Designing around rigidity was a challenge. Take a look at our design method on our recent "Egg Smash" challenge
Have you seen our recent video on 3D Printed parts, where we protected an egg from a brick falling at certain heights? If not, CHECK IT OUT HERE (VIDEO TO BE RELEASED SOON)!
Welcome... to the THUNDERCONE!
A quirky design, themed with all the shouting and loudness of 1990's WWF, with the gentle grip that would nestle and egg into a short, but very comfy, coma. We decided to go bold, go strong, and absorb/deflect the impact. Perhaps read this entire blog post with Macho Man Randy Savage's voice. It might assist!
OH YEAH!
Anyway, for a quick summary of the challenge and the obstacles we were to overcome - we were to protect an egg, from a falling brick at various heights (2, 3, 4 feet, and so on). We were only allowed to use 3D Printed materials, Nylon CF-10 FDM Thermopastic to be specific. This is nylon mixed with some carbon fiber, to keep it short.
We acquired the material's properties, and considered the print direction. As this makes the material Orthotropic, we decided to go with the higher compressive strength vertically. Again, theming with the attempt to absorb/deflect, or we considered making it sharp enough to break the bricks in half.
Seriously, watch the video it's quite fun.
Design Studies
First step, Design.
Now, to get down to business. We optimized the geometry of this by creating a design study. Setting these up is fairly simple. When we did create this, the design was in an earlier state - before the cosmetic additions. As well, we ran the design study in just the part of the "THUNDERCONE!"s outside shell. The basket (THUNDERBASKET!), we believed would be fine.
The first step to setting up a design study, is to create a simulation study based on the affect you want. In this case, we did a simple Static study. We were just looking to optimize strength. While a drop test may have been suitable here - we only had a limited amount of time to set this up. We decided to reduce the stress in the vertical direction, based off the fillet on the top of the cone.
We made a rough shape. If you want to see our "napkin sketch" ideas and how we came up with the rough shape, check out our blog here!
Below is a general idea of what we had. Our printable area was 14x10x14. 10 being Y. We started off big, and tried to reduce down. We wanted a cone shape so we just threw some numbers in there. The dimensions we wanted to optimize, were height, and width. Highlighted below.
We also had this egg shaped hole. We didn't change the dimensions of the hole itself much, just it's location on the part. The height dimension is also highlighted below.
Second Step, Simulation.
Our Simulation study looked like this:
We had a 10lb load in the -Y direction (the bricks were surprisingly light, maybe 2 or 3 lbs). We just overshot the weight by a lot to count for the initial impact force, and see where we were at. We mostly wanted to find the weak points doing this - not the accurate stress. However, at 10lbs, we were under the tensile strength.
This is when we decided to optimize. We were way over on mass. We had a limit of 500g. While this design probably would've survived a Tombstone Piledriver, but just straight up blasting through the floor of the ring, we needed to go smaller, and lighter.
Final Step, Design Study
Now we can move on to making a design study. Right click the bottom bar and select "New Design Study".
Start by grabbing some variables. I've already called out the three I want to play with earlier in this guide. Just ignore they're already in there, your list if you're setting this up for the first time will be empty.
Then you can start creating Parameters. Create names for you parameters. I recommend doing this one at a time. Once you create the name, select the dimension you want. For example, my height I named, "Height", and selected the dimension. This will automatically pull the values. You can change these if you'd like here - but I'd recommend changing them in the study.
Get those all loaded in there. Then load them into the design study. Drop down the Variable drop down and select the variables you want to load in. I'm saving the fillets for a different study, so we will skip these.
These will load in with default values for your range. Min, Max, and your step value. I know I can't have the hole lower than 3in or else it'll hit the bottom. And the top, I believe can only be about 5in or else it just wipes out the top.
Let's update that. I changed the step to 1in increments. That way we get lots of good scenarios.
Now, remember the weight constraint? We can put that in here too! However, design studies can only be in one unit. 500g is roughly 1.1lbs, so let's insert that into our constraints.
Create a Mass sensor referencing the body. You can create lots of other sensors here, volume, stress sensors, etc. These are your limits when optimizing. For example, you need to be under a certain stress, you can put that here, then optimize it down further.
Now load it in. Make sure you select the right criteria, I didn't while writing this guide and all my results were greater than 1.1lbs! Whoops!
Now the fun part - the Goals. These are your settings for what you want to optimize - your end goals. We want to reduce stress, while staying under the weight. The weight is a constraint, as we cannot go over it. This will remove scenarios that go over this constraint.
Load the info from the Simulation Study we set up prior. We want to reduce this stress as much as possible by utilizing the geometry. Von Mises is fine in this case.
You then need to reference the study. If you have lots of studies, you can check which one you want to reference at the bottom. It's a good idea to rename the studies if you have a lot.
Then, it's all set up! Run the study. This may take time depending on how many scenarios you have. It will automatically load the most optimal. We ran this a bunch of times - and actually Had to change some scenarios, so we removed a few scenarios after creating a lot of failed models this way. You can watch it update in real time.
All red studies are outside the boundary. Grayed out studies have rebuild errors.
If you'd like to investigate alternate scenarios, you can select them.
This also changes the model. So you can just swap back to the model tab and continue adding details! We had some fun with it and had some material to burn.
And that's how you make a design study! If you want to see how our design faired against the other teams, check out the video linked at the beginning. Let's just say, it was a "Stone Cold Stunner".
Otherwise, if you need help with your design study, you may be interested in an Ask an Expert session! If you have an Elite Subscription with us, you get 2 hours of these just in your regular renewals! We can also do these as standard service hours for training. Feel free to place a case on our website and request an "Ask and Expert" session!