Starting from the knowledge acquired, in previous courses, about structural calculation, machine design, materials, technical representation and numerical methods for solving mechanical problems, the aim of the course is to introduce the student to the synthesis of these topics for the effective design (sizing and checking) of some fundamental types of machine elements (axles and shafts, bearings, gears, transmission belts, threaded connections, springs, etc.) and of their assemblies in functional mechanical systems.

More specifically, the aims of the course are:

• to introduce the methods and analytical tools for mechanical structural design
• to apply the methods and tools of mechanical design to sizing and checking of the considered machine elements, with critical evaluation of the results
• to apply the basic concepts of linear-elastic structural finite element numerical analysis with critical evaluation of the results
• to present real case studies of mechanical assemblies, to be understood, analysed and designed

At the end of the course, students will have acquired theoretical and practical knowledge according to the objectives of the course.

In terms of knowledge and understanding, students will understand and know:

• the methodologies and the analytical principles of mechanical structural design
• the operating modes of the considered machine elements and the assemblies involving them
• the techniques for sizing and checking of the machine elements dealt with
• the theoretical foundations and operational techniques of linear-elastic numerical structural analysis by the finite element method

Regarding the application of the acquired knowledge and understanding, students will be able:

• to perform structural calculations of mechanical components and systems
• starting from the technical drawing, to understand and describe the functions of a mechanical system from a structural and functional point of view
• to size and check the addressed machine elements
• to set up and solve the linear-elastic numerical structural analysis of simple mechanical systems by the finite element method
• to apply the knowledge acquired to the design and assembly of a mechanical component to be tested in the laboratory

Through exercises, students will also acquire the ability to formulate independent judgment, namely:

• to evaluate critically the results of the structural design process of a mechanical system
• to evaluate critically the results of the linear-elastic numerical structural analysis of a simple mechanical system by the finite element method
• to acquire teamwork skills and practical evaluation of design choices through laboratory experience

1. The topics covered in the course concern:

   1. mechanical design: modes of failure, project specifications and requirements, sizing and checking, factor of safety, the role of materials, the role of regulations and standards.
   2. axles and shafts: design and sizing, static (strength and stiffness) and fatigue checks, critical rotating speeds.
   3. shaft-hub connections: design and sizing, press fits, couplings by key, splined profiles, pins.
   4. gears: design and sizing (synthetic stress factors), wear and bending checks, tolerances, profile correction.
   5. belt drives: design and sizing, analysis of the stress state in the belt. Flat, trapezoidal, synchronous belts. Choice of belt from catalog.
   6. springs: design and sizing, axial, bending and torsion springs, helical and leaf springs.
   7. bearings: ball, roller; calculation and use.
   8. bolted joints: axially loaded, shear, tension and tightening torque, gasket effect, sizing, static and fatigue checks.
   9. numerical exercises: structural analysis, sizing and check, using analytical methods, of mechanical components and structures with discussion and critical evaluation of the results. Application of finite elements to the solution of simple structural problems, critical analysis of the results and comparison with analytical solutions.
   10. experimental laboratory exercise: application of the knowledge acquired in the course to the design of a component to be manufactured and tested on a workbench available to students.

The topics of the course require the understanding and assimilation of topics addressed in the following preparatory courses:

Costruzione di Macchine 1 (Machine design 1)

Metallurgia e Materiali Non Metallici (Metallurgy and non-metallic materials)

Metodi Analitici e Numerici per l'Ingegneria (Analytical and numerical methods for engineering)

Metodi di Rappresentazione Tecnica (Methods for technical representation)

Metodi di Calcolo delle Strutture (Methods for structural calculation)

The exam consists of a written test consisting of two/three cases of design / calculation / checking of machine elements. The available time amounts to 1.5 hours. Any projects assigned during the course will also be evaluated during the final examination

There is no oral exam, except in exceptional cases and at the total discretion / need of the teacher

The final evaluation is intended to check the knowledge and understanding of the topics, the ability to apply such knowledge and understanding, the autonomy of judgment in choosing the correct and most effective methods for the given application case and in critically evaluating the results