Carbon Fiber Composites Overview
Carbon fiber composites (CFRP) are advanced materials combining carbon fibers with a polymer matrix, usually epoxy or thermosetting resin. This integration provides high tensile strength, low density, and high stiffness while enhancing durability and chemical resistance.
CFRP is widely applied in aerospace, automotive, wind energy, sports, and industrial applications, where lightweight and high-strength materials are critical.
Structure and Composition
CFRP consists of:
Carbon Fibers: Provide load-bearing capacity, high tensile strength, and stiffness.
Polymer Matrix (Resin): Transfers stress, protects fibers, enhances durability.
Fiber Orientation: Determines directional strength (unidirectional, woven, hybrid).
Table 1: Typical CFRP Composition
| Component | Fraction | Function |
|---|---|---|
| Carbon fiber | 50–65% | Load-bearing, carbon fiber strength |
| Epoxy resin | 35–50% | Transfers stress, protects fibers |
| Additives | <5% | Impact/fire resistance |
Density of CFRP: 1.55–1.6 g/cm³
Mechanical Properties
CFRP inherits carbon fiber properties but modifies them based on fiber orientation and resin type.
| Property | Range | Notes |
|---|---|---|
| Tensile Strength | 500–1,500 MPa | Carbon fiber composites strength |
| Elastic Modulus | 70–200 GPa | Stiffness along fibers |
| Compressive Strength | 200–800 MPa | Matrix-dependent |
| Shear Strength | 50–150 MPa | Laminate performance |
| Density | 1.55–1.6 g/cm³ | Lightweight material |
Key Points:
Unidirectional CFRP: highest tensile strength along fibers.
Woven fabrics: multidirectional strength, slightly lower modulus.
Matrix affects compressive and shear properties.
Thermal and Chemical Properties
Thermal Stability: 200–400°C depending on resin
Coefficient of Thermal Expansion: 0.1–1×10⁻⁶ /°C
Thermal Conductivity: 10–100 W/m·K along fiber
Chemical Resistance: Resistant to acids, alkalis, solvents
Dimensional Stability: Minimal shrinkage and deformation
CFRP is suitable for high-temperature and corrosive environments.
Manufacturing Processes
Prepreg Method: Fibers pre-impregnated with resin, cured under heat/pressure.
Lay-Up Method: Manual or automated layer placement, resin applied, then cured.
Filament Winding: Continuous fibers wound on molds, cured for cylindrical parts.
Resin Transfer Molding (RTM): Dry fibers in mold, resin injected under pressure.
Autoclave Curing: High-pressure, high-temperature curing for aerospace-grade laminates.
Internal link suggestions: Link “carbon fiber properties” and “carbon fiber structure” to related internal pages.
Comparative Material Properties
| Material | Tensile Strength | Modulus | Density |
|---|---|---|---|
| Carbon fiber | 3,500–7,000 MPa | 230–700 GPa | 1.6–2.0 g/cm³ |
| CFRP | 500–1,500 MPa | 70–200 GPa | 1.55–1.6 g/cm³ |
| Aluminum 6061 | 310 MPa | 69 GPa | 2.7 g/cm³ |
CFRP provides superior strength-to-weight ratio compared to metals.
Industrial Applications
Aerospace: Fuselage, wings, satellite frames – ~50% weight reduction vs aluminum.
Automotive: F1 chassis, sports car panels – improved stiffness-to-weight ratio.
Wind Energy: Turbine blades >50 meters – high modulus ensures minimal deflection.
Sports Equipment: Bicycles, tennis rackets, golf clubs – lightweight and strong.
Industrial: Pressure vessels, robotic arms, bridge reinforcement – high-load performance.
Consumer Electronics: Laptops, smartphones – lightweight durable casings.
Advantages and Limitations
Advantages:
High strength-to-weight ratio
Excellent stiffness and dimensional stability
Corrosion and chemical resistance
Tailorable mechanical properties
Limitations:
Brittle, low impact resistance
High production costs
Complex repair and recycling
Future Trends
High-modulus fibers for aerospace and wind turbines
Sustainable recycling techniques for CFRP
Hybrid composites (carbon, glass, aramid fibers)
Automated manufacturing: robotic filament winding, 3D weaving
Nano-enhanced composites (carbon nanotubes, graphene)