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Reinforced rubber products are one of the largest groups of composite materials, though rarely referred to as composite materials. Familiar examples are automobile tyres, hoses, and conveyor belts.
Reinforced rubber products combine a rubber matrix and a reinforcing material so that high strength to flexibility ratios can be achieved. The reinforcing material, usually a kind of fibre, provides the strength and stiffness. The rubber matrix, with low strength and stiffness, provides air-fluid tightness and supports the reinforcing materials to maintain their relative positions. These positions are of great importance because they influence the resulting mechanical properties.
A composite structure in which all fibres are loaded equally everywhere when pressurized, is called an isotropic structure, and the type of loading is named an isotensoidal loading. To meet the isotensoidal concept the structure geometry must have an isotensoid meridian profile and the fibres must be positioned following geodesic paths. A geodesic path connects two arbitrary points on a continuous surface by means of the shortest possible way.
To achieve optimal loading in a straight rubber hose the fibres must be positioned under an angle of approximately 54.7 angular degrees, also referred to as the magic angle. The magic angle of 54.7 exactly balances the internal-pressure-induced longitudinal stress and the hoop (circumferential) stress, as observed in most biological pressurized fiber-wound cylinders, like arteries. If the fiber angle is initially above or below 54.7, it will change under increased internal pressure until it rises to the magic angle where hoop stresses and longitudinal stresses equalize, with concomitant accommodations in hose diameter and hose length. A hose with an initially low fiber angle will rise under pressure to 54.7, inducing a hose diameter increase and a length decrease, whereas a hose with an initially high fiber angle will drop to 54.7, inducing a hose diameter decrease and a length increase. The equilibrium state is a fiber angle of 54.7. In this situation, the fibres tend to be loaded purely in tension, so ~100% of their strength resists the forces acting on the hose due to the internal pressure. (The magic angle for cylindrical shapes of 54.7 angular degrees is based on calculations in which the influence of the matrix material is neglected. Therefore, depending on the stiffness of the rubber material used, the actual equilibrium angle can vary a few tenths of degrees from the magic angle.)[ citation needed ]
When the fibres of the reinforcement structure are placed under angles larger than 54.7 angular degrees, the fibres want to relocate to their optimal path when pressurized. This means that the fibres will re-orient themselves until they have reached their force equilibrium. In this case this will lead to an increase in length and a decrease in diameter. With angles smaller than 54.7 degrees the opposite will occur. A product which makes use of this principle is a pneumatic muscle.
For a cylinder with a constant diameter, the reinforcement angle is constant as well and is 54.7º. This also known as the magic angle or neutral angle. The neutral angle is the angle where a wound structure is in equilibrium. For a cylinder, this is 54.7º, but for a more complex shape like a bellows which has a varying radius over the length of the product, this neutral angle is different for each radius. In other words, for complex shapes there is not one magic angle but the fibres follow a geodesic path with angles varying with the change in radius. To obtain a reinforcement structure with isotensoidal loading the geometry of the complex shape must follow an isotensoid meridian profile.
The mil fabric reinforcement can be applied on the rubber products with different processes. For straight hoses, the most used processes are braiding, spiralling, knitting, and wrapping. The first three processes have in common that multiple strands of fibres are applied to the product simultaneously on a predetermined pattern in an automated process. The fourth process comprises manual or semi-automated wrapping of rubber sheets reinforced with fabric plies. For the reinforcement of complex shaped rubber products like bellows most manufacturers use these fabric reinforced rubber sheets. These sheets are made by calendering of rubber onto pre-woven fabric plies. The products are manufactured by wrapping (mostly manually) these sheets around a mandrel until enough rubber and reinforcement is applied. However, the disadvantage of using these sheets is that it is impossible to control the positioning of the individual fibres of the fabric when applied on complex shapes. Therefore, no geodesic paths can be achieved and therefore also no isotensoid loading is possible. To obtain isotensoide loading on a complex shape, the shape must have an isotensoideal profile and geodesic positioning of the fibre structure is required. This can be achieved by using automated winding processes like filament winding or spiralling.
A fire hose is a high-pressure hose that carries water or other fire retardant to a fire to extinguish it. Outdoors, it attaches either to a fire engine, fire hydrant, or a portable fire pump. Indoors, it can permanently attach to a building's standpipe or plumbing system.
A composite material is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a material with properties unlike the individual elements. Within the finished structure, the individual elements remain separate and distinct, distinguishing composites from mixtures and solid solutions.
Carbon fibers or carbon fibres are fibers about 5 to 10 micrometers (0.00020–0.00039 in) in diameter and composed mostly of carbon atoms. Carbon fibers have several advantages: high stiffness, high tensile strength, high strength to weight ratio, high chemical resistance, high-temperature tolerance, and low thermal expansion. These properties have made carbon fiber very popular in aerospace, civil engineering, military, motorsports, and other competition sports. However, they are relatively expensive compared to similar fibers, such as glass fiber, basalt fibers, or plastic fibers.
Fiberglass or fibreglass is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth. The plastic matrix may be a thermoset polymer matrix—most often based on thermosetting polymers such as epoxy, polyester resin, or vinyl ester resin—or a thermoplastic.
A paper machine is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.
A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex cross-sections; and to work materials that are brittle, because the material encounters only compressive and shear stresses. It also creates excellent surface finish and gives considerable freedom of form in the design process.
Fibre-reinforced plastic is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass, carbon, aramid, or basalt. Rarely, other fibres such as paper, wood, boron, or asbestos have been used. The polymer is usually an epoxy, vinyl ester, or polyester thermosetting plastic, though phenol formaldehyde resins are still in use.
A hose is a flexible hollow tube designed to carry fluids from one location to another. Hoses are also sometimes called pipes, or more generally tubing. The shape of a hose is usually cylindrical.
Basalt fibers are produced from basalt rocks by melting them and converting the melt into fibers. Basalts are rocks of igneous origin. The main energy consumption for the preparation of basalt raw materials to produce of fibers is made in natural conditions. Basalt continuous, staple and super-thin fibers are produced and used. Basalt continuous fibers (BCF) are used for the production of reinforcing materials and composite products, fabrics and non-woven materials. Basalt staple fibers - for the production of thermal insulation materials. Basalt superthin fibers (BSTF) - for the production of high quality heat and sound insulating and fireproof materials.
An expansion joint, or movement joint, is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials. They are commonly found between sections of buildings, bridges, sidewalks, railway tracks, piping systems, ships, and other structures.
Glass fibre reinforced concrete (GFRC) is a type of fibre-reinforced concrete. The product is also known as glassfibre reinforced concrete or GRC in British English. Glass fibre concretes are mainly used in exterior building façade panels and as architectural precast concrete. Somewhat similar materials are fibre cement siding and cement boards.
Fiber-reinforced concrete or fibre-reinforced concrete (FRC) is concrete containing fibrous material which increases its structural integrity. It contains short discrete fibers that are uniformly distributed and randomly oriented. Fibers include steel fibers, glass fibers, synthetic fibers and natural fibers – each of which lend varying properties to the concrete. In addition, the character of fiber-reinforced concrete changes with varying concretes, fiber materials, geometries, distribution, orientation, and densities.
Textile-reinforced concrete is a type of reinforced concrete in which the usual steel reinforcing bars are replaced by textile materials. Instead of using a metal cage inside the concrete, this technique uses a fabric cage inside the same.
A braiding machine is a device that interlaces three or more strands of yarn or wire to create a variety of materials, including rope, reinforced hose, covered power cords, and some types of lace. Braiding materials include natural and synthetic yarns, metal wires, leather tapes, and others.
Carbon fiber-reinforced polymers, carbon-fibre-reinforced polymers, carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic, also known as carbon fiber, carbon composite, or just carbon, are extremely strong and light fiber-reinforced plastics that contain carbon fibers. CFRPs can be expensive to produce, but are commonly used wherever high strength-to-weight ratio and stiffness (rigidity) are required, such as aerospace, superstructures of ships, automotive, civil engineering, sports equipment, and an increasing number of consumer and technical applications.
Three-dimensional composites use fiber preforms constructed from yarns or tows arranged into complex three-dimensional structures. These can be created from a 3D weaving process, a 3D knitting process, a 3D braiding process, or a 3D lay of short fibers. A resin is applied to the 3D preform to create the composite material. Three-dimensional composites are used in highly engineered and highly technical applications in order to achieve complex mechanical properties. Three-dimensional composites are engineered to react to stresses and strains in ways that are not possible with traditional composite materials composed of single direction tows, or 2D woven composites, sandwich composites or stacked laminate materials.
3D braided fabrics are fabrics in which yarn runs through the braid in all three directions, formed by inter-plaiting three orthogonal sets of yarn. The fiber architecture of three-dimensional braided fabrics provides high strength, stiffness, and structural integrity, making them suitable for a wide array of applications. 3D fabrics can be produced via weaving, knitting, and non-weaving processes.
In materials science, reinforcement is a constituent of a composite material which increases the composite's stiffness and tensile strength.
