Data Management Speeds Up Simulation of Crash Test Dummy Models
- Tuesday, 01 June 2010
The idea for the automotive crash test dummy first came to life in the 1950s when U.S. Air Force flight surgeon Col. John Stapp realized that more of his fighter pilots were dying in car crashes than from accidents in their hi-tech jet aircraft. The Stapp Car Crash Conferences started that decade and continue today as a venue to share information on the latest research and advancements for improving vehicle crashworthiness and occupant safety.
A major challenge in the ongoing development of physical crash dummies is the need to reasonably represent how the human body responds in an automotive accident. The ultimate goal of crash dummy research is to aid in creating design improvements for both vehicles and occupant restraint systems to reduce injuries and save lives.
Energy-absorbing crumple zones and other structural innovations do help protect occupants during car crashes. The addition of air bags, combined with a properly worn lap/shoulder belt, reduces driver deaths by 61 percent in a frontal crash, according to the National Highway Traffic Safety Administration (NHTSA). But car manufacturers are now also legally obligated to certify the effects of crash events on the humans involved. As a result, crash dummies for front-impact (“Hybrid”), sideimpact (SID), and rear-impact (RID) have been developed, with engineers from around the world contributing over the years to their evolution. Today, physical crash dummies are a valuable part of every automotive OEM’s product design, development, and testing arsenal.
A single physical crash dummy can cost more than $200,000. Made from a variety of different materials, including custom-molded urethane and vinyl, they are based on true-to-life human dimensions (a typical “dummy family” includes several different dummies, ranging in size from a toddler to a large adult male). They have ribs, spines, necks, heads, and limbs that respond to impact in realistic ways. And they are loaded with sensors (44 data channels on the current frontimpact standard, the Hybrid III) that record up to 35,000 items in a typical 100 to 150-millisecond crash.
Automotive companies and government organizations continue to collaborate toward the acceptance of international safety standards (a WorldSID project is now underway) and harmonize methods of testing as the market for each country’s vehicles becomes increasingly global. But physical test dummies are only a part of the crash and safety certification process. As computer-aided engineering software and computing resources rapidly advance, there is increasing emphasis being placed on developing more accurate virtual crash dummies.
Simulating the Crash Simulator
Since a physical crash dummy is a manufactured product like any other, it is no surprise that engineers use realistic simulation with finite element analysis (FEA) software to guide its design, production, and performance. Given the power of FEA to cost-effectively reduce real-world testing, in the case of expensive crash dummies and more expensive vehicle prototypes, it definitely pays to simulate the simulator. You can crash a virtual car and dummy many times, much faster, and at far less cost than a single physical test.
Since the goal of simulating a simulator of the complex human body is to closely represent reality, the resulting data must correlate well with physical crash test results. So standardization of FEA models is critical. Each virtual dummy must exhibit responses to crash impact loads and accelerations in a precise, repeatable manner that mirrors what happens to its corresponding physical crash dummy.