ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

ME 582 Advanced Materials Science

Chapter 1 Introduction to Composite Materials

Dr. Jan GouComposite Materials Research Laboratory

Department of Mechanical EngineeringUniversity of South Alabama, Mobile, AL 36688

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Definition of Composite Materials

A composite is a structural material that consists of two or more combined constituents that are combined at a macroscopic level and are not soluble in each other

Reinforcing phase: fibers, particles, or flakes

Matrix phase: polymers, metals, ceramics

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Fiber-Reinforced Composites

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Fiber-Reinforced Composites (Cont’d)

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Characteristics of Composite Materials

High specific strength and modulus, as well as high fatigue strength and fatigue damage tolerance

Anisotropic

Designable or tailorable materials for both microstructure and properties

Production of both material and structure or component in a single operation - manufacturing flexible, net-shape, complex geometry

Corrosion resistance and durable

Other unique functional properties - damping, low CTE (coefficient of thermal expansion)

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Specific Modulus

ρ/1

4

2

EPLM =

Lightest beam for specified deflection under a specified load is one with the highest modulus

Axial Deflection

EAPL

=μ

Mass

ALM ρ=

ρ/E

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Specific Modulus

Critical Load

2

2

LEIPcr

π=

Second Moment of Area

64

4dI π=

Mass of Rod

ρππρ

/12

4 2/1

22

EPLLdM cr==

Lightest beam for specific stiffness is one with the highest value of ρ/2/1E

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Specific Modulus

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Specific Modulus

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Disadvantages of Composites

High cost of fabrication of composites

Mechanical characterization of a composite structure is more complex than a metal structure

Repair of composites is not a simple process compared to that for metals

Composites do not have a high combination of strength and fracture toughness compared to metals

Composites do not necessarily give higher performance in all the properties used for material selection: strength, toughness, formability, joinability, corrosion resistance, and affordability

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Fracture Toughness of Composites

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Material Selection Parameters

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Factors vs Mechanical Performance

Fiber Factors

Length

Orientation

Shape

Materials

Matrix Factors

Fiber-Matrix Interface

Chemical bonding

Natural roughness

CTE of matrix

Reaction bonding

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Corrosion11%

Aircraft -1%

Construction20%

Consumer7%

Electrical10%

Marine11%

Appliance -5%

Other- 3%Transport

32%

2000 U.S. Composites Shipments

Source: CFA (June 2000)Est. 3.9 Billion Lbs of Shipments in 2000

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Types of Composites

Particulate composites

Flake composites

Fiber composites

Nanocomposites

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Polymer Matrix Composites

Polymer matrix composites

Polymer: epoxy, polyester, urethane

Fiber: graphite, aramids, boron

Drawbacks of PMCs

Low operating temperature

High coefficients of thermal

High moisture expansion

Low elastic properties

Mechanical properties of PMCs

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Mechanical Properties of PMCs

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Mechanical Properties of Fibers

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Manufacturing of Glass Fibers

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Manufacturing of Carbon Fibers

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Role of Matrices in Composites

• Transfer stresses between the fibers

• Provide a barrier against an adverse environment

• Protect the surface of the fibers from mechanical abrasion

• Determine inter-laminar shear shear strength

• Determine damage tolerance of composites

• Determine in-plane shear strength

• Determine the processibility of composites

• Determine heat resistance of composites

Model of unidirectional composite

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Common Matrices in PMCs

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Thermoplastics and Thermoset

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Sheet Molding Compounds (SMC)

• Matrix: polyester resin, vinyl ester resin

• Used for compression molding process

• SMC - R: randomly oriented discontinuous fibers

• SMC – CR: containing a layer of unidirectional continuous fibers

• XMC: containing continuous fibers arranged in an X pattern

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Manufacturing of SMC

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Prepreg Manufacturing

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Bag Molding Process/Autoclave Process

prepreg (B-stage resin)

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Filament Winding Process

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Analysis of Laminated Composites

ME 582 Advanced Materials Science • Department of Mechanical Engineering Dr. Jan Gou

Hybrid Laminates

Interply hybrid laminates

Intraply hybrid laminates

Interply-intraply laminates

Resin hybrid laminates