Download - Adv Composites
-
8/10/2019 Adv Composites
1/33
-
8/10/2019 Adv Composites
2/33
SlideSlide 22
LectureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Advanced Composite MaterialsAdvanced Composite Materials
Content:Content:
Introduction;
Linear Elastic Stress-strainCharacteristics;
Stress-strain Relations for PlaneStress;
Plane-stress Stress-strain Relations ina Global Coordinate System;
Failure theories;
Materials Degradation;
Manufacturing Process andApplications.
-
8/10/2019 Adv Composites
3/33
SlideSlide 33
LectureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Assessment criteriaAssessment criteria
Course works
Group discussions 10 %
In-class assignments 10 %
Home works 10 %
Group design projects 30 %
Written examination 40%
Total 100 %
-
8/10/2019 Adv Composites
4/33
SlideSlide 44
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
IntroductionIntroduction
Definition of Composite Materials
In its most basic form a composite material is one, which is
composed of at least two elements working together to produce
material properties that are different to the properties of thoseelements on their own. In practice, most composites consist of a bulk
material (the matrix), and a reinforcement of some kind, added
primarily to increase the strength and stiffness of the matrix. This
reinforcement is usually in fibre form. Today, the most commonman-made composites can be divided into three main groups:
-
8/10/2019 Adv Composites
5/33
SlideSlide 55
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Polymer Matrix Composites (PMCs) These are the most
common and will be discussed here. Also known as FRP -
Fibre Reinforced Polymers (or Plastics) these materials use
a polymer-based resin as the matrix, and a variety of fibres
such as glass, carbon and aramid as the reinforcement.
Metal Matrix Composites (MMCs) - Increasingly found in
the automotive industry, these materials use a metal such as
aluminium as the matrix, and reinforce it with fibres such as
silicon carbide.
Ceramic Matrix Composites (CMCs) - Used in very high
temperature environments, these materials use a ceramic as
the matrix and reinforce it with short fibres, or whiskers such
as those made from silicon carbide and boron nitride.
-
8/10/2019 Adv Composites
6/33
SlideSlide 66
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
7/33
SlideSlide 77
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Most commonly, composite materials have a bulk phase, which is
continuous, called the matrix, and one dispersed, non-continuous,
phase called the reinforcement, which is usually harder and stronger.
The concept of composite materials is ancient: to combine different
materials to produce a new material with performance unattainable
by the individual constituents. The essence of the concept of
composites is this: the bulk phase accepts the load over a large
surface area, and transfers it to the reinforcement, which being
stiffer, increases the strength of the composite. The significance
here lies in that there are numerous matrix materials and as many
fiber types, which can be combined in countless ways to produce
just the desired properties.
Polymer Matrix CompositesPolymer Matrix Composites
-
8/10/2019 Adv Composites
8/33
SlideSlide 88
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Illustrating the combined effect on Modulus of the addition of fibres to
a resin matrix.
FRP Fibre-reinforcedpolymer/plastic
-
8/10/2019 Adv Composites
9/33
SlideSlide 99
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Overall, the properties of the composite aredetermined by:
The properties of the fibre The properties of the resin
The ratio of fibre to resin in the composite (Fibre Volume
Fraction (FVF), Vf)
The geometry and orientation of the fibres in the composite
-
8/10/2019 Adv Composites
10/33
SlideSlide 1010
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Components of Composite Materials
Bulk phase: matrix materialsBulk phase: matrix materials
Polymers
Metals
Ceramics
Reinforcement: fibers andReinforcement: fibers andparticulateparticulate
Glass
Carbon
Organic Boron
Ceramic
Metallic
InterfaceInterface
-
8/10/2019 Adv Composites
11/33
SlideSlide 1111
Lect
ureNote1
Lect
ureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
The reinforcement system in a composite material strongly
determines the strengthening mechanism in a composite. It is thusconvenient to classify composites according to the characteristics of
the reinforcement, such as length, orientation etc.
Classification of Composite Materials
-
8/10/2019 Adv Composites
12/33
SlideSlide 1212
Lect
ureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
13/33
SlideSlide 1313
Lect
ureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
A fibre reinforced plastic (FRP) has been recognised as one of
the most innovative materials in the applications ranging from
the aerospace industry to prevalent sport goods and facilities for
more than 30 years. It has been demonstrated that the FRP
could be successfully used to replace conventional materials for
most primary structural elements in modern aircraft with safe
and durability.
Fiber types: Carbon, E-glass and
Kevlar (Aramid)
Resin types: Polyester, Vinyl ester,
Phenolic and Epoxy
-
8/10/2019 Adv Composites
14/33
SlideSlide 1414
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Fabric types:
-
8/10/2019 Adv Composites
15/33
SlideSlide 1515
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Weft-knitted glass
fabrics
-
8/10/2019 Adv Composites
16/33
SlideSlide 1616
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
FibresFibres
Reinforcements are not necessarily in the form of long fibers. They
can be particles, whiskers, discontinuous fibers, sheets etc. A greatmajority of materials is stronger and stiffer in the fibrous form thanin any other form. This explains the emphasis on using fibers incomposite materials design.
Fibers used in advanced composites have very high strength andstiffness but low density. They also should be very flexible (toallow a variety of methods for processing) and have high aspectratio (length/diameter), that allows a large fraction of the applied to
be transferred via the matrix to the fiber.
Fibers are added to a ductile matrix (like polymers and metals)usually to make it stiffer, while fibers are added to a brittle matrix
(like ceramics) to increase toughness.
-
8/10/2019 Adv Composites
17/33
SlideSlide 1717
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
MatrixMatrix
Polymers used as matrix materials are commonly referred to as
resins. The matrix resin generally account for 30 to 40%, byvolume, of a composite material. In addition to maintaining the
shape of the composite structure, aligning the reinforcements
(fibres), and acting as a stress transfer medium, the matrix protects
the fibre from abrasion and corrosion. More importantly, thelimitation of a composite may well be a function of matrix
properties, such as thermal stability, chemical inertness, load
transferability, moisture absorbability, mouldability and curing
temperature.
-
8/10/2019 Adv Composites
18/33
SlideSlide 1818
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
ThermosetsThermosets
Thermosetting resins are the most common type of matrix system
for composite materials. They have become popular for a numberof reasons, including low melt viscosity, good fibre impregnation,
and fairly low processing temperatures. They are also lower in cost
compared to thermoplastic resins.
Polyester
Vinyl ester
Epoxy Polyimide
50 110
100 150
50 250280 320
40 90
127
100 20070 120
1.2 4.5
3 4
2 63.1 4.9
Resin type Tg Tensile strength (MPa) E (GPa)
-
8/10/2019 Adv Composites
19/33
SlideSlide 1919
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Resin SystemsResin Systems
Any resin system for use in a composite material will require
the following properties:
1. Good mechanical properties
2. Good adhesive properties
3. Good toughness properties
4. Good resistance to environmental degradation
-
8/10/2019 Adv Composites
20/33
SlideSlide 2020
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
The figure below shows the stress / strain curve for an 'ideal'
resin system. The curve for this resin shows high ultimate
strength, high stiffness (indicated by the initial gradient) and a
high strain to failure. This means that the resin is initially stiffbut at the same time will not suffer from brittle failure.
-
8/10/2019 Adv Composites
21/33
SlideSlide 2121
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and TechnologyIt should also be noted that when a composite is loaded intension, for the full mechanical properties of the fibre
component to be achieved, the resin must be able to deform to
at least the same extent as the fibre. The figure below gives
the strain to failure for E-glass, S-glass, aramid and high-
strength grade carbon fibres on their own (i.e. not in a
composite form). Here it can be seen that, for example, the S-
glass fibre, with an elongation to break of 5.3%, will require a
resin with an elongation to break of at least this value to
achieve maximum tensile properties.
-
8/10/2019 Adv Composites
22/33
SlideSlide 2222
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
InterfaceInterface
1. More often than not, the interface between fiber and matrix is rather
rough, instead of ideal planar.2. To obtain desirable properties in a composite, the applied load should
be effectively transferred from the matrix to the fibers via the
interface. This means that the interface must be large and exhibit
strong adhesion between fibers and matrix. Failure at the interface(called debonding) may or may not be desirable. This will be
explained later in fracture propagation modes.
3. Interfacial strength is measured by simple tests that induce adhesive
failure between the fibers and the matrix. The most common is the
Three-point bend test or ILSS (interlaminar shear stress test)
-
8/10/2019 Adv Composites
23/33
SlideSlide 2323
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Typical Internlaminar (Short Beam) Shear Test Set-up
-
8/10/2019 Adv Composites
24/33
SlideSlide 2424
LectureNote1
LectureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
A good bonding interface Debond at the interface
-
8/10/2019 Adv Composites
25/33
SlideSlide 2525
LectureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Mechanical PropertiesMechanical Properties
-
8/10/2019 Adv Composites
26/33
SlideSlide 2626
LectureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
Mechanical PropertiesMechanical Properties
-
8/10/2019 Adv Composites
27/33
SlideSlide 2727
Lec
tureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
28/33
SlideSlide 2828
Lec
tureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
29/33
SlideSlide 2929
Lec
tureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
30/33
SlideSlide 3030
Lec
tureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
31/33
SlideSlide 3131
Lec
tureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
32/33
SlideSlide 3232
Lec
tureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology
-
8/10/2019 Adv Composites
33/33
SlideSlide 3333
Lec
tureNote1
Lec
tureNote1
Advanced Materials for Design and TechnologyAdvanced Materials for Design and Technology