OVERVIEW

The general problem of modeling a mechanical system and its operating environment is addressed, describing and demonstrating different modeling approaches that are employed during a typical design process.

The problem is tackled in a practical way using a realistic example of a machine, the project of which is developed by students throughout the semester, working in groups of 2 or 3 people. This includes the conceptual design of the machine, the geometric proportioning of components, dynamic analysis, reliability analysis.

The concept is similar for all groups, but with differences that promote the development of original solutions. Each group presents their work on two occasions (mid-term and at the end) through a report visible to all and a discussion. The discussion is organized as a typical business meeting between pairs of groups: one group presents and describes their work, the other comments and criticizes the results.

AIMS AND CONTENT

LEARNING OUTCOMES

Provide theoretical knowledge and engineering skills on geometric, functional and structural modelling and design of mechanical systems.

In particular, students learn the use of Computer Aided Design and Engineering (CAD-CAE) tools and software for multibody analysis.

a) Geometric models: 3D CAD tools; parametric analysis and optimization. b) Kinematic models: constraint equations; laws of motion and kinematic synthesis; software tools. c) Dynamics of non-linear mechanical systems: multibody systems; software tools. d) Structural reliability: definition of actions, limit states, reliability estimation methods. e) Data exchange between CAD-CAE.

AIMS AND LEARNING OUTCOMES

Ability to use Computer Aided Design and Engineering (CAD-CAE) tools for the geometric and functional modelling of a mechanical system. Ability to analyse and evaluate concurrent solutions of kinematic and static schemes of mechanical systems.

Ability to create a mechanical system for performing a specified task

Ability to present and discuss their work through technical reports and presentations.

Ability to evaluate, discuss and criticize the work done by colleagues.

PREREQUISITES

Knowledge of the basic disciplines of mechanical engineering.

TEACHING METHODS

40% lectures on theoretical and practical topics

40% workshops where students in groups develop their projects under the guidance of teachers

20% discussion of projects carried out by students and led by teachers

SYLLABUS/CONTENT

The topics covered during the course follow the stages of progress of the project developed by the students. In detail, 4 phases are identified:

Conceptual design. Starting from the assigned requirements, the kinematic scheme of the machine is defined. In this phase the mechanical system is modeled as a set of rigid bodies connected by ideal kinematic pairs.

The topics covered include the description of the constraints, the definition of kinematic pairs, the kinematic analysis of classical elementary models.

Geometric proportioning. The shape and dimensions of the components are defined on the basis of the fundamental principles of mechanical construction. In this phase, the mechanical system is modelled through a parametric Computer Aided Design and Engineering (CAD-CAE) tool.

Topics covered include feature-based parametric solid modelling. Part models: sketcher, constraints, features, solid and sheet metal parts, advanced features. Assembly models: parts insertion modes, constraints, lability, kinematic aspects, operations on parts, exploded views and animations. Analysis of features; constraints, relations and parameters. Exchange of geometric models between heterogeneous CAD-CAE software tools. Use of commercial component libraries. Elements of mechanical design, embodiment design and choice and use of commercial and unified components. Develop a project with PTC Creo software. In addition, recalls of machine construction elements are provided.

Dynamic analysis. The dynamic response of the mechanical system subject to assigned forces is calculated. In this phase, the system is modelled according to the multi-body approach with deformability reproduced in a localized way.

Topics covered include: definition of a multi-body model in the PTC Creo environment starting from a CAD model; definition of constraints and flexibility; definition of trajectories by means of inverse kinematic analysis; application of external actions; performing dynamic analysis; extraction and analysis of quantities relevant for the description of the dynamic response.

Reliability analysis. Assigned uncertainties in the model parameters or in the parameters that define the operating environment, the probability of exceeding predefined bound states is assessed. This phase involves probabilistic modeling of uncertainties and actions.

Topics covered include: formulation of the reliability problem, boundary states, safety margins, methods of analysis; probabilistic description of uncertainties; implementation in Matlab environment of methods for the description and analysis of random quantities.

Presentation and discussion of the results. The results obtained during the development of the project are described and discussed by the students through 2 technical reports and 2 oral presentations carried out in the form of a peer discussion. Students are guided in the preparation of these activities through two lessons that illustrate good practices for writing a technical report and preparing a technical presentation.

RECOMMENDED READING/BIBLIOGRAPHY

Chirone E.; Tornincasa S., Disegno tecnico industriale vol. 1 e 2, Il Capitello

E. J. Haug, Computer Aided Kinematics and Dynamics of Mechanical Systems, 1989.

F. Cheli ed E. Pennestrì. Cinematica e Dinamica dei Sistemi Multibody, Casa Editrice Ambrosiana, Milano, 2005.

User manual of the considered softwares.

TEACHERS AND EXAM BOARD

Exam Board

MATTEO ZOPPI (President)

ABDELHAKIM BOURAS

GABRIELE REVERBERI

ELENA RIZZETTO

LUIGI CARASSALE (President Substitute)

LESSONS

LESSONS START

https://corsi.unige.it/9269/p/studenti-orario

Class schedule

The timetable for this course is available here: Portale EasyAcademy

EXAMS

EXAM DESCRIPTION

The evaluation of the students' results takes place through the correction of the two reports on the project and the group discussions. A final oral interview is provided, but optional, in which students are assessed on the theoretical and practical knowledge acquired.

ASSESSMENT METHODS

The assessment of the students' preparation takes place by evaluating the following aspects: quality of the project; quality of the report; clarity of presentation in the description of their project; ability to analyse the project of others; respect for the time allotted for one's exposure; discussion skills; ability to reply to the comments received; ability to synthesize.

Exam schedule

FURTHER INFORMATION

Pre-requisites :

Course needs basis acquaintances of Mechanics,and mostly it’s needed acquaintance of contents of Physics, Maths and Applied Mechanics courses, Industrial Technical Drawing