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Mast Bending test - Eccentric column loading

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faklord
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Mast Bending test - Eccentric column loading

Postby faklord » Thu Jan 19, 2023 10:17 pm

Following on from previous tests viewtopic.php?f=196&t=2414683 , it was decided to perform some further testing using an ‘eccentric column loading’ test method, as suggested by Kyle @ Project Cedrus (https://projectcedrus.com/)
This should provide results that are more representative of real use loading than those previously performed.

Masts tested:
Gong Aluminium V2 85cm
Gong Aluminium V2 70cm (this was cut down from 75cm)
Gong Carbon V2 85cm
Project Cedrus 90cm


The following chart summarizes the results.
The value ML/2𝜽 represents the bending stiffness and effectively provides a stiffness value per unit length. Ie 2 masts of different lengths but the same construction should show similar value, even though the measured deflections are different. However, some variation is to be expected due to end effects.
Stiffness.png

The following chart compares the weights of the different masts tested.
Note.
The Gong Aluminium masts were weighed complete with added Plate adapter and Fuselage adapters.
For the Gong Carbon mast the Plate adapter and Fuselage adapter are built in.
The weights for the Project Cedrus mast include the added weights of 2 different types of plate adapters (obtained from the Project Cedrus website). It could be argued that a fuselage adapter should also be added but the need for this is fuselage dependent.
Weights.png
The Project Cedrus mast is not only the lightest despite being the longest but is also the most stiff.

Details of Testing and Analysis are detailed in https://docs.google.com/document/d/10WB ... p=sharing/
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Re: Mast Bending test - Eccentric column loading

Postby Cdog » Sat Jan 21, 2023 12:59 am

Well that is interesting now where is my popcorn?

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Re: Mast Bending test - Eccentric column loading

Postby consumer » Sat Jan 21, 2023 2:01 am

Wowww! Way to step up to the challenge by Kyle and prove he was right. Thank you !

So what do you think about the conclusion from wakethief that the axis alu mast is less rigid than carbon in bending but is more torsionally rigid ?

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Re: Mast Bending test - Eccentric column loading

Postby faklord » Sat Jan 21, 2023 11:40 am

consumer wrote:
Sat Jan 21, 2023 2:01 am
Wowww! Way to step up to the challenge by Kyle and prove he was right. Thank you !

So what do you think about the conclusion from wakethief that the axis alu mast is less rigid than carbon in bending but is more torsionally rigid ?
I only have limited test data (2 carbon masts, 1 type of aluminium) but it concurs with the above wakethief conclusions. Ie:
-Carbon is better than Aluminium in bending
-Aluminium is better than carbon in torsion
No doubt it would be possible to design masts that reverse this ranking.

One of the issues is we don’t really know what are good/bad values for bending & torsional stiffness. Ie above a certain level, the fact that one mast has a slightly lower torsional stiffness than another might make no noticeable difference in use.
-This is supported, to an extent, by some subjective assessment:
In Kitefoiling: My Project Cedrus mast is a joy to use.
In comparison to various other aluminium and carbon masts I’ve used I’ve found it gives better control (I assume due to stiffness) and is much lighter (important for me as I often have long carries to the water). It’s too long for me to use for wingfoiling.

In Wingfoiling: I can only compare the Gong aluminium V2 (85 & 70) & Carbon V2 (85). In terms of control I can’t tell the difference. The Carbon seems to have less drag (but that might just my mind trying to justify the price difference :) ) It is definitely lighter but that is not of so much consequence for me (if it’s a walk, I use a trolley for my WF gear)

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Re: Mast Bending test - Eccentric column loading

Postby consumer » Sat Jan 21, 2023 3:41 pm

Thanks Faklord I agree completely. To put it another way we don't really know how much loading we experience by type and whether the deformation that occurs affects riding in some undesirable way. That being said, I predict that we are most sensitive to torsional deflection because there is little we can do in body movement to correct or counteract.

thanks again for these fantastic tests. Now we need Gong to get you a high modulus carbon mast to test next.

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Re: Mast Bending test - Eccentric column loading

Postby Cdog » Sat Jan 21, 2023 4:45 pm

What about that new hollow core Cabrinha mast?
Any opinions how that’ll stack up in this test

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Re: Mast Bending test - Eccentric column loading

Postby lifeinthehood » Sun Jan 22, 2023 3:12 am

Cdog wrote:
Sat Jan 21, 2023 4:45 pm
What about that new hollow core Cabrinha mast?
Any opinions how that’ll stack up in this test
Yeah I’m interested in seeing how this new Cabrinha mast is. It’s baffling that their marketing department isn’t making a big deal out of the 14.5 mm thickness. It’s not even listed in the official specs. That is quite an achievement for a hollow carbon mast.
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Re: Mast Bending test - Eccentric column loading

Postby vol » Wed Jan 25, 2023 2:36 pm

Great Cedrus advertising 🙂
but please add torsion stiffness test too

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Re: Mast Bending test - Eccentric column loading

Postby consumer » Wed Jan 25, 2023 4:29 pm

vol wrote:
Wed Jan 25, 2023 2:36 pm
Great Cedrus advertising 🙂
but please add torsion stiffness test too

his torsion data is here:

https://docs.google.com/document/d/1cSz ... sp=sharing

or page 3 of his last post viewtopic.php?f=196&t=2414683&start=20

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