2艺8 Year of Frst Production Arcraft DelIery FIGURE 1. 19. Composite Weight Growth in Military Aircraft as a Percentage of Empty Structural Airbus Industries, in its new A380 super jumbo jet will use a considerable amount of glass composite laminate, with an S-2 glass fiber reinforced epoxy prepreg sandwiched within either aluminum sheets or carbon fiber polymeric laminates The X-29 aircraft has forward swept wings, made possibly only by the use of advanced composite materials. The X-36 advanced research vehicle that takes vertical and horizontal empennage components is largely covered by a carbon fiber/epoxy Lockheed Martin, using RTM, is building an all composite vertical tail for an advanced fighter aircraft. The RTM process reduces past count from 13 to one elementary more than 1000 fasteners, manufacturing costs were reduced by mo 60%. The twelve foot tail weight almost 200 lbs, with skins more than 100 plies and thickness variation of force Boeing recently unveiled a Sonic Cruiser program, which is being treated as th first real product breakthrough in air transport construction since the widebody. This aircraft will be the size of 100-300 seat jets with a totally different configuration offerin costs only slightly higher than current subsonic planes. The designs will use largely mposite materials One of the newest fighter aircraft of the United States air Force is the F-22 Raptor. Thirty six percent of its wing by weight is a composite material while thirty five percent of its vertical stabilizers is a composite material. andms. Also, in 2001, Harris, Starnes and Shuart have provided an assessment for design lufacturing of large composite material structures for use in aerospace vehicles
23 Airbus Industries, in its new A380 super jumbo jet will use a considerable amount of glass composite laminate, with an S-2 glass fiber reinforced epoxy prepreg sandwiched within either aluminum sheets or carbon fiber polymeric laminates. The X-29 aircraft has forward swept wings, made possibly only by the use of advanced composite materials. The X-36 advanced research vehicle that takes vertical and horizontal empennage components is largely covered by a carbon fiber/epoxy composite material. Lockheed Martin, using RTM, is building an all composite vertical tail for an advanced fighter aircraft. The RTM process reduces past count from 13 to one, elementary more than 1000 fasteners, manufacturing costs were reduced by more than 60%. The twelve foot tail weight almost 200 lbs, with skins more than 100 plies and thickness variation of force. Boeing recently unveiled a Sonic Cruiser program, which is being treated as the first real product breakthrough in air transport construction since the widebody. This aircraft will be the size of 100-300 seat jets with a totally different configuration offering costs only slightly higher than current subsonic planes. The designs will use largely composite materials. One of the newest fighter aircraft of the United States Air Force is the F-22, Raptor. Thirty six percent of its wing by weight is a composite material while thirty five percent of its vertical stabilizers is a composite material. Also, in 2001, Harris, Starnes and Shuart have provided an assessment for design and manufacturing of large composite material structures for use in aerospace vehicles [3]
16.2 AUTOMOBILES BUSES and TRUCKS According to the Automotive Composite Alliance, Troy, Michigan, the use of thermoset composites by automobile companies has nearly doubled in the past decade, to 318 million pounds by 2000, and a projected 467 million pounds by 2004. Reinforced thermoplastics are in even greater demand. An example is the 2000 Ford Excursion SUV which uses SMC for the tailgate and cargo door assembly to reduce weight. As a result tooling cost investment was reduced by 75% from tooling costs for metal components, and designers were able to eliminate several components. The Los Angeles County Metropolis Transportation Authority has introduced a composite bus designed to extend service left from 12 to 25 years, reduce exp brake wear and increase fuel efficiency. It weights 21, 800 lbs, 9,000 lbs lighter conventional bus. The composite used is stitched glass fiber fabric with vinylester resin system produced by the VARTM process Composite drive shafts for World Rally cars will soon be used, as well as carbon fiber/epoxy laminate clutch disks for manual gear shaft systems, which provides superic traction with minimum slippage The commercial trucking industry started replacing welded steel components with molded hoods, roofs and other body parts with composite materials in the 1970s. Today all major commercial truck manufacturers use composites for weight reduction, design flexibility and improved durability The U.S. Department of Energy is leading a multi-agency program to develop the 2lst century truck. One of its goals is to take 15% to 20% of the weight out of a truck/trailer combination. This DOE program includes assessment of the most feasible applications of lightweight carbon fiber composites in these vehicles Composite hydrogen storage cylinders reaching 10,000 psi(700 Bar) pressure have recently been achieved. This is a major milestone because 80% more hydrogen fuel can be stored in a given volume at 10 ksi then at 5 ksi, thus significantly range of fuel cell vehicles 16. 3 NAVAL VESSELS According to a recent review by Mouritz, Gellert, Burchill and Challis [4], for al vessels composites were first introduced immediately after World War II in the construction of small personnel boat for the U.S. Navy. By the time of the Vietnam War, there were over 3,000 composite personnel boats, patrol boats, landing craft and reconnaissance craft in service. Prior to 1950 composite boats were some 16 meters in length, however, in recent years the lengths have increased until today there are al composite naval ships up to 80-90 meters lon Studies have shown that the structural weight of composite sandwich patrol boats should be up to 10% lighter than an aluminum boat and 36% lighter than a steel boat of similar size. The reduced weight can provide an increase in payload, greater range and/or reduced fuel consumption. It is predicted that the operating costs will be less than those of a steel design because of less maintenance(corrosion) and lower fuel consumption
24 1.6.2 AUTOMOBILES, BUSES and TRUCKS According to the Automotive Composite Alliance, Troy, Michigan, the use of thermoset composites by automobile companies has nearly doubled in the past decade, to 318 million pounds by 2000, and a projected 467 million pounds by 2004. Reinforced thermoplastics are in even greater demand. An example is the 2000 Ford Excursion SUV which uses SMC for the tailgate and cargo door assembly to reduce weight. As a result tooling cost investment was reduced by 75% from tooling costs for metal components, and designers were able to eliminate several components. The Los Angeles County Metropolis Transportation Authority has introduced a composite bus designed to extend service left from 12 to 25 years, reduce expensive brake wear and increase fuel efficiency. It weights 21,800 lbs, 9,000 1bs lighter than a conventional bus. The composite used is stitched glass fiber fabric with an epoxy vinylester resin system produced by the VARTM process. Composite drive shafts for World Rally cars will soon be used, as well as carbon fiber/epoxy laminate clutch disks for manual gear shaft systems, which provides superior traction with minimum slippage. The commercial trucking industry started replacing welded steel components with molded hoods, roofs and other body parts with composite materials in the 1970’s. Today all major commercial truck manufacturers use composites for weight reduction, design flexibility and improved durability. The U.S. Department of Energy is leading a multi-agency program to develop the 21st century truck. One of its goals is to take 15% to 20% of the weight out of a truck/trailer combination. This DOE program includes assessment of the most feasible applications of lightweight carbon fiber composites in these vehicles. Composite hydrogen storage cylinders reaching 10,000 psi (700 Bar) pressure have recently been achieved. This is a major milestone because 80% more hydrogen fuel can be stored in a given volume at 10 ksi then at 5 ksi, thus significantly increasing the range of fuel cell vehicles. 1.6.3 NAVAL VESSELS According to a recent review by Mouritz, Gellert, Burchill and Challis [4], for naval vessels composites were first introduced immediately after World War II in the construction of small personnel boat for the U.S. Navy. By the time of the Vietnam War, there were over 3,000 composite personnel boats, patrol boats, landing craft and reconnaissance craft in service. Prior to 1950 composite boats were some 16 meters in length, however, in recent years the lengths have increased until today there are all composite naval ships up to 80-90 meters long. Studies have shown that the structural weight of composite sandwich patrol boats should be up to 10% lighter than an aluminum boat and 36% lighter than a steel boat of similar size. The reduced weight can provide an increase in payload, greater range and/or reduced fuel consumption. It is predicted that the operating costs will be less than those of a steel design because of less maintenance (corrosion) and lower fuel consumption
The largest all composite naval patrol boats currently in service is the Skjold surface effect ship of the Royal Norwegian Navy, commissioned in 1999. It is 46.8 meters long and 270 tonnes full-load displacement and operates at a maximum speed of 57 knots with a catamaran hull. It is worth noting that the skjold has been filled with a large array of imbedded sensors in the hull to provide real-time information at strain levels generated during sea trials- another advantage of using composite sandwich construction In the late 1980s the Swedish Navy built a 30 meter long surface effect ship, the Smyge MPC2000 of sandwich construction using carbon, glass and Kevlar vinylester skins and a pvc foam core These lightweight materials provide, excellent corrosion resistance, good damage resistance against underwater shock loading (UNDEX) and stealth properties including low thermal and magnetic signatures and good noise suppression properties Mine countermeasure vessels(MCMV) made of a composite have resulted in innovative designs capable of resisting local buckling, due to hull girder stiffness and xcellent underwater shock resistance. The hull structures most commonly used are frame single-skin, unframed monocoque and sandwich constructions. In the monocuque construction thick skins of 0. 15-0.20 meters of composite are used. The composite sandwich construction has been used on the Landsort and Flyvefisker Swedish MCMVs The Royal Norwegian Navy has laminated the Oksoy, Alta, and Hinnoy. In the latter, sensors to monitor strains in the hull and deck have been used to determine the structural behavior of the ship when compared to design predictions and for hull condition monitoring to provide warning of structural overloads. Other sensors monitor vibrations enerated by the engines, water jet propulsors and other machinery shown,The longest composite naval ship built is the Swedish Visby (YS-2000)corvette, Figure 1.20, launched in June 2000. The ship is 72 meters long, with a full-load displacement of 620 tonnes. Because the Visby is to be used for surveillance, combat, mine-lay up, mine countermeasures and anti-submarine warfare operations the Royal Swedish Navy chose to construct the entire ship of composite materials rather than with traditional steel or aluminum. It is built of sandwich construction consisting of faces of hybrid carbon and glass polymer laminates covering a PVC foam core. The Visby is the first naval ship to significantly use carbon fiber composites in the hull. The introduction of carbon fibers increases the cost five fold compared to glass fibers, however, design tudies have shown that by using some carbon fibers in the composite skins the hull eight can be reduced by 30% without increasing fabrication costs greatly. Not only does the use of carbon fibers improve the ships' performance by increasing the range and cing the operating costs, but the carbon fibers provide adequate electromagnetic shielding in the Visby superstructure
25 The largest all composite naval patrol boats currently in service is the Skjold surface effect ship of the Royal Norwegian Navy, commissioned in 1999. It is 46.8 meters long and 270 tonnes full-load displacement and operates at a maximum speed of 57 knots with a catamaran hull. It is worth noting that the Skjold has been filled with a large array of imbedded sensors in the hull to provide real-time information at strain levels generated during sea trials – another advantage of using composite sandwich construction. In the late 1980’s the Swedish Navy built a 30 meter long surface effect ship, the Smyge MPC2000 of sandwich construction using carbon, glass and Kevlar vinylester skins and a PVC foam core. These lightweight materials provide, excellent corrosion resistance, good damage resistance against underwater shock loading (UNDEX) and stealth properties including low thermal and magnetic signatures and good noise suppression properties. Mine countermeasure vessels (MCMV) made of a composite have resulted in innovative designs capable of resisting local buckling, due to hull girder stiffness and excellent underwater shock resistance. The hull structures most commonly used are frame single-skin, uniframed monocoque and sandwich constructions. In the monocuque construction thick skins of 0.15-0.20 meters of composite are used. The composite sandwich construction has been used on the Landsort and Flyvefisker Swedish MCMV’s. The Royal Norwegian Navy has laminated the Oksoy, Alta, and Hinnoy. In the latter, sensors to monitor strains in the hull and deck have been used to determine the structural behavior of the ship when compared to design predictions and for hull condition monitoring to provide warning of structural overloads. Other sensors monitor vibrations generated by the engines, water jet propulsors and other machinery. The longest composite naval ship built is the Swedish Visby (YS-2000) corvette, shown in Figure 1.20, launched in June 2000. The ship is 72 meters long, with a full-load displacement of 620 tonnes. Because the Visby is to be used for surveillance, combat, mine-lay up, mine countermeasures and anti-submarine warfare operations the Royal Swedish Navy chose to construct the entire ship of composite materials rather than with traditional steel or aluminum. It is built of sandwich construction consisting of faces of hybrid carbon and glass polymer laminates covering a PVC foam core. The Visby is the first naval ship to significantly use carbon fiber composites in the hull. The introduction of carbon fibers increases the cost five fold compared to glass fibers, however, design studies have shown that by using some carbon fibers in the composite skins the hull weight can be reduced by 30% without increasing fabrication costs greatly. Not only does the use of carbon fibers improve the ships’ performance by increasing the range and reducing the operating costs, but the carbon fibers provide adequate electromagnetic shielding in the Visby superstructure
FIGURE 1.20. Visby By using composite materials weight savings of up to 65% have been achieved in the superstructure of naval vessels by replacing equivalent steel members It has been found that the yield strain in fiberglass composites is about 10 times that of steel, hence fatigue cracking in composite superstructures on a steel hull is expected to be reduced considerably. n that composite superstructures would be 15-70% Some naval studies have sh lighter than a steel superstructure of similar size. The Royal Navy has estimated that replacing an all steel helicopter hanger on a frigate by using a hybrid composite panel and steel frame construction will result in a weight saving of 31%(i.e,9 tons ). anothe tudy has shown that for a frigate, an all composite superstructure with stiffened sandwich composite panels will save 40% weight over a steel construction without greatly increasing the construction costs The French Navy is the first to operate large warships with a composite superstructure, this being the La Fayette frigate launched in 1992. The aft section of the superstructure is made of fiberglass sandwich composite panels, with a length of 38 meters, width of 15 meters, height of 6.5-8.5 meters and a weight of 85 tons. This makes it the largest composite superstructure on a warship. Additionally, the funnels on the La Fayette are also composite Based on a study by Critchfield [5] in the early 1990s, the U.S. Navy has designed, fabricated and put in use an all composite mast, designated as the Advanced Enclosed Mast/Sensor(AEM/S), on the USS Radford. The AEM/S system is 28 meters tall and 10.7 meters in diameter, hexagonal in shape and is the largest topside structure in place on a U.S. Navy ship. It is made of a frequency tunable hybrid composite material which allows for the passage of the ship's own frequencies through the composite structure with little loss while reflecting all other frequencies. Thus, the performance of the antenna and other on board sensors is improved while the radar cross-section
26 By using composite materials weight savings of up to 65% have been achieved in the superstructure of naval vessels by replacing equivalent steel members. It has been found that the yield strain in fiberglass composites is about 10 times that of steel, hence fatigue cracking in composite superstructures on a steel hull is expected to be reduced considerably. Some naval studies have shown that composite superstructures would be 15-70% lighter than a steel superstructure of similar size. The Royal Navy has estimated that replacing an all steel helicopter hanger on a frigate by using a hybrid composite panel and steel frame construction will result in a weight saving of 31% (i.e., 9 tons). Another study has shown that for a frigate, an all composite superstructure with stiffened sandwich composite panels will save 40% weight over a steel construction without greatly increasing the construction costs. The French Navy is the first to operate large warships with a composite superstructure, this being the La Fayette frigate launched in 1992. The aft section of the superstructure is made of fiberglass sandwich composite panels, with a length of 38 meters, width of 15 meters, height of 6.5-8.5 meters and a weight of 85 tons. This makes it the largest composite superstructure on a warship. Additionally, the funnels on the La Fayette are also composite. Based on a study by Critchfield [5] in the early 1990’s, the U.S. Navy has designed, fabricated and put in use an all composite mast, designated as the Advanced Enclosed Mast/Sensor (AEM/S), on the USS Radford. The AEM/S system is 28 meters tall and 10.7 meters in diameter, hexagonal in shape and is the largest topside structure in place on a U.S. Navy ship. It is made of a frequency tunable hybrid composite material, which allows for the passage of the ship’s own frequencies through the composite structure with little loss while reflecting all other frequencies. Thus, the performance of the antenna and other on board sensors is improved while the radar & cross-section
ature of the mast are reduced. Again, this result is achieved only by the introduction omposites. Other benefits include that the mast structure encloses all major antennas and other sensitive electronic equipment, protecting then from the elements and thus reducing maintenance. Propellers for naval ships and submarines have traditionally been made of a nickel-aluminum-bronze alloy because of the requirements for corrosion resistance and high yield strength. Although recent design and performance of composite propeller systems is classified, the use of modern composites manufacturing allows for continuous fibers to be aligned with the major hydrodynamic and tal forces along the blade and thus the potential for application in this area. The use of composites is now being introduced for propeller shafts on large ships (frigates and destroyers) where they account for 2%(100-200 tons)of total ship weight. Carbon fiber/epoxy and glass fiber/epoxy composite shafts have the potential to be 25- 80% lighter than steel shafts for the same purpose, while also providing noise suppression due to the intrinsic dampening properties of composites, and thus reducing the ship,s acoustic signature. Also, the non-magnetic properties of composite shafts reduce that signature. The Navy also anticipates fewer problems with corrosion, bearing loads, fatigue with a corresponding 25% reduction in cost over the service life of the For ship funnels, composites have been introduced on MCMV craft for many years. Composite stacks of course are used on the Visby. The U.S. Navy is also considering using composite stacks on the(DDG51) Arleigh Burke class destroyers. The advantages include weight savings, reduced radar cross-section and reduced infrared (thermal)signature. It has been reported that composite funnels in two Italian cruise liners resulted in a weight saving of 50% and a cost saving of 20% when compared to aluminum and steel funnels they replaced Composite steel rudders are also being developed because they are expected to be 50% lighter and 20% cheaper than metal rudders. One such application is the use of composite rudders on the Avenger class MCMV's In the case of composite applications for submarines, the United Kingdom has investigated the feasibility of lining the outside wall of steel pressure hulls with a sandwich composite. This effort is expected to increase the overall buckling strength, lower fatigue strains, reduce corrosion and lower acoustic, magnetic and electrical signatures. Furthermore, antennas and sensors may be imbedded in the composites Considering all of the aforementioned applications, Mouritz et al [4] point out the following. Despite the use of composite in naval craft for fifty years, the information and tools needed by naval architects is not complete. For example, simple analysis tools for determining failure modes of complex naval composite structures, particularly under blast, shock, collision and fire events, are virtually non-existent. Furthermore, the scaling ws for composites are complex due to their anisotropic properties, which makes the design of load-bearing structures more difficult than designing with metals. To overcome the lack of information, it is common procedure to design composite ship structures with safety factors that are higher than when designing for metals. Most composite structures are designed with safety factors between 4 and 6, although values up to 10 are applied when the structure must carry impact loads. The high safety factors result in structures
27 signature of the mast are reduced. Again, this result is achieved only by the introduction of composites. Other benefits include that the mast structure encloses all major antennas and other sensitive electronic equipment, protecting then from the elements and thus reducing maintenance. Propellers for naval ships and submarines have traditionally been made of a nickel-aluminum-bronze alloy because of the requirements for corrosion resistance and high yield strength. Although recent design and performance of composite propeller systems is classified, the use of modern composites manufacturing allows for continuous fibers to be aligned with the major hydrodynamic and centripetal forces along the blade, and thus the potential for application in this area. The use of composites is now being introduced for propeller shafts on large ships (frigates and destroyers) where they account for 2% (100-200 tons) of total ship weight. Carbon fiber/epoxy and glass fiber/epoxy composite shafts have the potential to be 25- 80% lighter than steel shafts for the same purpose, while also providing noise suppression due to the intrinsic dampening properties of composites, and thus reducing the ship’s acoustic signature. Also, the non-magnetic properties of composite shafts reduce that signature. The Navy also anticipates fewer problems with corrosion, bearing loads, fatigue with a corresponding 25% reduction in cost over the service life of the components. For ship funnels, composites have been introduced on MCMV craft for many years. Composite stacks of course are used on the Visby. The U.S. Navy is also considering using composite stacks on the (DDG51) Arleigh Burke class destroyers. The advantages include weight savings, reduced radar cross-section and reduced infrared (thermal) signature. It has been reported that composite funnels in two Italian cruise liners resulted in a weight saving of 50% and a cost saving of 20% when compared to aluminum and steel funnels they replaced. Composite steel rudders are also being developed because they are expected to be 50% lighter and 20% cheaper than metal rudders. One such application is the use of composite rudders on the Avenger class MCMV’s. In the case of composite applications for submarines, the United Kingdom has investigated the feasibility of lining the outside wall of steel pressure hulls with a sandwich composite. This effort is expected to increase the overall buckling strength, lower fatigue strains, reduce corrosion and lower acoustic, magnetic and electrical signatures. Furthermore, antennas and sensors may be imbedded in the composites. Considering all of the aforementioned applications, Mouritz et al [4] point out the following. “Despite the use of composite in naval craft for fifty years, the information and tools needed by naval architects is not complete. For example, simple analysis tools for determining failure modes of complex naval composite structures, particularly under blast, shock, collision and fire events, are virtually non-existent. Furthermore, the scaling laws for composites are complex due to their anisotropic properties, which makes the design of load-bearing structures more difficult than designing with metals. To overcome the lack of information, it is common procedure to design composite ship structures with safety factors that are higher than when designing for metals. Most composite structures are designed with safety factors between 4 and 6, although values up to 10 are applied when the structure must carry impact loads. The high safety factors result in structures