Seat Belt Crash Testing: you can still learn a lot from a dummy

Seat belt crash testing is one of the most effective safety strategies when designing seat belts for vehicles. The basic principle of a seat belt is very simple, as has to do with kinetic energy. When you are in a vehicle moving at 50 kph, you have a lot of kinetic energy, and after a crash, you have zero kinetic energy. The purpose of the seat belt is to help absorb that kinetic energy with the webbing around the hips and torso or rib cage, and the seat belt webbing stretches a bit so the stop is not quite so abrupt. However in a vehicle crash, it is uncertain which direction the kinetic energy of the occupant will be directed. Therefore all seat belt manufacturers should perform dynamic crash testing of their seat belt systems with specific anchor points, and not simply perform static tests.

A common seat belt is composed of a lap belt and shoulder belt. Lap belts rest over your pelvis while a shoulder belt stretches across your chest. These two belts are tightly secured to the frame of the vehicle in order to hold passengers in their seats. Because every vehicle has different anchor points that support the seat belts, and every vehicle had different seat designs and locations, every seat belt design must be tested together with the anchor points. This is a concept that is not covered by the testing requirements of the US Department of Transportation. The National Highway Traffic Safety Administration (NHTSA) had a legislative mandate under Title 49 of the United States Code, Chapter 301, Motor Vehicle Safety, to issue Federal Motor Vehicle Safety Standards (FMVSS) and Regulations to which manufacturers of motor vehicle and equipment items must conform and certify compliance. FMVSS 209 was the first standard to become effective on March 1, 1967, and specifies the requirements for Seat Belt Assemblies for Passenger Cars, Multipurpose Passenger Vehicles, Trucks, and Buses. FMVSS 209 outlines many comprehensive testing requirements for seat belts, however they don’t require third party testing companies to complete all of these tests. Additionally, and more importantly, they don’t require a sled crash test with specific seat belt anchor points. However this is a requirement of the United Nations Economic Commission for Europe (UNECE) Regulation No. 16. In Europe, where GWR has been testing and manufacturing for 29 years, the ECE-R16 requires crash tests for every seat belt model before we are allowed to sell that design. Therefore, GWR Safety Systems has decades of crash testing experience, and we are the only mid-market seat belt manufacturer in the United States to complete sled crash tests for all of our seat belt models.

A crash test is a form of destructive testing performed in order to verify safety standards in crashworthiness for various modes of transportation or related systems and components. For seat belts, frontal impact sled crash testing is a cost-effective way of testing their performance in an actual crash. GWR tests our components and seat belt systems using this method, with a decelerating sled that stops in a crash area with a hydraulic ram.

Each crash test is expensive so the collected data must be maximized. The dummy goes from traveling at 50 kph to 0 kph in a distance just over one foot. Therefore crash tests are conducted under rigorous scientific and safety standards, with the use of high-speed data-acquisition. Videos and graphs can show the displacement of different parts of the dummy, and show if the seat belt is passing or failing the tests.

While FMVSS 209 does not require crash testing for seat belt assemblies, in 1973, the NHTSA created crash test dummy specifications, and issued a regulation for occupant crash protection (FMVSS No. 208). Amendments to the 208 have been made and the science behind crash testing has evolved. FMVSS 208 requires vehicle crash testing for certain vehicles, however this can be prohibitively expensive for some vehicle manufacturers. If the vehicle fails the crash test due to the seat belt or anchorage point locations, the vehicle manufacturer has to redesign the anchorage points and complete a new vehicle crash test. This can significantly increase the cost to the vehicle manufacturer. Completing a sled test with the seat belt model and designated anchor points before the actual vehicle crash test can save significant costs to vehicle manufacturers.

To protect you and your family in a crash, GWR has to understand at a very granular level what happens to your bodies during that impact that lasts only a fraction of a second. Sled tests, dummies, and other technologies help us understand and measure the human body’s movement, and the performance of various safety features in a crash. Measurements from the tests are used to understand the best seat belt and restraint designs, and predict risk of injury to each part of the body with different safety system designs. Because every vehicle has different seats, anchorage points, and required seat belt designs, and since each member of your family have different sizes, weights, and movements, a lot of research and crash testing are required to ensure maximum safety. GWR is constantly using the results from these safety sled tests to improve the safety of our seat belt systems for all vehicles to provide better occupant protection.

THOR (Test device for Human Occupant Restraint) are advanced dummies that have more human-like responses throughout the body as well as advancements in instrumentation that will help assess more advanced restraint systems. NASA is evaluating the THOR dummy as a potential device to be used for occupant safety standards for the next generation of space vehicles.

When leaders in our industry ask “what is the different between GWR seat belts and the leading average seat belt?” they come to understand that GWR’s experience designing automotive seat belts and using automotive crash testing is unusual for a private seat belt manufacturer that designs seat belts for smaller production vehicles. In the automotive seat belt market, dominated by Autoliv, TRW and Takata, multiple sled crash tests are performed for every seat belt design with specific anchorage points to evaluate the pulse. Crash testing is an expensive part of the research and development of seat belts, but GWR’s experience with sled tests, and our ability to complete sled tests for our global customers with their specific anchorage points, saves them time in designing their belts, seats, and anchorage points. Our testing abilities also save them concern and money for their own required vehicle crash testing because they know in advance that their seat belts will perform as required. Additionally, GWR is an ISO certified company to ensure that our products consistently meet customer requirements, have a consistent level of quality, and that we continually improve.

Comments are closed.