Featured Discussions - Scan-and-Solve for Rhino2024-03-29T11:23:41Zhttp://www.scan-and-solve.com/forum/topic/list?feed=yes&xn_auth=no&featured=1Dauphin - Frame Redesign with SnStag:www.scan-and-solve.com,2011-08-03:6083097:Topic:172062011-08-03T05:47:03.153ZIan Boydhttp://www.scan-and-solve.com/profile/IanBoyd
<p>I have been using SnS for almost a year now (chair manufacturer). The affect on product reliability has been profound though I must qualify that by saying it has meant going back to the textbooks (most notably Shigleys) but the results have been rewarding.</p>
<p>The following is a little case study of a chair frame (German design) that went from being a fragile “breaker” to a zero return “battle tank” after some careful redesign. Bear in mind also that we are not permitted to change the…</p>
<p>I have been using SnS for almost a year now (chair manufacturer). The affect on product reliability has been profound though I must qualify that by saying it has meant going back to the textbooks (most notably Shigleys) but the results have been rewarding.</p>
<p>The following is a little case study of a chair frame (German design) that went from being a fragile “breaker” to a zero return “battle tank” after some careful redesign. Bear in mind also that we are not permitted to change the aesthetics of the chair and every other component (imported or local) must still fit perfectly.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2311994393?profile=original"><img class="align-full" width="640" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994393?profile=original"/></a></p>
<p>Pic 1 shows a chair with a broken frame (tip back failure).</p>
<p> </p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2311994855?profile=original"><img class="align-full" width="640" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994855?profile=original"/></a>The weak point is the junction between the back legs and the horizontal frame members, as shown in pic 2.</p>
<p>The first thing addressed was the welding. Originally welded down the two long sides only, this was amended to “all round”. A calculation showed that doubled the strength – a good start. This is a manual CO2 weld but that will shortly change to robotic CO2 or TIG.</p>
<p>The second change was the section of the rectangular back member (the part broken in photo 2). Originally 9.6mm this was increased to 12.7mm (1/2”, wall thickness 1.6mm). This caused a further problem with the fitting of the plastic seat – the fingers used to clip it on being further overstrained, causing occasional breakages. This was addressed by aligning the back bar with the back leg (rotated through 8 degrees) – not how it was meant to fit but this works well.</p>
<p>The third change was to re-specify the steel (back bar only) to SAE1010 structural tube. Wall thickness only available as 1.5mm but the increase in strength more than compensates for this.</p>
<p>The DIN tip back test calls for an 85Kg mass to be placed on the centroid of the seat with the front legs raised 30mm from the floor. SnS analysis showed that the original frame just fulfilled that requirement – but it clearly wasn’t sufficient. The revised design fails at twice that load. A guideline (apparently) is that static stress loading only fulfils around 55% of the requirement of a cycled fatigue test. The strength doubling therefore came as good news.</p>
<p>Since these changes were enacted (9 Oct 2010) not a single frame (out of thousands) has been returned. The drainage hole has been moved over slightly (aligned with tubular member) but the electroplaters won’t budge further on that. My argument is that if the welding is sound, drainage holes aren’t necessary, but the frame is now reliable.</p>
<p> </p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2311997529?profile=original"><img class="align-full" width="595" src="http://storage.ning.com/topology/rest/1.0/file/get/2311997529?profile=original"/></a></p>
<p>Pic 3 shows the close correlation between the actual failures and the SnS result. This is the new design, simulated in (235Mpa yield) mild steel. The final frame used SAE1010 for the rectangular tube and the wall thickness of the round tube was increased by 0.5mm. Increase in frame cost: R15.00 (US$2.22).</p>
<p>There are still occasional failures on the plastic back where the armrest meets the back leg but we are looking to localise that component – perhaps from polyamide (PA/Nylon) to glass fibre reinforced polypropylene (PP+GF). PP is manufactured in South Africa whereas PA is not, which helps keeps cost down. SnS will undoubtedly play a key role in that development.</p>
<p>Every new version of SnS has incorporated useful improvements. The programming team obviously listen to their users – a refreshing change. I have just set up my first strain gauge meter – th0se will be used in conjunction with SnS. For instance, where are the hot spots we need to pay attention to? Do the results (mathematical / SnS / strain gauge / displacement) corroborate?</p>
<p>An area of concern is recycled polymers. There is now great pressure to use recycled content but the people who write tender documents are blissfully ignorant of the loss in strength. We recently initiated a pilot program with the South African Plastics Recycling Organisation (SAPRO) to develop a national certification standard for recycled plastics. Recyclers will thus blend up pellets to match a datasheet. That can be used in SnS to help find the optimum recycled content for a given application. I can strongly recommend setting up a working relationship with such recycling organisations – there is a LOT to learn about how recycling really works.</p>
<p> </p>
<p>Thanks Vadim & Team!</p>
<p> </p>
<p>Ian</p> Dauphin Human Design Grouptag:www.scan-and-solve.com,2011-05-31:6083097:Topic:115102011-05-31T09:59:17.950ZIan Boydhttp://www.scan-and-solve.com/profile/IanBoyd
<p>Dear Reader</p>
<p> </p>
<p>We are using SnS now almost daily to help solve design problems with chair components. That alone saves us money; we can now discuss various options with our engineers in Germany rather than DHLing them samples and waiting weeks for a fail/nofail report.</p>
<p> </p>
<p>This is an example from just yesterday. One of the BIFMA certification tests is a 134Kg load to the midback of a chair. It must sustain this for at least 1 minute.</p>
<p> </p>
<p>Many older chairs…</p>
<p>Dear Reader</p>
<p> </p>
<p>We are using SnS now almost daily to help solve design problems with chair components. That alone saves us money; we can now discuss various options with our engineers in Germany rather than DHLing them samples and waiting weeks for a fail/nofail report.</p>
<p> </p>
<p>This is an example from just yesterday. One of the BIFMA certification tests is a 134Kg load to the midback of a chair. It must sustain this for at least 1 minute.</p>
<p> </p>
<p>Many older chairs were never designed for such stringent testing but must nevertheless be certified, even if to an older, 'softer' standard. In this case, the frame has been widened for 'heavier' persons and of interest is the back bracket (JBar) connecting the back frame to the mechanism.</p>
<p> </p>
<p>The first step was to move the 134kg load to the top bar and adjust the load to suit the extra leverage (see first pic attached showing measurements of moments, i.e. 96Kg).</p>
<p> </p>
<p>The second step was to model the existing bracket and compare it with an empirical test. The existing bracket yielded with only a 20Kg load!</p>
<p> </p>
<p>The most significant change is a respecification of material thickness from 8mm to 10mm (ribbing may be another option but not all suppliers have the tooling). It was also widened as far as possible. We considered up rating the steel from 235MPa (plain) to 380MPa (structural). The problem there is that the rest of the frame starts to fail.</p>
<p> </p>
<p>[In some components we have similarly uprated to structural steel, but only those elements that required it, which contains costs]</p>
<p> </p>
<p>Halving the load, which more or less simulates the DIN standard, gives us something more reasonable to work with. The frames themselves have never failed in service, only the bracket. So if we can balance the strength of those, we're unlikely to have failures (see second image).</p>
<p> </p>
<p>The next step is to have the part prototyped and test it physically. It will then go to R&D in Germany for them to test (pending discussing around DIN certification).</p>
<p> </p>
<p>Something new we have started is to bring the SnS result in as a background image before PDF'ing the drawing (see third image). That may later be augmented by a list of hyperlinks to PDF'd SnS reports.</p>
<p> </p>
<p>It is worth noting that since we started using SnS, not a single component analysed (in tens of thousands manufactured) has been returned with structural failure. Not one. It has however, meant a fair amount of time studying stresses (primarily Shiggleys textbook). Our overall reject rate has dropped from around 5% to 0.25%.</p>
<p> </p>
<p>If ever I came across an application that earns it keep, this is it.</p>
<p> </p> 3rd semester architecture exam FAUM - Multimedia course - using scan and solve in concrete structurestag:www.scan-and-solve.com,2010-11-30:6083097:Topic:23562010-11-30T14:41:00.000Zmario vergarahttp://www.scan-and-solve.com/profile/mariovergara
<a href="http://multimediosfaum.wordpress.com/2010/11/29/entrega-examen-multimedios/">http://multimediosfaum.wordpress.com/2010/11/29/entrega-examen-multimedios/</a>
<a href="http://multimediosfaum.wordpress.com/2010/11/29/entrega-examen-multimedios/">http://multimediosfaum.wordpress.com/2010/11/29/entrega-examen-multimedios/</a> A simple test with my cylinder--2tag:www.scan-and-solve.com,2010-11-28:6083097:Topic:23322010-11-28T17:13:30.000ZRichard.Lhttp://www.scan-and-solve.com/profile/RichardL
The same model,with the same conditions.<div>When you clip the resolution button,get more elements. </div>
<div>The solutions are different,sometimes the differences may be 'large',</div>
<div>It depends on the model.We have to try more ‘resolution’ to see the displacement converged.</div>
<div><br></br></div>
<div>Here are my conditions;</div>
<div>Material:Steel, Stainless (ferritic)</div>
<div>Bcs:the inside circular surface 123fixed,</div>
<div>Loads:10Mpa pressure on the left outside…</div>
The same model,with the same conditions.<div>When you clip the resolution button,get more elements. </div>
<div>The solutions are different,sometimes the differences may be 'large',</div>
<div>It depends on the model.We have to try more ‘resolution’ to see the displacement converged.</div>
<div><br/></div>
<div>Here are my conditions;</div>
<div>Material:Steel, Stainless (ferritic)</div>
<div>Bcs:the inside circular surface 123fixed,</div>
<div>Loads:10Mpa pressure on the left outside surface.</div>
<div><p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994861?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">elements=10,000</p>
<p style="text-align: left;"></p>
<p style="text-align: left;"></p>
<p style="text-align: left;"></p>
<p style="text-align: left;"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2311995164?profile=original" alt=""/></p>
<p></p>
<p></p>
<p></p>
<p style="text-align: left;">elements=100,000</p>
<p style="text-align: left;"></p>
<p style="text-align: left;"></p>
<p style="text-align: left;"></p>
<p style="text-align: left;"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2311995326?profile=original" alt=""/></p>
<p style="text-align: left;">Then i tried&got;</p>
<p style="text-align: left;"></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311995435?profile=RESIZE_1024x1024" alt=""/></p>
<p></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">a simple sample compared to see the convergence of the max displacement;</p>
<p style="text-align: left;"></p>
<p style="text-align: left;"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2311995550?profile=original" alt=""/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">The ‘resolution’ button is really mean it,but i think that we may use the element size to control the resolutions, </p>
<p style="text-align: left;">Can we?</p>
<p style="text-align: left;">In this sample the 'element size' transferred </p>
<p style="text-align: left;">from</p>
<p style="text-align: left;"></p>
<table id="propertytable" style="border-collapse: collapse; border-top-width: 2px; border-right-width: 2px; border-bottom-width: 2px; border-left-width: 2px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125);">
<tbody><tr><td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">element size</td>
<td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">{2.22434,2.22434,2.22434}</td>
</tr>
<tr><th colspan="2" style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px; background-color: rgb(210, 223, 238);">Computation Box</th>
</tr>
<tr><td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">min. corner</td>
<td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">{-45.6035,-45.2646,-16.6861}</td>
</tr>
<tr><td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">max. corner</td>
<td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">{45.5945,65.9525,-1.11575}</td>
</tr>
</tbody>
</table>
<p></p>
<p style="text-align: left;">to</p>
<p style="text-align: left;"></p>
<table id="propertytable" style="border-collapse: collapse; border-top-width: 2px; border-right-width: 2px; border-bottom-width: 2px; border-left-width: 2px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125);">
<tbody><tr><td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">lement size</td>
<td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">{0.941332,0.941332,0.941332}</td>
</tr>
<tr><th colspan="2" style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px; background-color: rgb(210, 223, 238);">Computation Box</th>
</tr>
<tr><td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">min. corner</td>
<td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">{-45.1819,-45.1981,-16.4237}</td>
</tr>
<tr><td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">max. corner</td>
<td style="border-top-width: 1px; border-right-width: 1px; border-bottom-width: 1px; border-left-width: 1px; border-top-style: solid; border-right-style: solid; border-bottom-style: solid; border-left-style: solid; border-top-color: rgb(31, 73, 125); border-right-color: rgb(31, 73, 125); border-bottom-color: rgb(31, 73, 125); border-left-color: rgb(31, 73, 125); padding-top: 1px; padding-right: 3px; padding-bottom: 1px; padding-left: 3px; width: 242px;">{45.186,65.8791,-1.36239}</td>
</tr>
</tbody>
</table>
<p></p>
<p style="text-align: left;"> </p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">But,the 'Computation Box' was changed(very small), too. Why? </p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">More test coming ...</p>
<p></p>
<p></p>
<p></p>
<p></p>
<p></p>
</div> Crossbeam for a 24 ft trailerable trimarantag:www.scan-and-solve.com,2010-10-03:6083097:Topic:13382010-10-03T08:01:27.000ZScan&Solvehttp://www.scan-and-solve.com/profile/ScanSolve
(Posted for <a href="http://www.scan-and-solve.com/profile/JodyCulbert">Jody Culbert</a>)<br></br><br></br>I just sent
the whole series of screenshots that I had sent to the client to help<br />
him understand the dynamics involved in the crossbeam design for a 24 ft<br />
trailerable trimaran. Instead of folding the aluminum tubes are <br />
telescoping and fixed by tapered stainless drift pins. There are HDPE <br />
(High Density Polyetheleyne) discs that provide clearance and smooth<br />
sliding action between the tubes and…
(Posted for <a href="http://www.scan-and-solve.com/profile/JodyCulbert">Jody Culbert</a>)<br/><br/>I just sent
the whole series of screenshots that I had sent to the client to help<br />
him understand the dynamics involved in the crossbeam design for a 24 ft<br />
trailerable trimaran. Instead of folding the aluminum tubes are <br />
telescoping and fixed by tapered stainless drift pins. There are HDPE <br />
(High Density Polyetheleyne) discs that provide clearance and smooth<br />
sliding action between the tubes and I have modeled contact faces for my <br />
restraints. One of the changes that SnS prompted was the diagonal stay <br />
wire was found to be more effective to let in pass through a slot in the<br />
bottom of the tube and then terminate on the top of the tube in a ball<br />
and socket insert which was able to be located well away from the<br />
localised stress risers on the pads and holes for the pins. When design tools like Rhino, Orca3d,<br />
and so many others that have spawned from RHino's success, are<br />
affordable and usable by amateurs and hobby users, then that is a great<br />
thing and will accomplish what desktop editing and publishing tools have<br />
done for the graphics industry in the past. I hope to be able to<br />
continue to provide feedback to you and your team and wish I had time to <br />
have downloaded your latest and explored a bit further. Thanks again<br />
and keep up the great work! <a href="http://www.scan-and-solve.com/profile/JodyCulbert">Jody Culbert</a><br/><br/><img alt=""/><br/><p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311992738?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311992866?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311993060?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994477?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994540?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994761?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994953?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311996028?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311998248?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2312002535?profile=RESIZE_1024x1024" alt=""/></p> Solid versus hollow test with Rhino designtag:www.scan-and-solve.com,2010-08-30:6083097:Topic:8832010-08-30T08:30:11.000ZGerard Petersenhttp://www.scan-and-solve.com/profile/GerardPetersen
My latest project contains a retractable roof (<a href="http://www.villo.nl">www.villo.nl</a>).<img alt="" src="http://storage.ning.com/topology/rest/1.0/file/get/2311992743?profile=RESIZE_1024x1024" width="721"></img> <br></br>
<br></br>Now it is an interesting question what the z-displacement is just before it is supported by the mast. The roof will be made of an aluminum frame covered with aluminum sheeting.<br></br><br></br><p style="text-align: center;"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2311992925?profile=original"></img></p>
<br></br>First I did a Scan and Solve test as if it is a solid piece of aluminum and specified a scalar force for the gravity. Then the question raised;…
My latest project contains a retractable roof (<a href="http://www.villo.nl">www.villo.nl</a>).<img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311992743?profile=RESIZE_1024x1024" alt=""/><br/>
<br/>Now it is an interesting question what the z-displacement is just before it is supported by the mast. The roof will be made of an aluminum frame covered with aluminum sheeting.<br/><br/><p style="text-align: center;"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2311992925?profile=original"/></p>
<br/>First I did a Scan and Solve test as if it is a solid piece of aluminum and specified a scalar force for the gravity. Then the question raised; what's the difference with a hollow structure made of frames, stiffeners and sheeting? So I set up a simple test to find out.<br/><br/><p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311993662?profile=RESIZE_1024x1024" alt=""/></p>
<br/>To keep it simple I modeled a simplified geometry both hollow and solid. One constraint of SNS is however that I can only select a single solid. When modeling the structure, several solids are created which are not connected. I tackled this issue by adding a small rectangular pipe connecting the outer shell with inner cavities. Thus creating an open cell structure.<br/>Furthermore I didn't use the gravity option but simply added a scalar load representing gravity.<br/><br/>The results for the z-displacement were:<br/>- Solid: -9.5 mm<br/>- Hollow structure: -19 mm<br/><br/><p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311993870?profile=RESIZE_1024x1024" alt=""/></p>
<br/>This seems a big difference, but wall thicknesses are small and I only used one internal stiffener.<br/>Attached is the test file.<br/>As I am not a specialist in FEM, I am interested in your comments.<br/><a href="http://issuu.com/gerardpetersen/docs/sliding_roof_deflection_analysis_of_villo_motor_ya">Please find a full report about Villo roof analysis over here</a><br/><br/>Gerard Petersen<br/> S&S vs Straus7 vs ANSYStag:www.scan-and-solve.com,2010-08-29:6083097:Topic:8112010-08-29T19:48:03.000ZHrvoje Petrovichttp://www.scan-and-solve.com/profile/HrvojePetrovic
Hi,<br></br><br></br>Finally I have found some time to make a small SnS test. I have taken the steel part from my last post and checked it in Straus7. The brick mesh I made in Straus is quiet nice and clean and the SnS resolution is reasonable.<br></br><br></br>Now the results: The deflections are similar in size, but the shapes are a bit different (the zero displacement spot in Straus is in the middle of the plate, in SnS a the upper edge of the plate). The stress peaks are at same places, but the stresses…
Hi,<br/><br/>Finally I have found some time to make a small SnS test. I have taken the steel part from my last post and checked it in Straus7. The brick mesh I made in Straus is quiet nice and clean and the SnS resolution is reasonable.<br/><br/>Now the results: The deflections are similar in size, but the shapes are a bit different (the zero displacement spot in Straus is in the middle of the plate, in SnS a the upper edge of the plate). The stress peaks are at same places, but the stresses are very different. Checked loads, checked material, checked restraints, checked model, checked analysis type - all the same between SnS and Straus.<br/><br/><p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311997058?profile=RESIZE_1024x1024" alt=""/></p>
<br/><p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311997301?profile=RESIZE_1024x1024" alt=""/></p>
<br/>Now I am a little bit confused, which one of the results is closer to reality? What could cause those differences?<br/><br/>Cheers,<br/><br/>Hrvoje.<br/> Academic Examplestag:www.scan-and-solve.com,2010-08-17:6083097:Topic:5282010-08-17T23:40:39.000ZWilliam Tiuhttp://www.scan-and-solve.com/profile/WilliamTiu
<p style="text-align: left;">I attach two examples that are frequently used in engineering courses.</p>
<p style="text-align: left;">The first one relates to an asymmetric beam where the end rotation is in a clockwise direction rather than what most students would think.</p>
<p style="text-align: left;"><img alt="" src="http://storage.ning.com/topology/rest/1.0/file/get/2311992581?profile=RESIZE_1024x1024" width="721"></img></p>
<p style="text-align: left;"><br></br></p>
<p style="text-align: left;">The other example is that of a thick walled vessel subjected to an internal pressure of 100 MPa. The vonmises…</p>
<p style="text-align: left;">I attach two examples that are frequently used in engineering courses.</p>
<p style="text-align: left;">The first one relates to an asymmetric beam where the end rotation is in a clockwise direction rather than what most students would think.</p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311992581?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">The other example is that of a thick walled vessel subjected to an internal pressure of 100 MPa. The vonmises stress (according to Lame's theorem) along the inner surface is 276 MPa. Would be good to be able to querry the values at specific points rather than rely on the maximum contour values to establish the actual predicted stress along the inner surface.</p>
<p style="text-align: left;"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2311992726?profile=RESIZE_1024x1024" alt=""/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">Normally, this 2nd problem is solved by considering a quarter section and applying symmetric</p>
<p style="text-align: left;">constraints. A wish list would be one where the direction of the restraint can be specified rather like</p>
<p style="text-align: left;">the vector loading system.</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">Regards</p>
<p style="text-align: left;">William<br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p> Bicycle disc braketag:www.scan-and-solve.com,2010-08-12:6083097:Topic:3402010-08-12T12:30:32.000ZCristian Luca Atzorihttp://www.scan-and-solve.com/profile/CristianLucaAtzori
This is a disc brake I developed in 2009, painfully calculated with other software with many mesh problems and finally tested in several down-hill races here in Italy.<br></br>It took me about 12 revisions of the geometry to reach this final design because it's a typical model-test-adjust task where the form must be optimized in order to be as light as possible without collapsing under known possibile load conditions.<br></br><br></br>I believe it's a perfect task for Scan-and-Solve and I was able to…
This is a disc brake I developed in 2009, painfully calculated with other software with many mesh problems and finally tested in several down-hill races here in Italy.<br/>It took me about 12 revisions of the geometry to reach this final design because it's a typical model-test-adjust task where the form must be optimized in order to be as light as possible without collapsing under known possibile load conditions.<br/><br/>I believe it's a perfect task for Scan-and-Solve and I was able to verify my results in a couple of minutes!<br/><br/><p style="text-align: left;"><a target="_blank" class="noborder" href="http://storage.ning.com/topology/rest/1.0/file/get/2311994765?profile=original"><img width="400" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994765?profile=RESIZE_480x480"/></a></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">The material used for the final test is an AISI430F Steel (I modified manually the materials.db file).</p>
<p style="text-align: left;">The 6 inner faces of the bolt holes are used as restraints.</p>
<p style="text-align: left;">The load is a single Vector force (0,-700,0)N applied to the inner face of a profiled hole.</p>
<p style="text-align: left;">Resolution is set to 50000 elements.<br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">This conditions are a good setup for this kind of simulation and can be used confidently in place of a dynamic analisys involving friction based on a complex mechanical model.</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><a class="noborder" href="http://storage.ning.com/topology/rest/1.0/file/get/2311994923?profile=original" target="_blank"><img width="400" src="http://storage.ning.com/topology/rest/1.0/file/get/2311994923?profile=RESIZE_480x480" alt=""/></a></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><a class="noborder" href="http://storage.ning.com/topology/rest/1.0/file/get/2311995031?profile=original" target="_blank"><img width="400" src="http://storage.ning.com/topology/rest/1.0/file/get/2311995031?profile=RESIZE_480x480" alt=""/></a></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">The initial force of 700N is used because I was asked to study a real life disc that collapsed during a race, and after some reverse engineering that was the max force it was able to handle.</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">This particular design, under the same conditions, collapses with 2100N, that's a security factor of 3 to 1.</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2311995169?profile=original" alt=""/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">On the upper left is the disc that collapsed during a race.</p>
<p style="text-align: left;">On the right there're two well known commercial discs, also analyzed in order to collect more data on the typical collapse conditions.</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">Below is the first preproduction model.<br/></p>
<p style="text-align: left;"><a class="noborder" href="http://storage.ning.com/topology/rest/1.0/file/get/2311995239?profile=original" target="_blank"><img width="400" src="http://storage.ning.com/topology/rest/1.0/file/get/2311995239?profile=RESIZE_480x480" alt=""/></a></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">I would like to encourage all the Scan and Solve team, this is a GREAT beta and I'll keep looking for every update.</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">Suggestions:</p>
<p style="text-align: left;">- when in View mode, it would be very usefull to know the min and max values of the Von Mises Danger Level, maybe with some spots in the geometry</p>
<p style="text-align: left;">- a list with the maximal (+ and -) values reached in N/mm2 (or N/m2) related to the graph would also be fantastic</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">EDIT: in the very first week all the suggestions were implemented, the team in SnS is doing and excellent job!<br/></p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">Best regards</p>
<p style="text-align: left;"><br/></p>
<p style="text-align: left;">Cristian Luca <br/></p>