{"id":25638,"date":"2011-06-27T12:51:00","date_gmt":"2011-06-27T12:51:00","guid":{"rendered":"https:\/\/www.padtinc.com\/2011\/06\/27\/using-user-defined-results-in-ansys-mechanical\/"},"modified":"2022-05-02T23:07:30","modified_gmt":"2022-05-03T06:07:30","slug":"using-user-defined-results-in-ansys-mechanical","status":"publish","type":"post","link":"https:\/\/www.padtinc.com\/2011\/06\/27\/using-user-defined-results-in-ansys-mechanical\/","title":{"rendered":"Using User Defined Results in ANSYS Mechanical"},"content":{"rendered":"\n

I first started contemplating this article several weeks ago, and I was planning on somehow working in a Jersey Shore reference.  But now that I\u2019ve relocated to Colorado and am recovering from a climbing trip that was a bit above my ability, my creative juices are a little low (they were used up trying to improvise my way up an overhanging roof pitch).<\/p>\n\n\n\n

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Hmm\u2026I\u2019m noticing there aren\u2019t a lot of foot-holds to get me over there, prussik to the rescue!<\/figcaption><\/figure><\/div>\n\n\n\n

Anyways, User Defined results were first introduced in R12 to grant the user access to element table items. <\/p>\n\n\n\n

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When you insert a user-defined result, you are required to fill in the \u2018expression\u2019 line in the details window. <\/p>\n\n\n\n

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Just like Johnny 5, ANSYS needs input<\/figcaption><\/figure><\/div>\n\n\n\n

You can look up everything that\u2019s available through the documentation, but we all know that no one reads the instructions<\/p>\n\n\n\n

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Reading is boring\u2026I\u2019ll wait until the movie comes out, I hear it stars the guy who voiced Johnny 5<\/figcaption><\/figure><\/div>\n\n\n\n

There\u2019s a much easier way to auto-populate the \u2018expression\u2019 line\u2026the Worksheet view!  To access this, first click on the \u2018Solution\u2019 branch and then select \u2018Worksheet\u2019 (tab in R12, button in R12.1 and newer).  This will show you a list of all the user defined result expressions.  Find one you like, right-mouse-click on it and select \u2018Create User Defined Result\u2019. <\/p>\n\n\n\n

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That\u2019s more like it<\/figcaption><\/figure><\/div>\n\n\n\n

This will insert a \u2018User Defined Result\u2019, the only work you need to do is scope it to a body (if necessary).  The only \u2018tricky\u2019 part of this process is that you need to solve the model first before using the Worksheet view.  This is because before the model has been solved, Mechanical doesn\u2019t know what is in the result file.  So if the worksheet view is blank or grayed out, it\u2019s because you haven\u2019t solved the model.<\/p>\n\n\n\n

So what\u2019s the benefit of using the User Defined Results?  Say you wanted to look at total strain, kinetic energy, or reaction force contour plots\u2026just to name a few.  In order to view any of those, you would either have to open the .rst file in MAPDL or use the User Defined Result.<\/p>\n\n\n\n

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Left = FX, Right = Total Strain<\/figcaption><\/figure><\/div>\n\n\n\n

Here\u2019s a quick description of the \u2018headers\u2019 available on the Worksheet tab.<\/p>\n\n\n\n

\n\n\n\n\n\n\n\n\n\n\n
U<\/td>\nDisplacement<\/td>\n<\/tr>\n
S<\/td>\nStress<\/td>\n<\/tr>\n
EPTO<\/td>\nTotal Strain<\/td>\n<\/tr>\n
EPEL<\/td>\nElastic Strain<\/td>\n<\/tr>\n
EPPL<\/td>\nPlastic Strain<\/td>\n<\/tr>\n
EPTT<\/td>\nThermal Strain<\/td>\n<\/tr>\n
ENFO<\/td>\nElement Nodal Reaction Forces<\/td>\n<\/tr>\n
NDIR<\/td>\nNodal Orientation Values<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n\n\n\n

There are more headers that are listed in the documentation (I know, we all agreed that was boring).\u00a0 However if you\u2019re looking for items stored in the NMISC or SMISC (for \u2018regular\u2019 or contact elements), those are accessible provided you properly format the expression line.<\/p>\n\n\n\n

So now let\u2019s go through an example where we actually use this functionality.\u00a0 A customer called in asking how to calculate the volume of a part above a specified stress level.\u00a0 Interesting question\u2026<\/p>\n\n\n\n

First we create a user defined result and use the ‘VOLUME\u2019 expression.\u00a0 So we\u2019re half-way there.\u00a0 Next, we need to understand about how the results are stored for a result item in the \u2018Solution\u2019 branch.\u00a0 Each contour plot is actually a vector in the form of element\/node vs result.\u00a0 You can see this for yourself by right-mouse-clicking on the item in the tree and selecting \u2018export\u2019.\u00a0 So right now we have a vector defined of element vs volume.\u00a0 Now we just need another listing of element vs stress.<\/p>\n\n\n\n

When you create a stress result in Mechanical, the default behavior is to show the nodal-stress, which represent the average of the adjacent elements.\u00a0 That\u2019s not what we want.\u00a0 If we look into the \u2018Integration Point Results\u2019 we see there are more options.\u00a0 Element mean seems like it might work for us, but when we export it, we see that it\u2019s still reporting stresses at the node, only now it\u2019s using a different integration scheme.<\/p>\n\n\n\n

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Averaged<\/figcaption><\/figure><\/div>\n\n\n\n
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Elemental Mean<\/figcaption><\/figure><\/div>\n\n\n\n

In order to access the average stress value of the element (not node), we need to use the User Defined Results.  We\u2019ll ask to evaluate the expression seqv (von Mises) and set the integration option of using the elemental mean.<\/p>\n\n\n\n

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Now when we export that result item we get what we want\u2026element vs stress:<\/p>\n\n\n\n

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Now we just need to export both vectors (volume and stress), then copy\/paste\/sort\/sum and you\u2019re done.  Don\u2019t forget the most important step\u2026billing for 4 hours of post-processing work.<\/p>\n\n\n\n

Long story short, all you MAPDL users who have been complaining about not being able to access element tables should take a look at the User Defined functions. <\/p>\n","protected":false},"excerpt":{"rendered":"

I first started contemplating this article several weeks ago, and I was planning on somehow working in a Jersey Shore […]<\/p>\n","protected":false},"author":31,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2323],"tags":[],"post-podcast":[],"_links":{"self":[{"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/posts\/25638"}],"collection":[{"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/users\/31"}],"replies":[{"embeddable":true,"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/comments?post=25638"}],"version-history":[{"count":0,"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/posts\/25638\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/media?parent=25638"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/categories?post=25638"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/tags?post=25638"},{"taxonomy":"post-podcast","embeddable":true,"href":"https:\/\/www.padtinc.com\/wp-json\/wp\/v2\/post-podcast?post=25638"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}