Humanetics' 3D-printed “elderly” crash test dummy
Crash test dummy manufacturer, Humanetics serves 100% of the OEMS and Tier I safety suppliers worldwide with anthropomorphic test devices (ATDs) for testing the safety of automobiles.
These crash dummies are designed to reflect the injuries that could occur in a real accident, and in doing so it is important to provide dolls in all ages and shapes. This has been a challenge, going from only male dummies, to dummies reflecting females, children and infants. Now, the company has now created the first ''elderly'' crash dummy with 3D printed internal parts used to replace expensive steel components.
It turns out that our older, ageing population is growing. In 2015 there were 40 million licensed drivers aged 65 or older in the United States, which represents almost one in every five drivers on American roads. Elderly occupants are more likely to sustain internal injuries when crashing, because their bones are more fragile and soft tissues less robust.
Crash dummies are typically ordered in small quantities or in low volume custom batches due to their expense and ability to be re-used multiple times. This is when Humanetics decided to look at 3D printing as a more cost-effective solution.
“It’s my job to look at the future,” said Mike Beebe, Chief Technical Officer at Humanetics. “I’ve been in the ATD business for 38 years and I’m always trying to figure out what new processes and materials we should develop going forward. One of the major discoveries we’ve made recently was that we could 3D print much of the elderly dummy. Now all of the components of the new elderly dummy, from the pelvis to the head assembly, are additively manufactured.”
When printing parts for the dummy, the team found it difficult to find a material that could withstand the forces and impacts of unique crash-testing environments. Rubber and plastic did not work, as the printed ribs began to crack after testing 20 times.
Design engineer Kris Sullenberg is responsible for day-to-day printing operation at the Humanities ATD manufacturing facility in Huron, Ohio. Sullenberg worked with Adaptive Corporation account manager Rich Tenaglia, who suggested the team use Markforged's Onyx, a carbon-composite material reinforced with continuous Kevlar fibres. A complete set of ribs was put to test on an elderly dummy and underwent 60-70 impacts with no visible deformation or damage.
“We’ve inflicted over 150 impacts to those Markforged-produced ribs to date,” Sullenberger said. “And we haven’t broken a rib yet.”
A full set of 3D printed ribs can be produced in just a week.
As a result of the test, Humanetics purchased its own Markforged Mark Two 3D printer, to make ribs and other skeleton components. The traditional process creates the rib out of a piece of spring steel that is formed and heat treated. A piece of damping material is glued to the inside of the rib to control the response to impact. The rib is left to set, then tested, and the damping material is trimmed several times to achieve the desired performance. While Humanetics is seeing Onyx material costs similar to those of the previous steel, the team can print a single rib in twenty-four hours and a full set in a week compared to the two to three weeks with traditional manufacturing.
“If we could use four or five printers at once we could print a full set of ribs in a day and a half instead of a week,” says Sullenberger.
Beebe and Sullenberg have learned that 3D printing can improve quality, and 3D printed moulds can be replaced in a day or two, saving between 40% and 60% in assembly and labor costs. Humanetics is also working on 3D printing organs to see how their qualities contribute to overall regional crash-test readings.
“Elderly people tend to have more flesh in front of the bones,” he pointed out. “This affects how a person moves within a seatbelt system and how the belt interacts with the passenger’s body during a crash. The ability to generate new organs using 3D printing technology will lead to shorter lead times, improved restraint systems, and safer vehicles.”
