Author Topic: Fun with materials  (Read 10765 times)

Offline tmazz

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Re: Fun with materials
« Reply #15 on: November 15, 2019, 04:11:33 PM »
Stands for Hollis Audio Labs.  I am Rich, you can call me HAL.

Just don't call me late for dinner.......
Remember, it's all about the music........

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Offline dBe

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Re: Fun with materials
« Reply #16 on: November 15, 2019, 07:53:26 PM »
I’ve done some impulse testing.  In order to standardize testing results I built a swing hammer out of a 1 x 2 and an old hammerhead.  I drilled holes at 3” intervals from 6” up to 24”.  Used a polished nail for a pivot.   Swung the arm from a vertical 2 x 4 from the same height every time relative to the hole placement.  Crude, but absolutely repeatable.  I set the gate for the first strike or moved the MUT back from the pendulum until it didn’t strike again after rebound.

Just a thought to standardize the impulse.

Offline dBe

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Re: Fun with materials
« Reply #17 on: November 15, 2019, 07:55:02 PM »


I've been tempted to take a hammer to some of my creations on more than one occasion. Not for testing though...

 :rofl:

Offline HAL

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Re: Fun with materials
« Reply #18 on: November 16, 2019, 06:14:21 AM »
My new test setup is a vice to hold the sample.  The accelerometer is attached with BlueTack to the sample.

I have a 12V solonoid door opener with a pulse generator being used backwards.  The solonoid pushes the actuator rear screw cap rapidly into the sample to tap it.  Totally repeatable as the pulse time is controlled by an Arduino pulse software pin set for output.  Built a solonoid driver circuit with diode protection to take the Arduino output. 

This is a modification to the swinging hammer or weight idea.

Hope to start testing the samples Peter sent of a bunch of materials soon.  Will see what happens.

Offline dflee

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Re: Fun with materials
« Reply #19 on: November 16, 2019, 07:53:42 AM »
First off I just gotta say I won't get a thing out of this topic. BUT
Y'all are first off quite intelligent and second the posts are awesome.
Enjoy reading when you put your thoughts into words.
Carry on

Don
"Enjoy pleasure, not because it is fleeting, but because it exists at all." Sacrament, Clive Barker.

Offline dBe

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Re: Fun with materials
« Reply #20 on: November 16, 2019, 10:59:51 AM »
My new test setup is a vice to hold the sample.  The accelerometer is attached with BlueTack to the sample.

I have a 12V solonoid door opener with a pulse generator being used backwards.  The solonoid pushes the actuator rear screw cap rapidly into the sample to tap it.  Totally repeatable as the pulse time is controlled by an Arduino pulse software pin set for output.  Built a solonoid driver circuit with diode protection to take the Arduino output. 

This is a modification to the swinging hammer or weight idea.

Hope to start testing the samples Peter sent of a bunch of materials soon.  Will see what happens.
Ahhhh. Cool. I was wondering how you are doin it.

Offline HAL

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Re: Fun with materials
« Reply #21 on: November 16, 2019, 01:46:28 PM »
The CLIOwin 8.51 Standard measurements system is running and calibrated to Audiomatica's automated calibration system. 

The accelerometer sensitivity is being adjusted for by the software for testing.

The PC display is the peak hold and waveform displays for the test waveform.

Offline HAL

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Re: Fun with materials
« Reply #22 on: November 19, 2019, 04:24:26 AM »
Modified the test rig as it had to much damping.  Needed to clamp the solonoid to the vise for stability.

Tested all the samples Peter J sent.  Also tried some constrained layer damping material CAE VB-2 as well.  Will be graphing the response plots and some comparisons.

Offline HAL

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Re: Fun with materials
« Reply #23 on: November 19, 2019, 01:52:56 PM »
Did some comparison plots of the impulse response measurements with the test setup of samples sent by Peter J.

First is the comparison of MEDEX and Ranger Board, The second is the comparison of MEDEX to MEDEX with CAE VB-2 constrained layer damping material applied.

Constrained layer damping needs more investigation.

Offline HAL

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Re: Fun with materials
« Reply #24 on: November 20, 2019, 12:54:59 PM »
Did the comparison plots of the impulse response measurements with the test setup of material samples sent by Peter J. 

Here are the samples sent with the material listed in the bottom of the graph,

Green is always the MEDEX sample for comparison.

Offline HAL

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Re: Fun with materials
« Reply #25 on: November 20, 2019, 12:56:47 PM »
Next set:

Offline HAL

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Re: Fun with materials
« Reply #26 on: November 20, 2019, 12:59:21 PM »
Next batch:

Offline HAL

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Re: Fun with materials
« Reply #27 on: November 20, 2019, 01:00:54 PM »
Last batch of measurements:

Offline dBe

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Re: Fun with materials
« Reply #28 on: November 20, 2019, 01:43:40 PM »
So, Rich:  what are your determinations at this point in testing?  From my end, it looks like the quartz countertop material is the most linear in decay and in my way of thinking that would be THE desireable characteristic.

Should I send you constrained layer material that I use when I build cabinets?  Ah, yes.  I think I should.  It will be coming to you in a few days.

Offline HAL

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Re: Fun with materials
« Reply #29 on: November 20, 2019, 06:06:44 PM »
Dave,
The Quartz has a nice decay vs frequency, but it also has the largest undamped resonance at 11.5KHz.  Might be a candidate for constrained layer damping trials.  It is just very heavy!  :o