For what concerns the Structural Mechanics module the following items will be analyzed: static failure, fatigue failure (high cycle fatigue, low cycle fatigue, thermomechanical fatigue) of materials and components. The design and verification procedures according to analytical calculation and the Standards will be presented for pressure vessels.

The Structural Mechanics module aims at giving the student the knowledge to understand the failure behavior under loading conditions, in case of static and cyclic loading, of structural components. It also aims at allowing to develop the main computations related to structural design and verification of vessels and related topics, taking into account of technical indications of Standards.

The knowledge of Fundamentals of Structural Mechanics topics are required, in particular the knowledge of stress status of the beam in the elastic field and the mechanical characteristics of metallic materials.

Overview on: 3D stress and strain status – Stress vector and tensor. Principal stresses and principal directions. Stress status invariants. Hydrostatic and deviatoric stress status. Mohr circles. Main loading conditions for beams. Deformation kinematics. Strain tensor. Principal strains. Relation between stress and strain: Hooke’s law. Static resistance. Tensile test. Brittle and ductile materials. Failure Hypotheses for brittle and ductile materials. Static safety factor. Effect of temperature on mechanical properties of metallic materials. Creep. Notch effect and stress intensity factor. Notch effect in static failure. Fatigue resistance. Phenomena related to fatigue and characteristic parameters. Whoeler curves. Fatigue limit. SN material diagram estimation. Influence of mean stress: Haigh diagram. Influence of load, of dimensions, of surface finish and of notch. Component fatigue limit. Haigh diagram and SN component curves. Fatigue safety factor. Fatigue with variable amplitude stresses. Multiaxial fatigue. Cyclic and thermos-mechanic cyclic behavior: low cycle fatigue, isothermal and thermomechanical. Parameters describing low cycle fatigue behavior and corresponding constitutive models. Parameters describing thermomechanical fatigue behavior and corresponding constitutive models. Damage models: classification, uniaxial models, multiaxial models. Residual life estimation. Case studies. Pressure vessels. Definition of the problem, differential equilibrium equation and its solution. Determination of stress status generated by internal and external pressure and by thermal gradient. Pipings. Axialsymmetric plates: axialsimmetric shells. Edge effect. Bolted joints, design and verification. Non destructive testing: RX, US Standards in design and manufacturing of pressure vessels: European Standard Pressure Equipment Directive (PED), EN 13445, ASME Code Section VIII Division 1 - Pressure Vessels.

A theory part will develop the required topics by means of analytical equations and model development and of analysis of case studies. Class exercises consist in the proposal and solution of exercises concerning practical problems involving concepts developed in lessons with the aim of improving the knowledge and to give the student an indication on the value of the main parameters. A laboratory practical activity will be done. Strains on a pressure vessel will be measured and the comparison with analytical results will be done.

On the Didactic Web Page the slides related to Lessons and to exercises will be available. Suggested text books are: • Shigley's mechanical engineering design, Richard G. Budynas, McGraw-Hill Education • A textbook of machine design, R.S. Khurmi J.K. Gupta, McGraw-Hill Education

Modalità di esame: Prova scritta (in aula); Prova orale obbligatoria; Elaborato scritto individuale;

Exam: Written test; Compulsory oral exam; Individual essay;

... The exam is in two parts: a written part (numerical exercises) and an oral part (theory). The total time for written part is 2.5 hours. The written part consists of two exercises, one per each part of the Course, which kind and complexity is similar to exercises done in classes. During the written part it is not possible to read notes or any other documentation; using a single personal A3 note with formulas is allowed, which will be prepared by the student. The oral part will take place according to a calendar which will be available within one day from the written part. The oral part consists in two questions, one per each part of the course, on theory topics. A score equal or higher than 18/30 in both exercises of the written part is required to access the oral part. During the Machine Design oral part, the student can bring the printed report of the experimental laboratory activity on strain measurement on pressure vessel. In this case, the report will be discussed with the professor and a maximum score of 1 point can be added to the average (oral and written parts) of Structural Mechanics. At the end of the oral part, a score related to each part of the Course will be assigned, basing on written and oral parts. The exam is considered positive if the student reaches a score equal or higher than 18/30 in each part of the Course. The final ranking is the average of the scores obtained in each part of the Course.

Gli studenti e le studentesse con disabilità o con Disturbi Specifici di Apprendimento (DSA), oltre alla segnalazione tramite procedura informatizzata, sono invitati a comunicare anche direttamente al/la docente titolare dell'insegnamento, con un preavviso non inferiore ad una settimana dall'avvio della sessione d'esame, gli strumenti compensativi concordati con l'Unità Special Needs, al fine di permettere al/la docente la declinazione più idonea in riferimento alla specifica tipologia di esame.