Energy efficient scientific methods

Materials Engineering

By

Drs J. Whitty and B. Henderson

Topics to cover

This lecture - Engineering materials Introductory Newtonian mechanics Stress analysis - assignment tutorial Linear Kinematics & Energy methods Rotary Kinematics Fluid Kinematics Thermodynamic - Assignment 2 Electrical circuit theory (21/05*) Revision Examination (open-book)

The scientific method

In essence you probably learned this in your earliest science class consisting of the following stages:

Introduce Theory/Hypothesis Methods (Logged) Results Discussion/Proof Conclusions

The Fathers of the method

Depending which text is referred to and hence which school of thought the ‘invention’ of the method is attributed to one of the following giants...

Newton Hooke Bacon Galileo Euler

Descartes

Assessment methods

Assignment 1: The scientific method & mathematical statistics

Milestone test 1: Mock examination mathematics questions

Assignment 2: Introductory mathematical engineering systems

modelling Milestone test 2:

Three mock-exam science questions Milestone test 3:

Computer modelling methods tutorial Examination (informal)

Why study Materials Engineering?

Learning Check

In groups define the following. Brittleness Ductility Elasticity Hardness Malleability Tensile Strength Toughness Yield Strength

What are the 5 main classes of materials ?

Session Learning Objectives

Define the common terminology used in the subject of engineering materials.

State and define structural engineering materials from a mechanical viewpoint.

Define the six main classes of materials and give engineering examples of their usage.

Answer examination type question(s) on the classes of materials

After the session the student will be able to:

Classes of Materials

1. Metals2. Ceramics3. Polymers

Semi-Conductors4. Composites5. Cellular (e.g. Timber)

Can you define these and give three examples of each?

Metals & Alloys

Quite Simply defined as a metallic element

It is strong and can be readily formed into practical shapes.

Its extensive, permanent derformability, or ductility.

A freshly cut surface has a characteristic metallic luster

metals share fundamental characteristics e.g.:they are good conductors of electrical current & heat.

An alloy is a metal composed of more than one element. E.g. brass is an alloy of copper and zinc

Ceramics

Ceramic materials are inorganic, nonmetallic materials. Most ceramics are compounds between metallic and nonmetallic elements for which the interatomic bonds are either totally ionic or predominantly ionic but having some covalent character

Source: http://www.engr.sjsu.edu/WofMatE/ceramics.htm

Polymers

Polymeric materials are characterized by long chains of repeated molecule units known as "mers". These long chains intertwine to form the bulk of the plastic. The nature by which the chains intertwine determine the plastic's macroscopic properties.

Source: http://plc.cwru.edu/tutorial/enhanced/files/polymers/struct/struct.htm

Polymer Classes

THERMOSETS THERMOPLASTICS ELASTOMERS MODIFIED NATURAL POLYMERS HOMOPOLYMER COPOLYMER

Composites

Composites: materials, usually man-made, that are a three-dimensional combination of at least two chemically distinct materials, with a distinct interface separating the components, created to obtain properties that cannot be achieved by any of the components acting alone.

Cellular Materials

If a material is porous (i.e. contains voids within the macro-structure) at wither the micro or macro-structural levels then the material is said to be a cellular material.

Though timber can also be thought of a natural composite; it is also the most important example of a cellular material. That is the theory of cellular solids adequately describe the behaviour of most timbers

Semi-Conductors

A relatively small group of elements and compounds has an important electrical property, semi-conduction , in which they are neither good electrical conductors nor good electrical insulators. Instead, their ability to conduct electricity is intermediate. These materials are called semiconductors; Typically these materials are one of two of the primary class of materials, viz. polymers or ceramics

Examination Type Question

State 4 classes of materials giving an engineering application for each. [10]

a) State reasons why cellular materials and the semi-conductors are sub-classes of materials [4]

b) Which of the classes of materials generally undergoes the least deformation at failure [2].

c) Which are the most ductile classes of materials and why [2].

d) Suggest an appropriate measure for the ductility of a material [2].

[20 Marks]

Summary

Define the common terminology used in the subject of engineering materials?

State and apply appropriate formulae to define structural engineering materials from a mechanical viewpoint?

Define the six main classes of materials and give engineering examples of their usage?

Answer examination type question(s) on the classes of materials?

Have we me the learning objectives, in particular are you able to:

If so when and where, were they met!

Websites

http://ceaspub.eas.asu.edu/concrete/elasticity2_95/sld001.htm

http://plc.cwru.edu/tutorial/enhanced/files/polymers/struct/struct.htm

http://www.engr.sjsu.edu/WofMatE/