Thermal machines and structural mechanics (Structural mechanics)

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.

Thermal machines and structural mechanics (Thermal Machines)

This course aims at providing the students with the fundamentals necessary to understand and critically analyze the performance of the main topologies of powerplants. The course will also provide a comprehensive overview of the state-of-the-art technologies capable to improve the plant efficiency and to reduce its pollutant emissions. Finally particular attention will be devoted to the regulation strategies in order to assess the impact of the off-design operations on the efficiency of the plants.

Thermal machines and structural mechanics (Structural mechanics)

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.

Thermal machines and structural mechanics (Thermal Machines)

At the end of the course the student is expected to be able to perform a preliminary design a new powerplant and/or to critically analyze the performance and the key operating parameters of an existing one. Moreover, he should be able to identify the most suitable methodologies to regulate the power output of the plant and to select the most suitable technologies to either increase its efficiency or reduce its pollutant emissions.

Thermal machines and structural mechanics (Structural mechanics)

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.

Thermal machines and structural mechanics (Thermal Machines)

In order to fruitfully attend the course, the student should have previously acquired the basic knowledge of Thermodynamics, Fluid Mechanics and Fluid Machines theory.

Thermal machines and structural mechanics (Structural mechanics)

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.

Thermal machines and structural mechanics (Thermal Machines)

Introduction Overview on the energy scenario & motivation for thermal machine analyses Steam Power Plants • Recap of fundamentals of the Rankine-Hirn Cycle • Analysis of real power plants and of the main technology trends • Environmental issues: overview plants pollutant emissions and on the aftertreatment technologies • Off-Design Operation. Gas Turbine Plants: • Recap of fundamentals of the Brayton Joule • From the ideal Cycle to the real one: analysis of the main sources of loss and of the most important operating parameters • Analysis of real power plants and of the main technology trends • Environmental issues: overview plants pollutant emissions and on the aftertreatment technologies • Off-Design Operation. Hydraulic Turbine Technologies* • Introduction: comparison among different methodologies to produce electricity from renewable sources • Key Features of main categories of Hydraulic turbines and their operating parameters • Definition of Turbine regulation and performance curves Wind Turbine Technologies • Introduction: comparison among different methodologies to produce electricity from renewable sources • Key Features of main categories of Wind turbines and their operating parameters • Definition of Turbine regulation and performance curves Internal Combustion Engines: • Introduction: comparison among different engine categories and configurations with a focus on powerplant applications • Efficiency analysis • Definition of internal combustion engine operating parameters and characteristic curves • Overview on the main technologies to improve the performance and the efficiency of the engine • Analyses of the engine pollutant emissions and of their aftertreatment technologies • Alternative fuels: biofuels and e-fuels *This topic could be skipped if already analyzed and discussed in …….

Thermal machines and structural mechanics (Structural mechanics)

Thermal machines and structural mechanics (Thermal Machines)

Thermal machines and structural mechanics (Structural mechanics)

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.

Thermal machines and structural mechanics (Thermal Machines)

Exercises: • 1st Exercise: numerical exercises on the regulations of steam power plants: 3 hours • 2rd Exercise: numerical exercises on the regulations of turbogas power plants: 3 hours • 3th Exercise: numerical exercises on hydraulic turbines: 3 hours • 4th Exercise: numerical exercises on internal combustion engines: 4.5 hours Laboratory (1.5 hour): • Overview on the main internal combustion engine components • Overview on the measurement systems to characterize the performance and the pollutant emissions of the engine.

Thermal machines and structural mechanics (Structural mechanics)

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

Thermal machines and structural mechanics (Thermal Machines)

The student is suggested to attend lectures and exercises, to use the notes provided by the teacher for the preparation of the exam, since there is no single text dealings with all the topics covered in the course. Possible books to deepen single topics, when needed, for future professional activity, are the following: • M.J. Moran, H.N. Shapiro, “Fundamentals of Engineering Thermodynamics”, 5th ed., John Wiley & Sons. • S.L. Dixon, C.A. Hall, “Fluid Mechanics and Thermodynamics of Turbomachinery”, 6th ed., Butterworth-Heinemann, Elsevier. • S.A. Korpela, “Principles of Turbomachinery”, Wiley & Sons. • Heywook J., Internal Combustion Engine fundamentals

Thermal machines and structural mechanics (Structural mechanics)

Slides; Esercizi; Esercizi risolti; Esercitazioni di laboratorio; Materiale multimediale ;

Thermal machines and structural mechanics (Thermal Machines)

Slides; Video lezioni dell’anno corrente;

Thermal machines and structural mechanics (Structural mechanics)

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

Thermal machines and structural mechanics (Thermal Machines)

Modalità di esame: Prova scritta (in aula); Prova orale facoltativa;

Thermal machines and structural mechanics (Structural mechanics)

Exam: Written test; Compulsory oral exam; Practical lab skills test; Individual essay;

Thermal machines and structural mechanics (Thermal Machines)

Exam: Written test; Optional oral exam;

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Thermal machines and structural mechanics (Structural mechanics)

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.

Thermal machines and structural mechanics (Thermal Machines)

- Written test (duration: 1h 25 m): it is divided into two parts: o The first part is composed by 8 multiple-choice questions to be answered within 30 minutes. The questions are concerned with the theory topics, but a few of them will require the solution of short numerical problems. Each correct answer will score 2 points, each blank (not given) answer will bring 0 points, and each wrong answer will bring -0.5 points. Each question will have only one correct answer. The maximum score for the first part is 16/15. o The second part will require the solution of two exercises within 1 hours, in the form of essay questions. The maximum score is 15/15. In order to be admitted to the second part, it is necessary to get a score >= 8/16 from the first part o The exam is not passed if the score from the first written part is strictly lower than 8/15 OR the one from the second part is strictly lower than 9/15. o The final mark of the written test is given by the sum of the two parts. The maximum achievable mark of the written part is 26/30. In order to achieve higher marks, the student has to attend the oral exam. - Oral Test: the student will discuss with the commission about the main topics of the course, and he may be asked to provide some of the mathematical demonstrations shown during the lessons. With the oral test, the student may increase or decrease the mark achieved during the written part of the exam. All the students with a sufficient mark (>=18) may ask the commission to attend the oral test.

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.