Creo Tutorials - Case Study - Slide Crank Linkage Kinematic & Dynamic Analysis

all right welcome back ladies and gentlemen now we're going to do some kinematic and dynamic analysis before I do though let me show you a little thing that you need to do before you do dynamic analysis before when I do that let me just explain what kinematic and dynamic analysis is kinematic analysis allows you to kind of calculate the position velocity and acceleration so if you think back to physics it essentially solves kinematic equations for you but then the dynamic analysis gives you force values it gives you reaction forces in all these pin connections we made because if you think about it this link rotating about the shaft it's going to produce it's going to have some sort of reaction some sort of dynamic load on the shaft because it has a torque applied to it and that that has to have some kind of load on it right it should make sense physically if you have engineering background you should understand what that means and I'm not going to try to teach you physics now but that's what dynamic analysis lets us calculate and it gives us values for that now what we can open up these parts right here again these parts are you know what makes these assemblies we make them separately but we can right click and open when you do that it opens that part in a separate window of its own it opens up a creo parametric window we're not in creo parametric assemblies assembly environment anymore we're in parametric modeling environment and what we can do here is we can right click not right click we can click file prepare model properties and right here in material you should have some sort of material selected I have steel you can assign it by hitting change and say steel and then click this arrow that points in the direction you know the right direction literally okay so once you do that you should have a material here with the red arrow pointed out to it if you just have a material and there's the red arrow pointed to it right-click it and say assign like this so right now there's no red arrow pointing to the steel that means it's not a sign if I right-click and end it's a assign now its assigned and then I hit OK and then I close it and I already have this as IPS so make sure your since IPS as well inch pound second I'm going to hit save I'm going to hit OK and then I'm going to close it with this feature again and do that to all of your components because if it isn't dynamic analysis is not going to work you can still do kinematic analysis on your components without material properties but you need material properties to assign a to do dynamic analysis and another thing I should mention about material properties I wonder if I can through here let me go okay so when you open up these material properties you'll notice that there's just you know 15 or 20 of them and if you want to have more materials in here you can make your own set of material properties and the way you do that is just click create new material and then it pops this window right here material definition you should know what these values mean Young's modulus damping thermal expansion coefficient you know pencils tensile stress ultimate stress these are all engineering terms you should understand what they mean they're not engineering specific terms but you should know what they mean and you can select the type of materials and you can define thermal properties appearance and all that fun stuff and the density is an important one so you can look these things up online and make your own materials and then you can save them in a flash drive in a folder of your own where you can have your own material library which is what I like to do because you know you don't want to keep reading materials and keep saving them you want to have it all saved in one folder and you know a convenient spot to just look at and look look up the MTL files so you're gonna save the mess not MTL files all right so that's that that's how you do material properties now to begin kinematic analysis we need to go into the mechanism environment and the way you do that is you click application then you click mechanism and this is the environment we're going to use to do any kind of kinematic or dynamic analysis so any analysis that involves moving parts you do that in creo mechanism there's more there's more areas where you can do things but this is the first place you come to if you want to do any analysis that involves moving parts and from this you should be going to finite element element analysis unless somehow you already have force values for it or load values for it which I don't know how you would get those but this is this is the first step so here we get to do things like assign motors virtually and which what I mean that by that is you can select an axis and say that we want to apply a motor a motion applied motion there so the way you do that is just click a several motor and then these select an axes right here it says pick pick an axis select the axis and it shows you which link it's going to rotate or which component it's going to rotate and it shows you the direction of the torque and all that stuff and then you go to profile and then you can select velocity and the units are degrees per second and I'm going to say 360 degrees per second that means it's going to go around once in one second it's very simple and very straightforward and then we can do our analysis so this is enough right now to do a kinematic analysis and I'm going to do that kinematic and dynamic actually so the way you set up and analysis is I should actually differentiate what we did now is put in a component in our mechanism that's going to affect the behavior but we haven't actually set up our analysis yet the way you set up your analysis is you can either go to this analysis tab right here click on mechanism analysis do playback and all that stuff and and have your windows open I like to do it through this mechanism kree though it's it's I think it's more convenient because you have everything right here you can mess around with more things like motors springs dampers which we'll go over later on but just keep in mind that you have a lot more available to you right here versus there then again you can do what you like but I'm going to start an analysis using this option right here analysis if you look at the icon it's the same icon mechanism analysis I'm going to right click and I'm going to say new when I do that it opens up this analysis definition window this is where we set up our analysis so instead of position I'm going to say it's kinematic motor is already selected that's the motor that we apply here remember it's a component and then we have our setup an out frame rate that's that's a that's kind of really what would you use to control how how well do you want to analyze I'm trying to find the right words here but this is what controls the precision if you will but let me just do two separate analysis so let me just leave it the way it is now with ten frame rate and time is ten and I'm going to just run this analysis so so look at this and and it's done and once you hit done under playback you're going to have your analysis saved another another I guess terminology I should explain you can set up your analysis right here but once it's done analyzing it's going to save all those calculations it did under playbacks so everything that you analyze in every calculation that was done it's saved in this low playback section right here and then I can go to measure so playbacks are saved and they're what supplement measures what is a measure so everything that we calculate we can display it we have to have some way to display it and that's what the measure tool allows us to do so we can see right here analysis definition from the play back we have that as something to supplement our measurements how do we measure something now we click new and then watch it gives me this window right here measure definition now the type this is where you can you know select different type of things you want to measure it let's say I want to measure the velocity I select velocity then it's asking me where do you want to measure the velocity I can select a point or a motion an axis I want you to understand what that means a motion of axis is pretty straight forward you can select a motion or axis but the point is where the most of the power comes in so you can have this part open up in a separate window in a parametric modeling window and you can place a datum point anywhere and then you can select that point as as your point a measure I'm going to select this tangent point right here because that's an automatically made one but I don't want to go in back and make a point but so I'm going to just select a tangent and I'm going to say apply okay so we have some numbers next to our measure now right here if we make this window a little bigger we have some measures we can graph this right here click this graph and we can display exactly how the velocity is and it's exactly what we expected because we applied a constant velocity and it's it is a constant velocity acceleration if we try to display now if we edit this measure right here by the way we can edit the measures we can edit them and we can say show me the acceleration at the same point so I'm going to leave it at the same point I'm going to hit apply and hit OK let's let's look at this acceleration is its I guess wow there's an acceleration there shouldn't be an acceleration should be a constant velocity but then again the acceleration isn't changing interesting what is the acceleration let me look at the value well whatever I guess I don't really care much but let's let's look at that's the acceleration why ok ok ok here so I stock so it matters where you measure things of course that link is going to have some acceleration but we applied the motor at a particular axis and if we measure the acceleration there it's it's zero I was doing something stupid there so edit let me edit this and when you measure the acceleration at points that are moving you know relative to the motor obviously we're going to have some acceleration and that makes sense but if you measure the axes there should be zero acceleration which it is and it makes sense everything's ok now I was worried there for a second what's going on over here okay so that's kinematic analysis but now let's try to measure and let me go into edit again and let me measure connection reactions and now it's asking me to select the neck sees again and I'm going to select this connection reaction right here and it's going to show me the connection reactions I'm going to apply hit ok and watch it's saying not computed because we didn't do dynamic analysis and when we do dynamic analysis we have access to everything that we did with the kinematic analysis and the force values and the reason I want to differentiate this is because if you have large assemblies dynamic analysis is going to run much slower so if you don't need to if you don't need the force values you only need to analyze the acceleration and velocity for things for mechanisms do kinematic analysis because it runs much slower much faster I'm sorry then dynamic analysis but before I even going to dynamic analysis let me go right here again under analysis I have analysis definition already set up but I'm going to edit that and if you remember I was talking about the frame rates and and let's let me go back to measure tool again this is this is so all over the place oh my god so let me go back to velocity let me go back to this point let me select this point again it okay select this edit definition okay so I want you to kind of look at this or if I can make this point clear with the the position measure instead okay that's fine let's apply this okay so that's the position I want you to look at the the gap between these circles this is what represents at the point at which a measurement is taken so every time you see the circle there's a new measurement happening and in between cRIO is guessing it's just trying to connect the dots that's crucial to understand because now if we change the concentration of these little dots these iterations at which cRIO takes measurements we can kind of improve the the credibility or I guess the accuracy of our analysis right but let me make that a bit more clear by applying an acceleration instead of a velocity so if you remember I applied a motor here with a with the 360 degrees per second of velocity now I'm going to modify that right here under motors that this is why I like to work with the mechanism tree because it allows me to just do things very quickly I'm going to go here I'm going to select several motors and I'm going to right click this edit definition go to the profile now instead of velocity I'm going to say apply an acceleration and I'm going to just say 360 you can set up an initial velocity if you like but I'm going to say it's zero and I'm going to say it has an acceleration of 360 degrees per second remember it's acceleration not velocity the acceleration is going to remain the same and I'm going to apply it I'm going to hit okay now I'm going to run the kinematic analysis again so watch we have we have this edit definition we have this adder definition option we can just go back but this time I'm going to run this 400 frames and I'm going to run this now if you notice this is you should have notice immediately this is much slower and the reason is because we have acceleration applied now we have things constantly changing but moreover we have hundred frame rate that's a lots of far higher iterations far higher number of iterations at which Krios taking measurements and calculating things so this time we should have those circles in our graphs far closer to each other I'm going to hit OK and now I'm going to go to measure again we still have the same measure at the same exact point but when we try to display a graph watch look at this the circles are so close together you're almost merging that that should kind of tell you that you know this this is um this is how you get high fidelity I'm zooming in right now I guess let me zoom out well zoom in wow there's only a zooming option I can zoom out isn't that fantastic okay so I'm just displaying this again let me zoom in just enough to kind of show you okay so if you look at the axis right here x-axis we're only looking at a certain certain interval of time not the entire ten seconds and it's it's it's much closer together this looks more like what it was for an entire 10-second span which is which is something we already we have only in one one second which makes sense because we you know increase the framerate by a hundred by ten times so that that fidelity makes sense but let's look at instead of position let's look at the velocity at the same point we hit okay and we measure it there we go the velocity is going up we expect that because we applied an acceleration now let's look at the acceleration itself it should have gone up as well okay okay it goes up tremendously it's 18,000 inches per second is something you're pretty fast okay so here's something to note here I guess let me make me select position again now here's a little subtle thing you can select your own coordinate systems so this is this is an important feature because you can select the coordinate system with respect to which you want your measurement to take place so this is not as important enforces but it's it matters quite a lot when you're worried about position so if you want to find the position of something moving with respect to a certain certain surface let's say you can make a new coordinate system and measure things there so let me do that so see right here under datum we can make an option something called coordinate system and I'm going to make a coordinate system right here I'm going to say that's my coordinate system and it's let's see let me just make a reference zero zero okay so I made a new coordinate system when we enable coordinate systems it shows us the coordinate system we made it shows us a bunch of others as well but I'm going to use this to kind of you redisplay my measure value for my position and I'm going to I want you to observe how it changes let me just edit this right now the coordinate system selected is let's say this one I'm going to select it I'm going to apply it I'm going to hit OK and I need to run the analysis nope no I don't we go back to the measure there we go so that's how this is let me change it to position I'm sorry okay so this is the position it's 6 something that's how far away it is and that's fine now I'm going to edit this and I'm going to change the coordinate system and I'm going to select this one watch I'm able to select the coordinate system that I made I hit apply I hit OK and immediately the value changed so with respect to this system we can see the actual motion of things now let me just get a little nicer angle right here so if you look at this this is actually showing us how it's moving with respect to that new coordinate system we made and you can do this because cRIO itself makes a bunch of automated coordinate system but you can have your own coordinate system one setting set in stone that you can use to measure other things and it's that's just something I like to do because it helps me understand where things are physically and it here's another cool little feature I guess to properly display the power of this so I closed down the measure window and I kept the graph open now under playbacks if you right-click it and you hit play you get this animation window right and then I hit play again and you can kind of replay the whole animation and and if you notice it's moving the entire mechanism and as its doing that it's tracking the girl the graph and the curves and tracking exactly where we are physically with respect to that coordinate acts coordinate system and it's it's you know showing us in real time so this is a good tool to kind of visually display how things are working out it's kind of slow and I can speed this up and there we go I've sped it up now and you know it's going to it's going to go a little faster but I'm just trying to show you the visual tools that you have available to you in creo and this is just kinematic analysis and you can have this animation like this and and you can use it to kind of display how motions working in an assembly or how assembly works physically so I'm going to close that and now we're going to do dynamic analysis so you at this point you should be familiar with kinematic analysis and I think I've shown you almost enough to do your own stuff but let's let's do dynamic so I'm going to right click this again well I want to try to I without sounding too redundant I wanted to I want you to understand that you add in a motor as a component of the mechanism itself but then you set up the mega analysis in this option right here and then select dynamic because I want you to kind of understand and have this intuition that everything you change in the assembly includes these motors and these forces because they're not part of the analysis there's something that you use and you do the analysis with but they're not part of the analysis but now when we do set up the analysis I can set this up to be dynamic and we already have our motors selected right there but now we have another option called external loads and here we're going to apply gravity this is why this is the dynamic option and it's it's fantastic we enable gravity and I'm going to change the frame rate back to 10 because dynamic analysis is calculated snow as slow as it is I don't want it to be even slower by having hundred frame count for 10 seconds and have thousand frames calculated so I'm just going to leave it at 10 and I'm going to hit OK and I'm going to run it and I'm going to overwrite the kinematic analysis that I have saved before so understand this if you name this analysis definition 1 it's going to replace the playback analysis definition 1 with the one you're running now unless you change the name then it's fine so it's calculating what the acceleration applied it's going to take fairly long amount of time I'm going to have a sip of water still going larger the assembly the longer it's going to take it's a good thing we change the frame count to 10 and set 100 otherwise we would still be at second one all right almost done okay so I can hit okay now and now I can go to measure and remember we already have that measure set up it doesn't change anything I can edit this and it's said to be positioned it should essentially be the same when I display it and it is it's it's essentially the same thing but now let's let's change that to a velocity we should still have essentially the same values apply okay measure and we do it's increasing constantly if you remember but now let's measure the connection reaction that's that's something we can measure now because we ran dynamic analysis I'm going to select a connection reaction and I'm going to select next ease and understand this you can only measure connection reactions at connections you have made that sounds redundant but wherever you have made let's say a pin connection or a slider connection those are the places where you can actually measure analyses we're at connection reactions you can't measure a connection reaction at a random point that's a that's not allowed so let's measure this graph and let's look at this graph and let's run the video or before we even run the video it kind of makes sense already it should be a positive negative reaction because when we move this way when we move the mechanism to the right there should be a reaction force acting against it and the same thing in the other direction but now let's just run the animation as as we're anthesis this is too high fidelity I think but let's let's run the animation as we're displaying the graph I kind of want to try to show you the graph clearly let me make this graph bigger okay let me do playback I'll let me hit play let me slow this down even more all right so I guess here's another point I can already make since we changed the frame rate to 10 you can kind of see how its kind of jumping to the positions and it's not really as high-quality as we would like it to be is it that's the reason why you would kind of increase the frame counts to increase kind of the accuracy of the result this this is very choppy and it doesn't really look as smooth okay it's just playing it again all right there we go so that's just the reaction force but now let's try to think about this this graph right here this is the connection reaction at an axis at this axis we would expect the connection reaction to go up because we're applying an acceleration that I want you to kind of think about that because the acceleration is it's applied the force that the connection force the reaction force is going to increase because we have our speed increasing constantly it's not something that's that's it's a static value we have our speed going up constantly if you remember the velocity graph it constantly goes up so the speed of the link rotating around that shaft is going up tremendously and this is exactly what we would expect of something that acts like that connection reaction would eventually go up and of course this would break eventually if it if it started rotating way too fast but it's not going to do any Creole but that's something you would do in FAA so that's that's the point of dynamic analysis but let me show you the dynamic analysis or I should let me change the measure to twos to the axes so before we measure the reaction for the slider connection let me measure the reaction here so it's going to show us the reaction between this and that okay select this alright so again it makes makes it should make sense to you that because it's starting to speed up slowly and it eventually does speed up let's look at this crap so up until here it's fairly tamed but you know as the speed Rises the connection reaction value rises as well and that should make sense to you and also if you are kind of intimidated by these gigantic numbers understand that this is in pound mass per second squared so if I go back and close this let me just not save this exit without saving file prepare let me change this to IPS now watch right here units manager pound mass but now if I change the value with the force value to pound force we're going to have something far more reasonable displayed let me set that interpret one-to-one close close let me save this now since I've changed the unit's it's going to want me to run the analysis again I'm going to go back to mechanism again we already have the setup the setups already there I'm going to just run it again and we're going to have to wait again for the announces to be done what was there it's starting to slow down even more towards the end of it because it's a guess increasing in the amount of calculations it has to do still going still going still going okay so we're fine done all right so let's look at the measure again and let's look at this value so now we have actual you know reasonable values displayed not really reasonable for the size of the assembly but you get the point as its increasing in speed the reaction forces are going up to up to four hundred five hundred pound pound force so that's you know since the last pound mass per second squared values were in kind of a thousands I just wanted to change that to show you that this is still kind of a reasonable measure but that's the connection reaction let me just measure the slider again just just cuz just to show you there we go so you know the maximum is about 140 pounds of course it's not really that much but that you kind of show you how to do dynamic analysis you should know how to do kinematic analysis now and you can change a bunch of these things but next next set of things we're going to do are mainly going to be concerned with this side of cRIO where we're going to be working with a mechanism a lot we're not going to be working with the assemblies as much we're going to make assemblies but the things we're going to try to get accustomed to our gears so we have something called gear options cam options 3d contact and belt connections so these are separate set of values that are available not values but constraints that are available in mechanism and we're going to mess around with those and we're going to try to do kinematic dynamic analysis with those and I'm going to do case that he's involving these tools and that's just what to expect next but this is it for now you should have a solid introduction to kinematic and dynamic analysis although although I guess my English is not really good enough to kind of explain a few things I hope that I hope that it's still helped and thanks for watching

Channel: Ashish Rana

Views: 58,242

Keywords: Creo Tutorials, Creo Assembly tutorials, Creo Mechanism Tutorials, Creo Kinematic Analysis tutorials, Creo dynamic analysis tutorials, Creo, PTC Creo

Id: xSPOs-mEkFY

Length: 33min 11sec (1991 seconds)

Published: Tue Jul 07 2015