Main aim and description of the course

The scope of this course is the development and the enhancement of the knowledge in the field of the design of components and parts for high temperature applications (e.g. in gas and steam turbines, internal combustion engines, steam and gas power plants and more in general for parts and machines working under high temperature service conditions), taking into account the specific mechanical properties of materials at high temperature. Moreover, the course aims at covering specific problems of structural integrity and durability of components and mechanical systems used in the power generation industry and in propulsion gas turbine engines.

Course topics

General subjects

Principles of mechanical design:Engineering design of mechanical components. Components and systems used in the power generation industry: design requirements. Structural mechanical design, general requirements.

Methods for the selection of materials in mechanical design: Materials available for the design of components and systems operating at high temperatures, Ashby’s method for the selection of materials, with particular emphasis on temperature dependent properties.

Durability and structural integrity assessment: complements on life and durability assessment of mechanical components and products; complements on high-cycle fatigue (HCF) and low-cycle fatigue (LCF) with special emphasis on high temperature effects, complements on fracture mechanics, creep of engineering materials, creep-fatigue interaction and creep-fatigue damage calculation, elements of thermo-mechanical fatigue, environmental effects (oxidation, etc.), with special emphasis on high temperature effects. Life and durability assessment and transferability of experimental results to the design of mechanical components.

Mechanical properties of materials for high temperature applications

High temperature metallic alloys: monotonic and cyclic properties; typical applications; short description of production technologies, with special emphasis on their effect on mechanical properties (e.g., superalloys for gas turbine blades);

Engineering polymers and composite materials for high temperature applications: temperature dependence on the mechanical properties; typical applications; characteristic temperatures; specific design methods (brief mention);

Ceramic coatings: typical mechanical properties; use; main failure modes; specific design methods.

Mechanical design

Components for high temperature applications: calculation of stress and strains under monotonic and cyclic loading (in particular, thermal stresses), effect of notches under elasto-plastic conditions, creep-fatigue interaction, durability assessment of typical components employed in the power generation industry (turbine blades, rotor discs, etc.).

Applications

Case studies:Simplified case studies of components employed in turbomachinery and internal combustion engines. Service strength, mechanical design.

Tutored design lab:Thermal stresses, creep and fatigue life calculation under service conditions of turbomachinery components.

Experimental lab: Experiments for the derivation of mechanical properties of materials for high temperature applications (to be activated depending on the attendance).

Lectures

This course is organised as following: 28 hours lectures on general concepts, 16 hours of tutored exercises, 4 hours of experimental lab, 16 hours of tutored computer lab, 12 hours of supervised computer lab for mini design projects, 6 hours for a technical visit to a company or lab. 

The final exam consists of a short written test (with at least one question requiring numerical/analytical answers and one open question about the general topics of the course) immediately followed by oral questions on the topics covered by the course and, eventually, questions about the mini-projects and the exercises of the tutored computer lab.