Jeffrey Croteau

Matched-Pair Rollover Impacts of Rollcaged and Production Roof Cars Using the Controlled Rollover Impact System (CRIS)

The authors of this chapter, from a comprehensive text on occupant and vehicle responses in rollovers, report on a study of three rollcaged and three production roof vehicles were exposed to matched-pair rollover impacts using the Controlled Rollover Impact System (CRIS). The CRIS consists of a towed semi-trailer, which suspends and drops a rotating vehicle from a support frame on the rear of the trailer. The authors found that the roof-to-ground contacts were representative of severe impacts in previous rollover testing and real world rollovers. Results showed that the seat-belted dummies measured nearly identical head impacts and neck loads, with or without the rollcage, despite significant roof crush in the production roof vehicles. The peak head accelerations and neck loads were a result of the roof striking the ground and stopping and were not related to roof/pillar deformation. If humans were subjected to these same impact conditions, the rollcaged vehicles would not have protected them. The authors conclude that the CRIS is a very reliable tool to conduct repeatable rollover impacts with controlled dummy positioning.

Head Excursion of Seat Belted Cadaver, Volunteers and Hybrid III ATD in a Dynamic/Static Rollover Fixture

In rollover accidents, seatbelted occupants sustain a lower fatality rate compared to unbelted occupants, primarily due to lower risk of ejection. However, seat belts do not typically prevent head contact with the vehicle interior during a rollover, due to occupant torso and head excursion. This chapter on head excursion of occupants is from a comprehensive text on occupant and vehicle responses in rollovers. In this chapter, the authors report on a total of 80 excursion tests: 51 tests with a Hybrid III 50th percentile male anthropomorphic test devices (ATD); 18 tests with a cadaver; and 11 tests with two male volunteers. Results indicate that vertical head excursion was minimized with a steep lap belt angle and short webbing length, in tests using a two-point lap belt. Tests using a three-point lap and torso restraint showed that the torso belt reduced vertical head excursion primarily by restricting forward torso rotation. The authors also note that the ATD had less vertical excursion than either the volunteers or the cadavers; while the ATD is a useful tool in testing the effectiveness of restraint systems, it may not fully simulate vertical and lateral head excursion of humans in rollover conditions.

Determining Closing Speed in Rear Impact Collisions with Offset and Override

This paper describes how considerable research has been dedicated to establishing the amount of energy absorbed during different types of collisions. Motor vehicle manufacturers began conducting barrier crash tests consistent with the Society of Automotive Engineering (SAE) suggested procedures in the early 1960’s. This allowed investigators to establish the amount of energy that went into metal deformation in the tested vehicle. Over the years, there have been many advances in establishing the amount of crush energy in a particular accident, including the development of several computer programs. Four two-vehicle, single-moving rear-impact crash tests were conducted to compare the effect of override and offset. Override comparisons were made using a moving, rigid barrier or a heavy truck as the impactor, and each pair of tests having either offset or full rear engagement. All four tests were conducted using a like make and model four-door sedan as the target vehicle. Each test had the same available crush energy for the car. The vehicles were instrumented with triaxial accelerometers, and the tests were documented with high-speed film cameras. Crush profile information is presented to compare the damage generated by the truck and moving barrier. Analyses of the stiffness characteristics of the car in the two collision types are presented. The paper focuses on methods of establishing crush energy in override and offset collisions.

HVE EDSMAC4 Trailer Model Simulation Comparison with Crash Test Data

Engineering Dynamics Corporation (ECD) recently updated the Human, Vehicle, Environment (HVE) software program to enable modeling of passenger cars and light trucks towing trailers. This paper reports on a comparison between the HVE EDSMAC4 collision module of the 3-dimensional computer simulation program and instrumented crash tests, in which one vehicle in each test was a pickup truck pulling a trailer. Use of the EDSMAC4 trailer model was found to provide better correlation between the simulation and test damage profiles, rest positions, vehicle trajectories, velocities, and Delta-V. It was also determined that the NHTSA (National Highway Traffic Safety Administration) derived stiffness coefficients are sensitive to the impact configuration and depending on the impact configuration, it may be necessary to refine the coefficients according to the configuration. (A) For the covering abstract see ITRD E106540.