How the CAFE Standards Influence Engineering & Design
We were all taught about idealized cantilever beams in college. Little did we know then, that even the simplest of parts have their own histories, and are affected by things as seemingly out of place as government regulations.
For example.. Let’s say you are awarded some new business. Your client wants a simple bracket – The length is 20″, and it is supporting a concentrated load 500 pounds at the end. The other end is mechanically grounded to a 5″x5″ patch. The safety factor with respect to yield must be greater than three. And the maximum deflection must be no greater than 1/4″.
You bring this to your design engineer, and they return with a simple rod with appropriate attachments at either end. All good and well.
Six months go by. You client, an automotive manufacturer, informs you that due to ever constrictive standards imposed on them (and therefore, you) by the Federal Government’s Corporate Average Fuel Economy (CAFE) regulations, your old design must meet the same design constraints, but be lighter.
“How much lighter?,” you ask.
“The lighter the better,” they answer. “Oh, and by the way – we’ve added a design constraint: You need to keep the first resonant frequency greater than 200 Hertz.”
That’s the bad news. The good news is that the now the end load is smaller.
You agree, and take the new requirements to your design team. They come back with a tube design.
This happens every year for a few more years. The CAFE requirements force progressively lighter designs. Customers (and therefore, the client) are increasingly pressuring to keep costs down. The form of the design becomes more distinctive over time.
After several design cycles, the constraints overwhelm your design team. It is apparent that a simple tube design will no longer meet project requirements. You decide to quarantine your team for a few hours, so that everyone can brainstorm about how to stay in the good graces of the client, by helping them stay in the good graces of the government.
Some interesting things come out of that exercise. None of them are feasible.
Everyone has contributed to the discussion except one. He’s the young, quiet guy in the back. He looks a little embarrassed. You convince him to spit out whatever he’s thinking. And so he does.
It seems that when he was in school, he attended a tour of a hydroforming factory. He tells you that this would be an ideal application for hydroforming manufacturing. Hydroforming for example, would allow you to put ribs in your tube – something that can’t be done with conventional forming. You’d have the extra stiffness without the extra material.
Naturally, you need to farm this out to hydroforming specialists. As it turns out, it was a good decision. Your VP even tells you so (happily), at your next yearly review.
Here at American Hydroformers, we are in the business of bringing success to automotive companies struggling to meet the demands of the consumer, the customer, and the government’s CAFÉ standards. For more information on how our hydroforming solutions can help your company keep current with the cafe standards, please contact us.