How to Choose the Right Composite Material
Composites are widely employed as they combine the benefits of many materials, such as high strength, low weight, and corrosion resistance, composites are frequently employed. The correct materials for a composite construction must be chosen, though, and this is not an easy process. The design requirements, the loading circumstances, the environmental conditions, and the cost-effectiveness are only a few of the variables that must be taken into account.
Factors to consider
Understanding the material qualities of the elements is the first step in selecting the appropriate materials for a composite construction. The most prevalent components are fibers and matrices, which serve as the composite’s binder and reinforcement, respectively. The fibers offer excellent stiffness and strength along their path and can be formed of carbon, glass, aramid, or other materials. The matrices, which can be formed of polymers, metals, or ceramics, provide the composite its ductility and shear strength. The mechanical behavior, durability, and compatibility of the composite are determined by the material qualities of the constituents.
High strength, low weight, rust-free, and durability are the features of composite materials that set them apart from traditional materials. Unique constructions that are projected to survive for more than 50 to 100 years need to be durable. Remember that the usage of composite materials depends on the intermediate glue that is used with them, such as epoxy, which has a high strength but low resistance to heat temperature and fire exposure.
The selection of the optimal mix of elements based on the design requirements is also considered in making the best material choice for a composite construction. The structural performance, service life, weight savings, and aesthetics of the composite construction can all be considered as design factors. For instance, a carbon fiber reinforced polymer (CFRP) composite with excellent thermal stability and fatigue resistance would be the best option if you require a composite structure that can tolerate high temperatures and pressures. GFRP composites, which have high toughness and fracture toughness, are an option if you require a composite structure that can withstand impact and abrasion.
Optimizing the material characteristics based on the loads and environmental circumstances is also a factor in selecting the appropriate materials for a composite construction. The composite’s layering order, matrix type, fiber volume fraction, and fiber orientation are only a few examples of the material parameters. These variables have an impact on the composite structure’s failure modes, strain distribution, and stress distribution. As an illustration, you may optimize the fiber orientation to correspond with the major stress direction if you require a composite construction that can support bending loads. The layer sequence may be optimized to alternate different fiber orientations if you need a composite structure that can resist delamination.
Characterizing the behavior of the material under various conditions is to be considered in selecting the best materials for a composite structure. Elastic modulus, strength, fracture toughness, and composite creep are all examples of material behavior. Numerous tests, including tensile, compression, shear, and fatigue ones, can be used to determine these qualities. The test findings can provide important details concerning the dependability and efficiency of the composite construction. For instance, you may define the material behavior to confirm compliance if you require a composite construction that can adhere to specific safety regulations.
Analytical or numerical modeling of the material response should be also considered. The connection between stress and strain, the criterion for failure, and the progression of the composite’s damage can all be included in the material response. These models can assist you in forecasting how the composite structure will behave and if it will fail under various loads and environmental scenarios. For instance, you may simulate the material reaction using finite element analysis (FEA) or other optimization techniques if you require a composite structure that can optimize its shape and size.
Investigating the potential for material innovation is another factor. The creation of novel composite elements, combinations, techniques, or applications is a form of material innovation. These developments may improve the composite structure’s usefulness, performance, durability, or sustainability. For instance, you can look into the usage of smart materials like shape memory alloys, piezoelectric materials, or self-healing materials if you require a composite structure that can adapt to changing conditions.
Cost vs. Performance
|Relative new market– There is plenty to learn and develop. To do this, it costs time and money.
|Low weight to high strength ratio- This is the prime factor in composites’ performance.
|Risk of delamination – Danger exists where two or more materials are joined together because of the possibility of air pockets, inadequate compression, or a high enough temperature. When delamination is place, the composite is vulnerable to more delamination, weakening, and losing its suitability for use. The most frequent cause of matrix parallel or perpendicular cracks is excessive stress that exceeds the matrix’s capacity to withstand it. When inappropriate materials are utilized as the matrix, delamination can also happen. This problem can be solved by altering the matrix or fortifying it with a different, stronger reinforcing material.
|Dimensional stability– Despite exposure to moisture, chemicals, and a variety of other environmental variables, composite materials can preserve their original strength and form.
|Complex fabrication – Although the spectrum of composites is so broad, some composites can be quite simple and effective for their intended use, while others can be exceedingly complex. The fabrication process can take hours of conception, research, and manufacture. This requires knowledge, resources, and time, and, as with any testing for a new product, there may be limits to how much can be learned about the new composite product, its durability, and its performance during its lifetime.
|Custom Design – They may be made to order, and during the design and production phases, a variety of aspects are taken into account to guarantee that the final product is the best design possible for its intended use, both visually and practically. Once a composite has been created, it may be modified as needed for continual advancements and produced to exacting standards. For merely aesthetic reasons, many people like composite materials. A composite may be created to meet all functional requirements while having its look adjusted to properly match a modern design. In the huge architectural, automotive, and marine sectors, this is tremendously helpful.
|High cost of raw materials – There are a variety of factors that affect the cost of the raw materials depending on the kind of composite in question. These consist of the resin, fiber, supplies, labor, and equipment. There are, of course, additional expenses to take into account, such as the cost of enforcing rules, research, quality control, and other factors.
|Resistance to corrosion – Composites have a natural resistance to corrosion. As a result, less frequent maintenance is required and the lifespan is extended. This is very beneficial in many fields, but particularly in the marine and maritime ones because sections there are frequently submerged in salt water or exposed to the most extreme weather.
|Repair cost– Although every effort is taken throughout composites manufacture to ensure that repairs are rarely necessary, when they occur, the cost of repairs can be high.
Once composites are installed, it can be challenging to find flaws and damage, but a technique known as non-destructive testing (NDT) can find damage that is hidden from view or in hard-to-reach places.
|Durability – Because composite materials are made with a specific use in mind, all known environmental, chemical, and other conditions are always taken into consideration during design and manufacturing. For instance, a composite material utilized in the marine industry will always be developed to be impervious to corrosion, watertight, exceptionally strong with dimensional stability, and able to tolerate extremes in weight and temperature.
|Labor-intensive– Because of how composite materials are made, there is a certain amount of labor and specialized equipment required in the various phases leading up to manufacturing. This may cost money. However, these costs decrease as composites become standard items in all the areas where they are often utilized. With the exception of any mentioned enhancements that may be made, the development and research stages are mostly complete, and composites show themselves to be appropriate for their application over time. The most effective portion of the process is currently the manufacturing stage, and with each new composite developed, knowledge from earlier studies is incorporated.
|Radar absorbent– Another significant advantage of composites is their potential to be radar transparent and absorbent materials (RAM). Thanks to the absorption of radio frequency interference, this is proving useful in many fields, including as wind turbines for wind energy as well as aerospace, defense, and all glass applications.
|Flexibility and Strength – Composite materials may be engineered to be as flexible and strong as needed for a given application. There are several methods to increase strength.
The Long-term Value
It’s simple to object to the price of carbon fiber and pick a less expensive substance in its place. It’s crucial that you consider value over the long run as opposed to value now.
Buying something less expensive might help you save money in the near run. However, as always, you get what you paid for. Cheaper materials may need to be replaced more frequently, which will require more effort and money on your part.
One of the primary justifications for using composite materials over traditional materials for components is weight savings. In addition to being stronger than other materials, composites may also be lighter. For instance, reinforced carbon fiber can be up to five times stronger than 1020 grade steel while weighing just one fifth as much, making it ideal for structural use.
The thermal, chemical, and electrical insulating capabilities of a composite material are additional benefits over those of a typical type of material. Composites, as opposed to traditional materials, can exhibit a variety of qualities that are rarely encountered in a single material.
Fiber reinforced composites, including fiber reinforced plastic (FRP composites), are being used more often in the design and production of finished goods intended for sale.
Research on “Self-Repairing” composite materials will provide engineers with major advantages when using composites in challenging or dangerous conditions.
It is important to note that composite materials are not the only ones that have a risk of repairs and maintenance. In places where non-composite materials are utilized, it is really far more prevalent. The entire idea behind developing composite materials for parts in so many sectors is that they may be specifically created for the task at hand. The allows the designer the opportunity to take into account all requirements and expectations for each element.
5. Working with Composite Materials
Workers using composites must be trained in its use such as:
- A suitable extraction or ventilation system must be used when performing tasks involving dry machining of carbon fiber.
- The SDS must be followed while doing tasks that require the use of solvents and resins. Working in well-ventilated spaces, employing a fume closet, or using a spray booth are all examples of this.
- To reduce the production of dust or particulates when milling carbon fiber,
- Processing the material when wet
- Using a hand tool without a motor
- Cutting ‘green’ or partially-cured material.
- Each work area must include emergency eyewash stations and hand washing facilities.
- Each work location must have a first aid kit on hand. All skin and eye contact must be avoided.
Safety Tips for Painting Composite Materials
As with any DIY project, careful planning is essential to a nice-looking, long-lasting result. However, even more crucial is adhering to all advised safety measures for the goods you use and the jobs involved.
- Wear gloves whenever working with fiberglass.
- When using bleach or solvents, wear gloves that can withstand liquids.
- When dealing with fiberglass, bleach, or sanding, put on eye protection.
- When using bleach or solvents, make sure there is enough ventilation.
- For every job, check the manufacturer’s specs first.
5.1 Safety Measures in Model Airplane Construction
The safety risks associated with numerous chemicals, including paints and solvents, are described in a Material Safety Data Sheet (MSDS). The law requires manufacturers to provide you this information. An MSDS is often available at the point of sale. In the absence of an MSDS, get in touch with the manufacturer, who will provide one to you. On all of your tools and any chemicals you use, read and pay attention to the cautions.
Hardware shops and home improvement stores both sell chemical gloves. They serve to safeguard your skin and stop chemical absorption via your skin. Use them when handling substances that you don’t want on your hands or in your skin, such as solvents.
Older chemical gloves had some sort of rubber construction and stuck together when removed. Since they fit extremely loosely, it was challenging to feel the area that was being worked on. If you have old-style gloves, wash them by turning them inside-out. When they are dry, flip them over right side out and dust them with baby powder.
Home improvement stores sell gloves with a cotton lining inside to keep them from fusing together. These gloves fit better and provide for greater feeling when worn. The lining makes it simple to put on and take off the gloves. You may buy latex gloves at home improvement stores. They offer a better grip and don’t obstruct my touch perception.
A high-quality charcoal mask and dust masks (the kind that resemble doctor’s masks) are available in a range of functions. To ensure that you know what you are buying, always read the box.
Do not purchase the mask if the packaging does not make it clear what the mask is meant to protect you against and, more crucially, what it is not meant to protect you from.
The main purpose of particle masks is to prevent you from breathing in dry airborne particles like sawdust. When dealing with some woods, a mask should not be viewed as optional because they might be hazardous. It doesn’t matter whether the dust is non-toxic if you’re spewing it out in huge clouds. No powder of any type should be allowed to enter your lungs. A particle or dust mask, however, won’t shield you from liquid particles.
Chemical protection systems
Many hardware stores and home improvement businesses sell Chemical Protection Systems. Use of dangerous liquid chemicals always requires the use of protective clothing.
Some paints and chemicals call for the usage of a straightforward chemical mask that filters the substance out using charcoal or a canister of a similar design. After the container is opened, canisters have a limited shelf life. For the mask to continue shielding you from harm, you must change the canisters as instructed by the manufacturer.
Use of a respirator with a self-contained air supply is necessary when handling really dangerous compounds. For advice on how to protect yourself, always check with the chemical’s manufacturer.
Remember that a mask won’t shield you from fumes if you can smell them while wearing one. While being unable to smell fumes does not automatically confer protection, being able to smell them does not imply that you are.
Although it should go without saying, you must first ensure that your scale modeling workstation has a level surface that is big enough to accommodate all of your model pieces and equipment. That may be a workbench, coffee table, picnic table outside, or a desk. Storage for your tools, components, paints, and any other stuff you could require on your construction trip is another crucial factor to take into account when first setting up. Maintaining order in your workspace will help scale modeling go more smoothly.
Therefore, make sure you’ve put up the required shelves and storage bins to keep everything organized before you unpack your kits. Space for a desktop or laptop computer is one more item to think about. Having a computer nearby allows you easy access to digital build instructions, video tutorials, and other model-related research.
Making room for a spray booth is a smart idea if you intend to airbrush your models. Additionally, it is very advised that your desk be close to a window.
The next thing you should put up is your lighting once you’ve decided where you’ll be building. Your office should ideally be next to a window or have a skylight above to let in natural light on a regular basis. You’ll need a room with great overhead lighting as well as a lamp for supplementary illumination if that is not an option for you. A magnifying lamp is an excellent alternative since it offers both direct, strong lighting and a magnifying lens for those smaller, more challenging portions.
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5.2 Tools Required for Working with Composites
List of essential tools
Here are hand and small power tools for composites work. These are especially helpful in doing a variety of work on composites.
This will serve as the location for cutting dry material, preparing vacuum-bagged material, trimming and fitting core sheets and for pretty much any composites operation. A few straightforward tools will simplify everything.
A big work area is good, and one that is covered with a cutting mat is even better! These may be purchased from sign supply businesses in sizes ranging from medium to huge. It is best to acquire them in one piece and thick enough so that you don’t cut through them because seams are uncomfortable. Thicknesses less than 6mm/0.25′′ are acceptable but more readily cut.
A spotless cutting mat works excellent for wet-layup when you pre-wet the material between the plastic. To remove the resin, you’ll need to return and wash it off with a solvent when you’re finished. This is superior than plywood or cardboard since you can cut off plies with a razor knife and it won’t leave pieces of itself around the borders of your tapes.
If you use a razor knife a lot, a safety ruler might be useful. These are a wise purchase because it’s all too simple to chop off fingers, which is always something to avoid! To make my rulers easier to glide about, I prefer to wrap the rubber bottom with teflon or packaging tape that is sticky. Furthermore, it prevents resin from adhering to the rubber pad and damaging it. When working with pregnant women, especially those who have a supporter on only one side, this is extremely useful.
Scissors and shears
Scissors or shears are needed to cut material such as wiss shears, Kevlar scissors with abrasive edge, mondial shears, Kai Scissors 12″. Smaller scissors can come in handy too especially for cutting detailed pieces.
When you build out composite components using resins – polyester, epoxy, whatever thermoset you’re using – you’re going to need some extra instruments to roll out the laminate and maybe press material into corners in addition to those scissors and the razor knife. There are a few fundamental tools to use such as different kinds of rollers, squeegees, and sharpie markers for marking.
The most accurate and trustworthy way to measure resin is by weight, thus a scale is quite helpful. This compact digital culinary scale is particularly useful for weighing a variety of items and is accurate to 1g. A larger scale is beneficial for heavier loads of stuff, and at some point, having a huge pallet scale on the floor is fantastic. Make careful to maintain your scale clean and guard it from spillage.
Many adhesives are available in two-part tubes that let you dispense only the amount you need at the exact mix ratio. For greater amounts, a static mixer may be utilized, and the mixture comes out completely blended. They can be manually combined in small batches using a stir stick and a plastic tray; preferably, one that can be used again.
Different adhesive producers will employ various mix ratios (tube sizes) and common tube varieties. For instance, the Mixpac DM 400 on the right is compatible with Gurit Spabond and other cartridges, while the 300X on the left is compatible with Proset cartridges.
Wet-out Tools (squeegee, laminating roller, brush, scissors)
Tools for wet layups don’t have to be elaborate. The key to truly wetting out the fiber with resin is the use of brushes and squeegees. A full-size paint roller may significantly speed up the process for larger items. Brushes with shorter bristles are more efficient in spreading glue and priming surfaces with little resin pooling. When the bristles are reduced, the brush becomes more squeegee-like.
There are many different sizes and types of wet-out rollers (also known as “laminating rollers” or “bubble-poppers”). Small ones are excellent for precise wet layup. Curved surfaces benefit from rollers with a contoured design. After each usage, disassemble them and clean them with solvent because if they become gummed up, they will no longer function as intended.
Summary of the importance of composite materials in model airplane construction
In the aircraft industry, composite materials are often employed and have helped engineers overcome challenges that would have arisen from employing the components separately. The constituent elements don’t totally melt or meld together in the composites; instead, they maintain their own identities. The components combine to form a “hybrid” material with enhanced structural qualities.
The next generation of high-performance, cost-effective aircraft designs will become a reality thanks to the development of lightweight, high-temperature resistant composite materials. By using such materials, airplanes will operate more efficiently and for less money out of the gate.
Composite materials offer an advantage over traditional metallic materials due to their better strength-to-weight ratios, despite the fact that they are now more expensive to construct. This relatively new material will not be able to totally replace conventional metallic alloys until methods are developed to lower initial implementation costs and address the problem of non-biodegradability of present composites.