How IIHS Crashes Vehicles

Did you ever wonder exactly what the Insurance Institute for Highway Safety (IIHS) crash tests entail?

Since 1995, it has been conducting frontal crash tests. Today there are two types: a moderate overlap test and a small overlap test.

The small overlap test has the test vehicle aligned with the barrier that it will crash into so that it is 25 percent (±1 percent) to the left of the vehicle centerline. The vehicle is accelerated by a propulsion system at an average of 0.3 g until it reaches the test speed of 40 mph (±0.6 mph), then released approximately 9.8 inches (25 cm) before the barrier, and the vehicle's rear service brakes are applied 1.5 seconds after the vehicle is released from the propulsion system.

The barrier for the test has a vertical steel plate on its front surface that’s 1.5-inches thick and 39-inches wide to a point where it curves back to a 115 degree arc; the length of that portion is 5.9 inches. That is mounted to a base unit that is a laminated steel and reinforced concrete block that weighs 319,330 pounds. The setup is such that the vehicle will continue to move forward when it hits the barrier.

Among the things checked for include fuel system integrity and high-voltage system integrity (for electrified powertrains). Then there is an array of sites—18 locations in all—both inside and outside of the vehicle, with the locations being measured (before and after) by a Romer Absolute Arm (hexagonmetrology.us/products/portable-measuring-arms/romer-absolute-arm) coordinate measuring machine. The sites include the steering column, left lower instrument panel, brake pedal, parking brake pedal, left footrest, seat bolts, left toe pan, upper dash, lower and upper hinge pillar and rocker panel.

The moderate overlap frontal crash test has the vehicle located so that it is offset by 10 percent from the centerline in relation to the side of the barrier. The barrier has three components: a deformable face that the vehicle collides with, an extension and the base. The face has two components, with a bumper element consisting of 1,723 MPa honeycombed material attached to a backing of 0.345 MPa honeycomb material. The extension is made with structural steel and has a 0.7-inch piece of plywood attached to a 1.8-inch thick face plate. The base measures 72 x 144 x 56 inches; it weighs 320,000 lb. The vehicle speed parameters and the sites measured are similar to the small overlap test.

IIHS looks at other aspects, too. There is a roof-strength test which is performed on a quasi-static test system from MGA Research Corp. (mgaresearch.com) that deforms the roof to a minimum of five inches, with the deformation occurring at a rate of 0.2 inches/second. And there is a head restraint and seat test which involves a crash test dummy on an acceleration or deceleration sled to simulate collision conditions.

And beyond crashes, there is a front crash prevention test that looks at how well vehicles perform automatic braking at both 12 and 25 mph, and whether there is frontal collision warning. And here is a headlight test that looks at how far the light extends on a track (there are five approaches: front straight, gradual left/right at an 800-foot radius and sharp left/right at a 500-foot radius); an intensity of at least 5 lux is necessary.—GSV