CAD Tools On A Wild Ride

Jon Titus wrote this great article in designnews and I thought I share it with you all.

"When the team at Dynamic Structures designed and built the large Canada-France-Hawaii Telescope enclosure on Mauna Kea, a dormant volcano, no one foresaw the company's future expansion to design, fabricate and assemble amusement rides. "Think of an amusement ride not as a structure but as a large complete machine and you'll understand the connection," says senior designer Craig Breckenridge.

Cadride Dynamic Structures designs roller coasters and theme-type rides. A roller-coaster vehicle rides along a track and nothing else occurs, except some screaming and white knuckles. The passengers just go along for the ride. In a theme ride, though, the vehicle travels along a track and interacts with things along the way. "For a theme ride, we work with a large team from the buying company," says Breckenridge. "So we regularly review and exchange many drawings and models. And we must design and fabricate rides with small tolerances. In a 1.5-mile ride, for example, we have many sections and we must keep the gap between them to within 30 thousandths of an inch."

"Most of the time we use Autodesk's Inventor for part of a ride and AutoCAD for the remainder," says Breckenridge. "The programs function differently and offer different capabilities. Here's an example: Most rides and roller coasters include mechanical track switches that let operators remove a vehicle or route a ride onto a different path. We create the switches in Inventor because they represent compact machines compared with the structure and mechanics of the rest of the ride."

"Often we create a track in AutoCAD and use Inventor to design a vehicle," continues Breckenridge. "Then we can put them together in 3D Studio (3ds) and produce an animation that shows what a ride will look like. We use Navisworks for visualization and dynamic simulation. Then we can play the video animation for clients so they can see what the vehicle looks like as seen from a spot on the ground. Or, we can show them what the ride looks like from the front seat."

"Navisworks also lets us check the reach envelope, or the space a passenger can reach from a moving vehicle," says Breckenridge. "We must ensure they can't reach out during the ride and touch something as they go past. We also run dynamic simulations that tell us the forces a passenger will experience during a ride. This analysis gives us the maximum g-force experienced on the center line of the rails. But we also must know the g-force on the passenger's heart line, or roughly just above the center of a human torso. When someone sits in a seat, their body can still move, much like a lever, and experience greater g forces than we would measure along the track's center line. We want to ensure a ride doesn't put too much strain on the rider.""


Thank you.