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Music to my ears

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Music to my ears

This morning I received a YouTube link from my son Tom who is teaching English in Japan.

http://www.youtube.com/watch?v=C_CDLBTJD4M

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What a wonderful setting for the art/musical installation.

Initial awe and amazement was soon replaced by lots of questions including; how did they arrive at the angles to control the speed and how did they make and tune so many notes?

This reminded me of a proof of concept I did some time ago with Andy, a top PTC Application Engineer. These engineers support customers so need to be able to make PTC Creo sing(!) and dance.  My question to Andy was "I want to create a set of wind chimes with specific notes/frequencies. Can PTC Creo Simulate tell me the resonant frequency of a tube and then alter the length of the tube to achieve a specific frequency?".

He came up with the attached models and the process described below.

The "chime.prt" PTC Creo model was used to run a PTC Creo Simulate modal analysis to find the natural frequency. The part is aluminium 2inches diameter, 0.125inches wall thickness and shows a natural frequency of 33.04Hz compared to 32.7Hz shown in this table:

http://home.fuse.net/engineering/chime_dimensions/Aluminum_125_200.pdf

Different sizes produced good results compared with the table.

The main reason for differences between the table and Creo Simulate will be material properties - Creo Simulate aluminium material definition was used for the analysis and might have different properties to those used in the table.  If data for the tube material you are using is not available, test the actual frequency of a tube cut to the same length as the PTC Creo model then change the material properties in the model until the Creo Simulate modal analysis result matches the actual tube.

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The Design Optimisation tools in PTC Creo make it easy to find the length of pipe for a specific frequency.  The "chime_opt.prt" has a design optimisation analysis which tries to find the correct length for a C5 note (523.30Hz) and ends up with a length of 756.416mm compared to 761.21mm in the above table.

Ideas for the classroom.

  • Students design a wind chime with several pipes tuned to the notes making up a chosen chord.
  • Individual students could model and create a tubular bell with specific a chosen note and as a group perform a short piece of music.
  • The tubular bells could be combined with actuators and programmable electronics to perform programmed tunes and maybe even Midi files.
  • Consider musical instruments with other shapes and designs including the Glockenspiel/Marimba bars in the Japanese video.

I wonder if this would work for the air inside an organ pipe or whistle....?

Teachers and students can learn how PTC Creo Simulate works here: Precision LMS for Schools.

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If you or your students try this please upload a description and images of the finished products.


Special thanks to Tom and Andy.


2 REPLIES 2

Re: Music to my ears

What kind of constraints are used on the chime in Simulate?

Thanks!

Chris

Re: Music to my ears

This model was created by an application engineer who no longer works for PTC.  My limited understanding is the analysis was 'modal' and carried out on the part. I hope this helps.