Manufacturing Issues Associated with Wing Joints - Coursework Example

Manufacturing issues Associated With Wing Joints Introduction The fuselage is a separate component. The wings form another component. There are manufactured in different ways. There is the need to bring the fuselage into contact with the wings. The place where the wings join the fuselage is called the wing joint. At the other end of the wing is the tip. The assembly is influenced by government regulation, materials used shape of the unit and the technology for joining components with close tolerances (Walczyk,2000). This joint takes the pressure of weight. That is for fuel and engines. It takes the pressure on landing and in flight. It must also provide the means for the controls mechanisms. This paper looks at modern approaches. In addition it considers the Airbus approach. Composite Materials Design These are new materials. It was therefore necessary to have new standards. Composite Affordability Initiative (CAI) has set the standard. It is the result of joint efforts. It results is established predictability in cost and material performance and testing. An aircraft with supporting wings including wing shells with good shear strength made of fibrous composite materials, particularly fiber-reinforced plastics, having members taking up tensile and compressive forces on the inside of the wing shells. The members have unidirectional fibers extending longitudinally of the wing, and fixing elements which can be joined detachably to fuselage attachments are provided on the members at the root end of the wing. Stringers are constructed on the inside of the wing shells and spaced longitudinally of the shells, their fiber component being formed by a fiber layer joined to the fiber layer of the wing shell. Fiber bundles are arranged between spaced stringers as unidirectional stiffening elements. The fiber bundles are embedded in the synthetic resin matrix of the plane load-bearing structure and extend longitudinally of the supporting wing. Groups of three fiber bundles extending adjacent each other are provided, of which the two outer bundles in each case form a loop at the root of the supporting wing to receive a bolt which has to be inserted in the loop perpendicular to the plane of the two fiber bundles. The inner bundle is turned down to form a second loop perpendicular to the first loop to receive a bolt which has to be inserted in and perpendicular to the plane of this loop. Both bolts act as connection members to attachment members on the fuselage. Fuselage Design factor. Friction stir welding is a patented method for joining tough-to-weld aluminum alloys. To form joints, friction stir welding (FSW) relies on the frictional heat generated by a rotating tool spinning on the surface of the aluminum. A pin-shaped protrusion on the tool carries heat from the surface down into the joint, creating a plasticized region that consolidates in the pins wake (Anand, (1999). Unlike traditional welding, the friction-stir process doesnt melt the material but stays roughly 100C below its melting temperature to avert distortions, porosity, and a loss of mechanical properties. This helps in building continuous joints. Welded joints have about three times the static strength offered by a single row of rivets. And the welded joints have a fatigue strength that is at least as good as a riveted joint ( Friction stir-welding2003) FSW also reduces the weight of the plane, shortens process cycle time, and decreases cost. This weight reduction comes not from the loss of rivets but from welding contribution to strong structures: Unlike laser or fusion welding, FSW enables the selective use of high-strength aluminum alloys to supplement the aluminum used throughout the plane (Curran, et al. 2006 ). Better-performing materials, in turn, permitted thinner, lighter wall sections and reduced flange widths. Manual Riveting Method . While manual riveting operations crawl along at less than 2 inches/min, and automated riveting walks along at 6 inches/min, FSW sprints at speeds greater than 20 inches/min. As for cost, the fast, highly automated FSW can save between $50,000 and $100,000 per plane. Authority Regulations The riveted structures have well-known design characteristics. Engineers will have to generate the reams of process and performance data required for FAA certification,. It will be still subject to ongoing review. It is possible to have wing joints assembled and do away with most riveting in favor of welded joints. Improved Welding Technique Friction stir welding, a patented method for joining tough to-weld aluminum alloys, got its start in marine engineering. To form joints, friction stir welding (FSW) relies on the frictional heat generated by a rotating tool spinning on the surface of the aluminum. A pin-shaped protrusion on the tool carries heat from the surface down into the joint, creating a plasticized region that consolidates in the pins wake. Unlike traditional welding, the friction-stir process doesnt melt the material but stays roughly 100C below its melting temperature to avert distortions, porosity, and a loss of mechanical properties. (Webb,2004).. Airbus Product Assembly Joining circular sections is relatively straightforward. A double-deck arrangement means that matching the twin decks to within a few millimeters accuracy is very difficult. The top and bottom fuselage sections are done separately. This would enable the upper and lower sections to be matched first, so that only a single deck at a time would have to be aligned. Then the upper and lower sections would be joined to create the fuselage. The wing will weigh around 3 5t if it is built as a monolithic item and would be mounted on a structure designed to minimize changes to the fuselage. This would be based around a single frame attached at the fuselage sides. It is necessary to support the wing centre section, and a smaller support at the front. The main centre frame would be supported by a simple triangulated structure within the fuselage. The process could then be used for both sections, but for the inboard element would need a small extension to the upper fuselage to accommodate the wing root. Another key decision rests on how the fuselage will be assembled. A particular design –shape can be influenced by fuselage characteristics. In some cases it can be too small to carry complete wing fuselage sections. This has driven studies of some interesting solutions to the manufacturing issues associated with assembly of aircraft wing root joints Economics There is no doubt that the cost of producing modern aircraft has to be the lowest possible. The aircraft will sell at a price which enables profitable airline operation. Advanced design concepts need to be developed to achieve the goal of reduced manufacturing costs (Hutchinson 2007). Clearly the use of thick plates keeps a major share within the total amount of Aluminum products needed. However very large quantities of the raw material being machined away in most current applications, end up in an extremely high buy-to-fly ratio. Cost effective design of aluminum components would tend to reduce the use of thick aluminum plates. It is important to increase the use of extrusions and forgings or to enter into entirely new manufacturing technologies in order to keep the buy-to-fly ratio as low as possible. Extensive research and technology programs were initiated. The Airbus system seeks to acquire and validate the necessary advances in the most promising manufacturing techniques (Composite airplane 2007, ). One example is aluminum castings with integrally extruded wing and fuselage panels in welded structures. Casting is the most consistent "near-net-shape" process. The cost saving potential of investment castings is considerable for aluminum alloys. Due to the good surface quality, practically no finish processing is required. The successful example is the Airbus bulk cargo door. It has now resulted in an additional application possibility for joints. Extruded panels for fuselage structures with integral stringers or alternatively, welded-on stringers compare very positively with todays riveting process in terms of weight and cost reduction. On riveted structures there is a substantial additional volume of stringer material and additional skin thickness to compensate for the rivet holes. Currently, the Airbus traditionally producing fuselage structures have made investments in large C02 laser beam welding machines. These machines are capable of producing integral panels, about 4m wide and about 10m long. Initial test panels are being manufactured to optimize the process and to collect statistical data. High welding speeds up to 15m/min and a high degree of automation allow a reduction in manufacturing costs of 20% compared to the automatic riveting process. A large wing structure, for example, is built up from 44 extruded panels, up to 28m long. Machining is still necessary to a certain extent, but first investigations show a double profit which could be obtained from reduced buy-to-fly values. It is also possible to have increased structural efficiency over conventional riveted structures (Composite airplanes 2007). Airbus wing design provides outstanding aerodynamic performance. However achieving this requires the use of complex double curvature wing panels, particularly near the root end where thickness is greatest. This presents an exacting manufacturing challenge, whether considering our current skins with fastened stiffeners or integrally stiffened panels. A process called Adaptive Creep Forming (ACF) is being developed by Airbus Industry partners. This provides for rapid panel forming to a precise contour with software control of adaptive tooling. The ACF process also supports our automated wing box assembly project. This system, currently at the demonstrator stage, is to provide a jig-less, tool-less high throughput assembly, using machine visual feature recognition and laser position scanning. This manufacturing process promises maximized use of factory facilities. It offers increased production rates and flexibility to introduce any developed or new products that are within the machine geometrical capacity, in principle by software changes alone. Welding Differences Friction stir welding is a non-fusion solid phase welding process based on research welding of thin fuselage structures, using laser beam technology, for welding. It is a continuous hot shear process. A non-consumable rotating tool made from a material harder than the work piece is passed along a joint between two closely butted sheets. The friction heat creates a plasticized region around the immersed welding pin which consolidates behind forming a solid phase bond. This process causes a more limited heat affected zone than conventional welding. This allows retention of a high proportion of parent metal properties for high strength heat-treated aluminum alloys. It is also suitable for long joints and high tracking speeds, using machines similar to those for milling. It offers the possibility of low cost, high integrity assembly of integral wing structures. These few examples of innovation in airframe design and manufacturing give an indication how Airbus can improve overall aircraft efficiency. Other Materials Advanced metal and composite materials combined with new manufacturing technologies are the possible means to face the economic challenge for meeting the expectations of the airlines for a 15% to 20% improved operating costs over current large transport aircraft. One should not deny, however, that significant efforts will be required in innovative technical and industrial approaches, in a world in which progress has become an increasingly self generating process. Conclusion There is the need to be profitable. Government regulation comes first. The assembly I impacted by many other factors. Work is affected if it is a new machine or if the work is being done on an existing machine. The material used is a factor. Of course the tools available must be considered. The level of automation and computer technology is extremely important. References Walczyk, D., Raju, V., & Miller, R. (2000). Fixtureless Assembly of Sheet Metal Parts for the Aircraft Industry. Proceedings of the Institution of Mechanical Engineers -- Part B -- Engineering Manufacture, [online] available from Academic Search Premier database. [24 Aug 2009] Anand, K. (1999, December). Development of process specifications for improving the surface finish in the steel grinding operation. Total Quality Management, 10(8), 1169-1177. Retrieved August 25, 2009, doi:10.1080/0954412997136, [online] available from Academic Search Premier database. [24 Aug 2009] Curran, R., Kundu, A., Wright, J., Crosby, S., Price, M., Raghunathan, S., et al. (2006, December). Modelling of aircraft manufacturing cost at the concept stage. International Journal of Advanced Manufacturing Technology, 31(3/4), 407-420. Retrieved August 25, 2009, doi:10.1007/s00170-005-0205-8 , [online] available from Academic Search Premier database. [24 Aug 2009] Webb, P. (2004, December). Flying in the face of convention. Manufacturing Engineer, 83(6), 28-31. Retrieved August 25, 2009, from Academic Search Premier database. , [online] available from Academic Search Premier database.[ 24 Aug 2009] Saadat, M., Sim, R., & Najafi, F. (2008, June). Modelling and analysis of Airbus wingbox assembly. Proceedings of the Institution of Mechanical Engineers -- Part B -- Engineering Manufacture, 222(6), 701-709. Retrieved August 25, 2009, doi:10.1243/09544054JEM898 , [online] available from Academic Search Premier database. [24 Aug 2009] Hutchinson, H., & Thilmany, J. (2007, October). computing. Mechanical Engineering, 129(10), 14-18. Retrieved August 25, 2009, from Academic Search Premier database. , [online] available from Academic Search Premier database.[ 24 Aug 2009] Composite airplanes are cheaper to build and fly. (2007, December). Advanced Materials & Processes, Retrieved August 25, 2009, from Academic Search Premier database. , [online] available from Academic Search Premier database. [24 Aug 2009] Friction stir-welding builds fuselage on new business jet. (2003, January). Advanced Materials & Processes, Retrieved August 25, 2009, from Academic Search Premier database. , [online] available from Academic Search Premier database. [24 Aug 2009] Read More