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Vehicles running in wet conditions may experience hydroplaning of one or more tires. Hydroplaning can, and often does, change vehicle braking, acceleration and handling characteristics dramatically. Proper analysis of this behavior requires accommodating the clearing of paths for the rear tires that may result from the front tires engaging the water-coated surface first. In this work, a hydroplaning analysis is presented that examines steady-state cornering under potential hydroplaning situations and includes lateral weight transfer, tire load sensitivity and path clearing potential. The sensitivity of vehicle understeer/oversteer characteristics to path clearing and vehicle dimensional characteristics is also examined.

Many vehicles are equipped with independent suspension systems on the front and/or rear axle. As opposed to a DeDion or beam axle, independent suspension systems have the potential to generate camber and toe changes as the suspension strokes from full jounce to full rebound. Each vehicle suspension design presents unique camber and toe curves to the tire. To improve handling, manufacturers often set static camber on such vehicle suspension systems to nonzero values so that when cornering, the outside suspension will deflect so as to maximize cornering power and vehicle stability. Then, under straight driving conditions, the tires tend to predominantly wear their inside shoulder edges, producing the phenomenon known as camber wear.

The current performance of a top fuel (T/F) dragster racing car is very high. The cars can accelerate from a standing start to well over 330 mph (528 km/h) in < 4.6 seconds! The engine of a T/F dragster can make considerably more power than can be put down to the track surface. Intentional clutch slippage prevents wheelspin for most of the ¼-mile (0.4 km) standard length racing run. Even though the drive tires used are highly specialized and specifically designed for this type of racing environment, more traction is needed. To create more traction, especially during the second ½ of the run, external wings have been employed by the designers of such cars. The size and configuration of the wings is limited according to sanctioning rules. Recent wing failures and accidents have made other options for the creation of downforce appear attractive. In the present work, we consider the potential for using the shape of the car itself to create the required down-force.

For a number of years, racetrack designers have been considering various designs for energy-absorbing or “soft” walls. Moving walls, water-filled barrels, tire walls and walls coated with various materials have all been suggested or employed to varying degrees of success. In this paper, a new concept involving a series of slats placed outward from the walls is outlined. First, fundamental requirements for a soft wall design are laid down. Then the development of the slatted wall is presented, along with a series of design variables able to be adjusted for particular applications. The slats have multiple modes of energy dissipation and absorption, and calculations show that the concept has good promise. Evaluation of various design alternatives can be largely done computationally, rather than experimentally, a great advantage given the expense of full-scale barrier testing.

We examine the characteristics, properties and potential idealized delamination failure modes of tires in this work. Calculations regarding tire failure stresses during tire failure scenarios, as well as during normal operation, are made. The calculations, though idealized, indicate that large chassis loads can result from the idealized failures.

Vehicles running in wet conditions may experience hydroplaning of one or more tires. Hydroplaning can, and often does, change vehicle braking, acceleration and handling characteristics dramatically. Proper analysis of this behavior requires accommodating the clearing of paths for the rear tires that may result from the front tires engaging the water-coated surface first. In this work, tire overlap is calculated for vehicles in steady-state cornering maneuvers for generalized vehicle dimensions and tire characteristics.

Vehicles operating in wet conditions may experience hydroplaning of one or more tires. Proper analysis of this behavior requires accommodating the clearing of paths for the rear tires that may result from the front tires engaging the water coated surface first. An experimental program was developed to study tire/road behavior during straight line braking maneuvers on a wet surface. Wheel rpm values were measured with operating ABS via CAN bus data. The experiments allowed qualitative estimation and visualization of the effects of path clearing on rear tires.

Recent research into the phenomenon of tire hydroplaning has concentrated on the effects of possible path clearing of the rear tires by the front tires. When this occurs, the rear tire behavior and hydroplaning properties will be different from what would occur had the tire been running in an undisturbed flow field. In the present work, we modify rear tire properties to simulate the path clearing effect and utilize the SIMON/HVE suite of simulation programs with a standardized double lane change maneuver to examine path clearing potential during transient vehicle behavior.

Many modern vehicles utilize so-called “space-saver” spare tires. Such tires are not fitted to the vehicle and driven on until a tire problem has arisen with a service tire, and are limited in the mileage and speed at which they can operate. They also may have quite different characteristics (rolling radius, tread pattern, contact patch width and length, aspect ratio, stiffnesses, self-aligning torques, etc.) than the service tires with which the vehicle is equipped. As such, they have the potential for presenting significantly different handling signatures to the driver when they are fitted.. In the present work, we present force and moment characteristics for two disparate space-saver spare tires. The tires were tested at the T.I.R.F. (TIre Research Facility), Calspan Corporation, Buffalo, NY.

During wet weather operating conditions, tire hydroplaning can occur, potentially altering the handling characteristics of a vehicle. The rear tires of the vehicle run in a path previously cleared by the front tires under some operating conditions. Although path clearing has been previously demonstrated both analytically and qualitatively, it is difficult to estimate the changes in the tire/road coefficient of friction resulting from path clearing because of the complexity of the hydroplaning flow regime. In the present work, we utilize wheelspeed information captured from the vehicle CAN bus and photography to examine potential variations in tire/road coefficient of friction that result from path clearing. Results suggest that differences in friction availability may result from such path clearing. Maneuvers performed include steady-state cornering tests, straight-line braking and ISO lane change maneuvers.

Hydroplaning behavior of a single tire running in stationary, undisturbed water of constant depth is a well-studied phenomenon, and has been examined both theoretically and experimentally. Most experimental tire studies have been conducted on drum or flat-track test machines or with towed tires, and correlative expressions for hydroplaning of a single tire have been developed from such tests. Vehicle testing, on the other hand, has typically involved full-scale, proving ground experiments in which gross vehicle motion and behavior were of interest without regard to individual tire contributions. In the present work, we examine the behavior of a vehicle with rear tires running in a path partially cleared by the front tires. Under such conditions, it can no longer be assumed that the rear tires are experiencing the same hydrodynamic conditions as the front tires, nor does their behavior correlate well with conditions obtained from individual tire testing.

Recent research on the effects of tire hydroplaning has examined the hydroplaning phenomenon and its potential effects on vehicle maneuvering from (1) geometric, (2) straight line braking/acceleration and (3) steady-state cornering maneuver points of view. In this work, we focus on the potential for hydroplaning during a transient maneuver: a standardized double lane change maneuver (ISO3888-1). Using both closed-form calculations and the HVE software suite, it is shown that partial hydroplaning has only a small-to- moderate potential to occur during portions of such maneuvers, but is not likely throughout the entire duration of the maneuver.

An experimental program to measure braking characteristics developed under emergency braking conditions by ABS-equipped vehicles was designed and performed. Variables examined included initial braking speed, vehicle type, tire pressure and data recording equipment utilized. All experiments were conducted on a closed airport taxiway constructed of sharp, brushed and heavily striated concrete. Tests were conducted with and without activated ABS systems on the test vehicles. Results showed that (1) with the ABS activated, faint roadway markings were visible only under a very few special circumstances, (2) tire/road μ-values and corresponding deceleration values varied only slightly for differing speeds and ABS conditions, (3) tire pressure made little difference in limited test results, and (4) there were differences in recorded results depending on the equipment used for data acquisition.