Showing papers on "Rollover published in 1978"

Testing the michigan double-bottom tanker

Abstract: A full-scale vehicle testing program was undertaken to analyze the rollover stability of double-bottom tankers (associated with a high incidence of rollover accidents in Michigan). The testing was part of a total research program which included yaw plane and roll plane analytical studies. Test vehicle loading, anti-rollover outriggers, instrumentation, and modification hardware are discussed. The baseline Michigan tanker was found to have an exceptionally low dynamic rollover stability, particularly in accident-evasion maneuvers. This instability probably accounted for most of the accidents in which the pup trailer alone rolled over. An improvement to the baseline double can be attained by installing, between the dolly and the semitrailer, a hitch which is rigid in both the steer and roll directions and by installing devices in the suspensions to eliminate excessive clearance in the left spring constraints. This modified tanker exhibits a rollover stability level comparable to that of the short Michigan single tanker. The pup trailer of the baseline vehicle has a lightly damped mode of yaw oscillation; it can become unstable if only the rear compartment is loaded and the speed exceeds 50 mph. Virtually all current double and single trailer combinations, and perhaps many straight trucks, incorporate a suspension feature which can reduce the dynamic rollover threshold by as much as 15%. This feature, involving free play in the vertical location of suspension leaf springs, can be almost eliminated with a minor modification. The findings on vehicle stability were combined with exposure to produce estimates of the comparative rollover rating of tanker fleets. It was concluded that fuel delivery using short Michigan single tankers yields the highest exposure to fire hazard of all known fleet options (excluding the unmodified double-bottom tanker), and fuel delivery using conventional 9000 gal. single tankers may yield an exposure to fire hazzrd equal to or greater than that of modified double-bottom tankers and large single tankers.

Analysis of the Rollover Dynamics of Double-Bottom Tankers

Abstract: A roll dynamic analysis was undertaken to determine the rollover threshold for typical double-bottom tanker vehicles and to compare that threshold with the corresponding values for other common tractor-trailer combinations. A secondary objective was to provide the methodology for predicting the effect of changes to vehicles and operational procedures in order to improve the rollover stability of such vehicles. A dynamic model of the vehicle in the roll plane was formulated for study of roll motions under arbitrary lateral force input time histories. The roll response and limit maneuver capabilities predicted by the model showed good agreement with those of actual vehicles. The model was used to predict the relative rollover thresholds of the double-bottom tanker (associated with a high incidence of rollover accidents in Michigan) and other tanker configurations for comparison with those of other commercial vehicles in a selected double lane-change maneuver. The model confirmed that double-bottom tankers of the current design exhibit a low rollover threshold compared to other commercial vehicles. The major sensitivity to rollover derives not so much from the lateral acceleration limit of the pup trailer as from the rearward amplification of the tractor lateral accelerations. The model demonstrated that a modification of the vehicle via a composite rigidified hitch/rubber mount enhances pup trailer stability through reduction of suspension backlash, and allows roll moment sharing among all the vehicles in the train. The result is a vehicle with manuever levels comparable with other commercial vehicles.

Development of vehicle rollover maneuver. volume i

Abstract: This report describes research aimed at investigating the rollover response characteristics of automobiles. Emphasis was placed on the development of a test procedure to evaluate performance under untripped flat-surface operating conditions. Both simulation and full-scale experimental methods were employed to examine the effects of a variety of configurational and operational factors on rollover response. Over 500 test runs involving seven vehicles in ten configurations were performed. Studies were made of the effects of initial speed, steering input patterns, braking techniques, suspension damping, loading, and tire characteristics. Testing was performed using both manual and automatic control methods. In addition to discussions of the results of these studies, the report contains a review of the involvement of rollover in actual accidents, analyses of the physics of tripped and flat surface (untripped) rollover, a discussion of the simulation study results, and an outline of a preliminary test procedure for vehicle rollover resistance evaluation.

Rollovers and injury on the ncss file

Abstract: Based upon 378 rollover cases on the NCSS file and 2,769 fatal rollover accidents on the FARS file, the following parameters appear to be important in an understanding of injury causation during rollover: (1) Ejection coincides with more injury: However, the contact codes associated with the injuries suggest that occupants are being hurt in the car - i.e., prior to ejection - as well as being hurt outside of the vehicle after ejection. Partial ejection may be more dangerous than total ejection because of the possibility of being crushed between the car and the ground; (2) Roof crush seems related to injury level, perhaps as a measure of the severity of the accident; (3) Intrusion also seems to be a good indicator of the severity of the accident because it is useful in predicting injury; (4) Other variables for which more information is required include: ejection route, injury contact points, and restraint use (by type used); and (5) Variables which do not seem significantly related to injury in rollovers are age (because the occupants tend to be young-under 30), quarter turns and stopping distance (possibly because these are very difficult to estimate), and fire/explosion (the incidence rates are the same for rollovers and non-rollovers).

Development of vehicle rollover maneuver. volume ii - executive summary

Abstract: This report describes research aimed at investigating the rollover response characteristics of automobiles. Emphasis was placed on the development of a test procedure to evaluate performance under untripped flat surface operating conditions. Both simulaton and full-scale experimental methods were employed to examine the effects of a variety of configurational and operational factors on rollover response. Over 500 test runs involving seven vehicles in ten configurations were performed. Studies were made of the effect of initial speed, steering input patterns, braking techniques, suspension damping, loading, and tire characteristics. Testing was performed using both manual and automatic control methods. In addition to discussions of the results of these studies, the report contains a review of the involvement of rollover in actual accidents, analyses of the physics of tripped and flat surface (untripped) rollover, a discussion of the simulation study results, and an outline of a preliminary test procedure for vehicle rollover resistance evaluation. The major conclusions from the study were that vehicle rollover response is dominated by the vehicle's rigid body geometry (with dynamic contributions from suspension effects) and that untripped rollover, even on high skid-resistance surfaces, is difficult to predict and accomplish.

Crashworthiness tests on two electric vehicles

Abstract: Crashworthiness aspects of two electric vehicles were evaluated in a modest test program One vehicle was subjected to low-speed pendulum and barrier tests and static rollover A second vehicle was subjected to dynamic rollover using the procedure specified in FMVSS 208 Potential safety problems were exposed, and are addressed in the paper /GMRL/