![]() As Figure 2-1 indicates, T is the track width (strictly, the average of the front and rear track widths), and H is the height of the vehicle’s center of gravity. The vehicle model leading to SSF characterizes the onset of rollover as a scenario in which the lateral forces become large enough that, if they continue long enough, rollover must result. Most conservatively, the onset of roll is defined as at least one wheel leaving the ground during the course of a test less conservative definitions require two-wheel liftoff or contact of the outriggers with the test pad.įrom the viewpoint of simulation, the onset of rollover may also be determined in a variety of ways. Test engineers define the onset of roll in a variety of ways. With few exceptions, vehicles that may roll over during a vehicle test are constrained by outriggers that prevent rollover. This chapter responds to the congressional request for “a comparison of the static stability factor test versus a test with rollover metrics based on dynamic driving conditions that may induce rollover events.” Following some brief background, the chapter provides a review of static measures of rollover In view of the challenges associated with dynamic testing, computer stimulations have been undertaken using mathematical models to predict vehicle behavior associated with rollover. ![]() Furthermore, repeatability may be difficult to achieve. Although dynamic tests are potentially helpful in understanding the events immediately preceding rollover, they are expensive and require safety precautions for test drivers. Alternatively, static tests of entire vehicles, such as the tilt table and side pull tests described later in this chapter, may be performed to obtain data that can be correlated with a vehicle’s rollover propensity.ĭynamic testing is performed on a test track and involves driving maneuvers. It may involve the measurement of vehicle parameters (e.g., center of gravity height, track width) that are then combined to yield static metrics related to a vehicle’s rollover propensity-for example, static stability factor (SSF). ![]() Static testing is performed in the laboratory. ![]() Testing generally falls into one of two categories: Vehicle tests and simulations typically deal with the onset of rollover rather than a full 90-degree roll. These lateral forces can be generated under a variety of conditions, such as contact with a mechanical obstacle (a curb, pothole, or furrow plowed during an off-road maneuver), or during maneuvers on the roadway.Ī wide variety of testing has been performed in an effort to understand rollover. 2 When lateral forces create a large enough roll moment about the vehicle’s center of gravity for a sufficient length of time, the vehicle will roll over. 1 The term “rollover” describes the condition of at least a 90-degree rotation about the longitudinal axis of a vehicle. Vehicle rollover is a complex event that has been the subject of many investigations since the 1950s. ![]()
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