You’ve got to admit that these life-sized dolls have a tough job, working to improve occupant protection. So it’s time to get to know the dedicated airbag testers a little better.
They don’t say a word. They know no fear. They sacrifice their torso, ribs, neck and head on a daily basis. Their everyday work frequently involves a “BANG.” Sitting in a car, a frontal collision with a wall at over 60 km/h, impact with other occupants or with airbags, playing the injured in a rear-end collision – this is the job of THOR-50M and WorldSID-50M. Their clients are manufacturers, suppliers, accident experts and automobile clubs such as the ADAC. THOR-50M and WorldSID-50M are crash test dummies, known in the trade as anthropomorphic test devices (ATD for short). “50M” stands for an average adult male, 1.75 meters tall and weighing 78 kilograms. These standard measurements have been used for years in the design and development of seats, belts and airbags for new vehicle models.
What is more, there is a whole clan of dummies: babies, children, (pregnant) women, the overweight, the elderly, plus special constructions for motorcycles and even dummy wild pigs. So those wishing to be equipped for all possible scenarios quickly have a “family” worth several million euros on the premises. Yet the investment pays off. Over recent decades, the dummies have ensured that cars with a passenger compartment and crumple zones have become safer than ever before. The findings about the stresses that can be tolerated by the human body are essential for setting limits and making more progress in technology.
Accident research started in the 1950s, in some cases with rather off-beat methods. The first experiments were conducted with animal cadavers such as monkeys and pigs, human corpses and human volunteers. Even managers took part in less dangerous customer presentations in order to demonstrate how effective the protection systems were. The first crash test dummies were shop-window mannequins with protheses. Today’s dummies are highly sensitive hi-tech devices that continuously become better at simulating the anatomy of the human body. Special materials are used to mimic bone and soft tissues, with an elastic vinyl skin covering tissues made of foam. The biomechanics in the dummies reproduce the movements of the human body. A dummy’s basic skeleton consists of steel and aluminum, while the skull is made from cast aluminum. The spine has rubber disks between the “bone elements” to provide flexibility. The most important regions of the body are fitted with up to 200 sensors measuring acceleration, forces, torsional moments, angles and deformations in real time. The humanoids’ bodies contain a lot of complex measuring kit, so they have to be reusable. Each one can cost between tens of thousands and millions of euros, depending on the design and the equipment it comes with. Some models can even be subjected to CT scans. Some crash test dummies have a service life of several decades and have been put through thousands of accidents.
Side impact, rear impact or frontal impact – specialized dummies are available for every type of accident.
This is the “Biofidelic Rear Impact Dummy.” Its “biofidelity” means that the materials used provide accurate and detailed information about the components of the human body, such as the skeleton. This allows much better conclusions to be drawn concerning injuries.
The name stands for “Child Restraint/Air Bag Interaction.” These dummies simulate infants and toddlers aged 6, 12 or 18 months in terms of their size, weight and mobility. They are used to test infant and child seats.
In 1971 General Motors presented the hybrid dummy. It was designed primarily for frontal impacts. It is now into its fourth generation.
The POLAR is a pedestrian test dummy developed by Honda. It is used to investigate how pedestrians are injured or killed when cars run into them.
The abbreviation stands for “Side Impact Dummy.” Since the 1980s its specialty has been accident scenarios with side impact. Its arms are only half-length.
The Test device for Human Occupant Restraint (THOR) is one of the most advanced dummies. It simulates the human body even more closely, has more authentic movements and delivers more precise measurements. It also supplies 3-D information about every crash.
When things get serious, a dummy will be clothed and made up – not to look pretty, but to mark the places in the test vehicle where it makes contact during the crash. Just as with human occupants, wearing a seat belt is obligatory. Then the dummy is ready to drive into a wall or some other obstacle. At Mercedes-Benz’ Technology Centre of Vehicle Safety (TFS) in Sindelfingen the longest crash track measures 200 meters. Here collisions are arranged with cars, buses and trucks at every conceivable angle. These noisy operations are filmed by high-speed cameras supplying high-resolution films that are then viewed in slow motion. And all this takes place under the watchful eyes of the safety engineers. The manufacturer also uses x-ray technology during the tests to investigate certain parts of the dummies’ bodies, including the inside. The tests always follow an identical plan, in order to deliver results that are as precise and comparable as possible. They generate several Terabytes of different data. In the latest generation, the data are saved in a black box inside the dummy. Older dummies are attached to cables that transmit data to a measuring system inside the car. After the crash, there is the job of analyzing the data.
When an OEM develops a new model to series maturity, it needs around 15,000 computer-based accident simulations and around 150 real crash tests. Because fully equipped test vehicles are expensive, individual components are subjected to sled tests without impacts. Volkswagen deploys this type of system at its Wolfsburg Centre of Competence for Safety, which can simulate lateral and rotational vehicle body movements both horizontally and vertically. After “knocking-off time” it’s back to the lab, where the dummies and their sensor systems come after every test to be fully checked, reprogrammed and recalibrated. If the dummy is missing an arm or has a broken rib, it does not remain an invalid but is given a replacement in reconstructive surgery. Mercedes-Benz carries out approx. 2,500 crashes per year at its facilities. Such tests are also conducted worldwide by the independent NCAP organizations, which award from zero to five stars and publish the ratings. The NCAP tests are not mandatory, but a new vehicle without a rating – or with a poor one – has little chance of being accepted by customers. The German ADAC automobile club is also “running into a brick wall” for research purposes. At its technology center in southern Germany it carries out dozens of crash tests on complete cars every year. The result is competition for greater safety, which ultimately benefits all road users.
Over 3,000 dummies are currently being deployed in “dangerous conditions” by the automotive sector, aerospace, the railways and the military. Most of them are supplied by the world market leader Humanetics. The firm based in the US state of Michigan created its first dummy in 1949 for the US military, to take measurements in stress tests for pilots. It was given the nickname “Sierra Sam” and was used to test ejector seats, aviation helmets and pilot restraints. It was the forerunner of the VIP-50 dummy used for tests in the auto industry. Mercedes-Benz first deployed a dummy in 1959. The company’s customers include nearly all automotive OEMs and major suppliers (tier 1). Since 2019 the engineers at Humanetics have been working on Thor AV (Alpha Version). This model has a special advantage compared with its brothers and sisters: it can lie down. If we are going to use autonomous vehicles in the future, we won’t be sitting all the time. Thor AV is destined to be an important companion for the tests on the way to autonomous driving.