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Viewing 1 to 30 of 2452
2017-06-05
Technical Paper
2017-01-1765
Albert Allen, Noah Schiller, Jerry Rouse
Corrugated-core sandwich structures with integrated acoustic resonator arrays have been of recent interest for launch vehicle noise control applications. Previous tests and analyses have demonstrated the ability of this concept to increase sound absorption and reduce sound transmission at low frequencies. However, commercial aircraft manufacturers often require fibrous or foam blanket treatments for broadband noise control and thermal insulation. Consequently, it is of interest to further explore the noise control benefit and trade-offs of structurally integrated resonators when combined with various degrees of blanket noise treatment in an aircraft-representative cylindrical fuselage system. In this study, numerical models were developed to predict the effect of broadband and multi-tone structurally integrated resonator arrays on the interior noise level of cylindrical vibroacoustic systems.
2017-03-28
Technical Paper
2017-01-1304
Alejandro Rosas Vazquez, Fernando Paisano, Diego Santillan Gutierrez
Abstract For many years, the use of in-mold fasteners has been avoided for various reasons including: not fully understanding the load cases in the part, the fear of quality issues occurring, the need for servicing, or the lack of understanding the complexity of all failure modes. The most common solution has been the use of secondary operations to provide attachments, such as, screws, metal clips, heat staking, sonic welding or other methods which are ultimately a waste in the process and an increase in manufacturing costs. The purpose of this paper is to take the reader through the design process followed to design an in-molded attachment clip on plastic parts. The paper explores the design process for in-molded attachment clips beginning with a design concept idea, followed by basic concept testing using a desktop 3D printer, optimizing the design with physical tests and CAE analysis, and finally producing high resolution 3D prototypes for validation and tuning.
2017-01-10
Technical Paper
2017-26-0279
Onkar P Bhise, S Ravishankar
Abstract Polytetrafluoroethylene (PTFE) is used extensively as the inner tube material in various Aerospace and Industrial hose constructs. The fluoropolymer exhibits various unique mechanical properties from other fluoropolymers including chemical inertness, non-adhesiveness and low friction coefficient making it an attractive solution for hose applications. PTFE material can be modeled using various material modeling approaches including linear-elastic, hyperelastic and viscoplastic depending on the level of accuracy required in predicting material response. Fluoropolymers, like PTFE, are considered viscoelastic-viscoplastic materials. In other words, the material exhibits both viscous and elastic characteristics when undergoing deformation but also possesses behavior in which the deformation of the material also depends on the rate by which loads are applied.
2016-12-21
Journal Article
2016-01-9082
Bradley Michael, Rani Sullivan, Dulip Samaratunga, Ratneshwar Jha
Abstract Polymer matrix composites are increasingly adopted in aerospace and automotive industries due to their many attributes, such as their high strength to weight ratio, tailorability, and high fatigue and durability performance. However, these materials also have complex damage and failure mechanisms, such as delaminations, which can severely degrade their strength and fatigue performance. To effectively and safely use composite materials in primary structures, it is essential to assess composite damage response for development of accurate predictive models. Therefore, this study focuses on determining the response of damaged and undamaged carbon epoxy beams subjected to vibration loadings at elevated temperatures. The Hilbert-Huang Transform (HHT) technique is used to analyze the beams’ modal response. The HHT shows potential in identifying the nonlinear damaged response of the beams.
2016-09-27
Technical Paper
2016-01-2084
Curtis Hayes
Abstract Successfully riveting aerospace fatigue-rated structure (for instance, wing panels) requires achieving rivet interference between a minimum and a maximum value in a number of locations along the shank of the rivet. In unbalanced structure, where the skin is much thicker than the stringer, this can be particularly challenging, as achieving minimum interference at the exit of the skin (D2) can often be a problem without exceeding the maximum interference at the exit of the stringer (D4). Softer base materials and harder, higher-strength rivets can compound the problem, while standard manufacturing variations in hardness of part and rivet materials can cause repeatability issues in the process. This paper presents a solution that has been successfully implemented on a production commercial aircraft.
2016-09-27
Technical Paper
2016-01-2113
Raphael Reinhold
Abstract Resin transfer molding (RTM) is gaining importance as a particularly economical manufacturing method for composites needed in the automotive and aerospace industries. With this method, the component is first shaped with dry fiber reinforcements in a so-called “preforming process” before the mold is placed in a RTM tool, injected with resin and cured. In recent years, Broetje-Automation has been developing innovative product solutions that are specially designed for these preforming processes and suitable for industrial use. For the first time ever, Broetje’s Composite Preforming Cell (CPC) makes large-quantity serial production of complex and near-net-shape preforms for composite components using this RTM process possible. With the additional integration of the patented 3D Composite Handling System Broetje impressively demonstrates its service and product portfolio in the area of innovative composite manufacturing technology and its know-how as a complete system integrator.
2016-09-27
Technical Paper
2016-01-2114
Matthias Meyer
Carbon composites have been on an odyssey within the past 15 years. Starting on the highest expectations regarding the performance, reality was hitting a lot of programs hard. Carbon composites were introduced on a very high technical level and industry has shown of being capable to handle those processes in general. In particular, production never sleeps and processes undergo a continuous change. Within these changes costs remain the most critical driver. As products are improving during their lifetime, they usually increase the degree of complexity, too. According to the normal cost improvement, this has drastic consequences for production. When setting up the first generation of composite production, the part being produced has been in the centre of attention.
2016-09-27
Technical Paper
2016-01-2117
Rustam M. Baytimerov, Pavel Lykov, Sergei Sapozhnikov, Dmitry Zherebtsov, Konstantin Bromer
Abstract The development of Additive Technologies (SLS/SLM, EBM, DMD) suggests the increase of range expansion of materials used. One of the most promising directions is products manufacturing from composite materials. The technology of composite micro-powders production on the basis of heat-resistant nickel alloy EP648 and Al2O3 is proposed. The aim of this research is to develop a method of producing composite micropowders for additive technology application. This method is based on modification of the metal micropowders surface by the second phase in a planetary mixer (mechanochemical synthesis).The obtained composite micropowders are compared with powders which are recommended for selective laser melting usage (produced by MTT Technology). The equipment used in the research: planetary mixer, scanning electron microscopy (SEM), optical granulomorphometer Occio 500nano.
2016-09-27
Technical Paper
2016-01-2123
Matthias Busch, Benedikt Faupel
Abstract The integration of omega stringers to panels made of carbon fiber reinforced plastic (CFRP) by adhesive bonding, which is achieved by baking in an autoclave, must be subject to high quality standards. Failures such as porosity, voids or inclusion must be detected safely to guaranty the functionality of the component. Therefore, an inspection system is required to verify these bonds and detect different kinds of defects. In this contribution, the advantages of a robotic inspection system, which will be achieved through continuous testing, will be introduced. The testing method is the active thermography. The active thermography has major advantages compared with other non-destructive testing methods. Compared to testing with ultrasonic there is no coupling medium necessary, thus testing will be significantly enhanced.
2016-09-27
Technical Paper
2016-01-2121
Pavel Lykov, Rustam M. Baytimerov, Artem Leyvi, Dmitry Zherebtsov, Alexey Shultc
Abstract The copper-nickel alloys are widely used in various industries. The adding of nickel significantly enhances mechanical properties, corrosion resistance and thermoelectric properties of copper. The technology was proposed of production of copper-nickel composite micro-powders by the gaseous deposition of nickel on the surface of copper powder. The vaporization of nickel was implemented by using magnetron. The relationship between mode of processing and the ratio of phases in the powder was investigated. The proposed method allows to modify the powder surface without deformation of the particles. The possibility of using of obtained composite powder in selective laser melting (SLM) was evaluated. It is assumed that the structure of the obtained composite material (SLM) will have inclusions of nickel and continuous chain of copper. This structure will have high mechanical properties and high electrical conductivity.
2016-09-27
Technical Paper
2016-01-2125
Henry Hameister
This paper presents an approach to how existing production systems can benefit from Industry 4.0 driven concepts. This attempt is based on a communication gateway and a cloud-based system, that hosts all algorithms and models to calculate a prediction of the tool wear. As an example we will show the Refill Friction Stir Spot Welding (RFSSW), a solid state joining technique, which is examined at the Institute of Production Engineering (LaFT) of the Helmut-Schmidt-University, University of the Federal Armed Forces Hamburg, for years. RFSSW is a sub-section of friction welding, where a rotating tool that consists out of three parts is used to heat up material to a dough-like state. Since Refill Friction Stir Spot Welding produces a selective dot-shaped connection of overlapping materials, the production requirements are similar to riveting or resistance spot welding.
2016-09-27
Technical Paper
2016-01-2129
Antonio Rubio, Luis Calleja, Javier Orive, Ángel Mújica, Asunción Rivero
Abstract Aluminum skin milling is a very challenging process due to the high quality requirements needed in the aeronautic and aerospace industries. Nowadays, on these markets, there are just two technological approaches able to face the manufacturing of this sort of wide thin blanks: chemical and mechanical milling by means of highly complex machines. Both solutions lead to a high investment requirement that affect directly on the application profitability on these industrial sectors. This paper presents a flexible machining system that allows milling skin shaped parts within required tolerances by means of an innovative universal holding fixture combined with an adaptive toolpath development. This flexible holding fixture can be adapted to the required shape and can hold uniformly the whole sheet surface. Besides, the solution includes an implementation that can adapt the machining toolpath by means of the skin thickness online measurement.
2016-09-27
Technical Paper
2016-01-2142
Pavel Lykov PhD, Artem Leyvi, Rustam M. Baytimerov, Aleksei Doikin, Evgeny Safonov
Abstract The treatment of solid surface by powerful streams of charged particles accelerated with power density ≥106 W/cm2 widely used for modification of different materials properties. The fast enter of electron beam power in the material of target causes the flow intense thermal and deformation processes. The changing of the structure, the phase composition, the microrelief of treated surface consequently happens. It is often accompanied by the hardening and increase of the wearing properties. The work proposed of using low-energy high-current electron beam as finish treatment of product obtained by selective laser melting of heat-resistant nickel alloy EP648. The subject of research was the surface properties of the product.
2016-09-27
Technical Paper
2016-01-2124
Sara Nilsson, Jonas Jensen, Mats Björkman, Erik Sundin
Abstract Carbon fiber-reinforced plastic (CFRP) is one of the most commonly used materials in the aerospace industry today. CFRP in pre-impregnated form is an anisotropic material whose properties can be controlled to a high level by the designer. Sometimes, these properties make the material hard to predict with regards to how the geometry affects manufacturing aspects. This paper describes eleven design rules originating from different guidelines that describe geometrical design choices and deals with manufacturability problems that are connected to them, why they are connected and how they can be minimized or avoided. Examples of design choices dealt with in the rules include double curvature shapes, assembly of uncured CFRP components and access for non-destructive testing (NDT). To verify the technical content and ensure practicability, the rules were developed by, inter alia, studying literature and performing case studies at SAAB Aerostructures.
2016-09-27
Technical Paper
2016-01-2101
Burak Deger, Fazli Melemez, Aykut Kibar lng
Abstract A hybrid drilling process of multi material stacks with one shot drilling recently emerge as an economical and time efficient method in aerospace industry. Even though the comprehensive experience and knowledge is available for the cutting parameters of composites and metals alone, significant gap exist for the hybrid drilling parameters. Determination of these parameters such as feed rate, spindle speed and pecking depth has vital importance so as to provide a robust and optimal process to ensure dimensionally high quality, burr and delamination free holes. Main challenge of hybrid drilling operation is to obtain required hole diameter with adequate homogeneity and repeatability. In this study, effect of cutting parameters on dimensional hole quality was investigated. In addition to the hole diameter tolerances, CFRP hole enlargement phenomena which is encountered as a specific drawback of metal-exit stack configurations is also addressed within the scope of this study.
2016-09-27
Journal Article
2016-01-2116
Peter Mueller-Hummel
Abstract Drilling holes into metal with MQL (Minimal Quantity Lubrication) is a normal procedure, because the drill is designed for drilling metal and the malleable capability of the metal compensates for the insufficient cutting capability of a worn out drill. Drilling composite materials using the same drill (designed for drilling metal) is a different procedure, because composite fibers are not malleable like metal at all. Due to this fact the tools become very hot trying to forge composite fibers like metal. The elastic behavior of the composite and the delamination inside the hole makes the tool temporary smaller than the diameter of the drill. The hole in the metal part of the stack remains slightly larger due to the heat and the thermal expansion rate. This paper shows how to drill metal and composite with the same diameter, so that achieving H8 quality is no longer a dream.
2016-09-27
Journal Article
2016-01-2112
Hilmar Apmann
Abstract As a new material FML, made by aluminum foils and Glasfiber-Prepreg, is a real alternative to common materials for fuselages of aircrafts like monolithic aluminum or CFRP. Since experiences within A380 this material has some really good advantages and develops to the status as alternative to aluminum and composite structures. To become FML as a real alternative to aluminum and carbon structures there are many things to improve: design, material, costs and process chain. So following one of the main goals for an industrial application for high production rates of aircrafts is the automation of production processes inside the process chain for FML-parts like skins and panels for fuselages. To reach this goal for high production rates first steps of automation inside this new process chain have been developed in the last two years. Main steps is the automated lay-up of metallic foils and Glasfiber-Prepreg.
2016-09-27
Journal Article
2016-01-2119
Gergis W. William, Samir N. Shoukry, Jacky C. Prucz, Mariana M. William
Abstract Air cargo containers are used to load freight on various types of aircrafts to expedite their handling. Fuel cost is the largest contributor to the total cost of ownership of an air cargo container. Therefore, a better fuel economy could be achieved by reducing the weight of such containers. This paper aims at developing innovative, lightweight design concepts for air cargo containers that would allow for weight reduction in the air cargo transportation industry. For this purpose, innovative design and assembly concepts of lightweight design configurations of air cargo containers have been developed through the applications of lightweight composites. A scaled model prototype of a typical air cargo container was built to assess the technical feasibility and economic viability of creating such a container from fiber-reinforced polymer (FRP) composite materials. The paper is the authoritative source for the abstract.
2016-09-27
Journal Article
2016-01-2118
Patrick Land, Luis De Sousa, Svetan Ratchev, David Branson, Harvey Brookes, Jon Wright
Abstract With increased demand for composite materials in the aerospace sector there is a requirement for the development of manufacturing processes that enable larger and more complex geometries, whilst ensuring that the functionality and specific properties of the component are maintained. To achieve this, methods such as thermal roll forming are being considered. This method is relatively new to composite forming in the aerospace field, and as such there are currently issues with the formation of part defects during manufacture. Previous work has shown that precise control of the force applied to the composite surface during forming has the potential to prevent the formation of wrinkle defects. In this paper the development of various control strategies that can robustly adapt to different complex geometries are presented and compared within simulated and small scale experimental environments, on varying surface profiles.
2016-09-27
Journal Article
2016-01-2126
Ali Mohamed Abdelhafeez, Sein Leung Soo, David Aspinwall, Anthony Dowson, Dick Arnold
Abstract Despite the increasing use of carbon fibre reinforced plastic (CFRP) composites, titanium and aluminium alloys still constitute a significant proportion of modern civil aircraft structures, which are primarily assembled via mechanical joining techniques. Drilling of fastening holes is therefore a critical operation, which has to meet stringent geometric tolerance and integrity criteria. The paper details the development of a three-dimensional (3D) finite element (FE) model for drilling aerospace grade aluminium (AA7010-T7451 and AA2024-T351) and titanium (Ti-6Al-4V) alloys. The FE simulation employed a Coupled Eulerian Lagrangian (CEL) technique. The cutting tool was modelled according to a Lagrangian formulation in which the mesh follows the material displacement while the workpiece was represented by a non-translating and material deformation independent Eulerian mesh.
2016-09-20
Technical Paper
2016-01-1996
David R. Markham, J. Michael Cutbirth
Abstract Modern military electronics systems are generating increasingly higher heat loads, necessitating larger capacity thermal management systems (TMSs). These high-capacity TMSs must meet the strict size and weight requirements of these advancing platforms. Commercially available compressor technology can generate sufficient cooling for these systems; however, they are too heavy and expansive. Mainstream Engineering Corporation has developed a compact, lightweight, high-speed screw compressor that can provide a large cooling capacity with a small package envelope. The compressor housing material is light-weight with a low coefficient of thermal expansion (CTE), allowing a wide operating temperature range. The compressor, with a nominal cooling capacity from 20 kW to 60 kW, was tested over a range of saturated suction conditions, pressure ratios, rotational speeds, and oil lubrication conditions.
2016-09-20
Journal Article
2016-01-2022
Ajay Rao, Vivek Karan, Pradeep Kumar
Abstract Turbulence is by far the number one concern of anxious passengers and a cause for airline injuries. Apart from causing discomfort to passengers, it also results in unplanned downtime of aircrafts. Currently the Air Traffic Control (ATC) and the meteorological weather charts aid the pilot in devising flight paths that avoid turbulent regions. Even with such tailored flight paths, pilots report constant encounters with turbulence. The probability of turbulence avoidance can be increased by the use of predictive models on historical and transactional data. This paper proposes the use of predictive analytics on meteorological data over the geographical area where the aircraft is intended to fly. The weather predictions are then relayed to the cloud server which can be accessed by the aircraft planned to fly in the same region. Predictive algorithms that use Time series forecasting models are discussed and their comparative performance is documented.
2016-09-20
Journal Article
2016-01-2071
Brian A. Hann
Abstract Laser Based Powder Bed Fusion, a specific application of additive manufacturing, has shown promise to replace traditionally fabricated components, including castings and wrought products (and multiple-piece assemblies thereof). In this process, powder is applied, layer by layer, to a build plate, and each layer is fused by a laser to the layers below. Depending on the component, it appears that only 3-5% of the powder charged into the powder bed fusion machine is fused. Honeywell’s initial part qualification efforts have prohibited the reuse of powder. Any unfused powder that exits the dispenser (i.e., surrounds the build or is captured in the overflow) is considered used. In order for the process to be broadly applicable in an economical manner, a methodology should be developed to render the balance of the powder (up to 97% of the initial charge weight) as re-usable.
2016-06-15
Technical Paper
2016-01-1850
Christian Thomas, Nouredine Atalla
In passenger aircraft the most important noise control treatment is the primary insulation attached to the fuselage. Next to its acoustic properties the primary insulation main purpose is the thermal insulation and the minimization of condensed water. In general it consists of fibrous materials like glass wool wrapped in a thin foil. Due to stringent flame, smoke and toxicity requirements the amount of available materials is limited. Furthermore the amount of material installed in aircraft per year is much smaller compared to needs in the automotive industry. Therefore the best lay-up of the available materials is needed in terms of acoustics. This paper presents a tool for numerical optimization of the sound insulation package. To find an improved insulation the simulation tool is used in interaction with a measurement database. The databank is constructed from aircraft grade materials such as fibrous materials, foams, resistive screens and impervious heavy layers.
2016-04-11
Journal Article
2016-01-9081
Sean A. McKelvey, Yung-Li Lee
Abstract Multiaxial loading on mechanical products is very common in the automotive industry, and how to design and analyze these products for durability becomes an important, urgent task for the engineering community. Due to the complex nature of the fatigue damage mechanism for a product under multiaxial state of stresses/strains which are dependent upon the modes of loading, materials, and life, modeling this behavior has always been a challenging task for fatigue scientists and engineers around the world. As a result, many multiaxial fatigue theories have been developed. Among all the theories, an existing equivalent stress theory is considered for use for the automotive components that are typically designed to prevent Case B cracks in the high cycle fatigue regime.
2016-04-05
Journal Article
2016-01-0497
Brian Falzon, Wei Tan
Abstract The development of the latest generation of wide-body carbon-fibre composite passenger aircraft has heralded a new era in the utilisation of these materials. The premise of superior specific strength and stiffness, corrosion and fatigue resistance, is tempered by high development costs, slow production rates and lengthy and expensive certification programmes. Substantial effort is currently being directed towards the development of new modelling and simulation tools, at all levels of the development cycle, to mitigate these shortcomings. One of the primary challenges is to reduce the extent of physical testing, in the certification process, by adopting a ‘certification by simulation’ approach. In essence, this aspirational objective requires the ability to reliably predict the evolution and progression of damage in composites. The aerospace industry has been at the forefront of developing advanced composites modelling tools.
2016-01-05
Journal Article
2015-01-9086
Geethanjali Gadamchetty, Abhijeet Pandey, Majnoo Gawture
The three parameter Ramberg-Osgood (RO) method finds popular usage for extracting complete stress-strain curve from limited data which is usually available. The currently popular practice of assuming the plasticity to set in only at the Yield point provides computational advantage by separating the complete nonlinear curve, obtained from RO method, into elastic and plastic regions. It is shown, with an example problem, that serious errors are committed by using this method if one compares the obtained results with results of complete stress-strain curve. In the present work we propose a simple Taylor series based approach based on RO method to overcome the above deficiency. This method is found to be computationally efficient. The proposed method is applicable for stress-strain curves of materials for which RO method provides a good approximation.
2016-01-01
Journal Article
2015-01-9084
Seyedmohammad Shams, Peng Yang, Rani Elhajjar
Abstract The disk spring offers the potential of significant weight savings when designed with continuous fiber reinforced composite materials. The internal stresses in a disk spring are ideally suited for composite material application due to their superior resistance to in-plane and bending stresses. In this study, a composite laminate disk spring is designed, analyzed and fabricated to take advantage of the low specific strength and weight and high damage tolerance of composite laminates. The design of the disk composite spring considers effects of the laminate stacking sequence and the geometric variables on the disk spring's mechanical performance. A continuum damage finite element analysis approach is used to understand the damage initiation and evolution as a function of applied load. Experimental analysis and a progressive damage analysis based on virtual crack closure technique are performed to evaluate the damage tolerance of the disk spring under fatigue loadings.
2015-09-22
Technical Paper
2015-36-0296
Ana Márcia Barbosa da Silva Antunes, Carlos Antonio Reis Pereira Baptista, Miguel Justino Ribeiro Barboza, André Luis Moreira de Carvalho
Abstract Fatigue is the main cause of mechanical failure in aircraft structures, in which aluminum alloys are employed in approximately 70% of their structural components. Among the microstructural characteristics of aluminum alloys, the hardening precipitates provided by the ageing heat treatment have an important influence in their mechanical properties. In this context, current studies have shown that the two-step ageing heat treatment (T6I4) improves the mechanical properties of 6xxx and 7xxx aluminum alloys. This investigation presents a study of high cycle fatigue behavior of aluminum alloys AA 6351 (T6 and T6I4) and AA 7050 (T7451 and T6I4) as well the influence of microstructural characteristics and two-step ageing heat treatment in the fatigue properties of these alloys. Fatigue tests were performed on smooth and notched specimens.
2015-09-15
Technical Paper
2015-01-2461
Enrico Troiani, Maria Pia Falaschetti, Sara Taddia, Alessandro Ceruti
Abstract The high number of hull losses is a main concern in the UAV field, mostly due to the high cost of on-board equipment. A crashworthiness design can be helpful to control the extent and position of crash impact damage, minimizing equipment losses. However, the wide use of composite materials has recently put the accent on the lack of data about the behavior of these structures under operative loads, such as the crash conditions. This paper presents the outcome of a set of tests carried out to achieve a controlled crush of UAV structures, and to maximize the Specific Energy Absorption. In this work, a small-scale experimental test able to characterize the energy absorption of a Carbon-fiber-reinforced polymer under compression was developed introducing self-supporting sinusoidal shape specimens, which avoid the need for complex anti-buckling devices.
Viewing 1 to 30 of 2452