On May 3, 2018 10:04:26 PM UTC, "mcrawf@nuomo.com [harryproa]" <harryproa@yahoogroups.com.au> wrote:
><<I have not seen a reference supporting delamination being related to
>tensile strength. Would you mind sharing? Typically delamination is
>related to over stressing the part afaik.>>
>
> DELAMINATION, TENSILE STRENGTH, A
>
>After a section of a laminated panel is compressed via impact or heavy
>weight, the skin needs to pop back up while remaining connected to the
>core material.

Is this not, literally, over stressing?
Did you actually read my post.

> This requires two things:
>
>- A core that will allow itself to be compressed non-destructively, so
>it can go back to its original shape.

This is a good point. A desired property, it seems, is the return to a functioning form after excessively overstressed.

But, again, you can't say XPS is a poor core if you use poor XPS as a core.

>- A core with enough tensile strength to stay connected to the skin as it springs back, and also to not separate internally, inside the core, as it gets pulled into shape.

Ya, but what property of composite engineering is 'when excessively overloaded, it does not fail'?

><<many different home built aircraft have been flying for going on 50
>years... Delamination is unheard of. Unless builder error. Or violent
>accident.>>
>
>True. But aircraft rarely experience impact or point loading other
>than on structures designed for it.

Did you actually read my post? I don't think you did. Just because I mentioned aircraft to point out how water changing temperature delaminates XPS, does not mean I think we should build boats the same way we build aircraft. In fact I said that, repeatedly. Did you read my post?

>If that composite airplane's wing hit a log, the manufacturer would probably insist on an x-ray, and/or rebuilding the entire section.

The home builders I know would do a thump test and go. Perhaps a transducer exam, but generally not needed.

You should read some crash rebuild reports.

>They'd look at me as if I were crazy if I were to say "Ahh, I'll just patch it with a sticky rubber sheet, or some underwater epoxy, and later use some penetrating epoxy and some extra cloth on it once I get to an airport with service hangar".

If you had a crash, and it was a homebuilt Rutan, you would be getting calls from all over the country from people who heard you had an issue and want to tell you exactly what you need to do and not to and exactly who to call to check your work.

><<Many of these have been known to be stored, outdoors, in northern
>costal states, for their entire lives, with the freezing rain, snow,
>sleet, and hail>>
>
> Yes. And so do many houses with shingle roofs.

Again, did you actually read my post? Cause it was about water. Not a recommendation on how to build boats.

> And then leaving it submerged during and after the stress.

Are you saying XPS cannot take water submersion? You know they use the low spec stuff as dock floats?

><<XPS has given years of service to some. It serves in some pretty
>tough environments.>>
>
>But airplanes aren't boats. Boats regularly experience stresses, impacts, immersion, and abrasion that you wold not see on aircraft.

Again, did you actually read my posts? They were about water.

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