29919 - Mechanical Behaviour of Materials T

Learning outcomes

Provide basic notions on the analysis of stresses and deformations, on the mechanical behavior of metallic materials subjected to static and fatiguing loads. To make students able to calculate simple structures and components of industrial interest formed by beams and rods.

Course contents

MODULE 1

REFERENCES OF STATIC GRAPHICS:
Operations on forces: sum of two or more forces. Polygon of forces. Composition of forces and couples. Funicular curve.

STATICS OF THE BEAMS:
The constraints. Constraint systems. Examples of labile, isostatic and hyperstatic structures. The constraint reactions. Calculation of the constraint reactions in isostatic structures. Examples: beams and arches.

THE CHARACTERISTICS OF SOLICITATION:
Normal effort, shear stress, bending moment, twisting moment. The pressure curve. The indefinite equilibrium equations for plane beams. Calculation of the stress characteristics through the indefinite equations of equilibrium. Examples. Tracing of internal action diagrams. Examples. The principle of superimposition of effects.

GEOMETRY OF MASSES AND AREAS:
Static moments. Determination of the position of the center of gravity of a section. Moments of inertia. Huygens-Steiner (or transposition) theorem.

Main axes of inertia. Practical applications: determination of the position of the center of gravity and the first and second order moments with reference to the sections most commonly used in engineering applications.

MODULE 2

TENSIONS:
Normal stresses and tangential stresses. Cauchy's theorem and indefinite equations of equilibrium. The St. Venant principle. Deformations and slippages: internal congruence equations. The elastic behavior of materials. Constitutive bond equations: Navier equations. The stress - strain diagram. The properties of tangential stresses: reciprocity theorem. The main tensions. The circle of Mohr. The resistance criteria: of Rankine, of Tresca, of von Mises.

THE FOUR CASES OF SIMPLE STRESS IN BEAMS:

NORMAL EFFORT: traction and compression. Tensions in the oblique sections. Beam length variation. The deformation work. Normal stresses in two or three directions.

BENDING: Straight bending. Trend of stresses and deformations. Position of the neutral axis. Resistance condition. The most convenient forms of the section. The deformation work. Deflected flexion.

TORSION: Tensions in circular cross-section beams subject to torsion. The condition of resistance. The torsional deformation. Drive shafts. The deformation work. The relationship between the normal (E) and tangential (G) elastic modules. Examples.

CUTTING: Elementary theory of cutting. Jourawsky's formula: proof and application. Rectangular section. Circular section. Thin sections. The deformations. Examples.

STABILITY OF THE ELASTIC BALANCE:

Critical tension according to Euler. Critical tension according to Johnson.

FATIGUE IN MECHANICAL COMPONENTS:

Introduction to the phenomenon. Fatigue characterization of materials. Fatigue resistance diagrams. Methods of fatigue verification of mechanical components.

Readings/Bibliography

E. Viola, Lezioni di Scienza delle Costruzioni, Pitagora Editrice Bologna, 2003.

E. Viola, Esercitazioni di Scienza delle Costruzioni, Vol. 1, Pitagora Editrice Bologna, 1993.

E. Viola, Esercitazioni di Scienza delle Costruzioni, Vol. 2, Pitagora Editrice Bologna, 1993.

O. Belluzzi - Scienza delle Costruzioni Vol I - Zanichelli, Bologna

Beer, Russel Johnston, DeWolf - Meccanica dei solidi - McGraw-Hill

R. C. Juvinall, K. M. Marshek, Fondamenti di costruzione di macchine, Città Studi Edizioni, 2017.

D. Croccolo, M. De Agostinis, G. Olmi, Esercizi di Comportamento Meccanico dei Materiali ed Elementi delle Macchine. Società Editrice Esculapio, Bologna, 2013. ISBN: 9788874886319.

Teaching methods

The course content will be entirely covered by the lectures. Lectures are supported by many practical exercises, aimed at guiding the students towards the solution of practical problems, based on the tools acquired during the theoretical lectures.

Assessment methods

Written test concerning the program carried out in class. Oral exam (optional). Passing the written test constitutes a requirement for access to the oral test. The written test consists of three exercises on the three main parts of the program. The oral test, which also focuses on all the topics covered during the lessons, leads to the achievement of an overall score that can be higher or lower than that of the written test.

The student must register on the list regularly by the indicated date.

Students not on the list and students who are not up to date with the payment of the enrollment installments and / or who have other impediments reported by Almaesami WILL NOT BE ADMITTED to the test. Each student is therefore STRONGLY INVITED to CHECK THEIR POSITION in a timely manner and, if necessary, to ADJUST IT BEFORE the exam itself.

Teaching tools

Slide, video projector, tablet with handwriting function and traditional whiteboard. The projected material will be made available to students at the end of each lesson.

Office hours

See the website of Stefano Fini