Investigation of injury potential through matched pair drop testing.

The National Highway Traffic Safety Administration has concluded that there is a relationship between roof intrusion and the risk of injury to belted occupants in rollovers events. Previous testing on many different production vehicle types indicates that damage consistent with field rollover accidents can be achieved through inverted drop testing from small drop heights. It has been shown in previous drop test pairs with Hybrid III dummies, that the amount of roof intrusion is related to occupant neck injury. This paper analyzes inverted drop testing performed on Ford F250 Crew Cab production and reinforced pickups. Each of these pickup tests used Hybrid III test dummies in order to evaluate the occupant injury potential in relation to roof intrusion. The reinforced truck's residual crush was an order of magnitude less than the production truck crush. These tests indicated that the reduction of roof crush resulted in a direct reduction in neck loading and therefore an increase in occupant protection. In addition, it was found that the restraint loading was inversely related to the neck loading of the dummies.

The effect of roof strength on reducing occupant injury in rollovers.

Roof crush occurs and potentially contributes to serious or fatal occupant injury in 26% of rollovers. It is likely that glazing retention is related to the degree of roof crush experienced in rollover accidents. Occupant ejection (including partial ejection) is the leading cause of death and injury in rollover accidents. In fatal passenger car accidents involving ejection, 34% were ejected through the side windows. Side window glass retention during a rollover is likely to significantly reduce occupant ejections. The inverted drop test methodology is a test procedure to evaluate the structural integrity of roofs under loadings similar to those seen in real world rollovers. Recent testing on many different vehicle types indicates that damage consistent with field rollover accidents can be achieved through inverted drop testing at very small drop heights. Drop test comparisons were performed on 16 pairs of vehicles representing a large spectrum of vehicle types. Each vehicle pair includes a production vehicle and a vehicle with a reinforced roof structure dropped under the same test conditions. This paper offers several examples of post-production reinforcements to roof structures that significantly increase the crush resistance of the roof as measured by inverted drop tests. These modifications were implemented with minimal impact on vehicle styling, interior space and visual clearances. The results of these modifications indicate that roof crush can be mitigated by nearly an order of magnitude, as roof crush was reduced by 44-91% with only a 1-2.3% increase in vehicle weight. Additionally, this paper analyzes the glazing breakage patterns in the moveable tempered side windows on the side adjacent to the vehicle impact point in the inverted drop tests. A comparison is made between the production vehicles and the reinforced vehicles in order to determine if the amount roof crush is related to glazing integrity in the side windows. Lastly, two drop test pairs, performed with Hybrid III test dummies, indicates that the reduction of roof crush resulted in a direct reduction in neck loading and therefore an increase in occupant protection.

Testing and injury potential analysis of rollovers with narrow object impacts.

Recent statistics highlight the significant risk of serious and fatal injuries to occupants involved in rollover collisions due to excessive roof crush. The government has reported that in 2002. Sports Utility Vehicle rollover related fatalities increased by 14% to more than 2400 annually. 61% of all SUV fatalities included rollovers [1]. Rollover crashes rely primarily upon the roof structures to maintain occupant survival space. Frequently these crashes occur off the travel lanes of the roadway and, therefore, can include impacts with various types of narrow objects such as light poles, utility poles and/or trees. A test device and methodology is presented which facilitates dynamic, repeatable rollover impact evaluation of complete vehicle roof structures with such narrow objects. These tests allow for the incorporation of Anthropomorphic Test Dummies (ATDs) which can be instrumented to measure accelerations, forces and moments to evaluate injury potential. High-speed video permits for detailed analysis of occupant kinematics and evaluation of injury causation. Criteria such as restraint performance, injury potential, survival space and the effect of roof crush associated with various types of design alternatives, countermeasures and impact circumstances can also be evaluated. In addition to presentation of the methodology, two representative vehicle crash tests are also reported. Results indicated that the reinforced roof structure significantly reduced the roof deformation compared to the production roof structure.