Most people look at the cross section of a human bone and see an incomprehensible tangle of sponge-like scaffolding. Jeffrey Brennan sees a secret mathematical formula for the design of lighter, stronger car and airplane parts.
The mechanical engineer learned about bone topology while studying for his master’s degree at the University of Michigan under Noboru Kikuchi, an engineer who was looking for ways to encourage bone growth to repair damage from diseases such as osteoporosis. Brennan thought the same mathematical principles could be applied to product design. When he finished his program in 1992, he brought the idea to Altair Engineering, which liked it and hired him.
Brennan tapped Kikuchi to help translate the math into OptiStruct, the industrial design software Altair was developing. The software uses algorithms to suggest parts that balance strength and weight to mimic the way bones have evolved over millions of years. For example, in a Nascar race car, the software suggested where it was safe to leave out metal in a sway bar and still retain strength—cutting the weight by 37 percent.
Today, Altair’s designs are in products ranging from Airbus A380 wings to engine parts in Volkswagen vehicles. But Brennan says customers were initially resistant to his curvy, unorthodox designs, which often look more like something from science fiction, with parabolas instead of straight lines and few sharp edges. “The early days were frustrating,” he says. “You know you had a structure that was mathematically correct, but it looked strange and companies had to take a leap of faith to apply this technology.”
Brennan says that when he started at Altair, the company had 15 to 20 customers for the software. He managed to maintain just enough interest from customers in the early years to keep developing the anatomy-inspired products. Now Altair, a $200 million company, has 20 engineers dedicated to that work and hundreds of customers for it. With federal requirements completed in August that call for U.S. automakers to double fuel efficiency by 2025, the funky topology of Brennan’s design ideas, with their weight savings of 40 percent or more, are becoming an easier sell, he says.
Altair isn’t alone. Scientists are studying commercial applications for everything from how horses’ shinbones maintain strength to the growth patterns of tree limbs, says Janine Benyus, co-founder of Biomimicry 3.8, a consulting firm that helps companies including Procter & Gamble, Nike, and Boeing study natural structures for use in product design.
The irony, Brennan says, is that using the technology to actually repair bones has remained elusive: “Human tissue is rapidly changing and dynamic. Soft tissue is very difficult to model,” he says. “It’s a lot easier to make it work with a bracket.”