<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:12px"><div><span></span></div><div></div><div id="yui_3_16_0_1_1430506880867_19838"><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19862" style="margin: 0in 0in 10pt;"><font id="yui_3_16_0_1_1430506880867_19861" face="Calibri"><font size="3">Scott.</font><span style="mso-spacerun: yes;"><font size="3"> </font></span><font id="yui_3_16_0_1_1430506880867_19860" size="3">First read the
section in the ABS rules in chapter 6 on</font></font> <span style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>Metallic
Pressure Boundary Components.<span style="mso-spacerun: yes;"> </span>If you don’t,
you will be lost.<span style="mso-spacerun: yes;"> </span></span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19859" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19858" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>The spreadsheet
is broken into four tabs (Instructions, Cylindrical shells, Spherical and Elliptical
head and Figures.)<span style="mso-spacerun: yes;"> </span>Decide what you want
analyze, i.e., shell plus stiffeners or the heads.</span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19857" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19856" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>Make a first
pass estimate of the shell thickness and the stiffener design dimensions and
spacing.<span style="mso-spacerun: yes;"> </span></span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19854" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19855" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>For an FEA for
a given loading you normally look for where in the structure you reach the
maximum stress levels.<span style="mso-spacerun: yes;"> </span>You stay way away
from the material yield point and beef up the weak area in an iterative
process.<span style="mso-spacerun: yes;"> </span></span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19852" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19853" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>The ABS hull
analysis goes about this differently.<span style="mso-spacerun: yes;">
</span>What is does is calculate a bunch of different Pa (Maximum allowable
Working Pressure) each associated with a different fail mode.<span style="mso-spacerun: yes;"> </span>For example if your light stiffeners are two wimpy,
then the failure mode would be predicted to be overall buckling in which
multiple light stiffeners cave in.<span style="mso-spacerun: yes;"> </span>In
this case, the ABS sheet would give a low number for the Pa associated with
this event.<span style="mso-spacerun: yes;"> </span>Let say your light
stiffeners are strong enough so that you don’t have overall buckling.<span style="mso-spacerun: yes;"> </span>Then ABS rules are going to start pointing to
other failure modes as indicated by a low Pa.<span style="mso-spacerun: yes;">
</span>For example, you may reach the yield point on the material at mid bay
between the light stiffeners.<span style="mso-spacerun: yes;"> </span>If this
was the case, and it was the lowest PA, then you would look and bumping up the
shell thickness.<span style="mso-spacerun: yes;"> </span>There is another
failure mode known as localized buckling.<span style="mso-spacerun: yes;">
</span>In this case, the shell buckles in between the light stiffeners in the
form of dents.<span style="mso-spacerun: yes;"> </span>The ABS calls these
lobes.<span style="mso-spacerun: yes;"> </span>For localized failure, there can
be 1, 2, 3 , 4 …of these lobes or dents.<span style="mso-spacerun: yes;">
</span>So the ABS sheets ask you to try 1, then 2 then 3 … as the number of
dents and for each, number, it recalculates the Pa.<span style="mso-spacerun: yes;"> </span>The calculation you are interested in is the
number of dents or lobes that associated with the lowest Pa.<span style="mso-spacerun: yes;"> </span>IF this failure mode occurred, this would be
the number of lobes.</span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19842" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19841" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>So after you
put your input data in and sweep through different numbers of lobes or dents, you
leave n set to this valve that gives the minimum Pa for localized buckling.</span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19844" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19843" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>The sheet does
one other test, in which it looks at light stiffener tripping.<span style="mso-spacerun: yes;"> </span>It looks at the design for the light stiffener
and calculates does it trip or not.<span style="mso-spacerun: yes;"> </span>If
it fails this test, you would beef up the light stiffener.</span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19845" style="margin: 0in 0in 10pt;"><span style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'> </span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19847" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19846" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>Now you are ready
to step back and look at what overall failure mode is predicted.<span style="mso-spacerun: yes;"> </span>You do this by looking at each of Pa.<span style="mso-spacerun: yes;"> </span>The Pa that has the lowest value is the
predicted failure mode.<span style="mso-spacerun: yes;"> </span>This could be 1)
Overall Buckling, 2) localized buckling or 3) Reaching the yield stress mid bay
4) reaching the yield near the light stiffer in the shell. or 5) stiffener
tripping.</span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19849" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19848" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>As a general
rule, prediction of reaching yield is more are accurate than the buckling
calcs.</span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19851" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19850" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>Most designers
would purposefully design their boat with most of the PA fairly close but with
mid bay yielding as the predicted failure mode.</span></div><font face="Times New Roman" size="3">
</font><div id="yui_3_16_0_1_1430506880867_19894" style="margin: 0in 0in 10pt;"><span id="yui_3_16_0_1_1430506880867_19893" style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>To build in a
factor of safety to the calculation, the ABS uses safety factors for each
calc.<span style="mso-spacerun: yes;"> </span>This is the Greek letter eta. The
default values in the sheet are given by ABS.<span style="mso-spacerun: yes;">
</span>No factor of safety would be an eta = 1.</span></div><font face="Times New Roman" size="3">
</font><div style="margin: 0in 0in 10pt;"><span style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>Finally at the
end of the day you have a magic Pa.<span style="mso-spacerun: yes;"> </span>The spreadsheet
then calculates the hydrostatic pressure associated with Pa to determine the
maximum safe operating depth.<span style="mso-spacerun: yes;"> </span>To see
what a crush depth would be, you can rerun the spreadsheet and relay all the
safety factors (eta=1) to one.<span style="mso-spacerun: yes;"> </span></span></div><font face="Times New Roman" size="3">
</font><div style="margin: 0in 0in 10pt;"><span style='line-height: 115%; font-family: "Arial","sans-serif"; font-size: 10pt; mso-fareast-font-family: "Times New Roman";'>Hope this
helps.</span></div><font face="Times New Roman" size="3">
</font></div><div id="yui_3_16_0_1_1430506880867_19800" dir="ltr">Cliff</div><br> <div id="yui_3_16_0_1_1430506880867_19882" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <div id="yui_3_16_0_1_1430506880867_19881" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_1_1430506880867_19885" dir="ltr"> <hr size="1"> <font id="yui_3_16_0_1_1430506880867_19884" face="Arial" size="2"> <b><span style="font-weight: bold;">From:</span></b> 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> Friday, May 1, 2015 2:03 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [PSUBS-MAILIST] exotic steel<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1430506880867_19880"><br><div id="yiv2003054991"><div id="yui_3_16_0_1_1430506880867_19879"><span id="yui_3_16_0_1_1430506880867_19878" style="color: rgb(0, 0, 0); font-family: Verdana; font-size: 10pt;"><div>Cool. Would someone be able to spend a few minutes explaining how to use the sheet? </div>
<div id="yui_3_16_0_1_1430506880867_19883">Also how do you use different materials? I see 516gr 70 is plugged into it. </div>
<div id="yui_3_16_0_1_1430506880867_19877"> </div>
<div>Thanks,<br>Scott Waters </div>
<div> </div>
<blockquote id="yiv2003054991replyBlockquote" style="color: black; padding-left: 8px; font-family: verdana; font-size: 10pt; margin-left: 8px; border-left-color: blue; border-left-width: 2px; border-left-style: solid;">
<div id="yiv2003054991wmQuoteWrapper">-------- Original Message --------<br>Subject: Re: [PSUBS-MAILIST] exotic steel<br>From: Jon Wallace via Personal_Submersibles<br><<a href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>Date: Fri, May 01, 2015 8:49 am<br>To: Personal Submersibles General Discussion<br><<a href="mailto:personal_submersibles@psubs.org" target="_blank" rel="nofollow" ymailto="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br><br>
<div class="yiv2003054991moz-cite-prefix"><br>Scott,<br><br>I use the excel spreadsheet calculator that Cliff Redus created a few years ago. You can download it from the web site.<br><a href="http://psubs.org/" target="_blank" rel="nofollow">PSUBS.ORG</a> -> Resources & Reference -> Design Tools -> Calculators & Data Sheets -> Stiffened Cylinder Calculator<br><br>Make sure you "Enable" macros. There are multiple tabs at the bottom of the sheet, one of them is for spheres and elliptical heads. It takes a little time to learn how to use it, but once you've "got it" in your head the spreadsheet is really easy to use. I've gone through it line by line and Cliff did a fantastic job converting the ABS specs into a useable tool.<br><br>Jon<br><br><br>On 5/1/2015 10:40 AM, via Personal_Submersibles wrote:<br></div>
<blockquote type="cite"><span style="color: rgb(0, 0, 0); font-family: Verdana; font-size: 10pt;">
<div>Jon,</div>
<div> </div>
<div>Where / how do you do the calcs? Is it difficult? I have never had anyone show me, so I have had to rely on others to do the clacs for me. As I get closer to solidifying my next submarine, being able to do more of the design work myself would be really helpful</div>
<div> </div>
<div>Thanks,</div>
<div>Scott Waters </div></span><br></blockquote><br>
<hr>
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