Print All Sections (Parts 1-4)

COMPOSITES BASICS: MATERIALS (PART 1)

Introduction

Fiber Reinforced Polymer (FRP) composites is 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. FRP composites are different from traditional construction materials such as steel or aluminum. FRP composites are anisotropic (properties only apparent in the direction of the applied load) whereas steel or aluminum is isotropic (uniform properties in all directions, independent of applied load). Therefore, FRP composite properties are directional, meaning that the best mechanical properties are in the direction of the fiber placement. Composites are similar to reinforced concrete where the rebar is embedded in an isotropic matrix called concrete.

Many terms have been used to define FRP composites. Modifiers have been used to identify a specific fiber such as Glass Fiber Reinforced Polymer (GFRP), Carbon Fiber Reinforced Polymer (CFRP), and Aramid Fiber Reinforced Polymer (AFRP). Another familiar term used is Fiber Reinforced Plastics. In addition, other acronyms were developed over the years and its use depended on geographical location or market use. For example, Fiber Reinforced Composites (FRC), Glass Reinforced Plastics (GRP), and Polymer Matrix Composites (PMC) can be found in many references. Although different, each of aforementioned terms mean the same thing; FRP composites.  

Benefits

FRP composites have many benefits to their selection and use. The selection of the materials depends on the performance and intended use of the product. The composites designer can tailor the performance of the end product with proper selection of materials. It is important for the end-user to understand the application environment, load performance and durability requirements of the product and convey this information to the composites industry professional. A summary of composite material benefits include:

	Light weight
	High strength-to-weight ratio
	Directional strength
	Corrosion resistance
	Weather resistance
	Dimensional stability low thermal conductivity low coefficient of thermal expansion
	Radar transparency
	Non-magnetic
	High impact strength
	High dielectric strength (insulator)
	Low maintenance
	Long term durability
	Part consolidation
	Small to large part geometry possible
	Tailored surface finish

Composition

Composites are composed of resins, reinforcements, fillers, and additives. Each of these constituent materials or ingredients play an important role in the processing and final performance of the end product. The resin or polymer is the “glue” that holds the composite together and influences the physical properties of the end product. The reinforcement provides the mechanical strength. The fillers and additives are used as process or performance aids to impart special properties to the end product.

The mechanical properties and composition of FRP composites can be tailored for their intended use. The type and quantity of materials selected in addition to the manufacturing process to fabricate the product, will affect the mechanical properties and performance. Important considerations for the design of composite products include:

	Type of fiber reinforcement
	Percentage of fiber or fiber volume
	Orientation of fiber (0o, 90o, +/- 45 oor a combination of these)
	Type of resin
	Cost of product
	Volume of production (to help determine the best manufacturing method)
	Manufacturing process
	Service conditions

Go to next section: Resins
á Top