Presentation Transcript

1. Industries utilizing composites , Section 1
2. Composites Defined, Section 1 Composites have actually been in use for thousands of years. Adobe bricks were made using a composite of mud and straw. It is the combination of the physical properties of each material that gives the composite material many of its physical characteristics. Today’s advanced composites, like carbon fiber, bring together combined properties we’ve come to know – lightweight, strong, durable and heat-resistant. Today, the benefits of components and products designed and produced in composite materials – instead of metals, such as aluminum and steel – are well recognized by many industries. Some of the advantages include:
3. History, Section 1 Composite materials in transport airplane components are being used for decades. Prior to the mid-1980s, airplane manufacturers used composite materials in transport category airplanes in secondary structures (e.g., wing edges) and control surfaces. In 1988, Airbus introduced the A320, the first airplane in production with an all-composite tail section and, in 1995, the Boeing Company introduced the Boeing 777, also with a composite tail section. Composite materials used in commercial airplanes typically are produced by combining layers of carbon or glass fibers with epoxy. In recent years, manufacturers have expanded the use of composites to the fuselage and wings because these materials are typically lighter and more resistant to corrosion than are the metallic materials that have traditionally been used in airplanes.
4. The rapid development and use of composite materials beginning in the 1940s had three main driving forces. Military vehicles, such as airplanes, helicopters, and rockets, placed a premium on high-strength, light-weight materials. While the metallic components that had been used up to that point certainly did the job in terms of mechanical properties, the heavy weight of such components was prohibitive. The higher the weight of the plane or helicopter itself, the less cargo its engines could carry. Polymer industries were quickly growing and tried to expland the market of plastics to a variety of applications. The emergence of new, light-weight polymers from development laboratories offered a possible solution for a variety of uses, provided something could be done to increase the mechanical properties of plastics. The extremely high theoretical strength of certain materials, such as glass fibers, was being discovered. The question was how to use these potentially high-strength materials to solve the problems posed by the military's demands.
5. History, Section 1 Composite Wings -The Wright Flyer was constructed of muslin fabric stretched over a spruce frame.
6. What Is a Composite Material? Two or more materials combined to perform some useful purpose Exhibits the best properties of the individual materials and includes additional qualities that the individual materials do not exhibit alone
7. Introduction to composites, Section 1
8. Introduction to composites, Section 1 Light Weight - Composites are light in weight, compared to most woods and metals. Their lightness is important in automobiles and aircraft, for example, where less weight means better fuel efficiency (more miles to the gallon). People who design airplanes are greatly concerned with weight, since reducing a craft’s weight reduces the amount of fuel it needs and increases the speeds it can reach. Some modern airplanes are built with more composites than metal including the new Boeing 787, Dreamliner. High Strength - Composites can be designed to be far stronger than aluminum or steel. Metals are equally strong in all directions. But composites can be engineered and designed to be strong in a specific direction. Corrosion Resistance - Composites resist damage from the weather and from harsh chemicals that can eat away at other materials. Composites are good choices where chemicals are handled or stored. Outdoors, they stand up to severe weather and wide changes in temperature.
9. Introduction to composites, Section 1 Strength Related to Weight - Strength-to-weight ratio is a material’s strength in relation to how much it weighs. Some materials are very strong and heavy, such as steel. Other materials can be strong and light, such as bamboo poles. Composite materials can be designed to be both strong and light. This property is why composites are used to build airplanes—which need a very high strength material at the lowest possible weight. A composite can be made to resist bending in one direction, for example. When something is built with metal, and greater strength is needed in one direction, the material usually must be made thicker, which adds weight. Composites can be strong without being heavy. Composites have the highest strength-to-weight ratios in structures today. Corrosion Resistance - Composites resist damage from the weather and from harsh chemicals that can eat away at other materials. Composites are good choices where chemicals are handled or stored. Outdoors, they stand up to severe weather and wide changes in temperature. Part Consolidation - A single piece made of composite materials can replace an entire assembly of metal parts. Reducing the number of parts in a machine or a structure saves time and cuts down on the maintenance needed over the life of the item.
10. Introduction to composites High-Impact Strength - Composites can be made to absorb impacts—the sudden force of a bullet, for instance, or the blast from an explosion. Because of this property, composites are used in bulletproof vests and panels, and to shield airplanes, buildings, and military vehicles from explosions. Design Flexibility - Composites can be molded into complicated shapes more easily than most other materials. This gives designers the freedom to create almost any shape or form. Most recreational boats today, for example, are built from fiberglass composites because these materials can easily be molded into complex shapes, which improve boat design while lowering costs. The surface of composites can also be molded to mimic any surface finish or texture, from smooth to pebbly. Dimensional Stability - Composites retain their shape and size when they are hot or cool, wet or dry. Wood, on the other hand, swells and shrinks as the humidity changes. Composites can be a better choice in situations demanding tight fits that do not vary. They are used in aircraft wings, for example, so that the wing shape and size do not change as the plane gains or loses altitude. Nonconductive - Composites are nonconductive, meaning they do not conduct electricity. This property makes them suitable for such items as electrical utility poles and the circuit boards in electronics. If electrical conductivity is needed, it is possible to make some composites conductive.
11. Introduction to composites, Section 1 Nonmagnetic - Composites contain no metals; therefore, they are not magnetic. They can be used around sensitive electronic equipment. The lack of magnetic interference allows large magnets used in MRI (magnetic resonance imaging) equipment to perform better. Composites are used in both the equipment housing and table. In addition, the construction of the room uses composites rebar to reinforced the concrete walls and floors in the hospital. Radar Transparent - Radar signals pass right through composites, a property that makes composites ideal materials for use anywhere radar equipment is operating, whether on the ground or in the air. Composites play a key role in stealth aircraft, such as the U.S. Air Force’s B-2 stealth bomber, which is nearly invisible to radar. Low Thermal Conductivity - Composites are good insulators—they do not easily conduct heat or cold. They are used in buildings for doors, panels, and windows where extra protection is needed from severe weather. Durable - Structures made of composites have a long life and need little maintenance. We do not know how long composites last, because we have not come to the end of the life of many original composites. Many composites have been in service for half a century.
12. Net-Shape Molded vs. Machined Metal, Section 1 Design flexibility, including parts consolidation Molded in tight tolerances, often eliminating machining operations High strength to weight performance Retention of properties Corrosion resistant in hostile environments and underload Outstanding dielectric strength and comparative track resistance Good surface appearance with molded-in color and texture
13. Fundamentals of Composites, Section 1 Low Cost Per Cubic Inch Dimensional Stability Corrosion Resistance Electrical Performance U.L. Recognition High Strength Rigid and Strong Design Flexibility Low Coefficient of Thermal Expansion Dimensional Accuracy FDA Compliance Low Smoke Density - Low Flame Spread Index Stain Resistance Microwave Transmissivity Low Resonance and Sound Dampening
14. Fundamentals of Composites, Section 1 Most materials are isotropic Meaning that their properties are the same in all directions Metals, polymers, ceramics Composites are anisotropic Meaning that their properties are different in different directions Wood, plywood
15. Fundamentals of Composites, Section 1
16. Composite Material Types, Section 1
17. Composite Material Types, Section 1 Polymer matrix composites (PMC) and fiber reinforced plastics (FRP) are referred to as Reinforced Plastics. Common fibers used are glass (GFRP), graphite (CFRP), boron, and aramids (Kevlar). These fibers have high specific strength (strength-to-weight ratio) and specific stiffness (stiffness-to-weight ratio) Matrix materials are usually thermoplastics or thermosets; polyester, epoxy (80% of reinforced plastics), fluorocarbon, silicon, phenolic
18. Why Thermoset Composites, Section 1 Low material cost per cubic inch Formulating latitude to meet specific requirements and cost parameters with good speed to market Dimensional accuracy and stability, combined with good property retention, over a broad range of temperatures Design flexibility in molding from thin to thick sections Non-melting, flame retardant and low smoke density Solvent resistant
19. Composites vs. Metal, Section 1
20. Composites vs. Metal, Section 1 Composites have a higher specific strength than many other materials. A distinct advantage of composites over other materials is the ability to use many combinations of resins and reinforcements, and therefore custom tailor the mechanical and physical properties of a structure. The lowest properties for each material are associated with simple manufacturing processes and material forms (e.g. spray lay-up glass fibre), and the higher properties are associated with higher technology manufacture (e.g. autoclave moulding of unidirectional glass fibre), the aerospace industry
21. Net-Shape Molded vs. Machined Metal, Section 1
22. Composites vs. Metal, Section 1 The use of composites and other advanced materials in aircraft design and manufacturing, resulting in an industry-leading product line of economical and environmentally-friendly jetliners – for Boeing it is the 787 and AIRBUS it is AWB 350 Composite materials maximize weight reduction – as they typically are 20 per cent lighter than aluminum – and are known to be more reliable than other traditional metallic materials, leading to reduced aircraft maintenance costs, and a lower number of inspections during service. Additional benefits of composite technologies include added strength and superior durability for a longer lifespan. To fully leverage these benefits, aircraft designers are continuously developing technologies to improve the speed of composite manufacturing, as it is more complicated than with traditional metallics. In addition, the company regularly seeks new-generation applications for composite materials during the development processes and beyond.
23. Damage Assessment and Repair Inspection, Section 1 Damage categories : According to FAA, damage is categorized according to its severity as follows. Category 1 Allowable damage that may go undetected by scheduled or direct field inspection, allowable manufacturing defects; damage below Allowable Damage Limit (ADL), e.g. barely visible impact damage (BVID). Category 2 Damage detected by scheduled or directed field inspection at specified intervals, e.g. exterior skin damage, interior stringer blade damage. Category 3 Obvious damage detected within a few flights, e.g. accidental damage to lower fuselage or lost bonded repair patch. Category 4 Discrete source damage immediately known by pilot to limit flight maneuvers, e.g. rotor disk cut through fuselage or severe rudder lightning damage. Category 5 Severe damage created by anomalous ground or flight events. Such damage represents damage/manufacturing events that are outside of design considerations. It does not drive stress analysis, it rather relates to a feedback lop from maintenance/operations to the authorities. Analogous to an automobile accident special directed inspections are needed for category 5 damage. Damage of categories 1 to 4 has to be taken into account during aircraft design. For damages of category 2 to 5 repair scenarios are required.
24. Who is responsible for the safety of composite structure? Damage Assessment and Repair Inspection, Section 1 The responsibility of the safety of an airplane, and subsequently of the safety of composite structure, is shared between three parties: The Airworthiness Authorities (e.g: FAA in US, EASA in Europe) are responsible for setting the certification standard and certifying that the airplane manufacturers and parts suppliers meet their standards. They also conduct periodic inspections of manufacturing facilities to ensure continued compliance with regulations, and oversee airplane repair facilities to ensure they follow the proper maintenance and training procedures. The airplane manufacturers are responsible for showing compliance with those regulations and building safe airplanes. They are also developing airplane maintenance programs and repair manuals and provide requested on-site technical assistance. The operators are responsible for operating airplane according to Airworthiness Authority rules and the manufacturer approved manuals. This includes performing adequate maintenance action when appropriate. Airplane operators also help maintaining the airworthiness of their airplane fleets by tracking their airplanes’ service history and reporting relevant repair and incident data to Authorities and the manufacturers.
25. Disadvantage of Composites, Section 1 In November 1999, America’s Cup boat “Young America” broke in two due to debonding face/core in the sandwich structure. American Airlines Flight 587, broke apart over New York on Nov. 12, 2001 (265 people died). Airbus A300’s 27-foot-high tail fin tore off. Much of the tail fin, including the so-called tongues that fit in grooves on the fuselage and connect the tail to the jet, were made of a graphite composite. The plane crashed because of damage at the base of the tail that had gone undetected despite routine nondestructive testing and visual inspections