Impact Hammer

Does anybody have VI for impact hammer testing using an Impact hammer and an Accelerometer....if U have plz share it ..i m in need of it...plz reply ASAP

Hi skartdesmart,
Here is a link to a devzone example that does impact testing using an accelerometer and an impact hammer. Here is another example that uses impact testing with a software trigger. Another example with analog trigger level sample. Hope these three examples were useful for you.
Good luck with your application!
Warm regards,
Karunya R
National Instruments
Applications Engineer

Similar Messages

NI cDAQ 9172 with 3 USB 9233 for collecting impact hammer data

Hello,
I am collecting data on a NI cDAQ 9172 with 3 USB 9233 cRIO. The software I am using is Sound and Vibration assistant. I have setup the necessary parameters and trigger. The impact hammer is connected on the USB 9233 module one and the rest of the channels on the first module and remaining two modules are accelerometer channels. Would I have a problem triggering the rest of the channels on module 2 and 3?
I have attached my project file for you to have a look at. Thank you very much for your help.
Attachments:
Xrx-run1_11-19-try1.seproj ‏239 KB

The data acquisition part of the project should have just one step. All the channels should be in the daq step of the project. In this way they are all sampled simultaneously and all channels will be triggered and sampled at the same time. This looks like you have this in your project.
I would consider using the cDAQ chassis as the holder of the 9233 which you have. In your project you have all the 9233's in the cDAQ chassis - this is also good.
Since your DAQ step has all the channels, the trigger applies to all the channels in the DAQ step. consider putting a time series plot on your view so that you can see all the data after the trigger. In other words drag the triggered data from the trigger step out onto a graph.
You can also review the the example which ships with the assistant for impact test. Pull down the help menu, select open example, select sound and vibration assistant, and then select the SVA_Impact Test example project.
Preston Johnson
Principal Sales Engineer
Condition Monitoring Systems
Vibration Analyst III - www.vibinst.org, www.mobiusinstitute.com
National Instruments
[email protected]
www.ni.com/mcm
www.ni.com/soundandvibration
www.ni.com/biganalogdata
512-683-5444

Any good VI for impact hammer modal analysis?

Including coherance tests, curve fitting, FRFs and mode extraction, etc?

I believe you will find most of what you will need in the order analysis add-on.
http://sine.ni.com/apps/we/nioc.vp?cid=10706〈=US
Preston Johnson is invloved with this package and has always been very helpful in all of my projects of this type.
Now if you do not wnat to get the add-on, I would suggest you break up this question into specific parts and post them seperately.
Trying to help,
Ben
Ben Rayner
Certified LabVIEW Developer
www.DSAutomation.com
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

NI-DAQmx: Impact Test real-imagine plot

Hello.
I am a student of mechanical engineering and I am not familiar with signal proccessing. I have to use LABView for a measurement experiment. In that project I have to use an impact hammer and an accelerometer to test surfaces of some specific meterials. My teacher tell me that I have to take the real-imagine plot of undamaged pieces as a model so I can use them at future for model. My problem is that the code I had write or the one that I use form NI example (NI-DAQmx: Impact Test) returns me a messy plot no matter how many hits I made. My teacher said me that as many hits I do the plot will be more clear but he cannot figure out what goes wrong either cause he is not familiar with labview neiher.
I wrote two different codes one using ready VI's and one that made the mathematic as my theory book say.
Please help me cause I am in a dead-end and can't move on with that.
I can post images from my codes or how I use the NI-DAQmx: Impact Test.
Thank you!

Hi Albert,
An accelerometer is a type of sensor that is used to measure acceleration and output a corresponding voltage. Using Data Acquisition (DAQ) hardware, you can acquire the voltage from the accelerometer. However, most accelerometers will need some form of current excitation, typically IEPE Excitation which is a widely used standard. You can view these sites for a discussion of Accelerometer Principles and Types of Accelerometers.
Some DAQ cards are custom built to not only acquire the voltage but to supply the excitation current at the same time, specifically Dynamic Signal Acquisition (DSA) cards. An acceleration task is an instance of a DAQmx input task specially created for measuring accelerometers. You can programmatically configure the task in the LabVIEW or create the task in Measurement and Automation Explorer (MAX), as seen in this Knowledge Base. You will notice in the screenshot below, when configuring an acceleration task in MAX, you can supply values for the accelerometer's sensitivity, units, and the amount of current needed by the accelerometer. All of these values can be found in an accelerometer's specifications document. By entering these values, an acceleration task will allow you take the voltage measurements and scale them into g's or whatever unit your accelerometer measures. This way you do not have to create a custom scale yourself.
Hope this explanation helps.
Regards,
Mallori M.
Mallori M
National Instruments
Global Customer Education Program Mananger
Calculate the time you will save with NI Training
Attachments:
ScreenHunter_01 Dec. 02 21.42.PNG ‏39 KB

Impact test force

I am newbie in labviewprogramming. Then I have enquiries about my project which is using labview. I amusing impact test with NI DAQ 6251, impact hammer B&K 8200 andaccelerometer B&K 4371 then attach it in a structure. I have done somenecessary setting and it works. I can get some graphical result for magnitude (dbchecked) phase, coherence and others are works too.
But, it is very important to meto get the value of the force when I hit the structure with the hammer. I shouldget this force value, to make the amplitude respond from accelerometer relativelycompared by the force. Can any one helpme what should I do with – especially – the labview program, so that it canresult in the force data. Then, how to get the value of the amplitude per force(m/N, in Y axis) versus the frequency (in x-axis) in a graph/chart. I really needyour help for my research.

recommend that you refer to related discussion:
http://forums.ni.com/ni/board/message?board.id=231&message.id=1258&requireLogin=False
Doug
NI Sound and Vibration

Pre samples to impact in Labview 7.0

Hello,
I am doing impact testing and acquiring signals with 4472 boards. I am using Labview 7.0. When I acquire data triggered off the rising edge of my impact hammer, data collection starts as the rise of my stimulis signal begins, just after it begins actually. I want to pad the impact signal with zeros before the impact spike. I use the "trigger settings" cluster in "ni4472_Start Acquisition (N Boards).vi" to establish the trigger type and edge, but I don't see anything about pre samples. I know a past student in my lab got presamples on 7.0 (with a very similar program to mine), but I can't figure it out. Any help?
Tristan Ericson
Ohio State University Mechanical Engineering
Dynamics and Vibrations
201 West 19th Ave Suite N350
Columbus, OH 43210-1142
Office: 614-292-9029
Lab: 614-247-8077
Fax: 614-292-3163
"No one is useless in this world who lightens the burden of another." - Charles Dickens

Hello,
The file ni4472_Start Acquisition (N Boards).vi was found in a library: NI4472 example (N Boards - Single chassis). The library was in a folder "example labview code" so I don't know where it came from. I'm sure we didn't write it. I've attached pictures that show this vi where triggering info is sent into it (It's the one that says "AI Start 4472" in the 1st picture). This vi is on the third level, in the DAQ configuration file, which is in the main program (the main program is the background in both pictures below).
In the file ni4472_Start Acquisition (N Boards).vi, we found two inputs into suv-vi's that had pre-triggering inputs: "AI Start" and "Start Master 4472" (shown in the second picture). I set both of these to 100, as shown in the picture, but when we ran the file and hit the hammer, no pre samples. Please let me know if you have any more advice.
If you want me to post any of these files, I'd be glad to. (Just need to figure out how).
Thanks again,
Tristan
http://www.pbase.com/diamond2a/image/72857779/original.jpg
http://www.pbase.com/diamond2a/image/72858216/original.jpg
Tristan Ericson
Ohio State University Mechanical Engineering
Dynamics and Vibrations
201 West 19th Ave Suite N350
Columbus, OH 43210-1142
Office: 614-292-9029
Lab: 614-247-8077
Fax: 614-292-3163
"No one is useless in this world who lightens the burden of another." - Charles Dickens

Filter Warning

Hello,
I am performing modal analysis using a impact hammer, USB NI 9233 cRIO DAQ and Sound and Vibration assistant. The steps have been set in Signal express as DAQ Acquire =>Trigger=>Filter=> Power spectrum => FRF => Save to Ascii.
I am facing two problems which I cant understand. Inspite of selecting data for saving as an ascii file it keeps giving me an error saying data file needs to be selcted. I selected the filtered data, FRF, coherence in separate save as ascii steps. Also the filter issues me a warning that the triggered data is not contiguous. What does this mean? I have selected the option of continuous samples in the DAQ Acquire tab. Do I need to change something else? I tried using both IIR and FIR filters and it still displays the error that Signal is not contiguous.
Thankyou.

Hello All! This is a duplicate post please make all responses to the following thread.
Cheers!
Corby_B
http://www.ni.com/support

Filter warning and ascii save error

Hello,
I am performing modal
analysis using a impact hammer, USB NI 9233 cRIO DAQ and Sound and
Vibration assistant. The steps have been set in Signal express as DAQ
Acquire =>Trigger=>Filter=> Power spectrum => FRF =>
Save to Ascii.
I am facing two problems which I cant
understand. Inspite of selecting data for saving as an ascii file it
keeps giving me an error saying data file needs to be selcted. I
selected the filtered data, FRF, coherence in separate save as ascii
steps. Also the filter issues me a warning that the triggered data is
not contiguous. What does this mean? I have selected the option of
continuous samples in the DAQ Acquire tab. Do I need to change
something else? I tried using both IIR and FIR filters and it still
displays the error that Signal is not contiguous.
Thankyou.
Solved!
Go to Solution.

Hello StuMtu,
Thanks for your post!
For the save to ASCII file problem I would say to make sure that you have a path specified in the File Settings Tab of the Save to ASCII/LVM file step. See the picture attached below. Also the warning you are getting about "contiguous" data means that the information that you are sending to the Filter step is not of a continuous Time Stamp Data. I am assuming here that you are only sending the trigger data from the 9233 to the Filter step. So for instance if your event happens 1 second apart then the data going to the filter is not continuous/contiguous. The data going to the filter is continuous but the time stamps do not fall right after the other. This is OK and its still going to filter your data but its just letting you know that your data is not continuous since each block of filtered data does not have a consistent time stamp. Let us know if this clears up your problems or concerns and have a great day!
Cheers!
Corby_B
Attachments:
SVA save to file.jpg ‏147 KB

Microphone frequency response function

Hi all,
I am trying to do an impact test with 3 types of sensors to investigate surface properties of a material.
The first sensor is the sensor in the modal hammer.
The second sensor is a geophone , whilst the last sensor is an air-coupled sensor in the form of a microphone.
Aside from the microphone which is directly connected to the laptop by USB, the instrumented hammer and the geophone is connected to the NI 9233 which is connected to the NI USB-9162 which finally connects to the laptop.
This hardware doesn't support analog triggering therefore software triggering is used.
I am using a vi example from http://www.ni.com/example/28438/en/
I have successfuly setup the LabVIEW VI to read the raw data coming in from all the sensors and to obtain the frequency response of the geophone due to stimulus signal created by the impact hammer.
I have tried to obtain the frequency response of the microphone due to the modal hammer however no results show up in the graph for the frequency response of the microphone.
My question is this, what is going on and how do I fix this so that I may obtain the frequency response of the microphone?
I have attached my vi for your consideration.
Solved!
Go to Solution.
Attachments:
Y2014M01D28 IRnMicFRFRecAll .vi ‏190 KB

I cannot fix your VI because I do not have DAQmx or the SVFA toolkit. What I have attached is a simulation which shows some of the concepts.
The left side simulates acquisition of two channels (hammer and geophone) via the DAQ device and one channel of sound (microphone). Don't worry too much about the details. I just threw this together quickly. The hammer signal is a square pulse, the geophone signal is one cycle of a sine wave with noise, and the microphone signal is one cycle of a triangle wave plus noise. Each of the pulses is dleayed from the start of the acquisition by different amounts to represent the trasmission delays of the sound and vibration. The values chosen are arbitrary and do not simulate any physics.
I used the sampling rate, block size, and duration controls from your VI, so the numbers of samples and the sampling rates should be the defaults from your VI. The three graphs one the left show the three signals as generated. Note that the Microphone graph has X-axis autoscaling turned off. Also the data is all in waveforms or arrays. I avoid the use of the Dynamic Data Type produced by Express VIs because it effectively obscures the data structure.
The right side shows one way to do the triggering. I used Basic Trigger Level Detection.vi from the Waveform Monitoring palette and the Get Waveform Subset.vi from the Waveform palette. Note that there are separate trigger VIs for the DAQ channels and the sound channel. Because they are not started at the exact same time and they do not have the same dt (= 1/sample rate), the waveforms cannot be combined to use a single trigger. The geophone signal is synchronized with the hammer signal so one trigger from the hammer can be used to get both subsets.
Note that with the default delays the microphone pulse occurs 30 ms after the geophone pulse but in the subsets it occurs about 4 ms before the geophone. This is due to the independent triggering.
Since you do not have a common signal or trigger for both devices (DAQ and sound), you cannot know exactly what the timing relationship is between them. On every run the differences in the start times will vary. So you will need to do some kind of calibration to determine the time delays. I am thinking of some kind of periodic stimulus which will produce several pulses to both the geophone and microphone. The first pulses will have indeterminate delays but subsequent pulses should have reproducible delays. The relative spacing and directions during the calibration runs should be the same as the hammer position for the real experiment.
Lynn
Attachments:
Sound and hammer sim.vi ‏28 KB

Is there any plan to for usb 9234 to support hardware trigger?

We expect to provide our low cost modal testing solution based on NI usb-9234 and ModalVIEW software. Hardware trigger is needed when using usb 9234 to perform impact testing.
Message Edited by Troglodyte on 07-11-2008 10:44 PM

Thank you for your post.
In order to keep the power of the board to a minimum, and to keep our prices very competitive, our customers use software triggering for applications such as impact hammer test. We are happy to coach your development team in the implementation of software analog triggering in LabVIEW, Our Sound and Vibration Assistant, or with our "C" Api. I have asked our Product Support Engineer to post a note regarding the "C" api function calls. Stay tuned.
Also, please feel free to contact us directly as the need arises.
Sincerely,
Preston Johnson
Principal Sales Engineer
Condition Monitoring Systems
Vibration Analyst III - www.vibinst.org, www.mobiusinstitute.com
National Instruments
[email protected]
www.ni.com/mcm
www.ni.com/soundandvibration
www.ni.com/biganalogdata
512-683-5444

The selected log is not prepared for viewing error

Hello,
this is literally my first day using signal express and up to now everything went fine recording voltage from accelerometer and an impact hammer. Without me changing any parameters as far as I remember I now get the errror 'the selected log is not prepared for viewing. Once recording has completed you must right-click on the log and select Make log viewable before viewing it'
Apart from the fact that there is no such option on the log (only the option of Show Value by right clicking)
I went to Tools--> Options--->Logging and made sure that the prepare log data for viewing is on the 'during logging' option.
I then changed that to 'after logging complete' to see if the error stops but nothing yet.
Any help would be appreciated

Hi,
turns out the problem was linked with not having enough space on the server were I saved the logs...when I deleted some previous work to make up space everything worked just fine. Problem solved, thank you for your interest.

Negative voltage signal

Hi everybody...
I m using an impact hammer to give excitation to a structure and i m measuring the response using an accelerometer...I want to measure the force with which i m hitting the structure with hammer...For that i am using a multiplier to multiply the voltage signal from impact hammer(in millivolts ) and the sensitivity of hammer namely 2.14 N/mV to get the force value indicated in a indicator....The problem i m facing now is that i m getting this value in negative which should not be so....
Please help me in this regard.....Suggest me possible solutions to arrive at the correct force value....
Awaiting for replies;;;;;

That's right.
     There are several possibilities:
     1.- As they suggested, just invert polarity.
     2.- Most sensors are strain sensors (we don't know what kind of sensor you have). They would generate either positive or negative voltage depending on which side they are bended to. Just like in a weight scale, we calibrate and use the static voltage (whatever it is), then output is positive if depressed, but would be negative if we pull from it. You would just flit over your sensor.
     3.- During impact, the material is bended producing certain polarity, then bounce back producing the opposite polarity. If you just use a digital sampling meter, your measurement will depend on the moment the data is sampled. If you need to record the peak, you also need an analog peak detector, which output is what you're trying to measure. But first, you need to know your polarity.
     Have fun.

Modal Analysis

Hello,
I am new to Labview and looking to do some modal testing. I have an impact hammer and accelerometer connected to my NI hardware (USB-6003).
Setup shown below:
In Labview, I have imported the voltage readouts from both the accelerometer and impact hammer using the DAQ Assistant as shown below:
I have looked at the VI's out there for doing this kind of analysis, and I do not have the understanding of Labview to adapt them to what I need. Can anyone lead me in the right direction or tell me how to modify my inputs to work with the existing VI's?
Also, I found a PDF showing exactly what I am looking for as far as functionality and output. I just want a graph of the frequency and the resonant frequency displayed like the one below:
Thanks,
Nick Rogers
Union Pacific Railroad

Nick,
You have several choices. Given that you've got a USB-6003 and are using it to get some data, I'm guessing that there are going to be more and other uses for this device, that you will want to use it to build a variety of Virtual Instruments to measure various things.
The ideal way to do this, as I'm sure you already realize, is to use LabVIEW, which has "Virtual Instrument" as part of its name (the V and I in LabVIEW). You can either (a) have your Company hire someone with LabVIEW skills to handle this, and other, projects, (b) contract out this Project, or (c) invest a little effort and learn how to do this yourself. My recommendation would be the latter -- you've already demonstrated the necessary talent and "curiousity" that would make learning LabVIEW (for you) fun and relatively easy (in my opinion).
Fortunately, there are a number of on-line Tutorials (I'll try to paste a link below) -- Google LabVIEW Tutorial. This Forum is the place to return to when you have code that "doesn't quite work" or a concept that you don't understand. Many students use it as a place to "Do My Homework For Me", and, for the most part, we successfully resist the impulse to do so, but encourage them to "keep trying, and Post Your Code".
http://www.ni.com/getting-started/labview-basics/
http://www.ni.com/academic/students/learn-labview/
http://www.ni.com/pdf/manuals/373427c.pdf
Bob Schor

Accept data only if the user wants to

Hello,
I am trying to acquire impact hammer data for modal analysis using NI cRIO USB 9233 and Sound and Vibration Assistant. I am trying to average the data over 15 hits and I want to look at the current hit, its coherence and FRF and only then select it for futher processing. Can I set a condition or loop where the next acquisition os started only after looking at the previous hit and reading.
I want to accept only good hits and data to average. I tried conditional repeat but that did not work.. Is there a way to set this capability in Sound and Vibration assistant.
Thank you.

Hello,
Jason that is actually a great idea. StuMtu, you can add a sequence step to the end of all your steps and configure it to display a message. When this message comes up you can create a snap shot of the data from that loop if you want or you can ignore it and go on to the next loop iteration. Let us know if this is what you were looking for and take a look at some screen shots below!
Cheers!
Corby_B
http://www.ni.com/support
Attachments:
Sequence.jpg ‏143 KB
Sequenc 2.jpg ‏173 KB

Choosing the appropriate accelerometer

i'm doing modal analysis on violins and have been mounting the accelerometer onto the corner of the bridge. the bridge weighs ~1.8gr and the accel i'm using weighs 0.2gr. i thought this would be a good setup however the cable from the accel is pretty stiff so am wondering if i might be better off with a slightly heavier accel (maybe 0.5gr) but with an almost silk-like flexible cable. any thoughts or comments would be appreciated, thanks in advance!

thanks for your thoughts lynn. it's actually pretty difficult to do the test you mention for anything other than gross acoustical changes. subtle things are difficult to track and i imagine this would fall into that category. what i can do is put a violin in a testing rig, tap with an impact hammer at the bridge, and do a transfer function of the spl at the microphone. i could do this without moving the instrument; just glue the accel on and re-test. if it doesn't show a difference in the frf then it's probably a pretty safe bet that it won't effect the modal analysis of the body (typical weight ~400gr.) thanks very much for the response, this is what makes these forums so helpful!

Impact Hammer

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