The Effectiveness of Glass Laminate Aluminum Reinforced Epoxy
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New York Institute of Technology The Effectiveness of Glass Laminate Aluminum Reinforced Epoxy FCWR 304: Prof. K. LaGrandeur Chelseyann Bipat 12/15/2011 2 Table of Contents Executive Summary ........................................................................................................................ 3 Introduction ..................................................................................................................................... 3 Method ............................................................................................................................................ 5 Results ............................................................................................................................................. 6 1. Strength ................................................................................................................................... 6 Impact Strength........................................................................................................................ 7 Tensile Strength ....................................................................................................................... 8 Elastic Stress ............................................................................................................................ 8 Fire Resistance ......................................................................................................................... 9 Corrosion Strength ................................................................................................................... 9 Shear Strength........................................................................................................................ 10 2. Cost........................................................................................................................................ 10 3. Density .................................................................................................................................. 11 Conclusions ................................................................................................................................... 11 Bibliography ................................................................................................................................. 12 3 Executive Summary When creating the world’s largest airplane, many factors have to be taken in consideration. One of the most important of these is the material that it is built from. Ideally, this material should demonstrate qualities that prove it nearly indestructible under the harshest conditions. Although such material does not yet exist, GLARE, short for Glass Laminate Aluminum Reinforced Epoxy, was chosen. This report examines its effectiveness for use, compared to previous materials used in aircraft construction. The results found through conducting this research shows that GLARE is effective in its role in aircraft construction because of its tensile strength, impact strength, fire resistance, corrosion resistance, and elastic stress, cost, and density. However, it is not effective in its shear strength. Introduction This report presents the results of an investigation done on the effectiveness of Glass Laminate Aluminum Reinforced Epoxy, also known as GLARE. This research was done by consulting various journal articles and books, and by extrapolating and interpreting data in published lab reports. Previously, aircraft were comprised of other composite material. The first aircraft were made of wood. Then, metal composite materials slowly began to become normal in the use of motorized, commercial aircraft. As the years progressed, carbon and glass composites began to creep into the aircraft industry, and are used in the today’s aircraft. These composites were mainly created at the Delft Institute of Technology in Holland, where most of the testing and entry of these materials into the aircraft industry took place. 4 Previous composites were used in the building of other aircraft, such as the Boeing 747. Designed in 1970, the 747 was (until recently) the world’s largest aircraft. The advent of such a large plane caused other aircraft manufacturers such as Airbus to seek to lay claim to the prestige associated with creating the world’s largest aircraft. To do this, however, Airbus needed a material that was structurally different from other materials, especially in strength and density. Strength and density of the material are important in the development of large aircraft like the 747, and future aircraft. This is because, when increasing the size of an aircraft, the weight of the aircraft increases proportionally. If an aircraft size is increased by a factor F, then the weight and volume of the aircraft is then increased by F3, and the wing area of the aircraft is increased by F2 (Vlot, 2001). Because of the significantly large increase in weight, a lighter, less dense material had to be developed in order to support the aircraft. GLARE then began to be developed up until the early 2000’s, when it was eventually selected for use in the fuselage (main body of an aircraft) of the world’s largest airliner, the Airbus A380. GLARE is a composite material comprised of alternating layers of glass/epoxy and aluminum, bonded together. The general composition of GLARE is shown below. Figure 1: Composition of GLARE (Ardakani, Khatibi, Parsaiyan, n.d.) 5 GLARE always consists of one more aluminum layer than glass/epoxy layer. For example, if there are three layers of aluminum, there will be two layers of glass/epoxy, as shown in Figure 1 above. When GLARE is made, the layers of aluminum are first anodized (coating it with a substance using electrolytes) and primed to increase corrosion strength. The layers of aluminum and glass/epoxy are then laid down alternately, with the aluminum layers on the outside for an increase in durability. Next, the materials are subject to intense pressure for a day, and then placed in a temperature of 100 degrees Celsius for up to four hours, in a process known as postcuring. However, GLARE does not always have to be laid down with the layers parallel to each other; GLARE can be modified to suit different part of the fuselage of the aircraft. For example, the glass/epoxy and aluminum can be bonded at different angles in order to either strengthen or weaken the material. Because of this composition and its ability for its composition to be modified, it is supposed that GLARE can be made stronger than a monolithic material (a material consisting of solely one material), such as aluminum. This report will investigate the strength properties of GLARE, as well as its economic advantages and/or disadvantages. These properties will then be used to compare GLARE to previous materials used in aircraft construction, such as aluminum alloy 2024-T3. From this comparison, the effectiveness of the material will then be determined. Method The following methods were used to examine the effectiveness of GLARE: 6 1. To determine background and history of the material, multiple texts by Ad Vlot, one of the major creators of GLARE, were consulted. 2. Various journal articles from databases were retrieved and were used in order to examine certain aspects of the strength of the materials and therefore the main quality of its effectiveness. 3. GLARE was then compared to an aluminum alloy 2024-T3, a material frequently used in aircraft construction. Results Over time, many experiments on the effectiveness of GLARE were conducted. This report outlines the effectiveness of the material based on the following qualities of the material: strength, cost, and density. These qualities are then compared to one of its counterparts, a monolithic material known as 2024-T3, which is an aluminum alloy commonly used in aircraft construction. 1. Strength The strength of this material was evaluated on six major properties: impact strength, tensile strength, elastic stress, fire resistance, corrosion strength, and shear strength. An overview of all the quantifiable strength qualities of GLARE, compared to 2024-T3 is shown in Figure 2 below. 7 Fig. 2: Quantifiable strength comparison between GLARE and Aluminum Alloy 2024-T3 14 Aluminum Alloy(2024-T3) GLARE 12 10 8 6 4 2 0 Density (x1000) Tensile Modulus Shear Strength Melting Point (degrees (x100) Celsius x100) Impact Strength The first of these properties is impact strength. Impact strength is important because of the materials that could possibly hit an airplane. Engine debris, birds, hail, or any material being hurled at an aircraft while it is moving at an extremely high velocity could cause significant damage to the outer structures of an airplane. For example, a bird simply hitting an aircraft while it is in the air could deliver as much as 500 J of energy. Because of this, impact tests on the materials that aircraft are constructed from are conducted (Wu, Yang, 2005). When tests were conducted on different compositions of extremely thin sheets of GLARE (as mentioned before, the layers can be arranged at different angles), it was found that they all showed similar amounts in energy absorption (Sadighi and Dariushi, 2008), which means that 8 regardless of the arrangement of glass/epoxy and aluminum, GLARE still displays the same amount of resistance. Furthermore, in other impact tests, when a projectile delivering only one joule of impact energy was aimed at the material, it took up to seventeen times of impact in order for the surface of the GLARE sheet to be penetrated (Ardakani, Khatibi,