Note: Because this is an ongoing series, viewers will not receive a certificate of completion.
Skill Level Intermediate
- [Instructor] This week I'm going to create a tensile membrane using a plugin and I've provided this exercise file for you to work with. It has masts and anchor points and it also has lines connecting these points of anchorage. Now, the actual tensile membrane isn't going to have straight edges, it's going to be bowed inward in arcs, so our first task really is to draw in those arcs. I'm going to double click on this line here to open that group and then go up to View, Component Edit, Hide Rest of Model so I can focus in just on these lines which represent the edges of the tensile membrane. And to start this process, I'm going to just draw a line from some arbitrary points along these edges to create a surface. And this will help me creating an arc because now I can see which plane it would be in. I'll use the arc tool and click the first point of the arc down here and the other endpoint up there and then I'm going to position the cursor along this face and I'd like to have that arc bulge about three feet. I'll type three feet, Enter. I'd also like to control the number of segments in that arc, so I'll type 32 S, Enter and that sets it with 32 sides. And then I'll select this edge here and delete that and I'll also delete that edge there. So, now instead of having a straight line connecting those anchor points, we have a nice smooth curve. We essentially need to repeat that for each one of these edges, so over here I'm going to draw another arc connecting these two dots and then I'm going to have that go along the face and I'll have that bulge maybe three foot six in this case and then I'll erase these lines which are no longer needed. Up here on the top, we want this to curve in, so I'm going to draw an arc from endpoint to endpoint and it's going to bulge out in the green direction, let's say it's going to be about three foot six. If I orbit over here, you can see that that is just parallel to the ground, so what I should do next is select the arc and that surface and rotate them and I'll rotate them by defining a rotation axis by dragging from this endpoint along this line to the midpoint and then I can rotate that in the red direction, I'll just orbit and you can see how I'm rotating that. I want it to rotate more or less close to the arc there, maybe a little higher, something like that. And then I'm going to erase this line here which is no longer needed. So, now on the other side, we basically want to just carry the symmetry of these two arcs over to the other side, so I'm just going to erase those lines. And then I'll take these two arcs and select them and just copy them over there in the red direction and then I'm going to scale them around with this factor of minus one and then move these back and connect them up with the other arcs. So, now we have a curved network that represents the boundary conditions of the tensile membrane that we want to make. Go to the Extension Warehouse and type in Soap and go to Soap, Skin and Bubble. Here it is. And go ahead and log in and install that. I'm already installed that. And then that won't bring in a tool palette and the way that that this plugin works is you need to select those boundary edges, so I'm going to select that object and explode it. And we just have those edges selected and then I'll click on Skin. And we'll go ahead and type in a number which represents the number of divisions and the default is 10. I'll type 40, Enter. So, now that creates a grid that has 40 squares in each direction and that looks acceptable, so I'll press Enter one more time and then the plugin gets to work simulating the tensile membrane based on the boundary conditions. I'll just move this out of the way and you can see the data on that. If I orbit around, you can see that this really goes down a lot. That's not really what I want. I don't want it to be sagging quite so much. So, I'm going to change one of the parameters for this. You do that by selecting the new object and then going here to the Ratio button and right now the ratio is defaulting to one. Let's try it at .3. Enter. That's going to recalculate that membrane based on that new ratio parameter, so you can do this until you get the shape that you want. In the simulation, this one took about 10 seconds in this case. And I really like the form. Now, I just need to clean it up. So, I'm going to select this object and double click on it to open it and then up here there's these extra lines that we don't need, so I'll use the eraser tool and just erase those. And I'm just going to look around and see if there's other lines I can erase. It looks like there's some here. These are just artifacts of the process of simulating that membrane. Now I think it's cleaned up. So, I'm going to go to the Select tool and triple click on that to select all those thousands of entities, right click and choose Soften Smooth Edges, check Soften Co-Planer and drag the slider a little it and you'll have all those edges disappear until you have a nice smooth surface. And now we need to think about the material. I'll go to the paint bucket and I'll assign this material which is already in the model to that surface. And then I'll select the surface itself and you can see in this case, that was assigned to the back face, so I'm just going to drag this onto the front as well. That way we have the same material on both front and back. And there we have a beautiful simulated tensile membrane.