been using a B&K system and having put in the constraint equations for a similar situation, is does not apply them. I'm wondering if I have to "Group" the feet and the plate before they work ? Any thoughts ? Cheers John Morey [ more ]
Registered Member Hi Ron, Yes, the support is sheet metal formed into a "U". The bends are not quite 90˚, however. The static view shows the correct angle since this is important. Can another possible problem be seen in the animation? [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ANIMATION SOFTWARE
Registered Member Here is one more link. On this forum under the heading "sale", Tony DeMatteo has an advertisement for his training package. http://maintenanceforums.com/eve/forums/a/tpc/f/6721004131/m/2391056783 I have taken Tony's course and can recommend him as a very good instructor. [ more ]
Registered Member Hi Irshad, There are a couple that I am aware of. I use ME'scope. http://www.vibetech.com/go.cfm/en-us/content/index Some examples can be found at Full Spectrum Diagnostics: http://www.fullspec.net/ One neat feature I use is activating the arrows showing the phase relationships between measurement points. Also handy is shading the different high vibration points with the accompanying table showing vibration levels. Pretty neat when you are trying to impress someone into getting work scheduled. [ more ]
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Asset Condition ManagementPosts About Modal Analysis and Operation Deflection Shape (ODS)
ODS WITH SINGLE CHANNEL ANALYSER
Registered Member This is specific to CSI, but you can use the Model 444C Strobe instead of the photo tach to set the frequency you want to compare. This way you don't have to stop the machine to put reflective tape on. Using the Strobe allows you to set the frequency to other than harmonics of 1xSS. [ more ]
Registered Member IRD's E-shape also allows you to tell it how many shapes you want to display. It takes a while to get all the data. Dave [ more ]
Registered Member CSI equipment will allow you to monitor the phase of different orders of turning speed with a single piece of photo cell tape in the monitor peak verses phase function. It allows you to input the order of turning speed you are interested in. [ more ]
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