Composites Used In Aircraft Structure Engineering Essay

Composites Used In Aircraft Structure Engineering Essay This report explores the uses of composites in modern aircrafts and investigates the technical effects of applying composites to aircrafts. In addition, this report also evaluates the future usage of composites in aerospace industry. Background Composites are defined as engineered materials made from two or more constituent materials with significantly different physical or chemical properties those remain separate and distinct on a macroscopic level within the finished structure. (Definition, 2010) The American Heritage Dictionary (Houghton Mifflin, Boston, 1981) comes close, with a complex material, such as wood or fiber glass, in which two or more complementary substances, especially metals, ceramics, glasses, and polymers, combine to produce some structural or functional properties not present in any individual component. The problem with even a good definition, of course, is that it is all encompassing, so that every material in the universe could in some sense be defined as a composite. (Composites Manufacturing, 2006) Composites are first introduced after crash cases of aircrafts due to metal fatigue in the 1950s. And since then the use of composites in aircrafts increases exponentially over time. Method of Investigation Information is obtained online in the form of e-books, news articles and industrial reports. Furthermore, relevant book from SP library had been used in this report. Scope of Investigation This report explores the history of composites. Besides, this report also explores the types of composites used in aircraft structure, for example carbon fiber, fiberglass and Kevlarà ¢Ã¢â‚¬Å¾Ã‚ ¢ aramid, as well as fabrication of the carbon fiber. Furthermore, this report discusses the technical effects and applications of composites in aircraft structure. Composites in the future such as self-repairing composites and shape memory composites are also discussed in this report. History of Composites Composites were introduced in the 1950s and 1960s, fiber-reinforced plastic, was introduced to substitute the usage of duralumin in the structure of aircrafts. Before composites were introduced, primary structure of aircrafts was made largely of aluminum alloy. Duralumin, a type of aluminum alloy, was widely used in aircrafts primary structure due to its high strength to weight ratio and good toughness. Furthermore, good corrosion resistance of duralumin makes it so suitable to be used under harsh condition. However, in 1950s, a fully loaded De Havilland Comet jet airliner crashed due to metal fatigue. This gave rise to demand of materials suitable for aircrafts primary structure with high fatigue resistance. English scientist, Norman de Bruline, was the first to propose the use of composite materials in aircrafts structures. Then, more and more composites were introduced to suit certain requirement of properties of aircrafts structure. Modern fibers, such as carbon-reinforced fibers, Kevlarà ¢Ã¢â‚¬Å¾Ã‚ ¢ aramid, glass-reinforced fibers and boron fibers, are the stiffest and strongest materials known. (Composites Manufacturing, 2006) Modern Composites Composites are well known for their favorable properties such as high strength to weight ratio, high stiffness, very high stress level, high fatigue resistance and good corrosion resistance. Some of the widely used composites in aircraft structures will be discussed below. In common, all composites are made of relatively weak bonding of lamination of materials. Hence, core in composite laminate is introduced to increase the laminates stiffness by effectively thickening it with a low-density core material. This can provide a dramatic increase in stiffness for very little additional weight, where lightweight implication is so crucial for aircraft structure. For example, application of honeycomb core provides stronger impact resistance to composite laminates. With its hollow cells, it provides good energy absorption and sound dampening effect to the laminates. Types There are many types of composites currently used in aircraft structure. However, in this part only carbon fiber, fiberglass and Kevlarà ¢Ã¢â‚¬Å¾Ã‚ ¢ aramid will be discussed. Carbon Fiber Carbon or graphite fiber is basically fiber that contains more than 90% of carbon. Carbon fibers are ideal for lightweight reinforcement, as well as high strength, high stiffness application in aircrafts structure, due to its unique combinations of properties. High-performance carbon fibers are available in a range of properties, product forms, and prices. Most of the Carbon Fibers are made from organic polymers, with chains of carbons connected to each other, such as polyacrylonitrile (PAN). (Composites Manufacturing, 2006) Fiberglass Fiberglass is a reinforcing material that is widely used in aircraft structure. More than 70% of the reinforcement of thermosetting resins is made of fiberglass. In general, the longer the fibers, the greater the strength of the fibers is. And continuous fibers are the strongest amongst all. Glass does not burn, and at high temperature glass retains its mechanical properties, up to 50 per cent of its strength at 700 °F. Furthermore, glass has excellent moisture resistance compared to metals. Thus, it is suitable for application on aircraft structures. Lime-alumina-borosilicate glass, or E glass, was the first glass developed specifically for continuous fibers production. It is designed for electrical applications, with its good adaptability and high effectiveness in processes and products, ranging from decorative to structural applications in aircrafts. (Composites Manufacturing, 2006) Kevlarà ¢Ã¢â‚¬Å¾Ã‚ ¢ Aramid Kevlarà ¢Ã¢â‚¬Å¾Ã‚ ¢ aramid, introduced commercially in the 1970s, is an aromatic long-chain polyamide polymer produced by spinning using standard textile techniques. It was introduced to replace steel in racing tires. Kevlarà ¢Ã¢â‚¬Å¾Ã‚ ¢ aramid is well known for its high tensile strength, low density and good impact resistance with about half the stiffness of graphite structure. These properties offer a better choice for materials used in aircraft structures. For example, Kevlarà ¢Ã¢â‚¬Å¾Ã‚ ¢ 49 aramid fiber is widely used as reinforcement for plastic composites in aerospace, marine, automotive, and other industrial applications. (Composites Manufacturing, 2006) Fabrication In general, the reinforcing and matrix materials are combined, compacted and processed to undergo a melding event. In this part, fabrication of carbon fiber will be discussed in details. Figure 1 below illustrates the brief process of fabrication of carbon fiber, from its precursor form to the fiber. Figure 1 Fabrication Of Carbon Fiber (Flow Chart, 2010) Firstly, acrylonitrile, CH2CHCN, a chemical compound derived from propylene and ammonia, is mixed with another plastic in powder form, and is then reacted with a catalyst in a solution polymerization process. In results, a polymer is formed. After that, the polymer is put under spinning process to form the internal atomic structure of the fiber. This process is done by heating up the mixture and pump through tiny jets into a chamber where the solvents evaporate. The polymer is then washed and stretched to align the molecules within the fiber. This complete process is called stretching. The final product after this process is known as precursor. Next, the fibers will undergo oxidation process. The fibers are heated in air to about 200 to 300 °C for 30 to 120 minutes, to convert the linear atomic bonding to ladder bonding. This is to prepare a more thermally stable bonding of fibers. After the fibers are stabilized, they are heated again to 1000 to 3000 °C for several minutes in a furnace. This has to be done in inert environment to prevent fibers from burning with presence of oxygen gas. As the fibers are heated, they start to lose their carbon atoms as well as non-carbon atoms while the remaining carbon atoms will form a tightly bonded carbon crystals that are aligned almost parallel to the longitudinal axis of the fibers. This process is known as carbonization. In some processes, two furnaces are operating in two different temperatures to provide a better control of heating rate. Lastly, the fibers will undergo surface treatments such as oxidation to provide better bonding properties, coating to protect fibers from external damage. (Composites Manufacturing, 2006) Technical Effects Generally, composites are superior in fatigue resistance, corrosion resistance, and high strength-to-weight ratio. These properties give composite aircrafts better fuel efficiency as well as better load capacity, as compared to the metal alloy counterparts. In addition, composites design offers lower maintenance cost compared to that of metal alloy design. Composite parts are manufactured as a whole, compared to metal parts are manufactured in the form of sheet metals and are connected by means of fasteners, the former greatly reduce maintenance cost by simplifying maintenance procedure. Figure 2 below shows the fuselage barrel section being manufactured in one piece, without the needs of fasteners. Figure 2 Boeing 787 DreamLiner Fuselage (Composites Material, 2004) However, composites are not as almighty as they have been told. For instance, most composite materials are poor in electric conductivity and such, causing them to be more susceptible to damage due to lightning strikes. Compared to metal alloy airframes, composite counterparts require extra procedure in order to take care of the electric charge from the lightning as well as static charge from friction when flying. Furthermore, unlike metals, composites break without sign or physical warning. Compared to aluminum alloy, composites do not bend when subjected to impact but break once they fail to withstand the load. Applications Composites are currently used widely in aerospace industry. Primary structures, for example fuselage, wings, ailerons, flaps, empennage, are made of composites in modern aircrafts. For example, composites contributed 50 per cent to the weight of Boeing 787 DreamLiner, whilst almost 100 per cent of the fuselage skin and wings surface are composites. Figure 3 below illustrates the usage of composites in Boeing 787 as compared to that in Boeing 777, has increased significantly. Figure 3 Goodbye Metal Planes (Goodbye Metal Plane, 2005) Secondary structures such as pressure bulkheads, floor beams, and landing gear door are also made of composites. Furthermore, composites are also used in interior. Composites In The Future Self-Repairing Composites Self-repairing composites are composites that are able to repair cracks on the aircrafts as they happen. Figure 4 below illustrates the fundamental of self-repairing composites. By designing a network of glass rods filled with resin, it is possible to stop the crack from propagating and repair the aerodynamics characteristic of the aircraft when crack happen in flight. Figure 4 Self Healing Artificial Skin (Self Repairing, 2007) However, there are limitations in self-repairing composites, for example, the supply of the resin in the network. A system with vascular network has to be developed to resupply the resin so that self-repairing composites serve their purpose from time to time. Shape Memory Composites Shape memory composites are composites that retain one or two shapes after being cold-worked. Figure 5 illustrates how shape memory composites retain shapes after being subjected to heat. Figure 5 Shape Memory (Shape Memory, 2007) This is highly useful in aircrafts design as it means the aerodynamics of the aircrafts can now be controlled according to whether maneuverability or stability is needed. Conclusion Composites are currently used as a better material used in aircraft primary structures, substituting aluminum alloy that had been used for decades. Due to composites superiority in corrosion resistance, fatigue resistance, and weight saving, it is expected that incoming models of aircrafts will use composites extensively. Application of composites in modern aircrafts once again proves that composites are more reliable than metal alloys in airworthiness. However, further development of composites should be done to overcome weaknesses found currently to further improve the safety of aircrafts.

Managing Information Overload Essay

In my opinion, organizations are likely to find better solutions thru informational overload using technical and social systems. Information overload has an ability to cause negative effects on an organizations performance. Within, technical and social systems there are a collection of complex components that solve problems within that system. Knowledge management uses the combination and utilization of technology at every phase that is available within the organization. Social and technical framework for management of knowledge is an appropriate method than an organization can use to handle problems due to information overload. In using both a social and technical approach within an organization allows an individual to gain the most insight within their performance. The relationship between people and technology does not matter in the process of solving different performance problems within an organization. The technical system is a tool used to identify problems within the organization that affect its performance. It supports the investment of knowledge management throughout the organization and its people. In doing so, this move enhances the technology and people within the organization to be used as interface models, and IT blueprints to ensure technology is implemented. (Liu & Errey, 2006) Conducting of business is at its present day of age within information technology. Within, the work environments today, they currently have access to various tools that assist with effective communication. (Pijpers, 2010) There is enough evidence to prove how these tools assist within an organization by keeping employees in an organization up-to-date, connect with others, remain productive and engage effectively with one another. In doing so, this shows the development of information technology thru internet and communicational technologies by bringing light problems to informational overload in addition to the increasing pace and development complexity in the society. (Strother 2012) Within an organization, many people find it difficult to deal with the information they receive within a continuous transformation in an organization with the increased unpredictable and complex effects on these actions. This leads the organization to stress and anxiety. (Blair 2010) This makes it challenging for the employees to comprehend the priorities in an organization and focus on the tasks that are achieved. Within reference to the introduction of the module, socio-technological design can be effective in the diagnosis of information overload that are present and not present in other organizations. Without knowledge in an organization nothing is possible and it is necessary to identify which place and at what extent the challenge exists within an organization. For example, within an organization knowledge is in repositories, documents, routines, practices, and processes. Social interaction among members plays a huge role in searching for knowledge. Knowledge management assists in renewing, developing, transferring, and sharing knowledge. This is based on produce value, economic wealth, and organizational performance. (Becerra-Fernandez & Sabherwal, 2010) This process creates value from its intellectual and knowledge based assets. Knowledge management leverges knowledge within an organization to provide a competititive edge. The fuctions within knowledge management acheives the goals of an organization to acquire additional knowledge within its operations to remain competitive. Management of knowledge can take the approach of being technology focused, people focused or social-technology focused. The people focus approach stresses that people are of primary importance in an organization. This results in developing and implementing significant strategies that encourage individuals to develop, store and disseminate knowledge. However, this approach is unable to solve problems alone. Technology management under knowledge management deals with collecting, modifying, storing, and manipulating knowledge through the use of technological resources such as computers and other machinery. Similar to people focus approach, this approach is not able to provide solutions to existing problems alone (Becerra-Fernandez & Sabherwal, 2010) This assumption is made by intoducing new technology by solving the existing problems in performance. Performance is perceived by people as complicated. The two approaches of people focused, and technolgy focused are effective in their area of focus. Therefore, there is a need for a more effective knowledge management approach that is taking advantage of these strengths. (Grant & Shahsavarani) Socio-technical refers to the balance between the social and technical systems that make up an organization. According to the perspective of socio-technical system, the capacity of an organization and its employees to perform effectively depends on knowledge. A systems concept seeks to emphasis a two way relationship between technology and individuals. A socio-technical design has a system of modifying changes, itself, and exploits creative capacities of human resource available for the organization. Computers are unable to make practical and crucial decisions. This means the attention of the human should stay in the loop at all times. These findings are assessed and identified in researching the socio-technical approach to handle information overload. In doing so, it shows for an organization to store and develop its’ knowledge they need to consider its culture and structuring roles. This ensures effective knowledge creation, sharing of information, and storage of an organizations reward system by motivating the employees to gain more knowledge. This is necessary for the organization to consider the huge significant role in the success of knowledge management initiative. All in all, organizational knowledge and knowledge management is the storage of information and additional data. Individuals that possess this ability make effective decisions to determine the success of the knowledge management initiative. This study considers the most significant methods that an organization uses to handle various problems from information overload including its complexity affecting knowledge management (Becerra-Fernandez & Sabherwal, 2010) The most effective approach in an organization is to increase the capacity, advance the intelligence and knowledge of individuals by using the people approach. However, this approach may not be enough because of various intrinsic limitation of the human brain. Thus, by advancing the information processing capacity complements an individual’s decision by making capacity with the support of computers thru technology. References Blair, A. (2010, November 28). Information Overload, Then and Now. Retrieved from The Chronicle: http://chronicle.com/article/Information-Overload-Then-and/125479/?sid=cr&utm_source=cr&utm_medium=en I. Becerra-Fernandez & R. Sabherwal. (2010). Knowledge Management: Systems and Processes. New York: M.E. Sharpe. J. B. Strother, J. M. Ulijn & Z. Fazal. (2012). Information Overload: An International Challenge for Professional Engineers and Technical Communicators. New York: John Wiley. Levinson, M. (2012). Knowledge Management Definition and Solutions. Retrieved from CIO: http://www.cio.com/article/40343/Knowledge_Management_Definition_and_Solutions Liu, X. and Errey, C. . (2006, February). Socio-technical systems: There’s more to performance than new technology. Retrieved from ptgGlobal: http://www.ptg-global.com/PDFArticles/Socio%20technical%20systems%20-%20There’s%20more%20to%20performance%20than%20new%20technology%20v1.0.pdf Pijpers, G. (2010). Information Overload: A S ystem for Better Managing Everyday Data. New York: John Wiley.

Why and How Censorship Lead to Ignorance in Young People - Free Essay Example

Sample details Pages: 4 Words: 1133 Downloads: 9 Date added: 2019/05/29 Category Society Essay Level High school Tags: Censorship Essay Did you like this example? When my 8th grade English teacher told me that To Kill a Mockingbird had been banned in many middle school classrooms in America I was shocked. I later learned that this was because of the strong racial themes present in the time that the story takes place, the 1930s. Though before then I had never heard of the idea of books being banned. Don’t waste time! Our writers will create an original "Why and How Censorship Lead to Ignorance in Young People" essay for you Create order I thought that the schools who banned the book were making a grave error in banning such a good and educational book; I mean, if I’m allowed to learn about those ideas in my History class, then why should those ideas be banned in my English class? For this reason and many more, banning books in high school libraries limits education and causes young people to become ignorant of the sometimes harsh realities of life. Though Ray Bradbury is against the censorship of books, in Fahrenheit 451 the fire chief, Beatty, makes the argument that many censored books contain controversial ideas which upset certain groups of people: â€Å"Dont step on the toes of the dog-lovers, the cat-lovers, doctors, lawyers, merchants, chiefs, Mormons, Baptists, Unitarians, second-generation Chinese, Swedes, Italians, Germans, Texans, Brooklynites, Irishmen, people from Oregon or Mexico. The people in this book, this play, this TV serial are not meant to represent any actual painters, cartographers, m echanics anywhere. The bigger your market, Montag, the less you handle controversy, remember that! All the minor minor minorities with their navels to be kept clean† (54). This quote is from Beatty’s conversation with Montag about how things came to be the way they are in the society of F451. While this is a valid argument, Bradbury disproves this argument when later in the book Faber makes the argument that without controversial ideas people stop wanting information about the world at all if it isn’t happy news which forms a bubble around each individual which â€Å"protects† them from reality: Patience, Montag. Let the war turn off the ‘families.’ Our civilization is flinging itself to pieces. Stand back from the centrifuge† (84). This is what causes the ultimate destruction of the main city of F451. In short, Bradbury argues that censorship ultimately leads to ignorance even among adults which shows that this argument would also hold true for teens. He is saying that this ignorance will ultimately lead to the destruction of society. A reason that many people give for the banning of controversial books in high school libraries is that they promote inappropriate ideas about sexuality. These ideas and themes include LGBTQ characters, nudity, rape, and other sexually explicit content (10 Reasons Books are Challenged and Banned). Many school administrators say that teens are too young to learn about these things. This argument is unsubstantiated because it doesn’t account for the fact that high school is the time when teens are supposed to be informed about these topics and learn how, though in the case of rape not, to do it. The argument that these sexual ideas are inappropriate is a false one because high school teens will soon be at the age when they will be able to experience those things; books containing this material can prepare teens to deal with those situations. Though the argument can be made that these books will corrupt teens perceptions of these topics when combined with a sexual education class where students are free to ask questions this will not happen. If the high school doesnt offer sex ed then students can always come to their parents with questions. If these books are read in tandem with a sexual education class or with the help of a parent, teens will understand the book even better and learn what is and isn’t acceptable. These school administrations, as stated perfectly by Sherman Alexie in his article titled: Why the Best Kids Books Are Written in Blood, are simply trying to protect their privileged notions of what literature is and should be (Alexie 2). Finally, controversial books shouldn’t be banned in high school libraries because while peopl e may say that themes of rape, racism, physical abuse, drugs, and alcohol might cause teens to start doing those things (10 Reasons Books are Challenged and Banned), they are underestimating the capacity of high school students to understand what they are reading. When a high school student reads a book, they already have shown that they are interested in seeking information or learning about a story. While reading YA novels, or novels in general, usually students will take the themes exhibited in the book and think about them. When some of the aforementioned ideas or themes appear in books while reading teens have a chance to think about the topic and usually, the story shows the reader how badly people’s lives are impacted by their bad choices. For example, in the book Thirteen Reasons Why, there are strong themes of suicide as this is what the story centers around. When reading this book high school students wouldn’t be inclined to kill themselves as the book doesn’t encourage suicide; if anything, it allows teens who are contemplating suicide to think about their decision and if it’s really worth it. To finish, censorship of books in high school libraries is something that limits the growth of students intellectually and sexually. Censorship also limits the capacity, ability, and will of teens to think for themselves about controversial topics; it prevents them from accessing novels that contain ideas that will help them form a well-advised opinion. Young adult books allow students to learn about these things by providing examples of what not to do and the outcomes of those actions. In addition, the cultural critics who are advocating for these bans are assuming that high school teens arent ready for the strong, explicit themes present in young adult novels (10 Reasons Books are Challenged and Banned); this ideology, as stated previously, displays great ignorance on the part of the critics. Hopefully, this paper has shown at least some of the reasons why and how censorship is something that will ultimately lead to ignorance in young people and a lack of education about the explicit ideas and themes seen in YA novels and, more importantly, the real world. Works Cited Banned Books Week, American Library Association, December 11, 2012. https://www.ala.org/advocacy/bbooks/banned (Accessed January 8, 2019) Gomez, Betsy. â€Å"10 Reasons Books Are Challenged and Banned.† Banned Books Week, The Banned Books Week Coordinator and the ALA Office for Intellectual Freedom, 26 Sept. 2018, bannedbooksweek.org/10-reasons-books-are-challenged-and-banned/ (Accessed January 8, 2019) Bradbury, Ray, and Neil Gaiman. Fahrenheit 451. Simon Schuster Paperbacks, an Imprint of Simon Schuster, Inc., 2018. Sherman Alexie Article Alexie, Sherman. â€Å"Why the Best Kids Books Are Written in Blood.† The Wall Street Journal, 9 Jun. 2011, https://www.ncte.org/library/NCTEFiles/Involved/Action/censorship/Authors-Rationales/Alexie_Sherman_BestKidsBooksWritteninBlood.pdf

Frequency Definition in Science

In the most general sense, frequency is defined as the number of times an event occurs per unit of time. In physics and chemistry, the term frequency is most often applied to waves, including light, sound, and radio. Frequency is the number of times a point on a wave passes a fixed reference point in one second. The period or duration of time of a cycle of a wave is the reciprocal (1 divided by) of frequency. The SI unit for frequency is the Hertz (Hz), which is equivalent to the older unit cycles per second (cps). Frequency is also known as cycles per second or temporal frequency. The usual symbols for frequency are the  Latin letter  f  or the Greek letter ÃŽ ½ (nu). Examples of Frequency Although the standard definition of frequency is based on events per second, other units of time may be used, such as minutes or hours. For example, a human heart may beat at a frequency of 68 beats per minute.A 78 record on a turntable turns at the rate of 78 revolutions per minute or 78 rpm.