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This work presents a study on the braking style and its implications on motorcycle stability. First, a simplified motorcycle model is used for highlighting basic phenomena which occur during braking and for developing an ideal braking strategy. Then, braking maneuvers are analyzed using a detailed multi-body model, which takes into account all relevant characteristics of a motorcycle, such as geometry, mass and inertia distribution, non-linear suspension and tire properties. Simulations are repeated for dry and wet road conditions, showing that the correct braking style should change as the adherence conditions change, according to the suggestions given by the simplified model. Finally, stability analysis is carried out for different speeds, deceleration rates and braking styles, showing that a correct braking balance may significantly improves vehicle stability.

This work presents a new multibody software designed for investigating two wheeled vehicles dynamics. This code, named FastBike, can perform time steady state analyses, time domain simulations and frequency domain analyses. The steady state analysis allows for the calculation of the vehicle trim in static condition, in straight running and in steady cornering, both at constant speed and in braking/accelerating phase. Time domain analysis is of use for simulating typical maneuvers such as lane change, slalom, entering in a curve, path following and free control simulations. Moreover, these maneuvers can be reproduced in braking or accelerating conditions. Frequency domain analysis tool includes stability analysis and free-modes calculations, frequency response function evaluations and rider emulator design. Furthermore, results of the experimental validation of FastBike, which were carried out on a sports motorcycle, are summarized.

This paper presents a numerical analysis of the modal properties of a motorcycle, in both straight running and curves. In particular, the importance of tire on the stability of a sports motorcycle is dealt with. The analysis was carried out using an eleven degrees of freedom model of a motorcycle, which describes both in-plane and out-of-plane dynamics. A detailed tire model, which takes into account both the geometrical and elastic properties of the tire carcass, was used. The properties of the tread rubber (like pneumatic trail and twisting torque) were considered, as well as the properties of the carcass (like size of cross section and carcass stiffness); their effects on natural frequency, damping ratio and modal vectors were analyzed. Furthermore, this paper deals with the interactions between in-plane and out-of-plane modes during steady state cornering, regarding root-locus and modal vectors.

This paper deals with the application of the optimal maneuver method to the assessment of motorcycle maneuverability. The optimal maneuver method is a novel approach to the analysis of vehicle performance. The essence of this method is the solution of an optimal control problem which consists in moving the vehicle, according to holding trajectory constraints, between two given endpoints in the “most efficient way”. The concept of “most efficient” is defined by a proper penalty function defined to express maneuverability. In this paper we briefly outline the method and give examples of its application to three classical maneuvers commonly used to test motorcycle handling: a slalom test, a lane change maneuver and a U-curve.

The acoustic phenomena which take place inside an intake system greatly influence the volumetric efficiency of an engine. This paper deals with the problem of improving the volumetric efficiency of a single cylinder engine for a wide range of frequencies. The proposed solution is the addition of tunable resonators to the intake system. The variation of resonator tuning makes it possible to exploit the acoustic vibrations for a wide range of piston frequencies in the best way. Several intake systems equipped with resonators are studied using analytical methods. The best results are obtained when an in-series resonator with a variable volume is placed near the cylinder and when a side-branch resonator with a variable cross section is connected to a constant volume resonator. Several results are presented which deal with the behavior of the intake system during the induction stroke and which show the effectiveness of tunable resonators.