Contact Modeling - Simulation Step-Up Series Part 1 - SOLIDWORKS

hi and welcome to part 1 of this presentation on contact modeling using SolidWorks Simulation my name is Ramesh lakshmipathi and I'm a senior technical sales specialist but does the system service corporation let's get started so why contact analysis I'll often times here working with the assemblies where you have multiple parts that are physically interacting to each other so contact provides for for a more natural physical interaction between the parts of the assembly now you can always these loads and the strains to enforce that physical interaction but the problem with that is that it it introduces artificial stiffness into the system so it's always a good practice to use contact interaction especially when the parts have similar stiffness when it comes to materials contact allows the mesh from from different geometry to interact with each other transferring loads and dilute those loads depend upon the contact area and the stiffness of the geometry in Solrock simulation there are multiple ways of defining contact conditions whether the parts are initially touching each other or have a clearance between them and later on they can come and physically interact with each other the overall process is easy and intuitive so it's apply every uses advantage to use contact definitions wherever applicable well I think it's important to understand the hierarchy of contacts the way it works in SolidWorks Simulation so the top level we have what's called as a component contact a component contact could be defined as global which means it's applicable to all the parts in the assembly or contact can be defined between specific parts of your assembly then you have local contacts where you can select surfaces edges vertices reference geometry geometry entities that you know will come into contact or physically interact doing the deformation process if we use the same geometry in various contact definitions then keep in mind that the local contact will always take precedence over the component tact which in turn will take precedence over the global contact definition now component contact comes in three different types the first one is bonded second one is free or no interaction and the third one is no penetration so you can see that at the default global contact definition dialog box you can simply select the contact type select the parts of interest and define the required component contact among those selected parts now if you check this box shown the global contact checkbox that will actually apply the contact definition do all the touching face pairs it at the top assembly level so again keep in mind global contact it's applicable to all the parts of your assembly and you don't have that option checked you can still define a component contact by specifying selecting specific parts in your assembly for your contact definition let's talk a little bit about compatible versus incompatible mesh so in your contact definition at the global level you'll see two options compatible mesh and incompatible mesh now keep in mind that these this option is only applicable to bonded conditions so when you have two surfaces that are initially touching using the compatible option imprints the smaller phase on the larger phase and forces the matching mesh on both surfaces now this is obviously the desired solution because the results are going to be more accurate in the contact areas however the problem with this is especially when you have slippage geometries the compatible mesh can actually cause meshing failure see you can see in the screenshot shown the blue part and the gray part have a perfectly aligned node at the common air interface and so those nodes are going to be obviously merged and the solution is going to be more accurate compared to incompatible mesh where this surfaces of interest of interest are meshed independent of the other and then internal constraint equations are used to enforce the displacement and the rotation between the two surfaces in order to simulate the bonded scenario so you can see this picture on the right side showing us the same blue and the gray part are actually mesh differently or independent of the off of each other you can see the nodes are not perfectly aligned however behind the scenes a program is using special constraint equations to enforce a bonded or a glued or a well-lit condition between those two parts at the common interface now it could be situations where you might have used split lines on geometric entities so when you have split lines like for example this picture is showing as edges from a split line on the cylinder cylindrical surface now this will actually force coincidence between the edges and the faces which means meshes will be always compatible regardless of whether you choose the compatible or the incompatible mesh setting so you can see this picture below clearly shows us that whether you choose an incompatible mesh and then run the measure the program will end up actually forcing the nodes to be coincident between the two touching geometric entities at the global contact definition level there's an option called non touching faces and this is a very powerful option to utilize especially when you are trying to enforce a bonded condition between let's say faces that might have an initial clearance between them so all you do is select this option specify max clearance distance and the measure will automatically go ahead and detect all those faces that have the type of clearance and automatically apply a bond incarnation are between those geometric entities the faces can be non parallel but there must be a common projected area between them otherwise this will not create the bonded condition now you can also apply bond and contact condition automate that process between shell to shell edges shell edges to solid phases shell edges to solid phases within a certain gap distance as well and here the valid edges that we talking about could be straight they could be parallel circular are and they should be non interfering if you are selecting if it only enforce this between circular edges again they should have the same radius concentric and they should also be on interfering all of the above scenarios the program uses an income in compatible mesh automatically to enforce the bonded condition so let's take a look I have this realm and assembly and I'm going to show you zoom in real close and show you there are the gap that you can see here and this and we have a gap like this all over this vellum and assembly so if I go ahead and set up my simulation study and and simply try to run this the solver is going to come back and complain about instability in the model so there is no way the program is going to be able to solve this problem because the only contact we have is a global contact bonded and that's only applicable between touching entities so right now if I can go ahead and enforce check that option non touching faces here it is having clearance valid two millimeters this will make sure that it automatically goes and selects or detects all those gaps and automatically uses a bonded condition so now once I've made that selection if I go and mesh and run this model they should take care of all those gaps and the model should actually run to completion so there you go so again a great way to automate the detection of gaps and enforce that modern condition without having to go through the quirks and the pains of having to create local contacts between you know those phases or entities having those gaps now the global contact is created automatically and you can see that the default condition is always set to the bonded condition now you cannot change this anywhere except for in the simulation options where you can go and set the contact type to either bonded no penetration a lot of penetration otherwise the default condition is always going to be assumed to be bonded okay so the global contact is created automatically it's set to the default bonded condition so this is kind of you know when you start an assembly set up the global contact type is always going to be set to boundary condition unfortunately there is no place to change this default setting now you can always come back here and edit the global contact definition and set the global contact to allow penetration if there isn't a reason to leave it pardon especially when you have an assembly where parts might be interfering and you want the meshing to actually go go go through and not stop because interference is very detected this could be an option that you can Center on the meshing that way you can get past any issues you know especially when you have multiple interfere interferences between parts now this I think again improves the meshing process and really forces you to consider each contact condition let's talk a little bit about the local contact now there is both manual way of defining local contacts and then later on we'll talk about automatic detection of contacts or touching faces for contact definitions but in terms of the manual local contact where you want to select specific geometric entities you can simply go and define a local contact select the contact type and then manually choose the source and target geometric entities the top one is always called the source selection and the target is the bottom selection box as you can see here you know please remember these and the sores in the target selection because later on we'll talk about what type of geometric entity entities can be really selected in the source and then the target and what some of the criterias that might be used to make those selections now you can also also choose friction if this is desired one of the things about friction is that we shouldn't be expecting the coefficient of friction and fe8 correlate exactly the test data there might be some sort of iterative adjustment where you will have to try three or four different iterations to do this is kind of a critical setting in your contact definition well turning on friction does add complexity the solution does take a little bit longer to solve and so it should be left off and really you know for a first pass analysis contact analysis I would leave this option unchecked and later on for more you know refine once we figure out the contacts are working properly the the model is stable then we can turn on friction to get an end solution that is more realistic a more accurate bottom line is you know in real world the friction is too difficult to measure and even more difficult to control so in Fe a use this option cautiously alright so let's move on to the automatic local contact detection this is kind of no a very neat tool to use especially when you have an assembly with multiple parts touching each other and you want an easy way for simulation to figure out you know what are those touching faces and automatically be able to create this contact conditions so that's what we're going to discuss in this section now what this involves is selecting an option for either detecting you're touching faces or non touching faces so with non touching faces you can see there is a min and Max clearance that can be specified to detect any face pair that might have a clearance between the specified values here and then we choose two or more components in the list and a to and between which we want the program to detect all the contacts and choose the type of contact now again it could be a bonded contact that you're trying to specify between touching faces or in most most of the majority of the cases the automatic option really allows a user to sell it to define the no penetration contact conditions very very easily now when it comes to no penetration contact here we are talking about a scenario where the faces can have a clearance between them or they might be initially touching but then during deformation they can lift off move away from each other so those are the type of that physical physical interaction is what we call is no penetration contact again with the no penetration you have several types of into mathematical formulations no - no no - surface and surface to surface we'll talk about these topics and a little detail later on but again a nice way an easy way to quickly go ahead and grab all the parts that your between which you want to detect the program to detect the phase space touching or non touching and then and then selectively define how you want what kind of contact condition you want to define on each one of those face pairs so bottom line this is kind of the fastest way to find and set contacts pair contact pairs that will not use the global component contact settings so again keep in mind local contact will always take proceed and so the global contact or the component contact so let's take a quick look so here's the assembly and let's go ahead and set up a quick simulation study that's done so here one of the things I typically tend to do is to define contacts manually I can explode the view in SolidWorks so let's go ahead and try to do that so I'm just going to grab this guy here move it this way the sky there you go so again a nice way to take advantage of the fact that simulation is integrated within SolidWorks so you can easily explode the view when you're defining you know literally anything in the simulation setup so here we are consider about contacts let's go ahead and do that so I can go ahead and launch my contact definition I can choose the type of contact I want here I'm selecting the default manual option so I can say I know that this face comes in contact with this face and as in plus that I can select the geometry geometric entities then I can select what the mathematical formulation is to be used and mostly the default setting is no to surface that works very well for all the cases surface to surface is more accurate more robust but it takes a little bit more time to solve because they're more constrain equations that we are using behind the scenes to enforce that type of contact situation but again you can see that manually using the exploded view is a neat way of enforcing or defining the contact condition now let's switch to the manual or sorry automatic contact definition so this is again I know a nice way to quickly grab all the parts from the graphics area as you can see and then I can just say find contact sets and right of the bat the program actually ends up I go in ourselves detecting all this face pairs now I can actually go ahead and say how I want to enforce the contact so it could be no penetration bonded allow penetration so let's do no penetration then I'm going to leave the default no to surface option click OK here to create the contact sets and I'm all set so again a nice easy intuitive way to err to create contact condition in SolidWorks Simulation alright so that concludes this presentation stay tuned for more a similar presentations on the simulation YouTube channel I'll see you next time thanks and have a great day

Channel: SOLIDWORKS

Views: 97,921

Keywords: solidworks, 3D CAD, Dassault Systemes, mechanical CAD, mechanical engineering, contact modelling, simulation, 3D design, tutorial, solidworks tutorial, 3dexperience, CAD designers, CAD engineers, contact modeling tutorial, contact modeling tutorial part 1, simulation tutorial, solidworks simulation tutorial, solidworks contact modeling tutorial

Id: Fa1uxmU2OHM

Length: 17min 46sec (1066 seconds)

Published: Fri Apr 22 2016