Subject: MOTORCYCLE VEHICLE DYNAMICS (A.A. 2021/2022)
Unit motorcycle vehicle dynamics
Mechanical Engineering (lesson)
in attesa di attivazione da parte del docente
Understanding the fundamentals of motorcycle kinematics.
Knowledge of the most relevant analytical approaches for studying the dynamics of motorcycles in both steady state and transient running conditions.
Gain insights into the features and the behavior of the main motorcycle components and sub-assemblies, with a particular focus on the characteristics of suspension systems and tire models and how they affect the vehicle performance in terms of comfort and drivability.
Understanding the fundamentals of motorcycle stability; knowledge of the tools for assessing motorcycle stability and of the techniques for experimental identification of modal parameters.
Knowledge of the multibody modelling approach and tools, in order to implement simplified numerical models for stability analysis in both steady state and transient conditions, as well as to perform sensitivity analysis of the main model parameters.
Use of commercial software with critical approach for simulating maneuvers, events and scenarios characterized by high non-linearity, and implementing proper control strategies.
Achieving the ability of developing numerical models for assessing and optimizing the motorcycle performance.
Knowledge of kinematics and dynamics of mechanical systems, and mechanical vibrations.
• Motorcycle kinematics
‒ geometry and kinematic parameters
‒ steering angle and trim
‒ tire cross section and trajectory in a turn
‒ architecture and kinematics of front and rear suspensions
‒ stiffness and damping characteristics
‒ determination of the reduced parameters
• Tire modelling
‒ analytical models
‒ semi-empirical models
‒ tire-road contact forces
• Motorcycle dynamics
‒ steady state rectilinear motion
‒ in-plane vibration modes
‒ road excitation models
‒ analysis of the effects of the motorcycle response on grip/handling and rider’s comfort
‒ transient rectilinear motion: acceleration and braking
‒ steady turning
‒ transient phases of cornering
‒ gyroscopic effects
‒ stability and motorcycle vibration modes
‒ influence of the main design parameters on stability
‒ techniques for experimental identification of the motorcycle modal parameters
‒ rider-motorcycle interaction (brief introduction)
• Numerical modelling of the motorcycle dynamics
‒ Lagrangian approach: stability in rectilinear motion; sensitivity analysis of the main parameters; stability in cornering; effects of structural stiffness on stability
‒ modelling with commercial software: simulating maneuvers characterized by high non-linearity; simulating critical events and scenarios; simplified models for traction-control/anti-wheelie and/or anti-lock braking systems
• Experimental tests and model validation
‒ experimental identification of physical parameters (mass, inertia tensor, tire characteristics, suspension characteristics, steering torque)
‒ estimation of kinematic quantities
‒ estimation of dynamic quantities
‒ virtual tests for implementing strategies to optimize the motorcycle performance: case studies
The course comprises: • theoretical lectures with blackboard, PowerPoint slides and the support of multimedia tools; • lectures and seminars held by experts from Academia and Industry; • classroom exercises with numerical tools and simulation software. All the contents are taught in English. Due to the COVID19 emergency, online access to the lessons (streaming or recorded lessons) will be granted.
Final examination on the program of the entire course. Three oral questions, about 10-15 minutes for each question. The candidate may be required to draw schematics and/or to write expressions/equations with pen and paper. The candidate must achieve a sufficient score (18 out of 30) for each question in order to pass the exam. The score is assigned on the basis of: • Knowledge of the specific topic (40 %) • Ability to analyze and discuss different scenarios and possible interactions with other topics (30 %) • Clarity in exposition and proper use of technical terminology (30 %) The final grade is computed as the simple average of the scores of the three questions. The exams may be taken online, depending on the evolution of the COVID19 emergency.
Achieving all the objectives of the course. In particular, developing the knowledge and the skills required to autonomously assess, analyze and optimize the dynamic response of motorcycles.
The slides shown during the course will be made available for download.
Suggested books (not mandatory):
• Cossalter V. Motorcycle Dynamics. 2nd ed. LULU, 2006.
• Pacejka HB. Tire and Vehicle Dynamics. 3rd ed. Oxford, Butterworth-Heinemann. 2012.