Crash Test Dummies

By SRT-Tom · Jun 22, 2019 ·
  1. SRT-Tom
    A crash test dummy is a full-scale anthropomorphic test device (ATD) that simulates the dimensions, weight proportions and articulation of the human body during a traffic collision. Dummies are used by researchers,automobile and aircraft manufacturers to predict the injuries a person might sustain in a crash. Modern dummies are usually instrumented to record data, such as velocity of impact, crushing force, bending, folding, or torque of the body, and deceleration rates during a collision. There is constant need for testing because each new vehicle has a different design.

    upload_2019-6-22_6-27-22.png

    The need for a means of analyzing and mitigating the effects of motor vehicle accidents on humans was felt soon after commercial production of automobiles began in the late 1890s, and by the 1930s, when the automobile became a common part of daily life and the number of motor vehicle deaths were rising. Death rates had surpassed 15.6 fatalities per 100 million vehicle-miles and were continuing to climb.

    Up until the early 1960s, cars had dashboards of rigid non-yielding metal, non-collapsible steering columns, no head rests, and protruding knobs, buttons, and levers. Without seat belts, passengers in a frontal collision could be hurled against the interior of the automobile or through the windshield. The vehicle body itself was rigid, and impact forces were transmitted directly to the vehicle occupants. As late as the 1950s,car manufacturers were on public record as saying that vehicle accidents simply could not be made survivable because the forces in a crash were too great.

    upload_2019-6-22_6-28-7.png
    1963 Plymouth Belvedere

    The first test subjects were human cadavers. They were used to obtain fundamental information about the human body's ability to withstand the crushing and tearing forces typically experienced in a high-speed accident. To simulate these impacts, steel ball bearings were dropped on skulls, and bodies were dumped down unused elevator shafts onto steel plates. Cadavers, fitted with crude accelerometers, were strapped into automobiles and subjected to head-on collisions and vehicle rollovers. As a result of design changes implemented up to 1987, cadaver research since saved 8,500 lives annually.

    upload_2019-6-22_6-29-19.png

    By the mid-1950s, the bulk of the information cadaver testing could provide had been collected. It was also necessary to collect data on accident survivability, research for which cadavers were woefully inadequate. In concert with the shortage of cadavers, this need forced researchers to seek other models.Chimpanzees rode rocket sleds,bears rode impact swings and pigs, in sitting positions, were crashed into a deep-dish steering wheels at about 10 mph.

    Some brave researchers took it upon themselves to serve as human crash test dummies. In 1954,USAF Colonel John Paul Stapp was propelled to over 1000 km/h on a rocket sled and stopped in 1.4 seconds.Lawrence Patrick, then a professor at Wayne State University, endured some 400 rides on a rocket sled in order to test the effects of rapid deceleration on the human body. While data from live testing was valuable, human subjects could not withstand tests that exceeded a certain degree of physical injury. To gather information about the causes and prevention of injuries and fatalities would require a different kind of test subject.

    upload_2019-6-22_6-30-11.png

    Although animal test data was still more easily obtained than cadaver data, the fact that animals are not people and the difficulty of employing adequate internal instrumentation limited their usefulness. Animal testing is no longer practiced by any of the major automobile makers; General Motors discontinued live testing in 1993 and other manufacturers followed suit shortly thereafter.

    With advances in computers and technology, General Motors developed the first reliable and durable crash test dummies- the Hybrid I in 1971 and Hybrid II in 1972. They had improved shoulder, spine, and knee responses, and more rigorous documentation. Though a great improvement over cadavers for standardized testing purposes, Hybrid I and Hybrid II were still very crude, and their use was limited to developing and testing seat belt designs. A dummy was needed which would allow researchers to explore injury-reduction strategies. It was this need that pushed GM researchers to develop the Hybrid III family of crash test dummies.


    upload_2019-6-22_6-31-0.png

    The Hybrid III made its first appearance in 1976. These dummies, which came in several heights and weights, were designed to research the effects of frontal impacts and were directed towards a specific age- for example, a typical ten year old, six year old, three year old, and a grown man and woman.

    The modern Hybrid III contains dozens more sensors than the earlier versions. These light-weight sensors account for 80% of the Hybrid III’s $250,000 cost. The dummy’s skeleton consists of aluminum, rubber, and steel parts for strength and sensitivity. The structure is surrounded by a layer of urethane-foam
    flesh and pliable vinyl skin. The crash dummy bodies contain the following devices:

    Potentiometers- Measure body displacement by translating movement into electric voltage (located in the chest and knees).

    Accelerometers- Measure the rate of acceleration in a particular direction along various points on the dummy (located in the head, chest, pelvis and feet).

    Load Cells- Interpret the forces and bending movements experienced by the dummy (located in the neck and legs).

    Before a crash test, researchers place four quadrant circle decals on the dummy to more easily track the movement on body parts on film. They also coat various regions of the body with multicolored paint, which transfers onto surfaces that are impacted.

    upload_2019-6-22_6-33-56.png

    Although Hybrid IIIs do a great job documenting the effects of frontal impacts, they are less useful in assessing the effects of other types of impact, such as side impacts, rear impacts, or rollovers. After head-on collisions, the most common severe injury accident is the side impact. As a result, the following new crash dummies were developed to measure these specific types of crashes:

    • SID (Side Impact Dummy) is a family of test dummies designed to measure rib, spine, and internal organ effects in side collisions. It also assesses spine and rib deceleration and compression of the chest cavity.

    upload_2019-6-22_6-35-2.png

    • BioRID is a dummy designed to assess the effects of a rear impact. Its primary purpose is to research whiplash, and to aid designers in developing effective head and neck restraints. BioRID is more sophisticated in its spinal construction than Hybrid; 24 vertebra simulators allow BioRID to assume a much more natural seating posture, and to demonstrate the neck movement and configuration seen in rear-end collisions.

    upload_2019-6-22_6-35-48.png
    • CRABI is a child dummy used to evaluate the effectiveness of child restraint devices, including seat belts and air bags. There are three models of the CRABI, representing 18-month, 12-month, and 6-month-old children.
    upload_2019-6-22_6-36-29.png
    • FGOA is a first generation obese anthropometric test device which can be used to study the automotive safety challenges for obese occupants, who are believed to have higher risk of mortality in automobile collisions comparing to non-obese occupants.
    upload_2019-6-22_6-37-15.png
    • THOR is the successor of Hybrid III. It has a more human-like spine andpelvis and its face contains a number of sensors which allow analysis of facial impacts to an accuracy currently unobtainable with other dummies. THOR's range of sensors is also greater in quantity and sensitivity than those of Hybrid III.
    upload_2019-6-22_6-38-4.png

    The results of car crash tests are communicated to the buying public, by the National Highway Transportation Safety Administration (NHTSA) through 5-star ratings for vehicles. These government safety ratings are printed on the new car window invoice (see lower right section of invoice, below).

    upload_2019-6-22_6-38-46.png

    The 2018 Dodge Challenger, fared well in the testing, and received the following NHTSA safety ratings:

    · Overall Rating- 5 stars
    · Frontal Crash- 4 stars
    · Side Crash- 5 stars
    · Rollover- 5 stars

    upload_2019-6-22_6-40-6.png

    Share This Article

Comments

To view comments, simply sign up and become a member!