On this part of the blog PADT will be sharing “information” that may not have a lot of real value, but that we enjoy. Look for links to things of high nerd value, a few jokes, silly pictures, and whatever else we feel might make you smile. There is a strict ban on LOL Cats, unless there is an engineering tie in.
Posted on February 7, 2019, by: Nathan Huber
I was on the gondola up at Keystone for night-skiing a week ago, after a long day at Beaver Creek, because the last thing I am going to do at 3:00 pm is try to make it back to Denver, as everyone knows it's hardly more than a parking lot at that point. As it gets later, there's nothing like a solo gondola ride, however, a solo ride would stop this story right about now.
On the gondola, I overheard a conversation where one gentleman was discussing how he was unable to open the hatch of his vehicle when his skis are in his roof rack. That's fair, I know older WRX wagons with the spoiler would not be able to open with skis on the roof no matter what, so I figured that was the case. It turns out, that was NOT the case. The reason his hatch would not open was that he orients the skis with the tails forward because it is 'more aerodynamic' that way... I was skeptical, but held my tongue, knowing that I had the tools at my disposal to investigate!
I decided to make a model that would allow me to simulate various conditions to get to the bottom of this. My initial hypothesis is that the addition of the ski rack and crossbars is what has the largest effect on aerodynamics, and orientation of the skis probably has a negligible effect after that. As a side note, I am solely concerned with aerodynamics in this case, and am not worrying about the amount of the ski's base material that is exposed for a given orientation. I am of the mindset that tree trunks and hidden rocks on the mountain are more of a danger to your bases than small rocks on the highway anyway. If you are waiting to comment, "Just get a roof box!", I understand as I own both a box and a rack at this point, and they both have their advantages, and I will not be exploring the aerodynamics of a box...
I was able to start by finding some faceted geometry of a Subaru Forester online (I'm from Colorado, can you tell?) and was able to import that into ANSYS Spaceclaim. Once in Spaceclaim, I was able to edit the faceted geometry to get nice exterior panel surfaces, which I then combined to get a single clean faceted exterior for the car.
After that, I used Spaceclaim to generate the remainder of the rack and skis, including crossbars, a ski rack, and a pair of skis (Complete with the most detailed bindings you have ever seen!). I made a combined part of the crossbars, rack, and skis for each one of my orientations, as this allows me to report the forces on each combined part during the simulation.
For the simulation, I used ANSYS Discovery Live, the newest tool from ANSYS that allows for instant and interactive design exploration. This tool lets me actively add my CAD geometry and shows results in realtime. I was able to start with just the car and then add and swap my ski/rack geometry with simple button clicks. With traditional simulation tools, I would have needed to create a mesh for each one of these cases, analyze them one at a time, and the post-process and compare results after the fact. After launching Discover Live, it's as easy as selecting the type on analysis I want to run.
Once I have selected 'Wind Tunnel' for my solution, I can select my geometry, and then am prompted for the direction of flow, as well as selecting the 'floor' of my domain. Once that is done, results show up on the screen instantly. I only needed to modify the flow velocity to ~65 mph. I am most interested in the force on the faces of the combined crossbars, rack, and skis in each orientation, so I created Calculations for each one, which is done by simply selecting the part and using the popup toolbar to create the graph.
I was already off and running. I ran each one of the cases until the force plot had become steady.
Seeing that the force results for the Tips Forward vs. Tails Forward cases were very similar, I decided I should also run a 'Bases Up' Orientation, even though I STRONGLY advise against this, as UV wrecks the base material of your skis/snowboard.
In addition to the contour plot shown in the images above, you can also use emitters to show streamlines and particle flow, which also give some pretty neat visualizations.
The graph plots show values for the Total Y Force for Tips Foward, Tails Forward, and Bases Up orientations to be 37.7 N, 39.1 N, and 37.1 N, respectively. Using Discovery Live, I was able to quickly run all 3 of these simulations, showing that there is not a major difference in the forces on the ski rack between the three orientations. So, put the skis on the roof in the direction that makes life easiest for you, and keep those bad boys paired to protect your bases from the sun, because splitting them isn't going to help with aerodynamics anyway!
Next steps would be taking a specific case and running in 2D, then 3D, in ANSYS Fluent.
Posted on December 19, 2017, by: Eric MillerFor our Christmas parties at PADT we generally have over 40 employees so a traditional secret Santa gift exchange takes to long. At some point, we downloaded a right-left gift exchange story from the internet and it was a big hit. When we ran out of stories on the internet, we started writing our own, usually in some sort of over-the-top style. This years Christmas party involved sorting employees into Elf Families for some games we played. That made it kind of obvious that we should make the story Elf Family related as well. Here is how it works:
Everyone gets their gift and forms a big circle in the middle of the room. Someone with a strong voice reads the story and every time the word LEFT is read, everyone passes the package they have to the left. Every time the world RIGHT is read, everyone passes the package they have to their right. You should pause a bit at each LEFT/RIGHT to give people a chance to pass.You can find previous years stories here: – Elf Family Christmas (2017) – Western Christmas (2016) – Star Wars Christmas (2015) – Fairy Tail Christmas (2014) – Science Fiction Christmas (2013) – Romance Christmas (2012) – Film Noir Christmas (2011)
Trouble in ElftownWay up on near the North Pole, just to the left of Santa’s workshop and right down the road from the Reindeer farms there sits a little village called Elftown. On the outside, it looked like the front of a Christmas card. Picturesque houses on the right and left side of the main street, and a giant Christmas tree right in the middle of town. But right under the surface things were not right. There was a tension in the town that left on its own, might not just tear apart the community, if left on its own it might destroy Christmas itself. The problem was that there was a war of sorts going on between the elf Clans. Specifically, the Toe clan and the Sweet clan were furious with each other. No one really knew who was right and who was wrong, but everyone was stuck right in the middle of the conflict, and many felt they were left with no option other than violence. It started at the last reindeer games when the Rightly Clan had decided to take the seats that belonged to the Leftover Clan. Now the members of the Leftover Clan were used to being left out of things. They lived right next to the Santa Express train tracks, but on the wrong side. So they were used to not being treated right. The only thing they had going for them was that their Reindeer Game seats were right on the track on the right side of the finish line. The Rightly Clan were on the left side, but they wanted the right side. So they marched right up and sat down, right there in the middle of the opening ceremonies. It would not be a big deal, the Rightly and Leftover clan fought all the time. The problem was that the Toe Clan had signed a contract right before the games with the Leftover Clan to outsource their toy assembly quota to them. That left the Sweet Clan out in the cold in terms of making their quota, right there two weeks before Christmas without either working-class clan to do the work for them. Right now, they were panicked. And the Toe Clan was mad that the Sweet clan had left negotiations and complained to Santa. So right there with Mr. and Mrs. Clause sitting on their thrones right in front of the crowd, the Toe and and Sweet Clans felt it was right to make the seating controversy about so much more. Harsh words, for elves, were exchanged back and forth. Then a snowball was thrown right at a crowd and it hit Santa right in the face. He stood right up and said “I’m am left with no option but to cancel these Reindeer Games right now! All of you need to leave now, right now! I said Right now I Say… ho ho hooooo!” Everyone left the stadium, but they left with a burning hate for each other. And right before Christmas, it reached a fevered pitch. Each clan was going through their store of toys and weaponizing what they could. Spikes were put right into baseball bats. Toy nerf guns were modified to file nails right out of their barrels. The social-economic stratification of Elftown, based on Santa’s distribution of responsibility to families that was based on payments of “left over” egg nog made right out in the open was the real cause. It was obvious regardless of if you were on the left or right of the political spectrum. As the moon passed right over the North Pole, because it was winter and the sun had left for the season, the families gathered in the main square. The Toes and the Rightly’s on the right, and the Sweets and… their allies, … other side They brandished their vicious modified toys and hurled insults back and fortth. On that Christmas Eve, right in the heart of the north pole, right where the spirit of Christmas was born and nurtured, Elftown was about to explode. And right before that fuse was lit, a small voice could be heard. “Riliburt? Riliburt ? Is that you holding a tennis racket with a spike right in the middle?” And then an even tinier, sweeter voice answered “Annibell? Why yes, I have to support my family, my clan I’m left with no choice” “Riliburt, I need to tell you something right now, right here in front of everyone, it can’t be left unsaid.Riliburt, I love you! That is right. I. Love. You!. “Oh, Annibell, I love you as well! But you are from the Toe Clan and I am a lowly Leftover, our love is not right.” At that point, every elf heart, in the left of every elf chest, skipped a beat. All of the anger stopped, just for a second, as they all contemplated love. Because stripped of the presents, and trees, and eggnog, Christmas was really about love. On the right side of the square, and on… the other side, everyone knew what the right thing was to do. They dropped their weapons right there and merged into a giant pointy eared mass of hugging elves. And right in the middle was the couple that reminded everyone that what they were all about to do was not right. That the Toes, the Sweets, the Rightly’s, and the Leftovers could all get along if they just remember that the right thing to feel was love and that they left hate and anger outside of Elftown. Peace on earth, goodwill towards men was the message they remembered, right there, at the top of the world, in a place called Elftown, just to the left of Santa’s workshop and right down the road from the Reindeer farms.
Posted on November 1, 2017, by: Eric MillerThe only day available for our company meeting was October 31st, so we combined the meeting with a Halloween celebration. We are an engineering company, so not everyone wore a costume.. but we did all have fun. Check out the slide show:
Posted on October 5, 2017, by: Eric MillerI have a lot of toys in my office and on my desk. Some might consider it unprofessional or even childish. I don't disagree. What they are missing is the power of toys and the power of play. I explore this idea in "Why I keep toys on my desk." Also for those of you who are readers of the PADT blog, I've included below some images of my favorite ones.
Posted on September 19, 2017, by: Nathan HuberIt is no mystery that I love my Subaru. I bought it with the intention of using it and I have continually made modifications with a focus on functionality. When I bought my roof crossbars in order to mount ski and/or bike racks, I quickly realized I needed to get a fairing in order to reduce drag and wind noise. The fairing functions as designed, and looks great as well. However, when I went to install my bike rack, I noticed that the fairing mount was in the way of mounting at the tower. As a result, I had to mount the rack inboard of the tower by a few inches. This mounting position had a few negative results:
- The bike was slightly harder to load/unload
- The additional distance from the tower resulted in additional crossbar flex and bike movement
- Additional interference between bikes when two racks are installed
Posted on February 9, 2017, by: Nathan HuberI had a really great time designing the Metal 3D printed shift knob from my previous blog post. I was curious what the other benefits of the knob may be besides being cool to look at and show off. What better way than to use the simulation software that we use here at PADT every day! One of the clear differences between my solid spherical knob and the Metal 3D printed version is surface area. Being that PADT is based in Tempe, AZ, some may say that we have "warm" summers down here. Couple the 120F days with a black car, and the interior can get very hot, at some points feeling like the sun itself has taken up residence inside the back seat. With modern A/C, this heat can be mitigated fairly quickly, only to attempt to shift into gear to be scalded by the shift knob! I wanted to see what the rate of cooling for the two knobs would be in a basic situation with some basic assumptions. Using ANSYS transient thermal, I initialized the knobs to 150F, temperatures that can be quickly reached in parked cars here in AZ. I added a convection heat transfer boundary condition on the outer surface of each shift knob, assuming a film coefficient of 50 W/m^2C, and that the ambient temp in the car is at a cool 70F. I ran the simulations for 5 minutes, and the results were in line with what I expected. As the 3D printed knob has more surface area for cooling, it's final temperature was ~84F, compared to the solid spherical knob at a final temperature of 115F! Want to learn more, check out the article in "Additive Manufacturing Media."
Posted on February 8, 2017, by: Eric MillerWe have great customers. The kind of cusomers that call up and ask "Hey, what do you think about having a Tesla test drive event for PADt employees" Duh. Yes. Please provide contact information. Then we thought this was an event better shared with other techno-speed-nerds. The Tempe Tesla show room people liked the idea so we put together an event for our ANSYS and Stratasys customers. (Just another reason to buy from us) The basic idea was simple, stop on by the PADT parking lot in Tempe and drive a Tesla Model S or Model X, or both. The Tesla people brought along their technical person and the test drive people were also very knowledgable about all the features in the three vehicles they let us drive. The course left the PADT parking lot, drove up to Elliot, then entred to 101, and then get off at Warner or Rey and head back, while the brave Tesla employee tried to keep cool. Especially when Oren was driving. For many of us, this was the first time we had driven one. Let me just say that the common factor across employees and cusotmers is that everyone had an ear-to-ear grin on their face when they got back from their test drive. These cars are not just fast (large numbers of electrons pushed through big motors equals lots of torque right away) but they are brilliantly engineered. From the user interface, to the seats to, to the suspension. Everything is done right. As a group of engineers that was almost as exciting as the raw power and impecable styling of the cars. It was a true nerdfest. We spent 10 minutes discussing regenerative breaking schemes and the idea of using regeneration all the time when you lift off the accerator instead of putting your foot on the break to slow down slightly. This is the type of paradigm shift that disrupts around one hundred years of automotive legacy. Why does the accelrator pedal have to be an accelerator pedal. Why can't it be an input for acceleration and deceleration based on position? We also spent even more time (I'm embarassed to say how long) talking about charging. And then the topic turned to autonomous driving and the sensors used. Good times. Good times. PADT's relationships with Tesla actually goes way back. When they were first starting out and were just a handfull of engineers, we provided some ANSYS training and did a consulting job for them on thermal management for an early battery system. So we proudly count them as a happy PADT customer. And of course PADT worked on the large Blink chargers and has supported many companies that are suppliers to tesla. Look for similar events in the future. No sales or seminars, just smart-people-fun type of events.
Posted on January 19, 2017, by: Eric MillerLet's be honest, the mouse and keyboard are outdated interface methods that serve us well, but voice recognition is pretty dang awesome and efficient. In "Voice recognition, the new thing in computing" I write an entire post using voice recognition about the pros and cons of voice recognition. That is almost meta. Please enjoy, it was a fun one to do.
Posted on January 6, 2017, by: Eric MillerFor our Christmas parties at PADT we generally have over 40 employees so a traditional secret Santa gift exchange takes to long. So a couple of years ago we downloaded a right-left gift exchange story from the internet and it was a big hit. We ran out of stories on the internet, so we started writing our own, usually in some sort of over-the-top style. This year, 2016, many of us had become addicted to West World, so a good old fashioned Western seemed appropriate. Everyone gets their gift and forms a big circle in the middle of the room. Someone with a strong voice reads the story and every time the world LEFT is read, everyone passes the package they have to the left. Every time the world RIGHT is read, everyone passes the package they have to their right. You should pause a bit at each LEFT/RIGHT to give people a chance to pass. You can find our older stories here – Elf Family Christmas (2017) – Western Christmas (2016) – Star Wars Christmas (2015) – Fairy Tail Christmas (2014) – Science Fiction Christmas (2013) – Romance Christmas (2012) – Film Noir Christmas (2011)
Trixie and the Christmas MiracleA train whistle echoed in the distance as US Marshal Dilan McRightland brought his horse Righty to a stop on the left side of the ridge. Down below, right in the middle of the valley was his destination, the place he had been headed right towards for three weeks. Wrightville Gulch. He’d seen a lot of dusty towns, not much more than a few buildings on the right and left side of a crooked street. Left to his own devices he would have left his job and gone right back to his family farm on left bank of Ohio river, right below Louisville Kentucky. But he had sworn an oath to uphold justice, to make sure that wrongs were righted, and that no criminal was left free to cause more harm. It was the right thing to do. He dug his heals into Righty and they headed right down the trial, towards an encounter that would have been best left alone. As he entered the town from the… south, he surveyed both sides of the street. On the right was a bank, livery stable, and what looked like a hotel that may not be where the ‘right type of people’ stay. The other side of the street held a saloon, blacksmith, general store, and a Chinese restaurant: Right and Wrong Noodles. Dilan assumed that the fugitive he was seeking was in the saloon. So he tied up Righty, using a left hitch not, and went right in the swinging doors. It took a while for his eyesight to adjust to the dim interior. A long mahogany bar filled the wall. On the… other side, there was a stair case that led to rooms on the second floor. Right in the middle of the room stood a giant Christmas tree. That was right, Dilan thought, today was Christmas Eve. It has been a long time since he had enjoyed a right proper Christmas. He began to day dream about snowy Christmas mornings when a shout brought him right back to reality. “Hey! You looking for me, stranger?” A man dressed in head to toe in black leather stood on the left side of the Christmas tree. “If you are Lefty Peterson, then yes.” Replied Dilan. “I’m US Marshal Dilan McRightland and I’ve traveled all the way to Wrightville Gulch, right here in the middle of no-where, to bring you to justice.” The two men stared at each other across the room, their right hands hovering over their six shooters, which for now were left in their holsters. “I don’t think you have it right, Marshal. When I left the Stanton brothers for dead, right in the middle of Dodge City, I left that life behind me. I’m clean now, I’ve got a wife and kids. I started over. You know what I did was right, they deserved to die. So the right thing for you to do is get back on your horse and get right out of town.” This left Marshall Dilan a bit baffled. What if Lefty was right? And then he stood up straight and looked Lefty in the eye. “The law is the law lefty, doesn’t matter if you think what you did was right, it is up to a jury to decide that.” Lefty looked right back, and snarled “The only way you are taking me back is as a corpse. If you don’t leave in a coffin yourself. Their right hands slowly moved to their guns. Just when they were about to draw a girl dressed like a dancer the left bank of the Sein in Paris, dashed right between them. “Stop right now!” she shouted. “Gosh Nabit! It’s Christmas Eve. Have you any heart left, either of you?” She turned to Lefty “Lefty, darling, you don’t have to die. If you think what you did was… justified, go with the marshal, argue your case.” She spun to face Marshall McRightland “And you, you come riding in here on Christmas ever, where we was having ourselves a right nice party, and you threaten our friend Lefty, that just aint right either!” Dilan stood. He could see the star on his chest reflected in the mirror behind the bar, and he could see the star right on top of the tree. And he looked right at the dancing girl, a small tear falling from her right eye. “Lefty” he said “you agree to let me handcuff you to that bar there, and we can have ourselves a right proper Christmas ever and morning. And then we ride out of here and you get your day in court. Does that sound…. All right?” Lefty thought for a minute, then responded “I right reckon that is the right thing to do. Right here and right now on Christmas eve, maybe some peace on earth is what we need.” And so on that Christmas Eve in a dusty town right in the middle of no-where, a little Christmas spirit, and a fiery dancing girl named… Trixie, brought a little peace on earth and goodwill towards men to a place called Wrightville Gulch.
Posted on December 8, 2016, by: Nathan HuberI have always had an issue with leaving well enough alone since the day I bought my Subaru. I have altered everything from the crank pulley to the exhaust, the wheels and tires to the steering wheel. I've even 3D printed parts for my roof rack to increase its functionality. One of the things that I have altered multiple times has been the shift knob. It's something that I use every time and all the time when I am driving my car, as it is equipped with a good ol' manual transmission, a feature that is unfortunately lost on most cars in this day and age. I have had plastic shift knobs, a solid steel spherical shift knob, a black shift knob, a white shift knob, and of course some weird factory equipment shift knob that came with the car. What I have yet to have is a 3D printed shift knob. For this project, not any old plastic will do, so with the help of Concept Laser, I'm going straight for some glorious Remanium Star CL! One of the great things about metal 3D printing is that during the design process, I was not bound by the traditional need for a staple of design engineering, Design For Manufacturing (DFM). The metal 3D printer uses a powder bed which is drawn over the build plate and then locally melted using high-energy fiber lasers. The build plate is then lowered, another layer of powder is drawn across the plate, and melted again. This process continues until the part is complete. The design for the knob was based off my previously owned shift knobs, mainly the 50.8 mm diameter solid steel spherical knob. I then needed to decide how best to include features that would render traditional manufacturing techniques, especially for a one-off part, cost prohibitive, if not impossible. I used ANSYS Spaceclaim Direct Modeler as my design software, as I have become very familiar with it using it daily for simulation geometry preparation and cleanup, but I digress, my initial concept can be seen below: I was quickly informed that, while this design was possible, the amount of small features and overhangs would require support structure that would make post-processing the part very tedious. Armed with some additional pointers on creating self supporting parts that are better suited for metal 3D printing, I came up with a new concept. This design is much less complex, while still containing features that would be difficult to machine. However, with a material density of 0.0086 g/mm^3, I would be falling just short of total weight of 1 lb, my magic number. But what about really running away from DFM like it was the plague? There we go!!! Much better, this design iteration is spec'd to come out at 1.04 lbs, and with that, it was time to let the sparks fly! Here it is emerging as the metal powder that has not been melted during the process is brushed away. The competed knob then underwent a bit of post processing and the final result is amazing! I haven't been able to stop sharing images of it with friends and running it around the office to show my co-workers. However, one thing remains to make the knob functional... it must be tapped. In order to do this, we need a good way to hold the knob in a vise. Lucky for us here at PADT, we have the ability to quickly design and print these parts. I came up with a design that we made using our PolyJet machine so we could have multiple material durometers in a single part. The part you need below utilizes softer material around the knob to cradle it and distribute the load of the vise onto the spherical lattice surface of the knob. We quickly found out that the Remanium material was not able to be simply tapped. We attempted to bore the hole out in order to be able to press in an insert, and also found out the High Speed Steel (HSS) was not capable of machining the hole. Carbide however does the trick, and we bored the hole out in order to press in a brass insert, which was then tapped. Finally, the shift knob is completed and installed! Want to learn more, check out the article in "Additive Manufacturing Media."
Posted on October 28, 2016, by: Eric MillerThe verdict is in, if the company barq! actually existed they would have raised a lot of seed money yesterday. Members of the Phoenix area startup community gathered at PADT to try out a new idea: what if the experts who mentor and coach startups tried their hands at pitching a company? The result was fun, funny, and educational. Local incubators/accelerators CEI, Seed Spot, and Tallwave joined PADT in pitching a totally made up company, barqk! to a group of judges who are startup experts. We talked about poop, doggy depression, bessel functions, big data, valuations, and the cat revolt. In the end we ended up with four fantastic examples of how to pitch a company and how to answer questions from investors. One of the best parts was that every single team finished their pitch in the 10 minutes they were given, and they covered everything that needed to be covered. Yes, it can be done! And the winner is... The Center for Entrepreneurial Innovation (CEI). Tom Schumann and Patti DuBois told a story, explained the product, and got across the value to the investors of the product . You can watch the recording of the presentations in the video below. Take some time to watch the pitches and get a feel for barqk!, and how different organizations approach telling the story and more importantly, attracting investors. The audience noticed that each team had a unique take that represented their strengths. https://youtu.be/dtNUkraKhqo Our judges were Jim Goulka from Arizona Technology Investors, Christie Kerner from ASU, Carine Dieude of Altima Business Solutions, and Linda Capcara with TechTHiNQ, and they did a fantastic job, especially with keeping a straight face when the contestants responded with some very inventive responses. Their contribution was important. If you are interested in doing a similar event, here is some background information: Rules:
- Each team gets a copy of the angel group funding application and a logo.
- Each team gets 10 minutes to pitch
- The judges have up to 5 minutes to ask questions
- The other presenters can listen in
- PowerPoint slides are allowed
- Some variation from the company application is allowed for humor or to fill gaps, but everyone should stick to the same basic material