34313 - Machine Design

Learning outcomes

The outcomes of the course are to provide the basic knowledge, the methods and the tools useful for the correct definition of the mechanical design activities. At the end of the course the students will be able to reproduce the representation of a simple mechanical system, to define the relationship between the elements, to calculate the constraints, to draw the stress diagrams and to compute the maximum tensile state of the components. Furthermore they will be able to verify the fatigue life of simple mechanical components and to calculate the strength of some basic bolted and welted structures. Finally they will be able to select the most appropriate rolling bearings to be positioned as constraints of shafts, pins and axes.

Course contents

Introduction to the study and to the analysis of a mechanical system.

Function analysis of a product; the kinematics and dynamic representation of a simple mechanical system and the relationships between the machine elements.

The rigid body equilibrium.

Work and power. Motion and energy transmission between the machine elements. Morphologic characteristics and the load analysis of the mechanical systems. Structural models and tensile state analysis. Stress concentration factors. Residual stresses. The normal stress. The bending stress. The shear stress. The torsion stress. The failure of materials under static loads. The equivalent uniaxial stress in case of static load.

The dynamic failure of the metals. The fatigue stress. The S-N (Wlöer) curves and the Haigh diagrams. The surface, gradient, dimension and load effects on the fatigue strength. The equivalent uniaxial stress in case of dynamic load. The medium stress effects on the fatigue strength.

The gear design. The tooth stress: the bending and the pitting strength. The cylindrical gears straight-toothed and helical-toothed. The conical gears. The loads produced by the gears on the shafts.

Fundamentals of bolted and welded structures: the static calculation.

The rolling bearings selection and their life prediction.

Readings/Bibliography

Texts references

Dario Croccolo, Nicolò Vincenzi - Lezioni di fondamenti e tecnica della progettazione meccanica - Società Editrice Esulapio - Bologna - 2011

Dario Croccolo, Massimiliano De Agostinis, Giorgio Olmi - Esercizi di Coportamento meccanico dei materiali ed Elementi delle macchine - Società Editrice Esulapio - Bologna - 2013

Dario Croccolo, Massimiliano De Agostinis, Giorgio Olmi - Esercizi di Costruzione di macchine e Tecnica delle costruzioni meccaniche - Società Editrice Esulapio - Bologna - 2013


Recommended reading

R. Giovannozzi

“Costruzione di macchine” vol I e II

Patron, Bologna



Niemann/Winter

“Elementi di macchine” vol I

EST Springer–Verlag Berlin, Heidelberg, New York

Teaching methods

The lectures concern the fundamentals problems of the mechanical design of products and systems. The practicing are collective and concern the application and practical solutions of theoretical problems proposed during the lectures.

Assessment methods

The exam consists in a written part and in an oral one. The written part consists in three exercises to be solved in which both the conceptual and the numerical results will be evaluated. The oral part consists in a discussion about the written part and about the theoretical arguments dealt during the lectures.

Teaching tools

PC projector. Overhead projector. Blackboard.

Office hours

See the website of Dario Croccolo

See the website of Stefano Fini