Introduction to FRP technology

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Introduction to Basic Material

Type and FRP Terminology

Dr. S Guo

November 2008

AVD 0412 /1

M y

M yx

M x

yMxy

M xy

M xy

M xy

N x

N y

N x M x

N y

N xy



Type of Materials

1. Homogeneous Body --- the material properties remain constant

at every point in a direction in the body.

Quasi homogeneous

--- for low variation on macro-scale

2. Inhomogeneous (Heterogeneous)

--- material properties vary from point to point

in a direction in the body

3. Isotropic Body --- the material properties

are the same at a point in every direction

in the body

AVD 0412 /2

a unidirectional ply

on a macro-scale;

but on a micro-scale

a metallic body

(10-6 m)

e.g. E =75 GPa G=27 GPa



Type of Materials

4. Orthotropic Body --- has three different material properties

in three mutually perpendicular directions at a point,AND has only three mutually perpendicular planes of

material symmetry at a point in the body

a unidirectional laminate

5. Anisotropic Body --- the material properties are all different in all

directions at a point in the body.

There is no plane of material

symmetry through a point in the body

AVD 0412 /3

a laminated body

is quasi-orthotropic ?


E1, E2, E3, G12…

Ei, Gij…



MECHANICS OF FRP COMPOSITE

1. Micromechanics

Study of the interactions of the constituent

materials (fibres and matrix) on a microscopic

scale (in fibre diameter or particle size).

On this scale, the FRP is inhomogeneous

AVD 0412 /4

2. Macromechanics

Study the FRP behaviour on a macro-scale

On this scale, the FRP is assumed

homogeneous and the properties of the

constituent materials in a direction are

averaged. This is usually applied to FRP

structural design and analysis. Z

x

y

Micromechnics

Macromechnics

fibre /matrix

lamina

laminate

S

1 2

y

x

y x

X

Y

s2

5

s

4

s

3

s1

structure



Lamina / Ply --- a flat arrangement of unidirectional

or woven fibres in a matrix of typical t = 0.125 mm.A unidirectional ply is orthotropic and assumed to be

homogeneous (on macro-scale).

Some Basic FRP Terminology

Material Axes (Principal Axes, Symmetry Axes) -- a set of mutually

perpendicular directions parallel & perpendicular to the fibre direction

AVD 0412 / 5

xy

z

12

Longitudinal (fibre) --- direction-1

Transverse (matrix) --- direction-2

Z

Y

X

P

Reference Axes (structural or loading Axes)

-- a set of mutually perpendicular directions

parallel and perpendicular to a reference

direction generally coincident with the

external loading system axes

material axes 1

2

x

reference axes y



Laminate --- a stack of plies with variousfibre orientations usually bonded by the

same matrix

Some Basic FRP Terminology

The lamination can be made to tailor the

directional properties of material to meet

structural design requirements

AVD 0412 / 6

xy

z



Type of Materials

1. Homogeneous Body -- the material properties remain constant

at every point in a direction in the body.

AVD 0412 /2*


on a macro-scale;

but on a micro-scale

Q. It is clear for one ply or in a plane.

For a body such as a 2-ply laminate however,

the properties in direction-1 such as E 1 at a

point in ply-1 may be different from a pointin ply-2 having different fibre angle. Is this

body homogeneous?

A. Since the two plies are bonded as one laminate,

the properties should be measured for the whole body (not individual lamina/material any more).

In this case, if the properties such as E 1 or E xin one direction remain the same at different points

(not separate ply), it is a homogeneous body (Macromechanics).

a metallic body

1

23

1

23

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Introduction to FRP technology