In the 1940s, researchers would throw just about anything at a wall — anaesthetised pigs, human cadavers — to gain an understanding of a high-speed collision’s effect on the body. Thankfully, the latest generation of crash test dummies use sophisticated sensor arrays to do that, not dead people.
Detroit’s Wayne State University was actually the first to begin research into the bio-mechanics of a car crash and the first to use cadavers as research subjects. Cadavers were chosen since, at that time, the most efficient way to obtain a basic working knowledge of the limits of the human body was to simply subject a human body to those conditions. That included them being dumped down unused elevator shafts and being strapped into a car for a head-on collision. Side note: Worst job of the ’40s? Being the guy that cleaned cadaver out of the cars after the test.
Cadavers were quickly dropped for legal and ethical reasons (like, how did they test the effects of impact on children? Child cadavers? Yes.) and replaced with animal testing. Pigs were especially popular because their organs so closely resemble our own and they’re inclined to “sit up”, which made them invaluable for decapitation tests. Live human testing was even briefly employed.
Air Force Colonel John Paul Stapp, for example, tested the effects of rapid deceleration on the human body by riding a rocket sled as it dropped from 100km/h to 0 in the course of 1.4 seconds. Prof Lawrence Patrick of Wayne State University would spray shattered glass in the faces of his willing students to simulate window implosions. But, as nobody would volunteer for the fatal crash test scenarios, researchers turned to dummies.
The latest generation of ATD (anthropomorphic test device) is the THOR (Test device for Human Occupant Restraint) crash test dummy. The THOR NT, at 5’10” and 172 pounds (78.3 kg), is a 50th percentile male dummy as it’s designed to mimic the average male in height, mass and proportion. The THOR line also includes dummies for women, children, infants — even a pedestrian with an knee design that incorporates lifelike meniscus and tendons. They’re tested in and outside the vehicle, as well as in flotation device development and aircraft safety (answering the age-old question: what happens if my tray table isn’t in the upright and locked position during landing)
THOR also has a more human-like spine and pelvis, which allows the dummy to assume the four most common seated postures for testing. The spine itself is packed with sensors including a thoracic spine load cell, three tri-axial accelerometer assemblies and four angular orientation (tilt) sensors to measure the degrees of torque, movement, and acceleration the spine endures during a crash.
THOR’s face features five compression load cells with impact plates — one at each eye, cheek, and one at the centre of the chin — to measure the total load applied to the face by, say, an airbag, steering wheel or windshield. No other dummy in the world can do that.
Nor can any other dummy measure lower body injury like the THOR can. Its femurs transfer force into the pelvis like a real person’s and its lower leg record impacts applied to the foot, ankle and lower leg. In all, the THOR’s sensors measure over a hundred channels of data for injury assessment. Data that is then translated into injury criteria — from minor abrasions to super decapitations — for the vehicle’s occupants. And while the THOR isn’t yet an official global standard, numerous major car manufacturers including Volvo, Toyota, GM, and Ford all maintain small armies of the $US175,000 dummies. Sure that’s a lot of money for something you’re just going to break anyway — but hey, it’s better than using dead kids.
[Gesac Inc, NHTSA THOR NT, Spectrum IEEE, THOR NT User’s Manual, Akihabara News, Crash Test Dummy Wiki, Baltimore Sun]
Top art: the AP
Monster Machines is all about the most exceptional machines in the world, from massive gadgets of destruction to tiny machines of precision, and everything in between.
You can keep up with Andrew Tarantola, the author of this post, on Twitter, Facebook, or Google+.