<html><head></head><body><p dir="ltr">I didn't mean to imply that composites are necessarily bad for the application, but rather that they are not easily predictable. Composite hulls usually require verification of theoretical results by physical testing. As for the theory, fiber reinforced matrix composites usually exhibit properties which are weighted averages of the individual component properties in proportion to their volume fractions, but they have failure modes which homogeneous isotropic materials do not, particularly with respect to buckling, delamination, and brittle fracture. Additional variables such as average length of fiber, the order of consecutive principal fiber orientations, layer thickness and so forth all have an effect on the ultimate part performance, making composite failures less predictable. That said, there have been a number of commercially successful composite pressure hulls, but there is a significant amount of work involved in validating
them.</p>
<p dir="ltr">Sean<br>
</p>
<br><br><div class="gmail_quote">On November 11, 2015 2:25:41 PM MST, Alan James via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1447268820803_18233"><span id="yui_3_16_0_1_1447268820803_18688">Sean,</span></div><div id="yui_3_16_0_1_1447268820803_18222"><span id="yui_3_16_0_1_1447268820803_18231">I just put it through the Deep Sea Power & Light program which</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18230"><span id="yui_3_16_0_1_1447268820803_18229">has basic geometries & a materials list with epoxy / fiberglass.</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18230">I had spent a lot of time a couple of years ago, researching the building<br /></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span id="yui_3_16_0_1_1447268820803_18454">of a fiberglass 1atm sub. The E glass / epoxy combination was the best</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span
id="yui_3_16_0_1_1447268820803_18633">(including price) for compressive strength.</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span id="yui_3_16_0_1_1447268820803_19358">Those carbon fiber pressure vessels are wound so a different kettle of fish.</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span id="yui_3_16_0_1_1447268820803_19474">Graham Hawke did a carbon fiber wound submarine pressure hull at one stage.</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span id="yui_3_16_0_1_1447268820803_19359">They do have carbon fiber masts which are both under compression & tension,</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span id="yui_3_16_0_1_1447268820803_19360">so the compressive strength can't be too bad.</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span>Alan</span></div><div dir="ltr" id="yui_3_16_0_1_1447268820803_18228"><span
id="yui_3_16_0_1_1447268820803_19362"> </span></div><br /> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1447268820803_18225"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1447268820803_18224"> <div dir="ltr" id="yui_3_16_0_1_1447268820803_18223"> <hr size="1" id="yui_3_16_0_1_1447268820803_18234" /> <font size="2" face="Arial" id="yui_3_16_0_1_1447268820803_18227"> <b><span style="font-weight:bold;">From:</span></b> Hugh Fulton via Personal_Submersibles <personal_submersibles@psubs.org><br /> <b><span style="font-weight: bold;">To:</span></b> 'Personal Submersibles General Discussion' <personal_submersibles@psubs.org> <br /> <b><span style="font-weight: bold;">Sent:</span></b> Thursday, November 12, 2015 8:44 AM<br /> <b><span style="font-weight: bold;">Subject:</span></b> Re:
[PSUBS-MAILIST] buoyancy<br /> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1447268820803_18226"><br />Sean,<br clear="none" />We have a New Zealand developed programme for design that is widely used in<br clear="none" />the pacific islands where Kiwis (NZ'ers) are involved. It covers piping,<br clear="none" />fabrication, ditch digging, construction of most things. It is called<br clear="none" />"TLAR". No guarantees go with it.<br clear="none" />Hugh <br clear="none" /><br clear="none" /><br clear="none" /><br clear="none" />-----Original Message-----<br clear="none" />From: Personal_Submersibles [mailto:<a shape="rect" ymailto="mailto:personal_submersibles-bounces@psubs.org" href="mailto:personal_submersibles-bounces@psubs.org">personal_submersibles-bounces@psubs.org</a>]<br clear="none" />On Behalf Of Sean T. Stevenson via Personal_Submersibles<br clear="none" />Sent: Thursday, 12 November 2015 8:26 a.m.<br clear="none" />To: Personal Submersibles
General Discussion<br clear="none" />Subject: Re: [PSUBS-MAILIST] buoyancy<br clear="none" /><br clear="none" />Alan, how did you do that calculation? What layer count, thickness,<br clear="none" />component volume fractions and principal fiber orientations did you use?<br clear="none" /><br clear="none" />Sean<br clear="none" /><br clear="none" /><br clear="none" />On 2015-11-11 12:15, Alan James via Personal_Submersibles wrote:<br clear="none" />> Hank,<br clear="none" />> I did a quick calc on a sphere of nominal dimensions made of epoxy / <br clear="none" />> fiberglass.<br clear="none" />> With external pressure it had a depth of 4347ft, with internal 3785ft. <br clear="none" />> I should have posted the results in psi, but you get the picture.<br clear="none" />> The big thing to me would be that if you ruptured it by hitting <br clear="none" />> anything, or so it failed, you would go down like a lead balloon.<br clear="none" />> Alan<br
clear="none" /><br clear="none" />_______________________________________________<br clear="none" />Personal_Submersibles mailing list<br clear="none" /><a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none" /><a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><div class="qtdSeparateBR"><br /><br /></div><div class="yqt2159376265" id="yqtfd88453"><br clear="none" /><br clear="none" />_______________________________________________<br clear="none" />Personal_Submersibles mailing list<br clear="none" /><a shape="rect" ymailto="mailto:Personal_Submersibles@psubs.org" href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br clear="none" /><a shape="rect" href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles"
target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br clear="none" /></div><br /><br /></div> </div> </div> </div><p style="margin-top: 2.5em; margin-bottom: 1em; border-bottom: 1px solid #000"></p><pre class="k9mail"><hr /><br />Personal_Submersibles mailing list<br />Personal_Submersibles@psubs.org<br /><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br /></pre></blockquote></div></body></html>