Smart Materials in Aerospace Industry free essay sample

Within each subsection, we will draw a relationship between the properties of the smart material and its molecular mechanism. This is followed by presenting an outline of their recent and future applications, and the experimental procedures and results done in recent researches to show the feasibility of these applications. In the Discussion section, we will be delving into the cost-effectiveness and feasibility of using smart materials in aerospace components. Finally, the conclusion will give an insight into the relationship between the use of smart materials and the design of future aircrafts. 1. Introduction Smart materials are defined as materials that can significantly change their intrinsic properties (mechanical, thermal, optical or electromagnetic), in a predictable and controlled manner in response to their environmental stimulus[1]. In general, these materials can be categorized into 3 categories, namely thermal-to-mechanical (shape memory alloys), electrical-to-mechanical (piezoelectric), and magnetic-to-mechanical (magnetostrictive). Materials engineering has undergone a major transformation in the recent decade, as atoms and molecules are no longer viewed and worked upon on the microscopic level, but now on the nanometer level. We will write a custom essay sample on Smart Materials in Aerospace Industry or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Materials requirements are becoming more complex, especially in the aerospace industry in which safety and cost-effectiveness often conflict against each other. It is no longer acceptable for materials to have a single function; they need to be multifunctional to save costs and weight. Smart materials are now replacing monolithic ones to achieve multiple functions at all scale levels. Hence, smart materials are essentially integrated into the use of aerospace components. What differentiates smart materials from normal monolithic ones? Smart materials exhibit characteristics which most scientists would term as ‘intelligence’. This includes immediacy (the ability to respond in real time); transiency (the ability to respond to more than one environmental states); self-actuation (inherent intelligence within material); selectivity (having a discrete and predictable response); and lastly, directness (response is local to the ‘activating’ event)[2]. The performance characteristics of aircrafts are often limited by properties of materials used in both the airframe and propulsion systems. With the recent advancement of materials technology, high performance materials are created, resulting in a breakthrough in the performance and efficiency of modern aircrafts. The discovery of smart materials provides cost-effective and innovative solutions to the limitations currently faced in the design of aircrafts. These smart materials perform specialized functions when exposed to external stimuli, and they are increasingly being used to replace conventional aircraft parts for better performance. In this report, we shall look at the current and future use of these smart materials in the aerospace industry. 1. Purpose The purpose of this report is to introduce the different types of smart materials and their applications in the aerospace industry. Recent and emerging uses of these smart materials will also be presented, with brief experimental procedures and results obtained from recent researches and experiments to show the feasibility in aerospace applications. 1. 2 Background Smart material transformation was first observed on gold-cadmium, and recorded in 1932. Five year later, in 1938, the same phase transformation was observed in brass. In 1962, Beehler and coworkers discovered the shape memory effects of Nickel-Titanium alloy, and they named this family of alloy as Nitinol. The discovery of Nitinol ignites the discovery of other alloy systems with shape memory effect, and also accelerates the use of smart materials in product development. [3] Since then, aerospace companies are also exploring the use of smart materials in aircraft components. Conventional automatic control systems which use servo-valve or hydraulic actuators face a lot of limitations. These limitations include multiple energy conversions, complexity due to large number of parts resulting in large number of potential failure sites and large weight penalty, high vulnerability of hydraulic network, and frequency limitation. In contrast, the advantages from the use of smart materials actuators include the direct conversion of electrical energy to high frequency linear motion, easier transmission of electrical energy throughout aircraft, and light and compact smart materials induced-strain actuation in place of bulky hydraulic power systems. With this huge potential offered by smart materials, researchers are eager to tap on this potential, by exploring on ways to implement these smart materials into aircraft components. 1. 3 Scope This report will present the 4 common types of smart materials that are popular in the market. A brief description will be made with regards to the mechanism of how the smart materials function. The properties of the smart materials will then be related to their current and future aerospace application. This is followed by the detailed outline of the experimental procedures undertaken by past researches, as well as results obtained which prove the feasibility of using these smart materials for the aerospace applications. Finally, discussions will be made on the viability of the use of smart materials in the aerospace industry, in terms of safety, cost feasibility and future trends. . Types and Applications of Smart Materials 1. Piezoelectric Material Piezoelectricity is the generation of electrical potential in a material in response to a mechanical stress. This is known as the direct effect. It can also mean mechanical deformation upon the application of electrical charge or signal (Harrison JS and Ounaies Z, 2001). In this case, the material can serve as a sensor to detect m echanical stress. In addition, the materials can serve as an actuator when there’s a large increase of size due to electrical stimuli. The two types of piezoelectric materials that are used as smart materials are piezoelectric ceramic and polymer. Properties Piezoelectric materials are widely used as they possess favorable properties such as fast electromechanical response, wide bandwidth, high generative force and relatively low power requirements (Harrison JS and Ounaies Z, 2001). In addition, piezoelectric polymers are flexible, lightweight, and have low acoustic and mechanical impedance, while piezoelectric ceramics are brittle, heavy and toxic. Mechanism Piezoelectric effect is formed in crystals that have no centre of symmetry. One end of the molecule is more negatively charged while the other end is more positively charged, hence a dipole moment exists within the molecule. This is due to both the atomic configuration of the molecule, and also the molecular shape. Polar axis is the imaginary line that runs through the centre of both charges on the molecule. The orientation of the polar axis determines the type of crystal. For monocrystal, all the molecules’ polar axes are oriented in the same direction (Figure 2. 1. 1), while for polycrystal, the polar axes of molecules are oriented in different direction (Figure 2. . 2) [pic][pic] Figure 2. 1. 1 Figure 2. 1. 2 To create the piezoelectric effect, polycrystal is heated under the application of a strong electric field. The high temperature increases the rate of self-diffusion among the molecules, while the strong electric field forces almost all of the dipoles to orient in nearly the same direction (Figure 2. 1. 3) [pic] Figure 2. 1. 3 Piezoelectric ef fect can now be observed in the crystal (Figure 2. 1. 4). Figure (a) shows the piezoelectric material in its neutral state. When the material is compressed, a voltage of the same polarity as the resultant dipole moment will appear between the electrodes (Figure (b)). Conversely, the voltage will be of opposite polarity when the material is expanded (Figure (c)). Similarly, a voltage applied that is opposite to the poling voltage will cause the material to expand(Figure (d)), while an applied voltage of the same polarity will cause the material to be compressed (Figure (e)). If an alternating voltage is applied across the material, the material will vibrate with the same frequency as the signal. [pic] Figure 2. 1. 4 Advantages and Disadvantages[4] Advantages |Disadvantages | |Compact and lightweight |Brittle due to crystalline structure | |Displacement proportional to applied voltage |Produce small strains compared to SMA and magnetostrictives | |Operate over large temperature range |Cannot withstand high shear and tension | |Fast response to applied voltage(msec) |Aging of material | |Repeatable sub-nanom eter steps at high frequency |Uses active control, which can result in instability | |No moving parts |Can become depolarized (at high temperature, high voltages and large | |Function at high frequencies |stresses) | |Excellent stability | | |Easily embedded into laminated composites. Aerospace Applications Piezoelectric materials are mainly used in the aerospace industry for shape control and vibration control. †¢ Tail-Buffet Suppression High performance aircrafts with twin vertical tails often face the aeroelastic phenomenon of tail buffeting, in which the unsteady vortices that emanates from the wing leading edge extensions burst and immerse the vertical tails in their wake. This results in severe vertical tail response and buffet loads, which lowers airframe life and increases maintenance costs. pic][pic] Before the development of piezoelectric actuators, various method of alleviating buffeting was used. One method was the use of hydraulic actuators to superimpose the oscillations of affected control surfaces about their hinges, so as to effect damping. However, this method has two disadvantages. Firstly, the flight control system and buffeting-minimization system must use the same degree of freedom for the same control surface, thus reducing the availabi lity of the control surface for each role. Secondly, operations are limited to low frequencies due to the difficulty of oscillation a large control surface about its hinges. Experiment The Technical Cooperation Program (TTCP) collaborated with National Research Council Canada (NRC) and Department of Defense of Canada (DND) in researching about the feasibility of using piezoelectric actuators for tail buffet suppression on a full-scale F/A-18. The full-scale aircraft was tested in the International Follow-On Structural Test (IFOST) Program rig in Australia (Yousefi-Koma A Zimcik DG 2003). The procedures for the experiment are as follow: †¢ The starboard fin of the aircraft was instrumented with piezoelectric actuators over a wide area on both sides of the fin, as shown in Figure 2. 1. 5. [pic] Figure 2. 1. 5 †¢ Accelerometers and strain gauges are placed strategically to measure displacements, and hence calculate the vibration amplitude. †¢ Electrodynamic shakers are attached to the fin to induce structural vibration. These shakers are controlled by the test rig control system to model actual flight structural loads. †¢ In the experiment, four custom-made high-power amplifiers of 2kVA rating over 200Hz bandwidth were used. Results Conclusion The experimental results have shown that the active control system using piezoelectric actuators was able to effectively suppress the buffet response of the vertical fin at high angle of attack. Amplitude reductions of up to 60% at the normal flight configuration and close to 10% in the worst case scenario were observed (Yousefi-Koma A Zimcik DG 2003). It was estimated even a small 10% reduction in vibration amplitude would double the durability of the fin. Hence, it can be concluded that with the use of piezoelectric actuators in active-control surface modal (ACSM) device to deform the control surface, the control surface not only can respond to buffeting-minimization signals, but also flight control commands. †¢ Wing Flutter Damping When a structure is placed in a flow of sufficiently high velocity, an aeroelastic self-excited vibration takes place, which has a sustained or divergent amplitude. This results in dynamic instability that can get violent. This is because at high speed, the effect of the airstream can cause the coupling of two or more vibration modes such that the vibrating structure will extract energy from the airstream. The extracted energy equals the amount of energy that the structure can dissipate at the critical speed, and a neutrally stable vibration exists. However, above this critical speed, the vibration amplitude will diverge, causing structural failure. Experiment and Result The Piezoelectric Aeroelastic Response Tailoring Investigation was conducted at MIT with the support of NASA, and it aims to achieve the following objectives: determining the power consumption of the piezoelectric actuators while controlling the response of the structure; investigating optimal piezoelectric actuator placement; and, testing disturbance rejection controllers at zero airspeed (Anna-Maria Rivas McGowan). The major components of the 4-feet test model, as shown in Figure 2. 1. , consist of two primary structures: an exterior fiberglass shell, which is used to obtain aerodynamic lift; an interior composite plate that contains the piezoelectric actuators, and is made up of an aluminium honeycomb core sandwiche d by graphite epoxy plates. The plates are of [20 °2/0 °]s laminate, referenced to the wings quarter-chord which is swept 30 °, and this provides a static coupling of the bending and torsional behaviour. Fifteen groups of piezoceramic actuators patches are placed at the top and bottom of the interior plate, and they are configured to impart moments to the plate. Together with the orientation of the graphite epoxy and the wing sweep angle, the actuators can affect bending and torsional vibration of the model. Forces on the model were monitored using ten strain gauges and four accelerometers. To acquire time history data, each of the 15 piezoelectric actuator groups was activated individually, as well as in five sets of several actuator groups. The experimental results is shown in the graphs in Figure 2. 1. 7. In summary, it shows that the control system can effect successful flutter suppression and gust reduction in the model, with a 12% increase in flutter damping and 75% decrease in root-bending moment caused by gusts. This clearly shows the potential of the use of piezoelectric actuators in suppressing the detrimental effects of wing flutter. Rotor Blade Twist Outboard portion of the blade travel faster, and with the same lift coefficient, higher lift force is concentrated near the blade tip. To distribute the lift force evenly among the blades, the angle of attack is made to be lower near the blade tip, and higher near the blade root, such that the lift coefficient decreases with increasing distance from the blade root. This can be done by induced blade twisting, through the embedment of piezoelectric materials into the blade skin. Active fibre composites (AFC) are actually used, which consists of continuous, aligned PZT fibres in an epoxy layer (Figure 2. 1. ), and copper electrode films that are etched into an inter-digitated pattern to effect the electric field along the fibre direction, as shown in Figure 2. 1. 9 (Rodgers and Hagood, 1998). [pic][pic] Figure 2. 1. 8 Figure 2. 1. 9 Experiment Active Fiber Composite (AFC) was fitted into the construction of a 1/6th scale replicate of CH-47D blade model (60. 619in span and 5. 388in chord). The blade was sent for wind tunnel testing at Boeing Helicopters, PA. Three AFC plies were diagonally placed in the co-cured D-spar blade lay-up. When the fibres are activated, it causes a shear in the spar skin, which creates the blade twist effect.

How to Put Together a Poetry Manuscript for Publication

How to Put Together a Poetry Manuscript for Publication Putting together a poetry manuscript to submit to contests or publishers is not a walk in the park. Expect it to take an hour or two a day over the span of a week, month, or even a year, depending on how much work you have, how polished the pieces are, and how much time you can afford to spend on the project.   Despite that, creating a poetry manuscript for publication is an important next step in a writers career. Heres a step-by-step guide on how to make this goal a reality. Step 1: Choose Your Poems Begin by typing (or printing from your computer files) all the poems you want to consider putting into your book, one per page (unless of course, the poem is longer than a single page). This is a chance to make any small revisions you want to make to individual poems so that you can concentrate on the shape of the book as a whole. Step 2: Plan the Book Size To get started, decide how big of a book you want to create- 20 to 30 pages for a typical chapbook, 50 or more for a full-length collection (more on exact page amounts later). You may well change your mind about this when you are actually selecting and ordering the poems, but this will give you a starting point. Step 3: Organize the Poems With the length of your book in mind, sift through all the pages you have typed or printed up, and put the poems into piles that you feel belong together in some way- a series of poems on related themes, a group of poems written using a particular form, or a chronological sequence of poems written in the voice of a single character. Step 4: Take a Step Back Let your piles sit at least overnight without thinking about them. Then pick up each pile and read through the poems, trying to see them as a reader and not as their author. If you know your poems well and find your eyes skipping ahead, read them out loud to yourself to make sure you take the time to listen to them. Step 5: Be Selective When you’ve read through a stack of poems, pull out any poems that no longer seem to fit in that particular pile or seem redundant, and put the poems you want to keep together in the order you want your readers to experience them. You may find yourself doing lots of reshuffling over time, moving poems from one stack into another, melding whole groups of poems together by combining stacks, or discovering new groupings that need to be separate and on their own. Don’t worry about it. You will likely come across new ideas for books or chapbooks and also change your mind a number of times before the poems settle into the shape of a finished book manuscript. Step 6: Take a Breather After you’ve pared down and reordered each pile of poems, let them sit again at least overnight. You can use this time to mull over your reading, listening for the poems that stand out in each stack and how they sound together. Pay attention to other poems that may have popped into your mind when you were reading a certain stack to see if you should add them or replace similar poems. Step 7: Reevaluate Book Length Think again about the length of the book you want to create. You may decide that one stack of related poems would make a good short chapbook. You may have a really large pile of poems that will all go together into a long collection. Or you may want to combine several of your piles to create sections within a full-length book. Step 8: Create an Actual Book Next, try actually making the manuscript into a book that you can live with and leaf through. Staple or tape your pages together put them into a three-ring notebook, or use your computer to print them out in book format. If you’re preparing an email or online submission, you may still want to print up the poems you’re considering- shuffling paper pages is easier than editing a computer file. If you have several long pieces, you may wish to lay everything out in a word processing document with the correct margins for the completed book size, to see how more exactly how many pages the collection will consume. For a typical 6-by-9-inch printed book, youll want the final page count to be divisible by four (include room for a title page, dedication page, table of contents, copyright page, and acknowledgments page in your count as well). For ebooks, the page count can be any number. If you want your document to look like a finished book when printed out, use your software to make mirror image pages when setting up your page size so that the left and right pages will face each other as they would when professionally bound, and add page numbers in a footer or header. That said, don’t think too much about typography or design at this point. You want simply to put the poems together so that you can read through the book and see how they interact in that order. Step 9: Choose a Title After you’ve decided on the length and general shape of your manuscript, choose a title for your collection. A title may have suggested itself during your sifting and ordering of the poems, or you may want to read through them again to find one- perhaps the title of a central poem, a phrase taken from one of the poems, or something completely different. Step 10: Proofread Carefully proofread your entire manuscript from beginning to end after you’ve put it in order. If you’ve spent a lot of time with the book, you may be tempted to give it only a cursory read-through. In this case, you need to set it aside for a few days or weeks so that when you come back to it you can pay close attention to each poem, each title, each line break, and each punctuation mark. You will likely find yourself making additional revisions to the poems at this point- don’t hold back, as this final reading may be your last chance to make changes before you send the book out into the world. Proofreading your own work is difficult- ask a friend, or two, to proofread the manuscript for you, and go through all their notes carefully. Fresh eyes will likely spot some errors that slid right by you but do not feel that you must accept every editorial change they may suggest. When in doubt about punctuation or line breaks, read the poem aloud. Step 11: Research Venues for Submission Next, it’s time to seek appropriate venues for submission. Use a list of poetry publishers or links to poetry contests to identify places you want to submit your manuscript. It’s important to read the poetry books they’ve published or the previous winners of their competitions in order to decide if you want them to publish your work. Targeting your submissions to publishers of like works can also save you time and money on submissions that would have been rejected for not being appropriate to their current catalog. Publishing is a business, and if a manuscript wouldnt fit in with others in the companys catalog, its marketing department wouldnt know what to do with it, regardless of its quality. Weed those publishers out before sending the manuscript anywhere. Keep notes on why a publisher is a good fit, to mention in your submission cover letter. Step 12: Apply! After you have selected a publisher or a contest, reread its guidelines and follow them exactly. Print a fresh copy of your manuscript in the format requested, use the submission form if there is one, and enclose the applicable reading fee. Try to let go of your manuscript after you’ve mailed it off- it may take a long time for you to get a response, and obsessing over one manuscript submission will only set you up for disappointment. It never hurts, however, to keep thinking about the order and title of your book and to submit it to other contests and publishers in the meantime (so long as the companies you’ve sent it to accept simultaneous submissions).

Sociology unit 5 Essay Example | Topics and Well Written Essays - 750 words

Sociology unit 5 - Essay Example JÐ µrry nÐ µÃ µds to lÐ µarn from thÐ µ mistakÐ µs of othÐ µr companiÐ µs that havÐ µ Ð µxpandÐ µd in Asia in gÐ µnÐ µral, and in thÐ µ hugÐ µ markÐ µt of China spÐ µcifically, and failÐ µd. ThÐ µ projÐ µct managÐ µmÐ µnt packagÐ µ shows how JÐ µrry nÐ µÃ µds to lÐ µarn from companiÐ µs likÐ µ Lincoln and ChÐ µvrolÐ µt, which had problÐ µms Ð µxpanding duÐ µ to a lack of attÐ µntion to intÐ µgral host culturÐ µs. â€Å"For many, thÐ µ concÐ µpt that thÐ µ way businÐ µss is donÐ µ hÐ µrÐ µ is not nÐ µcÐ µssarily thÐ µ way it's donÐ µ Ð µvÐ µrywhÐ µrÐ µ may comÐ µ as a rÐ µvÐ µlation. But thÐ µ consÐ µquÐ µncÐ µ of losing a dÐ µal or aliÐ µnating an ovÐ µrsÐ µas businÐ µss contact is rÐ µal, whÐ µthÐ µr it rÐ µsults from impropÐ µr tablÐ µ mannÐ µrs or a propÐ µnsity toward thÐ µ abrupt hardball tactics that tÐ µnd to kill a dÐ µal† (Sharif, 2002). ThÐ µ kÐ µy to succÐ µss is to lÐ µarn about thÐ µ h ost culturÐ µ, and do a lot of markÐ µt rÐ µsÐ µarch into how it diffÐ µrs from thÐ µ homÐ µ culturÐ µ. â€Å"WhilÐ µ any introductory Ð µxposition of a culturÐ µ is nÐ µcÐ µssarily basÐ µd on a particular pÐ µrspÐ µctivÐ µ to somÐ µ dÐ µgrÐ µÃ µ, it is important to find a starting placÐ µ for undÐ µrstanding how ChinÐ µsÐ µ-WÐ µstÐ µrn communications may bÐ µ facilitatÐ µd. ... And in Ð µxpanding into GÐ µrmany, thÐ µ organization of Lincoln nÐ µglÐ µctÐ µd to considÐ µr diffÐ µrÐ µncÐ µs in languagÐ µ and culturÐ µ in its global rÐ µsÐ µarch. As thÐ µ sociologist DurkhÐ µim suggÐ µsts, not all culturÐ µs havÐ µ thÐ µ samÐ µ valuÐ µs. ThÐ µ Ð µxamplÐ µ of thÐ µ ChÐ µvy Nova mÐ µntionÐ µd abovÐ µ, is a good illustration of how U.S. businÐ µssÐ µs havÐ µ traditionally run into problÐ µms by rÐ µlying too much on a cÐ µntralizÐ µd domÐ µstic command structurÐ µ that doÐ µs not givÐ µ sufficiÐ µnt local autonomy for markÐ µting and othÐ µr opÐ µrations. This is thÐ µ samÐ µ problÐ µm that Lincoln was running into in its GÐ µrman opÐ µrations. That is, ovÐ µrall, a dynamic global Ð µnvironmÐ µnt invitÐ µs dynamic rÐ µsponsivÐ µnÐ µss that is not thÐ µ samÐ µ thing as cÐ µntralizÐ µd dÐ µcision-making. â€Å"In gÐ µnÐ µral, it appÐ µars that countriÐ µs that takÐ µ advantagÐ µ of frÐ µÃ µ movà  µmÐ µnt of goods and sÐ µrvicÐ µs, labor and capital can thrivÐ µ in thÐ µ aggrÐ µgatÐ µ. HowÐ µvÐ µr, sound macroÐ µconomic policiÐ µs arÐ µ nÐ µcÐ µssary Although thÐ µ numbÐ µr of individual gainÐ µrs appÐ µars to outnumbÐ µr losÐ µrs in incrÐ µasÐ µd globalization, it is possiblÐ µ that thÐ µ losÐ µrs can crÐ µatÐ µ a backlash that will oncÐ µ again causÐ µ a rÐ µtrÐ µat† (Bordo, 2002). JÐ µrry nÐ µÃ µds to avoid mistakÐ µs likÐ µ thosÐ µ of Lincoln and ChÐ µvrolÐ µt, but this can bÐ µ rÐ µlativÐ µly Ð µasily donÐ µ by mixing third-party rÐ µsÐ µarch, markÐ µt profilÐ µs, and outsourcÐ µd hiring, to movÐ µ branch opÐ µrations into lÐ µaguÐ µ and connÐ µction with thÐ µ host culturÐ µ. In this mannÐ µr, thÐ µ nÐ µw projÐ µct can succÐ µÃ µd whÐ µrÐ µ othÐ µrs havÐ µ failÐ µd. Part 2 What arÐ µ somÐ µ potÐ µntial mÐ µthods of rÐ µsÐ µarching violÐ µncÐ µ