THE COURSE AIMS TO GIVE THE STUDENT CRITERIA AND METHODS TO CARRY OUT KINEMATIC AND DYNAMIC ANALYSIS OF MECHANISMS WITH REFERENCE TO THE MOST RELEVANT APPLICATIONS. TO FACE UP THE COURSE A GOOD KNOWLEDGE OF MECHANICS IS REQUIRED, ESPECIALLY WITH REFERENCE TO THE MOTION OF A RIGID BODY ABOUT PRINCIPAL AND NON-PRINCIPAL AXES OF INERTIA. AFTER THE COURSE THE STUDENT WILL BE ABLE TO DETERMINE THE PATH OF THE PARTICLES BELONGING TO THE BODIES CONNECTED TO FORM A MECHANISM, AND TO DRAW THE CONJUGATE CONTOURS OF A PLANAR RIGID PAIR. MOREOVER HE/SHE WILL ACQUIRE THE TOOLS THAT WOULD ENABLE HIM/HER TO SET UP THE COMPLETE KINEMATIC ANALYSIS OF MECHANISMS WITH ONE DEGREE OF FREEDOM. THE ANALYSIS OF MECHANICAL SYSTEMS WILL BE PRESENTED WITH REFERENCE TO DIFFERENT APPROACHES: QUASI-STATIC, DYNAMIC AND ELASTODYNAMIC. AFTER THE COURSE THE STUDENT WILL BE ABLE TO APPLY GENERAL METHODOLOGIES WHICH ENABLE HIM/HER TO EVALUATE FORCES, EFFICIENCY, POWER AND MECHANICAL COUPLING STABILITY.
teacher profile teaching materials
EDIZIONE, CEA Casa Editrice Ambrosiana, Milano, 2011.
Di Benedetto, A., Belfiore, N.P., Fondamenti di Teoria delle vibrazioni meccaniche, CEA Casa Editrice
Ambrosiana, Milano, 2007.
Programme
The variety of the mechanisms in applications. Basic definitions. Degrees of freedom. Classification of the kinematic pairs. Kinematic chains and mechanisms. Kinematic analysis. Plane motion of a rigid body. Velocity and acceleration fields. Kinematic analysis of planar mechanisms. Characteristics of infinitesimal plane motion. Inflection and stationary circles. Euler Savary formula. Planar polodes theory. Pairs with unilateral contacts. Construction of conjugate profiles. Oldham and universal (Cardan) joints. Expression of the transmission ratio. Double cardan joint. Parallel and anti-parallel four bar linkages. Drafting table and pantograph mechanisms. Hart and Peaucellier exact straight lines mechanism generators. Disaggregation principle in statics. Free body static force and torque analysis of complex systems. Applications of the theorem of the virtual works. Basic topics in Tribology. Surface analysis and characterization. Hertz formulae. Friction. An elementary model of adhesive friction. Friction basic mechanisms. Adhesion, abrasion, fretting, surface fatigue. Experimental classification of the worn surfaces: scuffing, scoring, spalling, case crushing, pitting, galling. Predictive models of wear and friction. Energy dissipated “Reye” method, Archard equation. Ball bearings: static force and fatigue modeling, Striebeck formula. Introduction to lubrication. Viscosity and viscosity index. Petroff’s law. One-dimensional Reye theory of hydro-dynamic lubrication. Lubrication of the Rayleigh step bearing. Film with linearly decreasing thickness. Kingsbury – Mitchell bearings. Hydro-static lubrication in the thrust bearing. Hydrostatic compensation. Journal bearings with hydrodynamic lubrication. Work, power and energy. Principles of energy conservation. Power flow analysis in the mechines. Efficiency. Dynamics of the material point. Dynamic of the rigid body. Newton Euler formulation of the dynamic problems. Dynamic analysis by means of the generalized principle of the virtual works. Traction coefficient in transmission. Gearings. The geometrical characteristics of gears with involute profiles. The mechanical interference in gearings. Advanced methods in kinematics: analytical and numerical methods. Dynamic analysis of multibody systems by means of the coordinate partitioning method and the elimination of the Lagrange’s multipliers. Vibration of systems with one degree of freedom. Free oscillation, damped oscillations and excited vibrations. Rayleigh method for the case of the free undamped oscillator. The function of the flywheel in machines. Flexural and torsional vibration in transmission shafts. Vibrations of system with n degrees of freedom. Dynamic problems and wear in breaks. Cams. Construction of cams with prescribed law of motion. Dynamic problems in cams. Constant acceleration cam. Exercises. Kinematic analysis of the slider crank and four bar linkages. Centrodes of the coupler motions. Static balance in different mechanisms. Lubrication. Kingsbury – Michell hydrodynamic bearings. Geometry of involute gearings. Evaluation of the efficiency of simple mechanisms. Analytical and numerical methods in the kinematic analysis of simple mechanisms. Inverse and direct dynamic problems in simple mechanisms. The application of the methods of Lagrange’s multipliers to the solution of direct dynamic analysis of Multibody systems.Core Documentation
Belfiore, N.P., Di Benedetto, A., Pennestrì, E., Fondamenti di meccanica applicata alle macchine, SECONDAEDIZIONE, CEA Casa Editrice Ambrosiana, Milano, 2011.
Di Benedetto, A., Belfiore, N.P., Fondamenti di Teoria delle vibrazioni meccaniche, CEA Casa Editrice
Ambrosiana, Milano, 2007.
Reference Bibliography
Belfiore, N.P., Di Benedetto, A., Pennestrì, E., Fondamenti di meccanica applicata alle macchine, SECONDA EDIZIONE, CEA Casa Editrice Ambrosiana, Milano, 2011. Di Benedetto, A., Belfiore, N.P., Fondamenti di Teoria delle vibrazioni meccaniche, CEA Casa Editrice Ambrosiana, Milano, 2007.Type of delivery of the course
The lessons are carried out with traditional through talk-and-chalk, extemporaneously given. During the total or partial lock-down due to covid-19 crisis, the lessons will be carried out, temporarily, via remote Microsoft Teams synchronous and interactive events.Attendance
Lessons Frequency is highly recommended.Type of evaluation
Written exam that includes exercises and theoretical questions, followed by an oral interview and a discussion of the exercise book. During the total or partial lock-down due to covid-19 crisis, the evaluation will be carried out, temporarily, according to the Rectoral Decrees D.R. n. 703/2020 del 5/05/2020, art. 1 and 2.