Studi teorici e sperimentali su maneggevolezza, stabilità e manovrabilità dei veicoli a due ruote

This dissertation is intended to address various issues relating to the dynamics of two-wheeled vehicles, especially as regards motorcycles. After defining the scope of the dynamics of two-wheeled vehicles from a general point of view, its close correlation with the design and development of new vehicles as well as the safety of driving has been highlighted. Hence the need of theoretical and experimental studies on dynamics in its fundamental aspects, i.e. handling, stability and maneuverability, has been stressed. In Section 1 the dynamics of two-wheeled vehicles has been dealt specifically as regards the handling and the stability. As regards the handling, an extensive bibliography on the state of the art of the theoretical and experimental studies has been firstly reported (Chapter 2), in which a series of typical and well defined maneuvers has been considered as a matter of study. Among these the maneuver of "steady turning" has been dealt separately and in greater detail, as well representative of the cornering behavior of the vehicle and particularly suited to be tested with appreciable experimental reproducibility. In this regard a methodology has been developed (Chapter 3) in order to analyze "steady turning" test and assess vehicle behavior as concerns the different aspects of steering torque - Acceleration Index - and steering behavior - Steering Ratio - . Similarly as regards the stability an extensive bibliography on the state of the art of theoretical and experimental studies has been firstly reported (Chapter 2), in which the main lateral vibration modes have been analyzed. "Weave" and "Wobble" have been considered separately and in greater detail being closely related to safety, in relation to the instability that may involve them under particular driving conditions and speeds. In this regard a methodology has been developed (Chapter 5) in order to analyze "weave" and "wobble" test and assess vehicle attitude in relation to stability at high speed - Damping Ratio -. The above methods have been actually applied in an extended test session conducted in collaboration with Goodyear Dunlop Tires Europe BV group. The target was to characterize a series of sets of tires in relation to their influence on the handling (Chapter 4) and the stability (Chapter 6) of two sport-touring motorcycles. The results obtained have been collected and summarized in a single exposure (Chapter 7). On one side they have been compared and correlated with the test riders evaluations, in order to ensure their compatibility and validity; on the other side they have been compared and correlated with some of the main parameters of tires, in order to obtain more insight for their development and design. In this sense the Acceleration Index, the Steering Ratio and the Damping Ratio have showed to be fully compatible with the riders evaluations, and acceptably sensitive in assessing the characteristics of the tires on vehicle performance. In Section 2 the dynamics of the two-wheeled vehicles has been addressed specifically as regards the maneuverability. An extensive bibliography on the state of the art of the theoretical and experimental studies concerning the maneuverability has been firstly reported (Chapter 2). Hence the Optimal Maneuver Method has been considered as a valuable tool in order to study the maneuverability of two-wheeled vehicles, making it possible to assess performance - LapTime - without any subjective influence of the test riders. In this regard, starting from the physical point of view of the maneuverability, the mathematical formulation of the Optimal Maneuver Method and its computer implementation has been described and developed in greater detail (Chapter 3). Then the theoretical basis of the Optimal Maneuver Method and the results of the calculation-code have been checked by the actual comparison against a wide range of telemetric data collected during Campionato Italiano Velocità 2006 - categoria SUPERBIKE (Chapter 4), in order to verify its agreement with the reality and hence its applicability to motorcycles design problems. After verifying objectively the effectiveness and reliability of the Optimal Maneuver Method, it has been really applied in a wide range of parametric studies and analyses concerning different aspects of the design of a racing motorcycle: the distribution of masses, the geometric configuration, the powertrain (Chapter 5). In this sense the Optimal Maneuver Method has proved to be extremely sensitive and reliable in the assessment of various parameters on the performance - LapTime - of the vehicle, and also with appreciable speed and simplicity.