{"id":30061,"date":"2017-05-30T17:32:19","date_gmt":"2017-05-30T17:32:19","guid":{"rendered":"https:\/\/www.padtinc.com\/2017\/05\/30\/assembly-modeling-with-ansys\/"},"modified":"2017-05-30T17:32:19","modified_gmt":"2017-05-30T17:32:19","slug":"assembly-modeling-with-ansys","status":"publish","type":"post","link":"https:\/\/www.padtinc.com\/2017\/05\/30\/assembly-modeling-with-ansys\/","title":{"rendered":"Assembly Modeling with ANSYS"},"content":{"rendered":"

In my previous article, I wrote about how you get what you pay for with your analysis package.\u00a0 Well, buckle up for some more\u2026but this time we\u2019ll just focus on handling assemblies in your structural\/thermal simulations.\u00a0 If all you\u2019re working on are single components, count yourself lucky.\u00a0 Almost every simulation deals with one part interacting with another.\u00a0 You can simplify your boundary conditions a bit to make it equivalent, but if you have significant bearing stresses, misalignments, etc\u2026you need to include the supporting parts.\u00a0 Better hope your analysis package can handle contact\u2026<\/p>\n

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First off, contact isn\u2019t just for structural simulations.\u00a0 Contact allows you to pass loads across difference meshes, meaning you don\u2019t need to create a conformal mesh between two parts in order to simulate something.\u00a0 Here\u2019s a quick listing on the degrees of freedom supported in ANSYS (don\u2019t worry\u2026you don\u2019t need to know how to set these options as ANSYS does it for you when you\u2019re in Workbench):<\/p>\n

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You can use contact for structural, thermal, electrical, porous domain, diffusion, or any combination of those.\u00a0 The rest of this article is going to focus on the structural side of things, but realize that the same concepts apply to essentially any analysis you can do within ANSYS Mechanical..<\/p>\n

First, it\u2019s incredibly easy to create contact in your assembly.\u00a0 Mechanical automatically looks for surfaces within a certain distance from one another and builds contact.\u00a0 You can further customize the automated process by defining your own connection groups, as I previous wrote<\/a> about.\u00a0 These connection groups can create contact between faces, edges, solids bodies, shell bodies, and line bodies.<\/p>\n

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Second, not only can you create contact to transfer loads across different parts, but you can also automatically create joints to simulate linkages or \u2018linearize\u2019 complicated contacts (e.g. cylindrical-to-cylindrical contact for pin joints).\u00a0 With these joints you can also specify stops and locks to simulate other components not explicitly modeled.\u00a0 If you want to really model a threaded connection you can specify the pitch diameter and actually \u2018turn\u2019 your screw to properly develop the shear stress under the bolt head for a bolted joint simulation without actually needing to model the physical threads (this can also be done using contact geometry corrections)<\/p>\n

\"image\" <\/picture><\/a> Look ma, no threads (modeled)!<\/p>\n

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If you\u2019re *just* defining contact between two surfaces, there\u2019s a lot you simulate.\u00a0 The default behavior is to bond the surfaces together, essentially weld them closed to transmit tensile and compressive loads.\u00a0 You also have the ability to let the surfaces move relative to each other by defining frictionless, frictional, rough (infinite coefficient of friction), or no-separation (surfaces don\u2019t transmit shear load but will not separate).<\/p>\n

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Some other \u2018fancy\u2019 things you can do with contact is simulate delamination by specifying adhesive properties (type I, II, or III modes of failure).\u00a0 You can add a wear model to capture surface degradation due to normal stress and tangential velocity of your moving surfaces.\u00a0 You can simulate a critical bonding temperature by specifying at what temperature your contacts \u2018stick\u2019 together instead of slide.\u00a0 You can specify a \u2018wetted\u2019 contact region and see if the applied fluid pressure (not actually solving a CFD simulation, just applying a pressure to open areas of the contact interface) causes your seal to open up.<\/p>\n

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Now, it\u2019s one thing to be able to simulate all of these behaviors.\u00a0 The reason you\u2019re running a finite element simulation is you need to make some kind of engineering judgement.\u00a0 You need to know how the force\/heat\/etc transfers through your assembly.\u00a0 Within Mechanical you can easily look at the force for each contact pair by dragging\/dropping the connection object (contact or joint) into the solution.\u00a0 This will automatically create a reaction probe to tell you the forces\/moments going through that interface.\u00a0 You can create detailed contour plots of the contact status, pressure, sliding distance, gap, or penetration (depending on formulation used).<\/p>\n

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Again, you can generate all of that information for contact between surface-to-surface, surface-to-edge, or edge-to-edge.\u00a0 This allows you to use solids, shells, beams, or any combination you want, for any physics you want, to simulate essentially any real-world application.\u00a0 No need to buy additional modules, pay for special solvers, fight through meshing issues by trying to \u2018fake\u2019 an assembly through a conformal mesh.\u00a0 Just import the geometry, simplify as necessary (SpaceClaim is pretty awesome if you haven\u2019t heard), and simulate it.)<\/p>\n

For a more detailed, step-by-step look at the process, check out the following video!<\/p>\n