Will Sixel's Posts - Scan-and-Solve for Rhino2024-03-29T05:42:46ZWill Sixelhttp://www.scan-and-solve.com/profile/WillSixelhttp://storage.ning.com/topology/rest/1.0/file/get/2537151956?profile=RESIZE_48X48&width=48&height=48&crop=1%3A1http://www.scan-and-solve.com/profiles/blog/feed?user=1l6c2miz12v7t&xn_auth=noScan&Solve Pro Analysis: Spirit of the Riverstag:www.scan-and-solve.com,2016-11-01:6083097:BlogPost:467422016-11-01T15:00:00.000ZWill Sixelhttp://www.scan-and-solve.com/profile/WillSixel
<p><span class="font-size-2" style="font-family: georgia,palatino;">For generations before axe first struck timber to develop the current civilization of Manitowoc, Wisconsin, the land was inhibited by culturally rich indigenous people. To commemorate those who once inhabited the area and so graciously protected the land, the bronze monumental sculpture <i>Spirit of the Rivers</i> is being built on the shores of Lake Michigan (read more about <i>Spirit of the Rivers…</i></span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">For generations before axe first struck timber to develop the current civilization of Manitowoc, Wisconsin, the land was inhibited by culturally rich indigenous people. To commemorate those who once inhabited the area and so graciously protected the land, the bronze monumental sculpture <i>Spirit of the Rivers</i> is being built on the shores of Lake Michigan (read more about <i>Spirit of the Rivers</i> <a href="http://spiritoftherivers.org/" target="_self">here</a><i>)</i>. While the craft of the monument radiates beauty and grandeur through reflection of indigenous culture and a powerful display of realism, the structural stability has yet to be analyzed to ensure it will stand the tests of Mother Nature and time. </span></p>
<p style="text-align: center;"><span style="font-family: georgia,palatino;"><span class="font-size-2"><a href="http://storage.ning.com/topology/rest/1.0/file/get/2545617434?profile=original" target="_self"><img width="400" src="http://storage.ning.com/topology/rest/1.0/file/get/2545617434?profile=RESIZE_480x480" class="align-center" width="400"/></a></span><span class="font-size-1">1/8th scale miniature of the <em>Spirit of the Rivers</em> monument</span></span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">There has been some unease within the Manitowoc area as to how stable the upcoming monument will be. Not only is the sculpture going to be of a significant size, it will also be carrying a great deal of weight. To test for areas of concern in the design, as well as some of the more extreme Wisconsin conditions, a wax model was built and 3D scanned into a precise digital model. This scan was eventually given to the team at Intact Solutions, and we have now performed a structural analysis of the bronze statue.</span></p>
<p style="text-align: center;"><span style="font-family: georgia,palatino;"><span class="font-size-2"><a href="http://storage.ning.com/topology/rest/1.0/file/get/2545630544?profile=original" target="_self"><img width="300" src="http://storage.ning.com/topology/rest/1.0/file/get/2545630544?profile=RESIZE_320x320" class="align-center" width="300"/></a></span><span class="font-size-1">Scanned 3D model in Rhino</span></span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">The digital model created via 3D scanning was scaled to size and manipulated to the desired artistic dimensions. The cast bronze was modeled as 1/4" (6.4mm) thick. Two stainless steel beams, one running from the foundation, entering the portaguer’s foot, and exiting through his head; and the other running along the interior hollow section of the canoe were added for support.</span></p>
<p style="text-align: center;"><span style="font-family: georgia,palatino;"><span class="font-size-2"><a href="http://storage.ning.com/topology/rest/1.0/file/get/2545633979?profile=original" target="_self"><img width="300" src="http://storage.ning.com/topology/rest/1.0/file/get/2545633979?profile=RESIZE_320x320" class="align-center" width="300"/></a></span><span class="font-size-1">Support beams added to model</span></span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">Before getting into the analysis, let’s review the material properties of bronze. The ultimate strength refers to the maximum stress material will handle without fracturing. Yield strength is the stress at which the material will permanently deform – that is, below this limit the material behaves elastically and will return to its original shape when the load is removed. Lastly, the fatigue limit refers to the maximum stress that can be applied an indefinite number of times without the material failing.</span></p>
<table style="”margin: 1em;" width="672" cellspacing="0" border="1">
<tbody><tr><td width="137" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;"> </span></p>
</td>
<td width="133" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">Ultimate Strength<br/></span></p>
</td>
<td width="133" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">Yield Strength<br/></span></p>
</td>
<td width="132" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">Fatigue Limit*<br/></span></p>
</td>
<td width="131" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">Density<br/></span></p>
</td>
<td width="113" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">Elastic Modulus</span></p>
</td>
</tr>
<tr><td width="137" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">Cast <br/> Silicon Bronze</span></p>
</td>
<td width="133" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">379.9 MPa <br/> (55,100 psi)</span></p>
</td>
<td width="133" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">170.3 <span style="font-family: georgia,palatino;">MPa</span><br/> (24,700 <span style="font-family: georgia,palatino;">psi</span>)</span></p>
</td>
<td width="132" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">103.4 <span style="font-family: georgia,palatino;">MPa</span> <br/> (15,000 <span style="font-family: georgia,palatino;">psi</span>)</span></p>
</td>
<td width="131" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">8360 <span style="font-family: georgia,palatino;">kg/m<span style="font-family: georgia,palatino;"><sup>3</sup></span></span> <br/> (0.302 <span style="font-family: georgia,palatino;">lb/in<sup>3</sup></span>)</span></p>
</td>
<td width="113" valign="top"><p style="text-align: center;"><span style="font-family: georgia,palatino;">110 GPa<br/> (16,000 ksi)</span></p>
</td>
</tr>
</tbody>
</table>
<p><span style="font-family: georgia,palatino;" class="font-size-1">*estimated from fatigue limit for similar alloy</span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">The Rhino 3D model was analyzed as a welded assembly of multiple materials in Scan&Solve Pro. Four cases were considered: gravity alone, side wind and gravity with and without the beams, and front wind and gravity. The wind generated forces were determined from coefficient of drag calculations for 90 kph (55 mph) winds.</span></p>
<p style="text-align: center;"><span style="font-family: georgia,palatino;" class="font-size-2"><a href="http://storage.ning.com/topology/rest/1.0/file/get/2545634401?profile=original" target="_self"><img width="400" src="http://storage.ning.com/topology/rest/1.0/file/get/2545634401?profile=RESIZE_480x480" class="align-center" width="400"/></a></span><span style="font-family: georgia,palatino;" class="font-size-1">Stresses due to only gravity</span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">The first simulation with gravity alone highlighted the primary areas of concern, indicated by red. Notably, the high stress regions were in the portaguer’s right ankle and where the canoe rests on his right shoulder, as well as in the woman’s right ankle. The shoulder region has a high stress because of the relatively small area the weight of the canoe is being applied through. This is partially alleviated by the vertical supporting rod.</span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">For the case where the wind is blowing into the side of the statue, the results are displayed below. The wind is blowing from right-to-left. This loading case, the bending caused by gravity and the wind causes the highest stress regions in the portageur’s right ankle and in the woman’s right ankle.</span></p>
<p style="text-align: center;"><span style="font-family: georgia,palatino;"><span class="font-size-2"><a href="http://storage.ning.com/topology/rest/1.0/file/get/2545634773?profile=original" target="_self"><img width="300" src="http://storage.ning.com/topology/rest/1.0/file/get/2545634773?profile=RESIZE_320x320" class="align-center" width="300"/></a></span><span class="font-size-1">Stresses due to wind blowing from side and gravity</span></span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">The deflection and load for the case where the wind is blowing to the front of the statue are shown below. Here, the deflections are multiplied by a thousand for visualization. The true predicted deflection is less than 0.8mm (1/32”). Most of the deflection shown is due to gravity – the back of the canoe is being pulled down, and also pulls the woman down and to the side due to the welded connection. For this load case, the front wind load causes the peak stress in the sculpture to be in the front of the woman’s right ankle. The stress in the portaguer’s ankle is actually lower in this case because it is more evenly distributed.</span></p>
<p style="text-align: center;"><span style="font-family: georgia,palatino;"><span class="font-size-2"><a href="http://storage.ning.com/topology/rest/1.0/file/get/2545658924?profile=original" target="_self"><img width="300" src="http://storage.ning.com/topology/rest/1.0/file/get/2545658924?profile=RESIZE_320x320" class="align-center" width="300"/></a></span></span><span style="font-family: georgia,palatino;" class="font-size-1">Amplified deflection shown with stresses due to wind blowing from front and gravity</span></p>
<p><span style="font-family: georgia,palatino;"><span class="font-size-2">The results show that the statue will be very robust. The safety factors listed in the following table were calculated using the material strengths above and the results from Scan&Solve. A safety factor of 4 would indicate that for the given load, the resulting stresses are a quarter of the material failure stress. For both high-wind cases, the safety factor was higher than 8. It is worth noting that most buildings are designed to a safety factor of about 2, showing the lasting strength of the monument.</span></span></p>
<p><span style="font-family: georgia,palatino;"><span class="font-size-2">Comparing the side wind load case with and without the support beams shows that the beams are able to reduce peak stress in the monument by almost a factor of two. In addition, the peak deflection in the statue was significantly reduced by adding the support beams. From an artistic sense, this is preferred since the statue deforming under its own weight would not necessary represent the original intent.</span></span></p>
<table cellspacing="0" border="1">
<tbody><tr><td width="111"><p align="center"> </p>
</td>
<td width="184"><p align="center">Fatigue Safety Factor</p>
</td>
<td width="287"><p align="center">Ultimate Strength Safety Factor</p>
</td>
</tr>
<tr><td width="111"><p align="center">Gravity only</p>
</td>
<td width="184"><p align="center">9</p>
</td>
<td width="287"><p align="center">16</p>
</td>
</tr>
<tr><td width="111"><p align="center">Side wind</p>
</td>
<td width="184"><p align="center">8</p>
</td>
<td width="287"><p align="center">14</p>
</td>
</tr>
<tr><td width="111"><p align="center">Side wind without support beams</p>
</td>
<td width="184"><p align="center">5</p>
</td>
<td width="287"><p align="center">9</p>
</td>
</tr>
<tr><td style="text-align: center;" width="111">Front wind</td>
<td style="text-align: center;" width="184">8</td>
<td style="text-align: center;" width="287">14</td>
</tr>
</tbody>
</table>
<p><span style="font-family: georgia,palatino;" class="font-size-2">Structurally, the monument will be more than sound. Our analyses indicate that there is a considerable factor of safety in the statue, showing that it will stand the test of time. We look forward to seeing the monument when it is completed!</span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">For more information about the <i>Spirit of the Rivers</i> monument, you can see their website <a href="http://spiritoftherivers.org/">here</a>. If you are interested in analyzing multi-material assemblies in Scan&Solve, check out our free to download Beta version <a href="http://www.intact-solutions.com/scanandsolve/download_wip_frontend.php">here</a>.</span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">Thanks for reading,</span></p>
<p><span style="font-family: georgia,palatino;" class="font-size-2">Will Sixel & Ben Mihelich</span></p>Assessing caster mount designtag:www.scan-and-solve.com,2015-08-19:6083097:BlogPost:438682015-08-19T20:33:27.000ZWill Sixelhttp://www.scan-and-solve.com/profile/WillSixel
<p><span class="font-size-2" id="docs-internal-guid-85e553cd-4780-d6e5-f4a4-a4c2a5666559" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">The object to be studied is a table saw with two wheels on one side of it. To make it fully mobile, two additional caster mounted wheels will be added to the opposite side of the table saw…</span></p>
<p><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;" id="docs-internal-guid-85e553cd-4780-d6e5-f4a4-a4c2a5666559">The object to be studied is a table saw with two wheels on one side of it. To make it fully mobile, two additional caster mounted wheels will be added to the opposite side of the table saw (location circled in red below).<br/></span></p>
<p></p>
<p><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545632409?profile=original"><img class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545632409?profile=original" width="353"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4781-89fe-0238-174e69c4e8a1"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">The design goal of the structure was to ensure that the deflection of the caster mount would not be significant. In addition, the structure was checked for areas of high stress, to ensure that yielding would not occur.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4781-9ab3-27a5-79a7749aba48"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">The total weight of the table is 250 lb, and each of the casters should be able to support the full weight of the table saw. Normally the weight would be equally distributed, but when moving over a crack or bump a wheel could carry the entire weight of the table saw.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4781-b123-9d41-7016a0db30e3"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">The corner of the table saw was modeled in Rhino. It was then intersected with a sphere, producing the object shown. This is to reduce the modeling size of the structure based on distance to the area of interest. In addition, the sphere intersection produces a single surface in Rhino, so applying the restraints is simple.<br/></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545632445?profile=original"><img width="500" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545632445?profile=RESIZE_1024x1024" width="500"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4781-d830-5bfa-698edf598a83"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">The proposed design is shown above. An angle iron will be welded to the side of the saw cabinet, and square tubing will be welded to the angle iron. The caster will be welded to the bottom of the square tubing, as seen above. The structure was then modeled as an assembly using the Scan&Solve Work-In-Progress. Modeling the caster mount as an assembly allows for easier design changes based on the results of a simulation, as the individual components were not joined with Boolean union.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4782-0568-df61-16a98082ab02"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">However, the wheel itself does not need to be simulated, since the deflection and stress in the mount are the most concerning. The 250 lb (1100 N) force will be applied to a small area on the caster mount, and the cut face of the model is fully restrained.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545633355?profile=original"><img width="500" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545633355?profile=RESIZE_1024x1024" width="500"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4782-1d35-80a7-e6b593693bb0"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">A small cylinder was created and positioned on the bottom face of the mount and the force was applied to this cylinder. The small cylinder is positioned to correspond to the location of the contact patch of the wheel on the ground. Use of the cylinder in this manner is similar to creating a point force. With its location near the edge of the plate we should expect to see bending and twisting of the tube. With the loads and restraints applied, the scenario was solved. The Danger Level is shown below.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545633549?profile=original"><img width="600" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545633549?profile=RESIZE_1024x1024" width="600"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4784-06e8-a1ca-6b2a83e709bf"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">The stresses in the structure are quite low. While there are some stress concentrations near the weld points, they are low enough to not be of concern. The maximum Danger Level is 0.0967: less than 10% of the material strength. So, the mount will not fail under the specified force. The magnified deflection of the structure is shown below; the original structure is shown in wireframe.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545633691?profile=original"><img width="500" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545633691?profile=RESIZE_1024x1024" width="500"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4784-6903-cbe8-74b04d42e95e"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">The shape of deflection is a combination of bending and twisting in the caster mount. However, the maximum displacement in the mount is only 0.005 in (0.127 mm). This deflection is quite low, so the mount should work effectively.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-85e553cd-4784-769d-af76-a409c1dd770c"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">If you are interested in working with assemblies in Scan&Solve, the new Work-In-Progress version is <a href="http://www.intact-solutions.com/scanandsolve/download_wip_frontend.php" target="_blank">available for download here</a>. All you need is a valid Scan&Solve license and you will be able to simulate composite assemblies and orthotropic materials.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">Thanks for reading!</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; font-family: georgia,palatino; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline;">Will</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>Evaluating CNC plasma cutter support stiffnesstag:www.scan-and-solve.com,2015-07-24:6083097:BlogPost:435702015-07-24T19:15:18.000ZWill Sixelhttp://www.scan-and-solve.com/profile/WillSixel
<p><span class="font-size-2" id="docs-internal-guid-f71dfaf4-c147-df6a-c3c8-74c0ce3d1975" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">This blog post will delve into another structural design problem that was solved with Scan&Solve. A CNC plasma cutter was designed and a question arose regarding the end plates…</span></p>
<p><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;" id="docs-internal-guid-f71dfaf4-c147-df6a-c3c8-74c0ce3d1975">This blog post will delve into another structural design problem that was solved with Scan&Solve. A CNC plasma cutter was designed and a question arose regarding the end plates supporting the CNC gantry: are the end plates stiff enough to resist the inertial forces from the cutter? For CNC machinery, limiting deflection is critical as it ensures quick and accurate machining.</span></p>
<p></p>
<p><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545629357?profile=original"><img width="500" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545629357?profile=RESIZE_1024x1024" width="500"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c14c-2937-ca54-ca07f37a2871"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">The CNC plasma cutter will accelerate along the gantry (horizontal axis in the image above) as it cuts the part. The acceleration produces an inertial force, causing bending in the vertical end plate (shown in green) which supports the gantry. Linear guides (blue) secure the end plate to a rail (yellow), giving the cutter its second axis of motion.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545629461?profile=original"><img width="300" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545629461?profile=RESIZE_320x320" width="300"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c14d-a52c-b927-7613941a65fb"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">To efficiently analyze this system, it can be broken down into smaller sections near the area of interest. In this case, the entire gantry did not need to be modeled to understand the bending of the end plate. Only part of the gantry near the plate was modeled in Rhino. As long as the gantry does not significantly bend under the applied load, the length of the gantry to model does not need to be increased.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545629955?profile=original"><img width="400" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545629955?profile=RESIZE_480x480" width="400"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c14e-0774-7e94-367d4ff43b8f"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">Now, we will specify the restraints for the Scan&Solve simulation. The restraints at the bottom need to restrain the model in the Y and Z directions, but not over-restrain it and artificially limit the bending of the plate. The vertical faces of the guides were restrained in the Z-direction and the horizontal faces were restrained in the Y-direction. While these restraints may seem counter-intuitive, they produce realistic results that allow for limited bending in the guides.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545629988?profile=original"><img width="400" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545629988?profile=RESIZE_480x480" width="400"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c14e-8f43-2c97-4676c2a46545"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">However, there is an issue with modeling the rail as a zero-displacement restraint. Since the rail and guides are both made of steel, the rail is equally stiff as the guides and will also deform under stress. However, as long as the displacements of the guides remain small relative to the bending of the plate, the contributions of the rail deflection can be neglected.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c14e-adb7-7500-51c0bd38cd7f"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">The end face of the gantry beam was also restrained to limit its ability to bend in a direction that would not likely occur if the full gantry were modeled. The loaded face was restrained so it would remain in its original orientation, but would be allowed to move in the Y-direction. The end of the beam was similarly restrained in the X-direction to also keep the beam straight. These restraints are shown below.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545654994?profile=original"><img width="400" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545654994?profile=RESIZE_480x480" width="400"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c14f-a4f1-934d-cd73b837b00e"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">The following image shows the effect of not restraining the loaded end of the gantry. The gantry has deformed in a way that would not be possible if the full model were considered, as the gantry would not deflect downwards so significantly under a horizontal force.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545655170?profile=original"><img width="250" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545655170?profile=RESIZE_320x320" width="250"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c151-09bc-bee5-f25d2a9b89b8"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">The applied load was considered to be a result of linear acceleration along the gantry. The specified acceleration was 0.9m/s/s and the mass of the plasma cutter is 6kg, so from Newton’s second law and a modest factor of safety, a 10N force was applied to the end of the gantry. This force was applied axially to the end of the gantry. The model was simulated with Scan&Solve and the following shape of deflection was found.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545655259?profile=original"><img width="250" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545655259?profile=RESIZE_320x320" width="250"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c151-6487-f63c-663e1b41bc8e"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">Two designs were considered to reduce the bending of the end plate. First, a square tube of identical dimensions as the gantry was joined to the back face of the end plate. The second design extended the gantry through the plate and added two gusset plates connecting the extended portion of the gantry to the end plate. These gussets extended to the bottom of the plate to maximize their contribution to the bending stiffness.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545657701?profile=original"><img width="500" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545657701?profile=RESIZE_1024x1024" width="500"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c151-b8ee-30c6-617a9d5c72a8"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">Both designs were quite successful in reducing the bending of the plate and deflection of the gantry. The square tube and the gusset plate design both obtained quite similar maximum displacements, reducing the maximum displacement by over a factor of 10.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt; text-align: center;"></p>
<table style="margin-left: auto; margin-right: auto;" class="c9" cellspacing="0" width="438">
<tbody><tr class="c8"><td class="c6" colspan="1" rowspan="1">Design</td>
<td class="c11" colspan="1" rowspan="1"><p class="c1"><span style="font-family: georgia,palatino;" class="font-size-2">Maximum deflection (cm)</span></p>
</td>
</tr>
<tr class="c8"><td class="c6" colspan="1" rowspan="1"><p class="c1"><span style="font-family: georgia,palatino;" class="font-size-2">No ribs</span></p>
</td>
<td class="c11" colspan="1" rowspan="1"><p class="c1"><span style="font-family: arial,helvetica,sans-serif;" class="font-size-2">9.1e-4</span></p>
</td>
</tr>
<tr class="c8"><td class="c6" colspan="1" rowspan="1"><p class="c1"><span style="font-family: georgia,palatino;" class="font-size-2">Square tube support<br/></span></p>
</td>
<td class="c11" colspan="1" rowspan="1"><p class="c1"><span style="font-family: arial,helvetica,sans-serif;" class="font-size-2">7.3e-5</span></p>
</td>
</tr>
<tr class="c8"><td class="c6" colspan="1" rowspan="1"><p class="c1"><span style="font-family: georgia,palatino;" class="font-size-2">Gusset plates with extended tube</span></p>
</td>
<td class="c11" colspan="1" rowspan="1"><p class="c1"><span style="font-family: arial,helvetica,sans-serif;" class="font-size-2">7.5e-5</span></p>
</td>
</tr>
</tbody>
</table>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt; text-align: center;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c152-a1c4-4c94-b5bde8c4bb27"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">The square tube deflection is shown on the left, and the gusset plate deflection is shown on the right. The shape of deflection is quite similar for both designs.<br/></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;"><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545661342?profile=original"><img width="500" class="align-center" src="http://storage.ning.com/topology/rest/1.0/file/get/2545661342?profile=RESIZE_1024x1024" width="500"/></a></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c153-01cc-7749-9be3505ac6bd"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">At this level of displacement, the bending of the gantry beam is noticeable compared to the bending of the plate. This is in contrast to the first bending illustration, where the plate was bending much more than the gantry. In addition, the rail mounts have begun to twist, which is just noticeable in the image showing the deflection of the gusset plate design.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c153-10e1-f66e-41876d23821b"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">To proceed with trying to achieve further stiffness, the stiffness of the rail itself must be modeled as well as an extended length of the gantry. However, it is likely that further stiffness would be difficult to achieve without changing the thickness of the plate, gantry, or the size of the rail and guides.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;" id="docs-internal-guid-f71dfaf4-c153-2057-d47d-c978c7534647"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">The meshless advantage of Scan&Solve was particularly useful in enabling rapid analysis of design changes. Being able to change a model and immediately run an analysis to measure its effect is an immense timesaver.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">Thanks for reading! If you have any questions, feel free to ask in the comments.</span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span class="font-size-2" style="font-size: 14.6667px; color: #000000; background-color: transparent; font-weight: normal; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; font-family: georgia,palatino;">Will</span></p>Analyzing tube failure with Scan&Solvetag:www.scan-and-solve.com,2015-06-26:6083097:BlogPost:438402015-06-26T21:30:00.000ZWill Sixelhttp://www.scan-and-solve.com/profile/WillSixel
<p>This story starts with an unexpected failure, as many engineering problems do. My hope is to show the great utility of Scan&Solve at every stage of the design process.</p>
<p>Two tabs were being used as a bolt mount attached to steel tubing. However, the steel tubing failed, causing the tab to break away. The tab appeared to have failed from the bottom first, then the tab separated after flexing away from the tubing. The top tab, now having to bear the entire load, then deformed as…</p>
<p>This story starts with an unexpected failure, as many engineering problems do. My hope is to show the great utility of Scan&Solve at every stage of the design process.</p>
<p>Two tabs were being used as a bolt mount attached to steel tubing. However, the steel tubing failed, causing the tab to break away. The tab appeared to have failed from the bottom first, then the tab separated after flexing away from the tubing. The top tab, now having to bear the entire load, then deformed as seen in the picture below.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545617077?profile=original"><img width="250" class="align-center" style="padding: 20px;" src="http://storage.ning.com/topology/rest/1.0/file/get/2545617077?profile=RESIZE_320x320" width="250"/></a>By design, the bolt should have failed first, with a shear load failure of approximately 1700 lb. Only the portions of the frame close to the failed tab were modeled in Rhino, with restraints chosen to be far away to not affect the stresses around the tab. The simplified model lets Scan&Solve allocate more elements to the area of interest. Even so, to avoid numerical singularities, these analyses used resolutions between 100,000 and 400,000 elements. A more simplified model of the frame could have been used to reduce the length of tubing, thus increasing the grid density near the tabs.</p>
<p>For the initial failure analysis, a 1500 lb load applied from the bolt to the tabs was added in the direction perpendicular to the tubing. The 1500 lb load was shared between the inner faces of both tabs. However, this result predicted failure would begin to occur at the top edge of the bottom tab.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545617184?profile=original"><img width="600" class="align-center" style="padding: 20px;" src="http://storage.ning.com/topology/rest/1.0/file/get/2545617184?profile=RESIZE_1024x1024" width="600"/></a></p>
<p>While high enough loads were eventually present to separate the top edge of the tab, it was the bottom edge of the tab which detached first. This indicates that the loading which caused the failure was not purely perpendicular to the tubing. A 100 lb vertical load was applied to the bottom of the tab, which could be transmitted to the tab by the head of the bolt.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545617422?profile=original"><img width="300" class="align-center" style="padding: 20px;" src="http://storage.ning.com/topology/rest/1.0/file/get/2545617422?profile=RESIZE_320x320" width="300"/></a></p>
<p>This load case produced a result very similar to the failure observed. The vertical load changes the failure location to be the bottom corner of the tab, and begins to induce a tensile bending stress at the bottom edge of the tab.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545617489?profile=original"><img width="600" class="align-center" style="padding: 20px;" src="http://storage.ning.com/topology/rest/1.0/file/get/2545617489?profile=RESIZE_1024x1024" width="600"/></a>This high stress level is maintained throughout the thickness of the steel tubing, indicating that the stress concentration is not merely a numerical artifact of the sharp boundary between the tab and tubing.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545627341?profile=original"><img width="600" class="align-center" style="padding: 20px;" src="http://storage.ning.com/topology/rest/1.0/file/get/2545627341?profile=RESIZE_1024x1024" width="600"/></a>So, how do we alleviate this issue? An alternate tab design was considered. The tabs would be created as a single U-shaped piece and then welded to the tubing. However, with the 1500 lb horizontal force and 100 lb vertical force still present, the analysis of the new design showed that the tubing would fail in a similar manner as the original design. The tensile bending stress caused by the vertical load will still be large enough to cause failure near the bottom edge of the tab.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545627536?profile=original"><img width="500" class="align-center" style="padding: 20px;" src="http://storage.ning.com/topology/rest/1.0/file/get/2545627536?profile=RESIZE_1024x1024" width="500"/></a>A view inside of the tubing is included below. The high stresses are maintained throughout the width of the tab, and are present on the inside and outside surfaces of the tubing. Although this U-shaped tab was not the design which failed, the stress concentrations are consistent with the failure that was observed.</p>
<p><a target="_self" href="http://storage.ning.com/topology/rest/1.0/file/get/2545627728?profile=original"><img width="500" class="align-center" style="padding: 20px;" src="http://storage.ning.com/topology/rest/1.0/file/get/2545627728?profile=RESIZE_1024x1024" width="500"/></a>Essentially, there is no simple fix that will make the frame resistant to this particular failure. The ideal solution is to change the geometry causing the vertical load to occur, thus eliminating the bending stress within the tubing. An alternative solution is to increase the thickness of the tubing in this region to better distribute both the bending stresses and horizontal stresses.</p>
<p>However, those analyses will have to be a blog post for another day. Hope you enjoyed the read,</p>
<p>Will</p>