The Basics of FRP

What are Fiber Reinforced Polymers?

Fiber Reinforced Polymers (FRP) have been defined using many terms.  Around the world FRP also goes by other names depending on market and geographic location; Fiber Reinforced Composites (FRC), Glass Reinforced Plastics (GRP), and Polymer Matrix Composites (PMC) are examples.

To keep things simple, here is a clear, concise definition.  Fiber Reinforced Polymer composites are defined as a polymer (plastic) matrix, either thermoset or thermoplastic, that is reinforced (combined) with a fiber or other reinforcing material with a sufficient aspect ratio (length to thickness) to provide a discernable reinforcing function in one or more directions.

Four Main Ingredients of Fiber Reinforced Polymers

  • Resins
  • Reinforcements- Fibers and Forms
  • Fillers
  • Additives and Modifiers

Capacity Capabilities Solutions

Through the proper selection of reinforcement, resin, and manufacturing process, a composite is design-engineered to exacting specifications for cost-effectiveness and performance.  At Beetle we can take your design idea and turn it into a constructible solution.

We will exceed your expectations for project timing, design and integration, and finished product quality. We offer unrivaled industry know-how and precision capabilities to help assist you with your specific challenges.

Anisotropic vs. Isotropic

There are significant differences with respect to mechanical properties when comparing FRP with metals such as steel or aluminum.  FRP are anisotropic, that is, they posses mechanical properties only in the direction of the applied load.  In other words, their best mechanical properties are in the direction of the fiber placement.  Conversely, steel and aluminum are isotropic, giving them uniform properties in all directions, independent of the applied load.

Dimensional Stability

According to an Introduction to Dimensional Stability of Composite Materials, 2004, by Ernest G. Wolff, dimensional stability is a relative term; it does not really exist except within the artificial confines of a tolerance, specification or measurement accuracy.  This is because, at an atomic level all materials respond to internal or external stresses, to temperature, to the absorption of solutes, to radiation, gravity, and most likely any conceivable phenomenon.

That being said, composites have exceptional inherent dimensional stability potential due to their unique formulations.  Because composites are customizable, they can be designed to maximize the benefits of structural properties. They are often selected by engineers when applications requiring stringent dimensional stability under a variety of extreme conditions exist.

Because composites have good dimensional stability or structure, and other properties such as light weight, strength, toughness, damage tolerance, fatigue and fracture resistance, notch sensitivity, and general durability, they are desirable for many applications in a variety of industries.

For example, composites are used in structural applications for aircraft, spacecraft, automobiles, railcars, automobiles, sports equipment, missiles, infrastructure, chemical processing, and energy generation devices, such as cooling towers and wind turbines.


There are four main ingredients that FRP are comprised of: resins, reinforcements, fillers and additives/modifiers.  Each ingredient is equally important and all ingredients play an important role in determining the properties of the finished FRP products.  To simplify, think of the resin (polymer) as the glue or the binding agent.  The mechanical strength is provided by the reinforcements.


The primary functions of the resin are to transfer stress between the reinforcing fibers, act as a glue to hold the fibers together, and protect the fibers from mechanical and environmental damage. Resins are divided into two major groups known as thermoset and thermoplastic. Thermoplastic resins become soft when heated, and may be shaped or molded while in a heated semi-fluid state and become rigid when cooled. Thermoset resins, on the other hand, are usually liquids or low melting point solids in their initial form.

Reinforcements- Fibers and Forms

There are four main types of fibers commonly used in the FRP industry; glass, carbon, natural and arimid. Each has their own advantages and applications. Similarly, reinforcements are available in forms to serve a wide range of processes and end-product requirements. Common materials used as reinforcement include woven roving, milled fiber, chopped strands, continuous, chopped or thermoformable mat. Reinforcement materials can be designed with unique fiber architectures and be preformed (shaped) depending on the product requirements and manufacturing process.


Fillers are used as process or performance aids to impart special properties to the end product. Some examples of inorganic fillers include calcium carbonate, hydrous aluminum silicate, alumina trihydrate and calcium sulfate.  In some circumstances, fillers and additives play a critical role in lowering the cost of compounds by diluting expensive resins and reducing the amount reinforcements.  Furthermore, fillers and additives improve compound rheology, fiber loading uniformity, enhance mechanical and chemical performance and reduce shrinkage.

Additives and Modifiers

Additives and modifiers perform critical functions despite their relative low quantity by weight when compared to the other ingredients; resins, reinforcements and fillers.  Some additives used in thermoset and thermoplastic composites include: low shrink/low profile (when smooth surfaces are required), fire resistance, air release, emission control, viscosity control, and electrical conductivity, are among others.

An important note is that FRP products can be custom made for their intended use.  Understanding the intended function and services of the FRP, will aid the design and manufacturing processes to allow for an optimal finished product (i.e. corrosion resistance).  Modifiers can include catalyst, promoters, inhibitors, colorants, release agents and thixotropic agents (fumed silica and certain clays).

Key Benefits of Using FRP

There are a multitude of key benefits realized when utilizing FRP in your project design.

For starters they are light-weight, extremely strong, low maintenance, durable, weather resistant, corrosion and abrasion resistant, and in many cases cost-effective.  FRP are the ultimate materials solution.

  • Light Weight
  • Directional Strength
  • Weather Resistant
  • Radar Transparency
  • High Dielectric Strength
  • Long-Term Durability
  • Noise Reduction
  • Custom Surface Finish
  • Does Not Require Cathodic Protection
  • High Strength to Weight Ratio
  • Corrosion and Abrasion Resistant
  • Non-Magnetic
  • High Impact Strength
  • Low Maintenance
  • Part Consolidation
  • UV Resistant
  • Dimensional Stability
  • Low thermal conductivity
  • Low coefficient of thermal expansion