# 85817 - Chassis and Body Design and Manufacturing

## Learning outcomes

The outcomes of the course are to provide the advanced knowledge, the methods and the tools useful for the correct design and verification of the chassis components. The students will learn how to tackle the design of a motorbike frame by means of both analytical and numerical FEA tools. A special focus will be put on joining methods suitable for lightweight structures (adhesives, bolts, welds). The design of some key components, such as suspension elements, will be examined in depth. At the end of the course, the students will be able to select the most appropriate structural solutions based on the product mission, taking into account both the performance targets (e.g. stiffness, weight) and the expected failure modes the product must be designed against (e.g. fatigue, wear), in the framework of the requirements set by the relevant International Standards.

## Course contents

INTRODUCTION

Statically indeterminate structures: force method and displacement method. Strain energy methods. Rotating-node and translating-node frames.

THREADED JOINTS

Screws: static and fatigue dimensioning and assessment. Calculation methods according to Eurocode 3 and VDI 2230. Axial preload and tightening torque. Determination of the coefficients of friction according to ISO 16047. Friction coefficients requirements according to the automotive field normative. How to account for data scatter in dimensioning threaded joints. Load introduction factor. Prying load. Residual shank torsion. Self loosening and self-relaxation issues.

Numerical modeling of threaded joints, 1d and 3d approaches.

WELDED JOINTS

Static and fatigue dimensioning and assessment.Failure criteria. Calculation method according to Eurocode 3 (steel) and Eurocode 9 (aluminium).

Numerical modeling of welded joints.

ADHESIVELY BONDED JOINTS

Static and fatigue dimensioning and assessment. Single-lap joints: Volkersen and Goland&Reissner theories. Cylindrical joints: dimensioning according to the Loctite method. Hybrid joints: interference fit plus adhesive.

Numerical modeling of adhesively bonded joints.

MECHANICAL SPRINGS

Flat and leaf springs. Helical compression, extension and torsion springs. Calculation methods according to EN 13906. Belleville and ring springs (basics). Elastomeric springs.

EXPERIMENTAL STRESS ANALYSIS

Strain gauges: materials, measuring circuits, data acquisition. The gage factor. Single grid strain gauges and rosettes. Determining residual stresses by the hole-drilling strain gauge method.

TUTORIALS AND CASE STUDIES

## Readings/Bibliography

Lecture slides: these will be made available on the internet (e.g. through the AMS Campus repository).

G. Genta, L. Morello, The automotive Chassis, Springer.

A. M. Wahl, Mechanical Springs, 2nd Ed. Mc Graw Hill Book Company.

A. Freddi, G. Olmi, L. Cristofolini, Experimental Stress Analysis for Materials and Structures: Stress Analysis Models for Developing Design Methodologies, Springer.

## Teaching methods

The course content will be entirely covered by the lectures. Lectures are supported by many practical exercises, aimed at guiding the students towards the solution of practical problems, based on the tools acquired during the theoretical lectures.

## Assessment methods

The examination consists of a written test, made up of two exercises dealing with the topics of the course. The test lasts three hours, every kind of printed support is allowed.

## Teaching tools

Blackboard, overhead projector, PC

## Office hours

See the website of Massimiliano De Agostinis