closeup of fiberglass, kevlar/aramid and carbon fiber

Composite Materials Guide: Types, Properties, and Industrial Applications

Definition: Composites

Composites are engineered by combining reinforcement fibers such as fiberglass, carbon fiber, or aramid with polymer resins to create lightweight structures with exceptional strength, stiffness, and corrosion resistance. Unlike traditional materials such as steel or aluminum, composites can be engineered to deliver very high strength-to-weight ratios, making them ideal for industries where structural performance and weight reduction are critical.

For example, carbon fiber composites can achieve tensile strengths exceeding 500,000 psi while weighing roughly one-fifth as much as steel and about half as much as aluminum, giving them one of the highest strength-to-weight ratios of any structural material.

Summary

Fibre Glast supplies high-performance composite materials including fiberglass, carbon fiber, Kevlar® (aramid), epoxy, vinyl ester, and polyester resin systems, along with structural core materials and specialty reinforcements engineered for strength, corrosion resistance, durability, and weight reduction.

These advanced materials are widely used across industries, including aerospace, marine, automotive, infrastructure, and energy, where traditional materials cannot meet performance requirements.

This guide explains how composite materials work, the major types of composites, and how engineers select materials for applications.

Composite Materials Explained

Composites consist of multiple components that work together to create a high-performance structure. These components each play a distinct role in overall performance.

Core Components of Composites

Component Role in Composite Structure
Reinforcement fibers Provide tensile strength and stiffness
Polymer matrix (resin) Binds fibers together and distributes loads
Core materials Increase stiffness while minimizing weight

Common Types of Composites

Composite Type Reinforcement Typical Applications
Fiberglass reinforced polymer (FRP)
 Glass Fiber Marine structures, tanks, infrastructure
Carbon fiber reinforced polymer (CFRP)
 Carbon Fiber Aerospace, automotive, robotics
Aramid fiber composites
 Kevlar / aramid Impact-resistant structures

Quick Facts About Composites

  • Composites combine reinforcement fibers and polymer resins
  • Carbon fiber composites can provide strength-to-weight ratios up to five times higher than steel
  • Fiberglass reinforced composites can remain structurally stable for 50+ years in marine environments
  • Sandwich structures using foam or honeycomb cores dramatically increase panel stiffness
  • Composites are widely used by professionals across industries and by hobbyists alike

Learn More: Fundamentals of Composites and Getting Started in Composites

Composites Compared to Steel

Steel has long been the go-to material in manufacturing and construction. It is strong, reliable, and widely available. But composites bring a different set of advantages to the table. They're significantly lighter, naturally resistant to corrosion, and can be engineered to meet specific performance requirements that steel simply can't match. See the comparison chart here.

Use this guide to explore the fundamentals, materials, and applications of composite systems.

Table of Contents

  • What Are Composites?
  • Types of Composite Materials
  • How Fiber and Resin Work Together
  • Fiberglass Reinforced Composites
  • Carbon Fiber Reinforced Composites
  • Advanced Resin Systems
  • Core Materials and Sandwich Structures
  • Performance Characteristics
  • Real-World Engineering Considerations
  • Applications of Composite Materials Across Industries
  • How to Choose the Right Composite
  • Industries That Use Composite Materials
  • Why Fibre Glast
  • About This Guide
  • Key Takeaways
  • Frequently Asked Questions About Composite Materials
  • Composite Materials Learning Center

What Are Composites?

Composites are engineered systems made by combining two or more distinct components to create a structure with improved performance characteristics.

Most structural composites combine:

  • Reinforcement fibers such as fiberglass, carbon fiber, or aramid fibers
  • Polymer matrix resins such as epoxy, polyester, or vinyl ester

The fibers provide structural strength and stiffness, while the resin matrix binds the fibers together and distributes loads throughout the laminate.

Composite laminates can be designed to optimize strength, weight, corrosion resistance, and fatigue durability.

Learn more in: About Reinforcements

Learn more in: About Resins

Types of Composites

Composites are generally classified based on the type of reinforcement fiber and resin system used.

Fiberglass Reinforced Polymer (FRP)

Fiberglass composites combine glass fiber reinforcement with polymer resins to create strong, corrosion-resistant materials.

Common uses include:

  • Marine hulls and decks
  • Industrial tanks and piping
  • Structural panels
  • Infrastructure components

Learn more in: The Ultimate Fiberglass Repair Guide

Carbon Fiber Reinforced Polymer (CFRP)

Carbon fiber composites offer extremely high stiffness and strength while maintaining very low weight.

Typical applications include:

  • Aerospace structures
  • Automotive performance components
  • Robotics and advanced manufacturing

Learn more in: What is Carbon Fiber Used For?

Aramid Fiber Composites

Aramid fibers such as Kevlar® provide excellent impact resistance and toughness.

These composites are commonly used in:

  • Ballistic protection
  • Aerospace panels
  • Sporting equipment

Learn more in: Carbon Fiber vs Kevlar (Aramid)

Sandwich Composite Structures

Many advanced composites use sandwich construction, where lightweight core materials are placed between composite skins.

Common core materials include:

  • Foam core
  • Honeycomb core
  • Balsa core

Learn more in: Guidelines for Sandwich Core Materials

How Fiber and Resin Work Together in Composite Laminates

Composites achieve their performance through the interaction between reinforcement fibers and the surrounding resin matrix.

Reinforcement Fibers

Fibers carry most of the structural load in a composite laminate.

Common reinforcement materials include:

  • Fiberglass fabrics
  • Carbon fiber fabrics
  • Aramid (Kevlar) reinforcement

These fibers provide high tensile strength and stiffness.

Learn more in: About Reinforcements

Polymer Matrix (Resin)

Resins bind reinforcement fibers together and protect them from environmental damage.

Common resin systems include:

  • Epoxy resins
  • Polyester resins
  • Vinyl ester resins

Learn more in: About Resins

Core Materials

Core materials increase structural stiffness while keeping composite parts lightweight.

Typical core materials include:

  • Foam cores
  • Honeycomb cores
  • Balsa cores

Learn more in: Guidelines for Sandwich Core Materials

Performance Characteristics of Industrial Composites

Property Composite Advantage
Strength-to-weight ratio Often higher than steel
Corrosion resistance Excellent in marine environments
Fatigue resistance High durability under cyclic loads
Thermal stability Dependent on resin system
Electrical insulation Non-conductive options available

Real-World Engineering Considerations

Selecting composite materials requires balancing strength, durability, weight, and cost.

For example:

  • Carbon fiber laminates provide extremely high stiffness but may be brittle under impact
  • Fiberglass laminates provide greater flexibility and impact resistance

Similarly, resin selection affects long-term durability. Vinyl ester resins are often used in chemical environments because they resist moisture absorption and corrosion better than standard polyester resins.

Understanding these trade-offs helps engineers to design composite structures that meet performance requirements.

Applications of Composite Materials Across Industries

Composite materials are used across a wide range of industries, for example:

Aerospace

By weight, over 50% of large aircraft are comprised of composite materials.  These carbon fiber reinforced components are used in aircraft fuselages, wings, and structural applications.

Marine

More than 90% of recreational boat hulls are constructed of composite materials. Gel coat is used on boat hulls as the durable outer layer to protect the structural fiberglass from water, UV damage, and abrasion. Color gel coat provides a smooth, glossy finish and can be easily repaired. 

Automotive

Fiberglass is most widely used, making up over 90% of all composites in the automotive market.  While carbon fiber accounts for less than 1% of total composite usage, it is used in nearly all high-performance vehicles for functional components.  In the broader luxury segment, over 50% of vehicles contain carbon fiber for both structural and cosmetic purposes.

Infrastructure

Tank lining repairs, for example, use vinyl ester, chopped strand Mat (CSM) and a clear coating to create a smooth, durable, highly chemical-resistant impermeable barrier to resist acids, alkali and solvents.  Composites are also used in bridge reinforcement, structural repair, and corrosion-resistant piping systems.

Renewable Energy

Modern wind turbines depend entirely on composite materials. Blades are constructed with fiberglass reinforced outer shells and carbon fiber reinforced structural components, a combination that delivers the stiffness and fatigue resistance required to survive decades of continuous cycling in harsh outdoor environments.

How to Choose the Right Type of Composite

Selecting the right composite material requires balancing performance, environment, and cost:

  • Structural load requirements
  • Environmental exposure
  • Temperature conditions
  • Manufacturing process
  • Weight constraints

Engineers often choose fiberglass for durability and cost efficiency, while carbon fiber is preferred when maximum stiffness and weight reduction are critical.

Learn more in: What do I need for my composites project?

Industries That Use Composite Materials

Composite materials are widely used in:

  • Aerospace / Aviation
  • Amusement
  • Arts /Modeling
  • Automotive
  • Construction / Infrastructure
  • Education
  • Energy
  • Fabricators
  • Manufacturing
  • Marine
  • Sports

Why Fibre Glast

Since 1957, Fibre Glast has supplied industrial-grade composite materials to engineers, fabricators, and manufacturers who cannot afford to compromise on material quality. Our technical team works directly with customers to match reinforcement fibers, resin systems, and core materials to the specific demands of each application, whether that means selecting a vinyl ester resin for a corrosive chemical environment or specifying a carbon fiber layup for a weight-critical aerospace structure.

Every shipment includes a Certificate of Conformance, and our ISO 9001 and AS9120B certified quality systems ensure that the material you receive meets the specifications your design depends on. From small quantities for prototype development to bulk chemical shipping by land or air, Fibre Glast provides the materials, expertise, and reliability that serious composite work requires.

Our technical team works directly with customers to match reinforcement type, fabric weight, and resin system to the specific demands of each application — whether that's selecting a woven roving for a marine hull layup or specifying a fiberglass-epoxy system for a corrosive industrial environment. To support the material selection process, our Materials Calculator helps engineers and fabricators quickly estimate quantities and compare options before committing to a system.

Capabilities include:

  • Same-day shipping for orders placed before 2:30 PM ET
  • Custom cut-to-length, custom color gel coat, small quantities
  • Worldwide distribution

About This Guide

This guide was developed by the Fibre Glast technical team to provide engineers, fabricators, and manufacturers with a practical overview of composite materials and their applications.

Key Takeaways

  • Composites combine reinforcing fibers and polymer resins
  • Carbon fiber composites offer extremely high stiffness
  • Fiberglass composites provide corrosion resistance and durability
  • Core materials increase stiffness while minimizing weight
  • Composite materials are used by professionals across virtually all industries and by hobbyists alike

Frequently Asked Questions about Composite Materials

What are composites made of?

Composites combine reinforcement fibers and polymer resins to form lightweight structural laminates.

Why are composites stronger than steel by weight?

Fibers carry loads efficiently while resin distributes stress, producing extremely high strength-to-weight ratios.

What industries use composite materials?

Aerospace / Aviation, Amusement, Arts / Modeling, Automotive, Construction / Infrastructure, Education, Energy, Fabrication, Manufacturing, Marine, and Sports markets rely heavily on composites.

What is the difference between carbon fiber and fiberglass?

Carbon fiber offers higher stiffness and lower weight, while fiberglass provides greater impact resistance and lower cost.

What resin should I use for marine applications?

Vinyl ester and epoxy resins are commonly used because of their superior resistance to water absorption.

Are composite materials corrosion resistant?

Yes. Fiberglass and carbon fiber composites resist corrosion far better than steel.

How long do composites last?

Fiberglass composites can last 50+ years in harsh environments.

What are sandwich panels in composite structures?

Sandwich panels use lightweight core materials between composite skins to increase stiffness.

What are the limitations of composites?

Composites offer significant performance advantages, but they are not without limitations. Upfront material and tooling costs are generally higher than steel or aluminum, which can make composites less economical for high-volume, low-performance applications.

Carbon fiber composites, while extremely strong in tension, can be brittle under impact loading and may delaminate when struck. Composites are also anisotropic, meaning their strength properties vary depending on fiber orientation, which requires more sophisticated engineering analysis than isotropic materials like steel.

Finally, composite parts are more difficult to inspect for internal damage, often requiring ultrasonic or other non-destructive testing methods.

Can composites be repaired?

Yes, in fact, maintenance/repair is one of the largest demand needs from our customers. Composites can be repaired effectively when the correct materials and procedures are followed.

Surface damage such as gel coat cracks or minor scratches can be addressed with gel coat repair compounds.

Structural damage - including delamination, cracks, or impact damage to the laminate - can be repaired by removing the damaged material and rebuilding the laminate with compatible reinforcement fibers and resin systems. The key to a successful structural repair is matching the original fiber orientation, resin system, and laminate thickness to restore the mechanical properties of the original part.

Fibre Glast supplies materials for both cosmetic and structural composite repair.

Composite Materials Learning Center

Explore Fibre Glast's additional educational resources:

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