What are the materials of the FRP boats?

In the past few decades, the shipbuilding industry has undergone two revolutions. The first is of course the shift from wood to fiberglass, but the second is more subtle because the buyer has just found it overwhelmed. The transition from traditional fiberglass methods to a series of peculiar materials and techniques can even transform experienced FRP ship operators with buzzwords and jargon.

However, the concept is basically the same. Glass fiber reinforced plastics are still fibrous materials in resin-bonded materials. In the early years, glass fiber was glass fiber, but it soon became a variety of synthetic plastic fibers. For many years, glass fiber has been manufactured from fabrics, rovings, mats and resins that you can buy at any hardware store. However, today, a degree in chemical engineering is useful when reading the instructions for a new ship.

Some of these advances come from the efforts of sea racing and marine sailing manufacturers to produce lighter, stronger and therefore faster FRP vessels, but the real impact comes from the energy crisis. Since fiberglass is a petrochemical product, the elimination of one fiberglass per fiberglass ship can save the builder a lot of cost, so it is necessary for the manufacturers of the FRP ship to study how to make the ship lighter, not Cause any loss. For motorboat manufacturers, a light but sturdy FRP boat is also more fuel efficient in the minds of buyers.

Most of the research and development actually comes from the aerospace industry. Power and weight have always been the main concerns. The tricks of technology have become waterfalls, and many ship owners do not know the changes.

Let's take a look at the materials of the FRP ship and define some new languages.

Resin

There are three types of resins (polyester, vinyl ester and epoxy) listed below, and they all have a place in the shipbuilding world. An important factor is that the builder can correctly match the resin to the type of reinforcement being used to match the strength. For example, a vinyl ester resin is desirable for S glass, but when used with E glass, the reinforcing material will fail prior to the resin.

Polyester:

This is a resin commonly used in the shipbuilding industry today, and most ship owners are familiar with it. It is cheap and usually versatile. It has poor tensile (elongation) properties and is therefore not suitable for modern high performance FRP vessels, but is adequate for most FRP vessels. The most common polyesters are phthalic acid based polymers, but newer isophthalate-based polyesters are gaining popularity. Isophthalate is more resistant to water and chemicals, is more resistant to wear, and has higher impact and fatigue (bending) properties. Most modern gel coats are made of isophthalic resin, and it is likely that isophthalate will become a common shipbuilding resin in the future.

Vinyl ester:

Compared to polyesters, vinyl esters are believed to have better stretch characteristics than polyesters, so they are closer to the strength of various foreign reinforcement materials. Vinyl esters have good water and fatigue resistance, but are also more expensive than polyester resins. An important feature of vinyl esters is their excellent secondary bond strength, so bulkheads or purlins added to the cured FRP hull will be stronger than polyester hulls.

Epoxy resin:

This is a high performance resin with a matching price tag. Due to the early thickness of epoxy resins, epoxy resins are known for their difficulty in working, but many modern epoxy resins are quite fluid. Epoxy resin adheres to a variety of materials than any other resin, making it ideal for joining cores, purlins or other items.

Glass fiber cloth

Woven fabrics using continuous yarns are the most common fabrics weighing between 4 and 15 ounces per square yard. The heavier weight, commonly referred to as roving or woven roving, consists of a twistless yarn weighing 48 ounces per yard. The finished roving is similar to burlap and, like all cloths, has good bidirectional strength; that is, in the N-S and E-W directions. Lighter fabric weights can be found in a variety of weave patterns, such as twill, satin and matt, for different purposes.

E-Glass:

This is the most commonly used fiberglass cloth in the shipbuilding industry today. You can buy E glass in a marine hardware store and bond it with polyester resin. It is spun from a fused plastic into fine fibers and then woven into a cloth or loosely gathered into a roving.

S-Glass:

This is a high performance fiberglass cloth for the aircraft industry. It is three to five times more expensive than E-glass, but it is much stronger. Developed by Owens-Corning, it has higher tensile strength, impact strength and flexural strength of 20-40% than E-glass. There are two types of S-glass: S-1, which meets key aerospace standards and are very expensive; and S-2 for the marine industry. In Europe, S-glass is called R-glass.

mat:

The mat is typically made of E-glass and held in place by a random 2 to 3 inch fiber from a resin-soluble adhesive. Pads are primarily used for the thickness (and stiffness) of architectural fiberglass laminates. The pad is resistant to "print through" where the woven roving is shown on the outer layer of the hull, but it also soaks a large amount of fiberglass and is relatively low in weight.

Unidirectional fiber:

This is one of the advancements in reinforcement materials. It consists of a unidirectional fiber chain that is bonded together by a single fiber, bonded or stitched laterally, just as a bamboo fence is bundled together by several wires. Obviously it has a high directional strength and can therefore be used in load-specific areas. Because it is non-woven, there is no kinking, and the staff is more likely to "wet" with the resin because it does not hold the air like a cloth.

Biaxial fiber:

Technically, most fabrics are biaxial, but modern definitions refer to fabrics composed of unidirectional fabric layers that are not interwoven with each other. A layer is simply placed on the next layer to create a non-kinked ribbon.

Triaxial fiber:

This is a layered material similar to a biaxial cloth, except that the fibers are oriented in three directions, typically 120 degrees from each other to distribute the load.

Non-traditional fiber;

carbon fiber:

These graphite fibers provide excellent stiffness as well as high tensile strength and compressive strength and are often used with S glass or other foreign materials to provide acceptable impact resistance which would otherwise be very low. Carbon fiber is very expensive, but in many cases it can go beyond metal. Many companies produce carbon fiber worldwide, depending on the carbon content of the fiber itself, some for high-strength applications and others for high modulus (hardness). It is the most expensive fiber reinforcement available, and costs more per pound than 100 times normal E glass. Carbon fiber is second only to Kevlar, and carbon fiber is superior in rigidity to any other fiber at a given strength.

Kevlar:

The trade name of DuPont products, used to refer to DuPont's aramid fiber, the world's only manufacturer. An aromatic polyamide (often abbreviated as aramid), Kevlar is a nylon form originally developed in the mid-1960s to strengthen the band of radial tires with "Fiber B". This unique product is quickly used for other purposes, and the public generally considers Kevlar to be a bulletproof jacket. In fact, there are two forms of Kevlar available. Kevlar 29 is used for wiring, cables and bulletproof sleeves, while Kevlar 49 is used as a reinforcing fiber in plastic composites. Kevlar has the highest specific tensile strength of any commercial fiber in terms of strength of weight comparison. It is five times stronger than steel and twice as strong as E glass, which allows the Kevlar FRP hull to maintain the same strength as the E-glass hull, only a fraction of the weight. Impact strength is also a Kevlar strength that withstands repeated shocks and resists the tendency of crack propagation of other reinforcing fibers. Kevlar's negative impact is a significant weakness in compressive strength, so it is often used with other fibers that balance this property.

Nomex:

A chemical developed by DuPont, Nomex is known for its fire performance and is used in fire protection for firefighters and racers. It is an aramid which turns into a honeycomb paper-like substance.

Hybrid:

These are reinforced fabrics that combine two or more different types of fibers. A common mixture is a mixture of Kevlar and carbon fibers. Kevlar offers high impact resistance while carbon fiber provides rigidity. The combination of S glass, Kevlar and carbon fiber also optimizes certain properties at minimal cost.

Core material

Core materials are often used to reduce weight and increase stiffness. Some builders surrounded the entire ship. Others built from solid fiberglass below the waterline, and others used a mixture of coring and solid glass throughout the fiberglass boat.

Balsa core:

When used for the first time as a FRP hull rib, the FRP ship manufacturer puts the balsa woodwork of the long plank into the hull, but this method leads to decay and structural damage as the water passes through the entire board "prank". At the beginning, balsa wood was a long time, but modern balsa is now the most widely used coring material on board. The solution comes from cutting the grain, turning to the edges, and creating a checkerboard pattern of telomeres that do not transfer moisture. The result is a core material that is rigid, lightweight, and inexpensive, with good impact quality and high compressive strength. An additional feature is the low noise, thermal variation, and vibration of the insulation quality of balsa wood. A negative factor is that balsa can absorb the resin and make the hull heavier, but quality work can prevent this from happening.

PVC foam:

Airex and Klegecell (kledge-a-cell for pronunciation) are the most commonly used commercially produced foam cores today. Both are closed cell foams made of polyvinyl chloride, but each has different characteristics. Airex is a non-crosslinked polyvinyl chloride that makes it more flexible and resistant to damage. Klegecell is a very hard crosslinked foam. Ships built abroad usually use Divinecell, a Scandinavian version of Klegecell.

Honeycomb core material:

The honeycomb core is like its name: a honeycomb-like material that provides the highest stiffness of any core of equal weight. Compression and shear strength are second to none, which can be expected from materials originally used for floor and bulkhead aircraft. Nomex Honeycomb Core is the most common FRP boat, although it is definitely a luxury for owners looking for the last ounce of weight savings. Surprisingly, some honeycomb cores are made of paper. The kraft paper is impregnated with resin and then formed into a honeycomb to make it waterproof and strong, but the paper honeycomb is heavier than the polyaramid. The "skinning panel" is a ready-made honeycomb panel, similar to a plywood, which can be made of teak veneer or a variety of other cover panels that can be cut into ready-made honeycomb separators.