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By:Sam McFadden
Date: 7/26/2001, 7:06 pm
In Response To: why d'ya think that is, Sam? (Les Nightingill)


I didn't intend to make a generalization regarding composite vs. wood construction. The comment was that some tensile data for cedar (axis along the grain) and plain weave glass/epoxy (axis along one fiber direction) showed that there was not much difference between the two in terms of stiffness and failure strain. Of all the styles of woven fibers (exluding the 3-dimensional stuff), plain weave has the most misalignment along any given fiber - all that over and under variation in the weave. Before a fiber can fail in tension, it has to straighten out, which requires force. Because the epoxy matrix constrains the fibers, but is also compliant (low stiffness) and able to sustain some plastic deformation, what we see on the stress-strain record is a lower modulus, and a larger strain to failure than if the fibers had been perfectly aligned. Overcoming this effect is one of the reasons for different styles of weave, such as crows-foot or harness satin. But what is good for one application may not be good for another. In some cases, there is merit in trying to match the stiffness of different lamina, rather than just trying to maximize the properties of a given layer.

Does this help?


Messages In This Thread

Paddle Rehab *Pic*
Chip Sandresky -- 7/25/2001, 7:22 pm
Sand aggressively
Paul G. Jacobson -- 7/26/2001, 2:43 am
Re: Sam, what is your opinion?
Tony -- 7/26/2001, 1:36 pm
Re: Sam, what is your opinion?
JimC -- 7/26/2001, 5:15 pm
Re: I'll just have to make another :)
Chip Sandresky -- 7/26/2001, 7:34 pm
Re: Sam, what is your opinion?
Sam McFadden -- 7/26/2001, 3:07 pm
why d'ya think that is, Sam?
Les Nightingill -- 7/26/2001, 4:41 pm
Sam McFadden -- 7/26/2001, 7:06 pm
That helps a lot, thanks Sam *NM*
Les Nightingill -- 7/26/2001, 9:45 pm
Pete Rudie -- 7/26/2001, 2:40 pm
Re: Dynel?
Sam McFadden -- 7/26/2001, 3:25 pm
Penetrating epoxy *Pic*
Pete Rudie -- 7/26/2001, 1:03 pm
Re: The Celtic knot....
Shawn Baker -- 7/26/2001, 5:43 pm
Re: The Celtic knot....
Pete Rudie -- 7/26/2001, 6:36 pm
Nick Schade - Guillemot Kayaks -- 7/27/2001, 9:10 am
posting proceedure?
Elliott -- 7/26/2001, 1:43 pm
Re: posting proceedure?
Pete Rudie -- 7/26/2001, 2:19 pm
Re: posting proceedure? *Pic*
Elliott -- 7/27/2001, 8:12 am
John Monfoe -- 7/28/2001, 4:58 am