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Technical Discussions
michael ruthrof
Consultant, -
red-ant, Germany, Joined Jul 2007, 4

michael ruthrof

Consultant, -
red-ant,
Germany,
Joined Jul 2007
4
01:19 Jul-08-2007
Help! Measurement of sound velocity in polyesther monofilament

I was asked to do a measurement of sound velocity in polyesther monofilament. The filament is about 1mm thick. Can this be done with normal US equipment? Is there anybody who has Experience with this kind of Measurement?
I would be very graetful for any comment or help, even for questions, that wil bring us in a good direction....


    
 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
06:20 Jul-09-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
Many years ago (in the 1970s), my former colleague Lawrence Lynnworth of Panametrics did a lot of work with applications of this type, using magetostrictive transducers to generate extensional and torsional waves in thin rod waveguides which in turn were coupled to small threads and wires and in one experiment, to strands of spider web. He published quite a bit on this work in IEEE journals and elsewhere... if you do a net search under Larry's name you'll find a lot of references.

For a while, we sold the specialized transducers and waveguides as a commercial product but there turned out to be relatively little interest and so we discontinued them many years ago. If you can find a working Panametrics KT-55 transducer and rememdur waveguide on the secondhand market, that will probably do the job for you. Unfortunately, we can no longer supply them.


    
 
 
Thomas Vogt
R & D, - -
Guided Ultrasonics Ltd, United Kingdom, Joined Apr 2007, 22

Thomas Vogt

R & D, - -
Guided Ultrasonics Ltd,
United Kingdom,
Joined Apr 2007
22
01:20 Jul-10-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
Hi Michael

As Tom Nelligan suggested, guided waves can help you with this. What diameter is your filament?

If you can join it to another wire you can excite both longitudinal and torsional wave modes and calculate both the bulk shear and bulk compressional velocity.

I have done this myself as part of my PhD thesis which you can download from the Imperial College London website:
http://www.imperial.ac.uk/ndt/public/publications/abstracts/vogt.htm

I had in fact purchased the Panametrics transducer with the Remendur (magentostrictive) wire, but I ended up just making my own transducers (so I could cover a range of frequencies).

Please let me know if you are interested in this and I will be happy to help.

Regards,
Tom


----------- Start Original Message -----------
: I was asked to do a measurement of sound velocity in polyesther monofilament. The filament is about 1mm thick. Can this be done with normal US equipment? Is there anybody who has Experience with this kind of Measurement?
: I would be very graetful for any comment or help, even for questions, that wil bring us in a good direction....
------------ End Original Message ------------




    
 
 
MIchael Ruthrof
Consultant, -
red-ant, Germany, Joined Jul 2007, 4

MIchael Ruthrof

Consultant, -
red-ant,
Germany,
Joined Jul 2007
4
03:33 Jul-11-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
TX for the fast responses. I will see through the texts mentioned in your answers.

Since it is a filament on a production machine, there is no possibility to adopt to an end of the filament. the only chance is to go radial close to the running wire (at speed with 1-10 m/s).
The diameters will vary: so we start from 0,1mm up to 3 mm.

Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?

Best Regards Michael

----------- Start Original Message -----------
: Hi Michael
: As Tom Nelligan suggested, guided waves can help you with this. What diameter is your filament?
: If you can join it to another wire you can excite both longitudinal and torsional wave modes and calculate both the bulk shear and bulk compressional velocity.
: I have done this myself as part of my PhD thesis which you can download from the Imperial College London website:
: http://www.imperial.ac.uk/ndt/public/publications/abstracts/vogt.htm
: I had in fact purchased the Panametrics transducer with the Remendur (magentostrictive) wire, but I ended up just making my own transducers (so I could cover a range of frequencies).
: Please let me know if you are interested in this and I will be happy to help.
: Regards,
: Tom
:
: : I was asked to do a measurement of sound velocity in polyesther monofilament. The filament is about 1mm thick. Can this be done with normal US equipment? Is there anybody who has Experience with this kind of Measurement?
: : I would be very graetful for any comment or help, even for questions, that wil bring us in a good direction....
------------ End Original Message ------------




    
 
 
Tom Nelligan
Engineering,
retired, USA, Joined Nov 1998, 390

Tom Nelligan

Engineering,
retired,
USA,
Joined Nov 1998
390
05:18 Jul-11-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).

I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.

----------- Start Original Message -----------
: Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?



    
 
 
michael
michael
07:32 Jul-11-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
TX again for your input, also there is no practical equipment on the merekt to fullfill our measuring task.

What is still not quite clear to us is: theoretical if you put a acoustical shock to the filament and place two normal accelerometers and measure the time between the two receiving shocks (or in case of reflections the smalelest time between two events) one would have the sound velocity with a simple v=x/t formula. Or is there something totaly wrong in our thoughts?

----------- Start Original Message -----------
: Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).
: I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.
: : Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?
------------ End Original Message ------------




    
 
 
michael ruthrof
michael ruthrof
07:33 Jul-11-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
----------- Start Original Message -----------
: TX again for your input, also there is no practical equipment on the market to fullfill our measuring task.
: What is still not quite clear to us is: theoretical if you put a acoustical shock to the filament and place two normal accelerometers and measure the time between the two receiving shocks (or in case of reflections the smalelest time between two events) one would have the sound velocity with a simple v=x/t formula. Or is there something totaly wrong in our thoughts?
: : Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).
: : I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.
: : : Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?
------------ End Original Message ------------




    
 
 
Thomas Vogt
R & D, - -
Guided Ultrasonics Ltd, United Kingdom, Joined Apr 2007, 22

Thomas Vogt

R & D, - -
Guided Ultrasonics Ltd,
United Kingdom,
Joined Apr 2007
22
07:52 Jul-11-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
Hi Michael,

you need to specify what exactly it actually is that you want to measure.

The term 'sound velocity' has only got a unique meaning in gases and non-viscous liquids where there is only one mode of propagation - the longitudinal (or compressional).

As soon as you have a solid bulk medium you have two modes - shear and longitudinal.

When you also get to deal with the boundaries of a medium, such as in your wire, you potentially have MANY modes of propagation with different velocities, and the velocities even change with frequency (dispersion). In a wire type geometry, there are three families of modes which propagate in the axial direction: longitudinal, torsional and flexural.

But I think before you start reading up on it it is worth thinking about what it actually is that needs to be done - is it for monitoring the quality and consistence of the product online? Why did you chose "sound velocity" as the parameter you want to monitor? Can you not take measurements of samples at the end ofthe production?

Regards,
Tom

----------- Start Original Message -----------
: : TX again for your input, also there is no practical equipment on the market to fullfill our measuring task.
: : What is still not quite clear to us is: theoretical if you put a acoustical shock to the filament and place two normal accelerometers and measure the time between the two receiving shocks (or in case of reflections the smalelest time between two events) one would have the sound velocity with a simple v=x/t formula. Or is there something totaly wrong in our thoughts?
: : : Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).
: : : I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.
: : : : Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?
------------ End Original Message ------------




    
 
 
michael ruthrof
Consultant, -
red-ant, Germany, Joined Jul 2007, 4

michael ruthrof

Consultant, -
red-ant,
Germany,
Joined Jul 2007
4
01:56 Jul-13-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
Hello Tom,

Our customer wants to measure sound velocity in that filament to online monitor the quality of the produced filament. I think the costumer wants to see the E-modul changing online when production parameters are changed. Unfortunality the customer won't tell us. They just want to have a device to measure the "sound velocity" in a filament. Okay now we know there are different modes of propagation, but there is still one sound velocity right? It just became harder to measure it, because the received signal will contain more than one "answer" to the impuls give by the actuator.

But is there no comercial device on the market to measure the sound velocity in filaments?

----------- Start Original Message -----------
: Hi Michael,
: you need to specify what exactly it actually is that you want to measure.
: The term 'sound velocity' has only got a unique meaning in gases and non-viscous liquids where there is only one mode of propagation - the longitudinal (or compressional).
: As soon as you have a solid bulk medium you have two modes - shear and longitudinal.
: When you also get to deal with the boundaries of a medium, such as in your wire, you potentially have MANY modes of propagation with different velocities, and the velocities even change with frequency (dispersion). In a wire type geometry, there are three families of modes which propagate in the axial direction: longitudinal, torsional and flexural.
: But I think before you start reading up on it it is worth thinking about what it actually is that needs to be done - is it for monitoring the quality and consistence of the product online? Why did you chose "sound velocity" as the parameter you want to monitor? Can you not take measurements of samples at the end of the production?
: Regards,
: Tom
: : : TX again for your input, also there is no practical equipment on the market to fullfill our measuring task.
: : : What is still not quite clear to us is: theoretical if you put a acoustical shock to the filamentand place two normal accelerometers and measure the time between the two receiving shocks (or in case of reflections the smalelest time between two events) one would have the sound velocity with a simple v=x/t formula. Or is there something totaly wrong in our thoughts?
: : : : Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).
: : : : I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.
: : : : : Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?
------------ End Original Message ------------




    
 
 
Thomas Vogt
R & D, - -
Guided Ultrasonics Ltd, United Kingdom, Joined Apr 2007, 22

Thomas Vogt

R & D, - -
Guided Ultrasonics Ltd,
United Kingdom,
Joined Apr 2007
22
04:25 Jul-13-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
----------- Start Original Message -----------
: Hello Tom,
: Our customer wants to measure sound velocity in that filament to online monitor the quality of the produced filament. I think the costumer wants to see the E-modul changing online when production parameters are changed. Unfortunality the customer won't tell us. They just want to have a device to measure the "sound velocity" in a filament. Okay now we know there are different modes of propagation, but there is still one sound velocity right? It just became harder to measure it, because the received signal will contain more than one "answer" to the impuls give by the actuator.
: But is there no comercial device on the market to measure the sound velocity in filaments?
: : Hi Michael,
: : you need to specify what exactly it actually is that you want to measure.
: : The term 'sound velocity' has only got a unique meaning in gases and non-viscous liquids where there is only one mode of propagation - the longitudinal (or compressional).
: : As soon as you have a solid bulk medium you have two modes - shear and longitudinal.
: : When you also get to deal with the boundaries of a medium, such as in your wire, you potentially have MANY modes of propagation with different velocities, and the velocities even change with frequency (dispersion). In a wire type geometry, there are three families of modes which propagate in the axial direction: longitudinal, torsional and flexural.
: : But I think before you start reading up on it it is worth thinking about what it actually is that needs to be done - is it for monitoring the quality and consistence of the product online? Why did you chose "sound velocity" as the parameter you want to monitor? Can you not take measurements of samples at the end of the production?
: : Regards,
: : Tom
: : : : TX again for your input, also there is no practical equipment on the market to fullfill our measuring task.
: : : : What is still not quite clear to us is: theoretical if you put a acoustical shock to the filament and place two normal accelerometers and measure the time between the two receiving shocks (or in case of reflections the smalelest time between two events) one would have the sound velocity with a simple v=x/t formula. Or is there something totaly wrong in our thoughts?
: : : : : Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).
: : : : : I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.
: : : : : : Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?
------------ End Original Message ------------

Michael,

As mentioned before, in a solid there is not one single sound velocity, you need to specify the mode when you talk about velocity.

Ok, now, if you want to measure the E-Modulus your best bet is to use the fundamental longitudinal mode at low frequencies as the velocity is then approx sqrt(E/rho). It also happens to be the fastest mode of propagation at low frequencies so in principle you could use it in a simple transmission set-up. I don't know of any commercial system designed to do this.

If you like I can try to refer you to a university, which may be interested in taking on a project like this.

Regards,
Tom


    
 
 
michael ruthrof
Consultant, -
red-ant, Germany, Joined Jul 2007, 4

michael ruthrof

Consultant, -
red-ant,
Germany,
Joined Jul 2007
4
01:14 Jul-16-2007
Re: Help! Measurement of sound velocity in polyesther monofilament
Hello Tom,

to have a contact to a university would be great. Is there any chance to have a german university close by Augburg/München?

Best Regards Michael

----------- Start Original Message -----------
: : Hello Tom,
: : Our customer wants to measure sound velocity in that filament to online monitor the quality of the produced filament. I think the costumer wants to see the E-modul changing online when production parameters are changed. Unfortunality the customer won't tell us. They just want to have a device to measure the "sound velocity" in a filament. Okay now we know there are different modes of propagation, but there is still one sound velocity right? It just became harder to measure it, because the received signal will contain more than one "answer" to the impuls give by the actuator.
: : But is there no comercial device on the market to measure the sound velocity in filaments?
: : : Hi Michael,
: : : you need to specify what exactly it actually is that you want to measure.
: : : The term 'sound velocity' has only got a unique meaning in gases and non-viscous liquids where there is only one mode of propagation - the longitudinal (or compressional).
: : : As soon as you have a solid bulk medium you have two modes - shear and longitudinal.
: : : When you also get to deal with the boundaries of a medium, such as in your wire, you potentially have MANY modes of propagation with different velocities, and the velocities even change with frequency (dispersion). In a wire type geometry, there are three families of modes which propagate in the axial direction: longitudinal, torsional and flexural.
: : : But I think before you start reading up on it it is worth thinking about what it actually is that needs to be done - is it for monitoring the quality and consistence of the product online? Why did you chose "sound velocity" as the parameter you want to monitor? Can you not take measurements of samples at the end of the production?
: : : Regards,
: : : Tom
: : : : : TX again for your input, also there is no practical equipment on the market to fullfill our measuring task.
: : : : : What is still not quite clear to us is: theoretical if you put a acoustical shock to the filament and place two normal accelerometers and measure the time between the two receiving shocks (or in case of reflections the smalelest time between two events) one would have the sound velocity with a simple v=x/t formula. Or is there something totaly wrong in our thoughts?
: : : : : : Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).
: : : : : : I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.
: : : : : : : Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?
: Michael,
: As mentioned before, in a solid there is not one single sound velocity, you need to specify the mode when you talk about velocity.
: Ok, now, if you want to measure the E-Modulus your best bet is to use the fundamental longitudinal mode at low frequencies as the velocity is then approx sqrt(E/rho). It also happens to be the fastest mode of propagation at low frequencies so in principle you could use it in a simple transmission set-up. I don't know of any commercial system designed to do this.
: If you like I can try to refer you to a university, which may be interested in taking on a project like this.
: Regards,
: Tom
------------ End Original Message ------------




    
 
 
Dr. A. K. Chakraborrty
Dr. A. K. Chakraborrty
09:51 Aug-03-2008
Re: Help! Measurement of sound velocity in polyesther monofilament
Dear Sir,

I am unableto measure the sound velocity by ultrasonic measurements in emulsified viscous material. How to get it? Is it because of air bubbles in the emulsions?

Regards

Dr. A. K. Chakraborty
Central Institute of Mining & Fuel Research
3rd floor, MECL Building
Seminary Hills, Nagpur - 440 006. India
Ph: 0091-712-2510604


----------- Start Original Message -----------
: Hello Tom,
: to have a contact to a university would be great. Is there any chance to have a german university close by Augburg/München?
: Best Regards Michael
: : : Hello Tom,
: : : Our customer wants to measure sound velocity in that filament to online monitor the quality of the produced filament. I think the costumer wants to see the E-modul changing online when production parameters are changed. Unfortunality the customer won't tell us. They just want to have a device to measure the "sound velocity" in a filament. Okay now we know there are different modes of propagation, but there is stillone sound velocity right? It just became harder to measure it, because the received signal will contain more than one "answer" to the impuls give by the actuator.
: : : But is there no comercial device on the market to measure the sound velocity in filaments?
: : : : Hi Michael,
: : : : you need to specify what exactly it actually is that you want to measure.
: : : : The term 'sound velocity' has only got a unique meaning in gases and non-viscous liquids where there is only one mode of propagation - the longitudinal (or compressional).
: : : : As soon as you have a solid bulk medium you have two modes - shear and longitudinal.
: : : : When you also get to deal with the boundaries of a medium, such as in your wire, you potentially have MANY modes of propagation with different velocities, and the velocities even change with frequency (dispersion). In a wire type geometry, there are three families of modes which propagate in the axial direction: longitudinal, torsional and flexural.
: : :: But I think before you start reading up on it it is worth thinking about what it actually is that needs to be done - is it for monitoring the quality and consistence of the product online? Why did you chose "sound velocity" as the parameter you want to monitor? Can you not take measurements of samples at the end of the production?
: : : : Regards,
: : : : Tom
: : : : : : TX again for your input, also there is no practical equipment on the market to fullfill our measuring task.
: : : : : : What is still not quite clear to us is: theoretical if you put a acoustical shock to the filament and place two normal accelerometers and measure the time between the two receiving shocks (or in case of reflections the smalelest time between two events) one would have the sound velocity with a simple v=x/t formula. Or is there something totaly wrong in our thoughts?
: : : : : : : Extensional waves in a thin rod medium are roughly analagous to longitudinal waves in a bulk medium, and torsional waves are roughly analagous to shear waves... you can find more info on these modes on-line. If you were trying to calculate elastic modulus by acoustic means, you would need both extensional wave and torsional wave velocities (or in bulk tests, longitudinal wave and shear wave).
: : : : : : : I'm afraid I don't know any practical way of performing your test on fast-moving filament that is so small.
: : : : : : : : Since we only want to measure the sound velocity, I do not understand the differens between the torsional wave and the other wave from. Do you have to take care to the different wave forms to do a measurment of sound velocity?
: : Michael,
: : As mentioned before, in a solid there is not one single sound velocity, you need to specify the mode when you talk about velocity.
: : Ok, now, if you want to measure the E-Modulus your best bet is to use the fundamental longitudinal mode at low frequencies as the velocity is then approx sqrt(E/rho). It also happens to be the fastest mode of propagation at low frequencies so in principle you could use it in a simple transmission set-up. I don't know of any commercial system designed to do this.
: : If you like I can try to refer you to a university, which may be interested in taking on a project like this.
: : Regards,
: : Tom
------------ End Original Message ------------




    
 
 

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