First of all, he added small fillets to the areas of the latch where stress concentrations are expected, at the “root” of the latch. He also “cut” the model in half, in order to take advantage of its symmetry through the use of symmetry constraints, which can be found among the Advanced Fixtures available in SolidWorks Simulation.

The symmetry fixtures will simulate the half of the latch that was cut from the model. Having this fixture in place will prevent any displacements across the plane of symmetry, but allow displacements on the plane of symmetry. The idea behind this is to reduce the number of equations necessary, as well as the solving time. In order to use this constraint, right click on Fixtures, and select Advanced Fixtures, Symmetry. He selected the left planar face of the latch to define the plane of symmetry, as you can see in the following image.

Chris also talked to me about the possibility of improving results by any of two options: manually refining the mesh and using mesh controls, or making use of the h-adaptive solution method, which is available only for static analysis and solid elements. Why is this going to improve results? Well, simply because any solution obtained through FEA will depend on our choices for discretization (a.k.a. meshing). Different choices for meshes will also cause different discretization errors, and we can estimate these errors by making systematic (planned and gradual) changes to the mesh and analyzing the impact of such changes in the results of our study. This is often called a convergence process. The way we can do this is by simply starting with a study that uses an average element size mesh, and then, in subsequent studies, gradually refine the global mesh (reduce the size of the elements), while keeping an eye on any changes in stress and strain in the whole model or in areas of interest (in this case the fillets). We’ll know the process is converging when any further refinement of the mesh produces insignificant changes in the magnitude of the results. This can be a long and tedious process.

Further manual refinement consists of applying mesh controls to the areas of interest in the model. Basically, mesh controls allow us to refine the mesh locally, only in those areas of interest where we expect high concentration of stress, while the rest of the model is meshed using a much larger element size, thus reducing the number of equations and time needed to solve the study, at least when compared to global mesh refining. Mesh controls can be applied to edges, vertices, faces or entire components of assemblies, and they need to be applied before meshing the entire model.  The way to apply mesh controls is by right clicking on the mesh icon in the Simulation Study tree and select Apply Mesh Control.

Here in this image you can appreciate the way Chris applied a mesh control to that couple of fillets. He selected the two faces and used an element size of 0.029 in and a Ratio of 1.5.  This Ratio parameter simply specifies the ratio between element sizes in consecutive transitional layers when going from the global mesh element size to the local mesh element size. A Ratio of 1.5 is usually default.

Chris also applied mesh controls to the curved face of the cutout you see on the bottom of the latch, where stresses also concentrate, and to that edge on the tip of the latch, that he created by means of a split line, and used to define the Use Reference Geometry Advanced Fixture that I applied in the original study to make sure the latch had that 5 mm displacement, remember?

He then meshed the rest of the model using the default mesh element size. Notice in this image the transition between mesh element sizes in different areas of the model.

So that’s the manual way to do it, but this refinement process can also be automated, by using the h-adaptive Solution Method. By the way, the “h” refers to the size of the element, so the convergence process through mesh refinement is actually called “h convergence process”, since the size of the elements is gradually reduced.

To make use of the h-adaptive solution method right click on the name of the study in the Simulation Study tree and select Properties, then select the Adaptive tab, and under Adaptive method option select h-adaptive.  You have a few options to choose from here.  From the help document, “Target Accuracy sets the accuracy level for the strain energy norm in the model, which is not the same as stress accuracy level.” A default value of 98% means that the convergence process will stop if the difference in the strain energy norm between two loops drops below 2%. Accuracy Bias instructs the solver how to concentrate on getting stress results: Local (all the way to the left) will cause the solver to concentrate on getting accurate peak stress results for those very localized areas with high strain energy errors (the fillets) by highly refining the mesh in those areas, while Global (all the way to the right) will cause the solver to ignore high, localized strain energy errors and concentrate on getting accurate overall stress results for the whole model.  The maximum number of loops will tell the solver how many times to repeat the process of mesh refinement. Looping will end when Target Accuracy is achieved or when the maximum number of loops is reached. If Mesh Coarsening is selected, it simply means that during the mesh refining process our original mesh can actually be made coarser in some areas of the model, as the solver sees fit. This way the mesh will be refined only where needed.

This is the mesh that my friend Chris achieved for the latch by using the h-adaptive solution method with default values and a maximum number of loops of 3.

As my friend pointed out to me, the h-adaptive method is useful not only to save us from the tedious process of manual mesh refinement, but also for those times when we’re not exactly sure where the areas of high concentration of stresses will be.

Thanks, Chris!

I named him Troubles because it suits his personality. He’s always in the mood for mischief and looking for ways to get into all sorts of places.  Unfortunately for me, one of his favorite places to explore is inside my kitchen cupboards, where I keep the aluminum foil, the sugary cereal, and other goodies. Up until a couple of days ago, I used to think I had the situation under control thanks to the leftovers of the childproof latches I had installed on those cupboard doors to keep my own kids out of them. That’s when I contemplated in horror how the cat managed to push the latch down and swing the cupboard door open.  Wait a minute?  I thought those things were supposed to be hard to open even for a small child! Not that it requires a lot of effort, but, I mean, how strong is a cat, anyway?

Motivated by this question, I decided to make a simple model of a childproof latch and use SolidWorks Simulation to estimate the force that is required in order to push the latch down and open the cupboard door.  First of all, the kind of latch I’m talking about is a simple vinyl one, such as the one in this picture.

The long narrow piece goes attached to the inside top corner of the cupboard door and there’s a small piece that goes secured to the frame of the cupboard, and that will serve as a stop for the latch. When the child attempts to open the door, the latch will get trapped by the other piece, allowing the door to open only partially, unless the latch is pushed down enough for its tip to pass underneath the other piece.  I’m not so good at explaining this, but I’m sure most everyone has seen one of these before.

So this is what I did… I made a very simple model of the latch, as you see here. My model included some filleted edges, but they are not really necessary or useful for this analysis, as you will see in a bit, so I decided to suppress the fillets and run an analysis without them.  Doing this usually makes the calculations easier and faster, and the results aren’t affected, unless, of course, there’s a concentration of stress in the corners and you are interested in knowing   the stresses precisely in the filleted areas.

Next thing I needed to do was create a new Simulation study using this configuration without fillets, and establish some boundary conditions.  I applied a fixed geometry fixture to the back of the rectangular plate, to simulate how it would be securely attached to the cupboard door, unable to rotate, slide or move in any direction. This is done simply by right clicking on Fixtures and selecting Fixed Geometry from the menu.

I applied a second fixture to this study. This fixture makes the study slightly unusual, because what I was used to do was to apply some boundary conditions (usually some fixed geometry) and then a force and that’s it, let SolidWorks calculate stresses, displacements, etc. due to that force. In this case, however, I’m trying to find the magnitude of a force that will generate a certain known displacement, and this second fixture is going to help me in that task.

I knew I needed the very tip of the latch to displace some 5 mm down, so I used an advanced fixture to specify this translation.  If you right click on Fixtures and select Advanced Fixture, you’ll open a property manager where you’ll be able to choose from several different advanced fixtures available. In this case, I used Use Reference Geometry.  At first, I made the mistake of thinking that what I wanted was for the that small rectangular face on the tip of the latch (shown in pink) to displace down 5 mm along the vertical face adjacent to it (shown in green), and so I used those two faces to define the fixture, as you can see in the image. 

This, however, was a mistake because, after meshing the model and running the simulation, it produced the following result.  Notice something funny about this image? Look closely. If you were paying attention, you probably noticed that both faces remain parallel to their original positions throughout the deformation process, which is not the way you expect the latch would deform when pushed down. You can see it clearly in the image, as the original model has been superimposed on the deformed one.

So, I tried again, only this time I used different entities to define the fixture. Instead of a face, I used an edge on the tip of the latch.  I specified that I needed that edge to translate 5 mm down in a direction normal to the Top plane, as you can see in the following image. 

Well, that seemed to do the trick! After meshing the model and running the simulation, I obtained results that were more like what I was expecting.

By the way, in case I haven’t mentioned it before, I don’t have Simulation Premium, I was running this analysis in SolidWorks Simulation, but even though SolidWorks Simulation is usually limited to the small displacement kind of analysis (linear analysis), where the deformation of the model is so small it really can’t be noticed by the naked eye, it is also possible to solve some large displacement, non-linear problems, as well,  and obtain some accurate results, provided that there is no permanent deformation.  This one is a large displacement kind of problem, since 5 mm is an extremely noticeable deformation, however, this deformation doesn’t appear to be permanent, since the maximum stress is way below the yield point for this material.  To run an analysis making use of the large displacements option, simply right click the analysis name on the tree, select Properties, Options, and check the option Large Displacement, as you see in this image.  However, if you don’t select this option yourself and, while running the simulation, SolidWorks Simulation detects that this is a problem where large displacements are involved, it will give you a warning about it and ask you about running the simulation using this option. Don’t ignore the warning, since it can lead to incorrect results.

Once the stress distribution was calculated, I was able to estimate the force necessary to push the latch down 5 mm by right clicking on the Results folder and selecting List Result Force from the menu. I selected the rectangular face of the tip (in green), clicked Update, and found that the magnitude of the force should be approximately 5.5 lbs, applied normal to this face. 

I checked these findings by running an analysis the “typical” way, applying a force of 6 lbs normal to that same face, and the displacements plot showed the kind of large displacements I was expecting, once again with a maximum stress way below the yield point.  One thing to notice here is that if you look at the stress distribution plot for this problem I just talked to you about, you’ll see that the magnitude of the stress appears to be higher on the particular edge that was used to define the second fixture, when compared to the stress on rest of the latch’s tip, that is. This, I think is a consequence of applying the fixture using the edge, and not necessarily relevant, but I could be wrong.

Oh, I almost forgot! My brother is on the look for 3D modeling software for his personal use.  He’s not looking into SolidWorks, mainly because he can’t afford it and also because he’s in the area of architecture and doesn’t feel SolidWorks would be what he needs. After spending quite a long time convincing him that AutoCAD 2010, even with all the bells and whistles it’s been given, is NOT a 3D modeling software, he decided to take a look into other software, such as Rhino, and I must admit he’s got me curious about it. Well, it seems so affordable that if it’s really something useful for mechanical /product design, I may save my pennies and get a copy for my personal use.  So here are some questions for you:  Do you use Rhino combined with SolidWorks? If so, what is your experience with it? What kind of design have you done that you used Rhino for and what part did SolidWorks play in the rest of the design? Did you need other software of addins?

Anyway…  Transforming the plain round head of the funkey into a mouse’s head began by changing the sketch for the revolved surface from an arc (spherical head) to a partial ellipse (oval shaped head).  I also changed the axis of revolution, just tilted it up a bit.

Next step was to modify the ears. Instead of revolving the sketch 360 degrees as before, I only revolved it 180 degrees and then thickened the surface to a solid, by using the command Thicken, then mirrored the ear with respect to the Front plane and filleted the edges.

On the Top plane I made a sketch to aid me in the process of shaping the mouse’s snout. I used the sketch to trim the face’s surface with it. In the image, you can see the surface I’m removing in purple and the sketch appears in blue on the Top plane. Notice that there is a projection of this sketch on the back of the head, but I didn’t select that surface to be removed as well.

After trimming the surface, I patched the hole with a new surface using Fill Surface.  I didn’t really want to just patch the hole; I wanted this surface to have a more pronounced shape, different to that of the face. My goal was to create the nose of the mouse, so I thought if I added a point as a constraint curve (the one you see in the image), the new surface would have to pass by that point and I’d be able to shape it that way into a mouse’s snout. Well, the idea was good in part, but you can’t really depart that much from the original shape by using this method, or else the Fill Surface will fail. This is as far as I was able to locate that point.  I get a bump in the surface, but not so much for a mouse’s nose.

And this is where I decided to try my luck with the Freeform tool.  By the way, before you read any further, I would like you to take a look at a very nice video that Mark Biasotti shared with all the community through the SolidWorks Discussion Forums. You can find the video at: http://files.solidworks.com/special-videos/freeform demo.zip  This video explains in more detail how to use the Freeform tool.

Did you check out the video? Great! Now I’ll tell you how I used Freeform with my mouse.  First of all, I established that the boundary conditions at the edges would be Contact. Why? Well, because I wanted to deform that surface considerably and I knew the result would certainly not be tangent or have the same curvature of the face, but that was OK with me. For your own projects, however, you may want to keep the edges tangent or have the same curvature, so keep an eye on that.  I also established that the deformation would be symmetrical with respect to the Front plane by choosing Direction 1 Symmetry. What this means is that whatever I do to one side of the surface will automatically be done to the other side, thus making my work easier.  Notice the plane of symmetry in the middle of the nose. In this particular case, the plane is coincident with the Front plane of the model.

Next, I added a few curves (they appear in green in the image) by clicking on Add Curves and placing them pretty much wherever I thought I needed them.  On most of these curves, I also placed a few points, by clicking on Add Points and placing them over the curves I had just added previously. Each one of these points would allow me to push and pull from it, thus deforming the surface. Pulling a point in one of these curves will affect the appearance of the rest of the surface, at least up to the next curve. It sounds complicated, but each one of the points also has a Triad that gives you some control over the whole deformation process. You can either pull directly on the screen or enter numerical values for each axis direction in the property manager.

While you are at it, if you take a closer look at the edges of the surface being deformed, you’ll notice some arrows/vectors. If you click on them, a Triad will show up and by manipulating this Triad you’ll be able to adjust the tangency and vector direction of the surface right at the edges.  This will also affect the look of the rest of the surface.

So, basically, this is what I did with Freeform. I spent a few minutes pushing and pulling, adding and removing points. Just dynamically changing the surface until it looked the way I wanted it. I wasn’t really worried about creating the best of surfaces at this point, or if the mouse would be able to be manufactured or not; I just wanted the looks. Nevertheless, with some effort and perhaps a sketch or two to guide the deformation, I believe better results can be achieved with this tool.

Moving on with the rest of the mouth. Before deforming the surface, I had made an offset copy of it to serve as the back of the mouse’s mouth, by using the Offset Surface tool, as you see here.

Then, once the surface had been deformed, I trimmed it again using another sketch I made, again on the Top plane. This sketch will help me shape the smiling mouth. You can see the sketch in blue and the purple area is the surface to keep.

Once I had the gap for the mouth, I opened a 3D sketch and placed a two-point spline from corner to corner, like you see here.

I used this 3D sketch to create a couple of surfaces using Fill Surface. This is one of them.

And this is the other one.

Notice that the surfaces intersect the one for the back of the mouth that was previously created using Offset surface.  It’s time for some trimming.

First, I trimmed both new surfaces against the one I had created for the back of the mouth. In the image you see the parts in purple are the areas to keep and the surface in black is the one for the back of the mouth, used as the trimming tool.

I trimmed the back of mouth surface against the other two in a very similar way and then knitted all three surfaces together.

The eyes were made in a very similar way to the mouth. First, using a sketch to trim part of the surface of the face…  The sketch appears in blue and the area in purple is the one being removed.

I then opened a 3D sketch, converted the edge of the snout, thus creating a spline, and trimmed the spline  to the edges of the eye hole, like you see here. This sketch will be used to loft a surface for the eye.

This is the loft for the eye. As you see here, the lofted surface was created between the edge of the eye hole and the 3D sketch. I added a start constraint using the Top plane to define Direction Vector. I just wanted to give the eye some volume and make it look like it was popping out of the face.

The rest of the features for the face are fairly simple. The black little nose was made using a surface revolve and the teeth are just a couple of extrusions.

I’m still fascinated by the Freeform tool, however. I want to explore it further and see what else it can do and what other applications it can have, but most importantly, learn to control it a lot better than this in order to achieve the best results possible.

I didn’t really spend much time in modifying this model; I didn’t have more than a couple of hours to spare.  So, basically I reshaped the head (partial ellipse instead of an arc), made a few trims, lofts, and filled surfaces here and there, and most importantly, shaped the snout using Freeform command.  I’ll explain all that in more detail in my next post.

Now, I’m not sure this mouse could even be manufactured as it is. I just wanted the looks, and it was also a good exercise in the use of the Freeform command. I used to feel much intimated by it, but I’m finding that it’s not really that hard, and the best of all is that I can go back and edit the Freeform anytime I want. Perhaps with a bit more practice I will be able to model really neat stuff.  I didn’t have a layout of some kind to guide myself in shaping the snout, so I just pulled and pushed until it looked good to me. I know it could look much better than that…

Now, please, somebody tell me this does look like a mouse!  I was never the artistic or creative one of the family, you know?

Tell you more soon!

I used that spline and the sketch of the parting line I had made for the body to create a parting line for the arm as a projected line of the two.

Next, I created a couple of sketches on the Front plane to help shape the lower and upper half of the arm when seen from the side.  Here’s the sketch for the lower half of the arm. It’s a spline sketched on the Front plane. Its endpoints are coincident to endpoints of a 3D sketch that is a copy of the parting line for the arm that was  just created previously. To make that copy simply open a 3D sketch, select the projected curve that is the parting line for the arm and use Convert Entities.  The spline is also tangent to a couple of construction lines which are perpendicular to the sketch of the parting line for the body, as you can see in this image.

My next step was to create three planes parallel to the Right plane where I would sketch cross sections of the lower half of the arm, as you can see here. These cross sections will be used as guide curves for a lofted surface, just like with the foot.

Each of these cross sections is a two point spline. There’s a piercing relation between one endpoint of the spline and the sketch of the lower half of the arm that was created previously and another piercing relation between the other endpoint of the spline and the 3D sketch that is a copy of the arm’s parting line. The spline is also made tangent to those two construction lines you see there, one vertical and one horizontal.

After I had my cross sections ready, I created a surface loft, using the sketch of the lower half of the arm and the 3D Sketch that is a copy of the arm’s parting line as profiles, and the cross sections I just created as guide curves.

The upper half of the arm was also modeled in a very similar way, with a surface loft between an upper half arm sketch and the arm’s parting line, only in this case I didn’t use any guide curves. I realized that for the kind of surface I wanted to create, the results were the same if I simply adjusted the start/end constraints to be Normal to Surface for the upper half sketch (with the end tangent length adjusted to 0.17) and Direction Vector for the parting line (with end tangent length adjusted to 0.54). The direction vector, by the way, was defined by one of the construction lines in one of the cross sections I sketched for the lower half loft. According to the Help document, Start and End Constraint applies a constraint to control tangency to the start and end profiles. Normal to Profile applies a tangency constraint normal to the start or end profile, while Direction Vector applies a tangency constraint based on a selected entity used as a direction vector. The tangent length controls the amount of influence on the loft. The effect of tangent length is limited up to the next section.

At this point, the arm looked pretty much like a fin. I trimmed the upper and lower halves using the rest of the body as the trimming tool. The purple area is the part of the surface that will be kept.

To finish shaping the arm from a fin to something more funkey-like, I created a third surface loft.  I started off with more auxiliary geometry. First, I created three planes parallel to the Front plane where I would sketch profiles for the loft (shown in purple). Two of these profiles are splines with a piercing relation to a 3D sketch copy of the arm’s parting curve (shown in yellow), and the third one of them is a point coincident with that 3D sketch copy of the arm’s parting line.

Next, I created a lofted surface using those three profiles and the 3D sketch copy of the parting line as a guide curve.

Then I trimmed this surface using the upper half of the “fin” as a trimming tool. The purple area is the part of the surface that was kept.

I trimmed the new surface and the upper half of the “fin” using a sketch as the trimming tool, as you see in the image. The idea was to remove a section from both surfaces and create a new surface that will blend them together (more or less) nicely at the elbow. The purple areas, as usual, are the ones being kept.

To blend both surfaces at the elbow, I decided to use a surface loft. I tried the Filled Surface first, but I didn’t get nice results.  So, I created a 3D sketch and converted the right edge of the hole in the “fin”  to use it as one of the profiles for the surface loft. Then, I made the surface loft, using the 3D sketch I just created and the edge of the other surface as profiles, and a copy of the arm’s parting line as the guide curve. Notice that the Start and End constraints for both profiles as Tangent to Face. This setting was the one that produced the smoothest results, without puckering at the corner where both profiles meet.

The next step was to take care of the funkey’s “hand”. First, I opened a sketch in the same plane where I had sketched the biggest cross section for this surface loft, converted the edge of the surface as you see in the image and joined the ends with a line to form a closed boundary for a planar surface.

Then used Planar Surface command with the sketch I just created.

I trimmed this planar surface using the body as the trimming tool. Again, the purple area is the one that’s kept.

Next, I trimmed the planar surface again, this time using the fin as the trimming tool. The purple area is the one that is being kept. In this case, you don’t see the portion of surface that is discarded because it’s extremely small, but enough to make other features such as Knit fail.

Now I trimmed the upper half of the “fin” using the lofted surface as a trimming tool. In this case, the area in purple is the one being discarded.

At this point, I discovered a tiny hole right in the corner where the surfaces meet that needed to be filled; otherwise it would prevent the knit surface feature from working. I used Fill Surface to patch it.

After patching the hole, I knitted all the arm surfaces together, including the tiny patch, and trimmed them using the body of the funkey as trimming tool. The area in purple is the one that is kept.

Then I mirrored the arm with respect to the Front plane. And then I trimmed the funkey’s body using the arms as trimming tools. This had to be done in two separate trims; one for each arm. Then simply knitted all three surfaces together: the two arms and the rest of the body.

I filleted the edges of the “hands” using a variable radius fillet. Notice the different values for the fillet at each one of the control points.

After patching the bottom of the funkey and the neck with a couple of planar surfaces, all that was left to do was to make the head, but that was easy, all I had to do was revolve three arcs and then trim the surfaces with respect to each other.

Wow! That was some long post! I didn’t think there would be so much to say about this model, and I simplified a lot to avoid making it way too long. If anyone needs the model, I’ll be glad to share it, of course. I apologize with those of you who are experts at surfacing if my model is too amateurish for you, but as I said before, I’m just getting started.

I think I like surfacing…

First of all, I created a plane that was parallel to the Right plane and used it to trim the bottom of the body, using the Trim Surface command with the plane as the trimming tool. This plane will also be where the spline that is the shape for the bottom of the feet will be sketched.

Next, I created some auxiliary geometry. First, I created an axis between the Front and Top planes. The purpose of creating this axis is to use it as a reference when creating the plane of symmetry for the foot, which needs to be 130 degrees from the Top plane and pass through that axis.

Once I had a plane of symmetry for the foot, I sketched a spline on the plane I used to trim the bottom of the body (I called it Funkey bottom plane); this spline is the silhouette of the foot when seen from below.  Notice that I sketched only one half of the silhouette and mirrored it with respect to a construction line that would be collinear with the foot’s plane of symmetry. This is because having the whole shape of the bottom of the foot helped me visualize how wide and/or long to make the feet.  Once again, I don’t have many dimensions, but I do have some relations in place. Notice the two construction lines that are perpendicular to the line of symmetry. The spline was made to be tangent to these two lines at each end.

Next, I sketched a spline on the foot’s plane of symmetry. This spline will give me the shape of the foot when seen from the side. I made the endpoints of the spline coincident with the endpoints of the one I had sketched previously and, once again, the spline is tangent to those two construction lines you see there at both ends.

That construction line that appears at 0.12 in from one of the sides is there simply to help me create a series of planes perpendicular to the symmetry plane and that will be needed to sketch cross sections of the foot.  In this image you can see the planes and the cross sections that were sketched on each one of them.

Each one of these cross section sketches is a two point spline. There’s a piercing relation between one endpoint of the spline and the sketch of the bottom of the foot, and another piercing relation between the other endpoint of the spline and the sketch of the silhouette of the foot when seen from the side that was created previously.  The spline is made tangent to those two construction lines you see there, one vertical, and one horizontal.

Once I had my cross sections ready, I used them to create a surface loft using the sketch of the side view of the foot and only half of the spline in the sketch of the bottom of the foot as profiles (use the selection manager to pick only half of the spline and not the whole sketch). The cross sections I sketched previously were used as guide curves. Notice that the start and end conditions were set to Normal to Curve. It doesn’t always work this way, but in this particular case, it made the loft look a lot smoother.  Now, I know there’s a singularity right where the two profiles meet, so perhaps in the future I should try using a patch like I did for the body, although it doesn’t look bad this way.

Next, I mirrored the lofted surface with respect to the foot’s plane of symmetry.

And mirrored the result with respect to the Front plane.

Next I simply trimmed the surfaces using Trim Surface.  I used the option Mutual Trim, which means that both surfaces will work as trimming tools and will be trimmed by each other at the same time. It also means that the resulting surfaces will be knitted together.  Notice that there are three surfaces as trimming tools: the body and the two feet. The areas in purple will be kept and the areas in green will be discarded.

This one is my version of the funkey. It doesn’t look exactly the same, but I’m excited no matter what. I know it’s not perfect and there’s probably a bunch of things I should’ve or could’ve done differently. I certainly appreciate comments and corrections, but remember I’m just a novice at surfacing, so go easy on me.

This has the potential of becoming a huge post, so I’ll probably have to break it down in pieces. Let’s start with the body.

The first thing I did was to create some geometry that would help me build the shape of the funkey. I sketched a spline on the Top plane that would follow the silhouette of the funkey’s body when seen from the front or from the top if you think of it as laying down on its back.  I only needed one half of the silhouette, since I was planning on taking advantage of the symmetry by constructing only half of the body and mirroring it with respect to the Front plane.

On the Front Plane, I sketched a spline that would be the parting line for the body when seen from the side. I don’t really have much knowledge of plastic mold design, but I observed the toy and the parting line followed this curvy shape all along the body.  Notice that I almost have no dimensions on my sketches and almost all of them are under defined. This was really an exercise and I was constantly dragging and moving spline handles and points, but I suppose that you could define the sketch completely if that’s what you wish to do.

Next, I used Insert, Curve, Projected, to create the parting line for the body as the projection of the first and second splines I had sketched previously.  Make sure to use the option Sketch on Sketch for this one. The curve created this way is a spline and it’s a 3D sketch because it’s not resting on any plane.

I sketched a third spline on the Front plane. This will be the sketch that follows the shape of the lower half of the body when seen from the side (Front plane).  Again, I don’t really have dimensions because I was constantly playing with the shape of the body, but I have a few relations in place. First there’s a piercing relation between this spline and a circle that I sketched on a plane I called Neck Plane.  The funkey has a circular neck.  By adding relations between the splines and this circle I’m trying to help shape the transition.  On the other end of the sketch, you’ll notice some construction lines and some tangent and perpendicular relations.  One of the construction lines is tangent to the parting line created previously. Another construction line was made perpendicular to the first one and the new spline (lower half sketch) is made tangent to this second line.  I wanted to add draft, and that’s why you see another two lines separated by a 2 degrees angle. My plan was to make my spline tangent to this other construction line, but the shape wasn’t really good, so I decided not to try to add draft, at least until I practice more and learn proper ways to do it.  By the way, those grey lines you see between the points of the spline are what is called the control polygon. I find that I have a better time controlling the shape of a spline by dragging the points in the control polygon than by manipulating the handles. To see the polygon, just right click on the spline and select Display Control Polygon.

Next, I created a series of planes, parallel to the Right plane that would help me sketch cross sections of the body. The purpose of these cross sections was to aid me in the process of creating a surface loft.

Each one of the sections was a two point spline. One end of the spline had a piercing relation to the parting line (the 3D sketch created as a projected line) and the other end had a piercing relation to the lower half sketch.  The spline was made tangent to a vertical line on one side and a horizontal line on the other.

Next, I used the cross sections as profiles to create a surface loft, and the parting line and lower half sketch as the guide curves.

This gave me part of the lower half of the body, but there was still some of it left to do. I decided to use Fill Surface to build a patch on that area. You know, when I think about it, there’s other things I could’ve done, like a loft surface to fill up that part or simply change the way I did the loft, by using the parting line and lower sketch as profiles and the cross sections as guide curves. I probably would’ve needed less guide curves too, as many guide curves tend to make the result a bit bumpy. Yes, there’s other things I could’ve done, but I wanted to practice with fill surface so I went this way.

The first thing I needed to do was to create these two auxiliary surfaces you see here.

The edges of these three surfaces were then used as boundaries for the patch created with Fill Surface. Notice the curvature control for each of the edges. Two of them are Tangent and one is Contact.  According to the help document, “Contact creates a surface within the selected boundary. Tangent creates a surface within the selected boundary, but maintains the tangency of the patch edges. Curvature creates a surface that matches the curvature of the selected surface across the boundary edge with the adjacent surface.”  These settings worked for me because those were the ones that made the result look the smoothest, but I’ve found that you have to experiment with it a bit sometimes.

After this step, I hid the auxiliary surfaces, knitted the two lofts together and mirrored the result with respect to the Front plane.

The upper half of the body was made in exactly the same way, leading to this result.

Next, I created a plane parallel to the Neck Plane and used it to trim the surfaces, by using the Trim Surface command, with the plane as the trimming tool.

After knitting both halves together, I proceeded to create the neck.  First, I extruded a surface using the same circle I had sketched previously on the Neck Plane.

I trimmed this surface using a line I sketched on the Front Plane. I had previously segmented this line using Tools, Sketch Tools, Split Entities.

The idea was to partition the extruded surface in four equal parts to facilitate a loft between its edges and the edges of the rest of the body. As you can see in the image below, this surface loft uses the edges of both surfaces as profiles and the lower half sketch and a copy of the parting line (made by using Convert Entities on a 3D sketch) as guide curves.

I did something similar for the other edge, except now using the upper half sketch; instead of the lower half sketch.

After that, I simply knitted both edges and mirrored the result with respect to the Front plane.

What I ended up with was this gourd-like shape that would be the body of my funkey. I know it’s not perfect. I played with the profiles and splines for a bit, trying to make it look a bit better. It could be smoother, but it’s a good start, I guess.  Next time, I’ll show you what I did for the rest of the funkey.

This example shows how easy it is. First, you set up and run your Motion Study (Motion Analysis only), then you click on Simulation Setup, select the component you want to investigate, and set up a time of duration in the timeline.

Then you click on Calculate Simulation Results, and let SolidWorks take care of the rest.

This is what you’ll see after the analysis has been concluded. If you run the animation now, you can see the stress distribution on the component as it is moving in the assembly. Neat, isn’t it? Of course, you still have the option for SolidWorks Simulation of importing motion loads, just the same as you used to in the past.