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Viewing 1 to 30 of 15854
2015-09-29
Technical Paper
2015-01-2791
Srinivas Anantharaman, Manoj Baskaran
Nozzles tip Temperature (NTT) of an injector is a critical parameter for an engine as far as reliability of engine is concerned. It is required to ensure that the injectors operate under its operational limit because higher operating temperatures would result in enlargement of the nozzle spray tip, resulting in higher through flow, producing more undesirable power. This could result in failure of other components in the engine. In this paper we identify the various parameters that are critical for NTT and thereby predict the NTT by having the known input parameters. Response surface methodology and artificial neural network are used to identify the parameters, estimate the significance of each parameter and predict the NTT. Based on this analysis, even without the use of an instrumented injector NTT can be predicted at various working conditions of the vehicle on different terrains.
2015-09-29
Technical Paper
2015-01-2765
Shannon K. Sweeney
Abstract This paper presents simple but comprehensive modeling of the loads on the rubber sandwich-type mounts that often suspend the drum(s) in vibratory compactors or asphalt rollers. The goal of the modeling is to predict the overall performance of the rubber mount system. The modeling includes calculations to 1) identify and quantify all predictable low-frequency loads on the rubber mounts during normal vehicle operations, 2) predict the steady-state high-frequency vibration response of the drum, rubber mounts, and vehicle frame during compaction operations, 3) predict the heat generation in the rubber mounts from their hysteretic damping, and 4) predict the fatigue life and life distribution of the rubber mounts. Some typical results of the modeling are provided along with some brief criteria to assess suspension performance. Other, unpredictable suspension loads are discussed but not modeled.
2015-09-15
Technical Paper
2015-01-2600
Gustavo Franco Barbosa, Elton Candia Cordeiro, Fábio Rodrigues Costa
This paper presents a full automated solution that uses robots for manufacturing business jets primary parts. The purpose of this technological innovation is to increase productivity, improve the quality of final product, reduction of costs with maintenance and consumable materials, in addition to meet the requirements of ergonomics, occupational health and safety. So, it has been sought better results in terms of process efficiency and technological innovation faced to competitive market requirements related to industrial automation. The aim is to improve the manufacturing processes of the furniture parts, striving for excellence in every step by further adding value and reducing wastes in order to reduce manufacturing costs and enable greater customer satisfaction.
2015-09-15
Technical Paper
2015-01-2607
Matthias Meyer
STAXX Compact 1700 is a new machining centre, designed for the production of carbon fibre parts, using the fibre placement process. It produces prepreg carbon fibre stacks near to net shape which need to be moulded. As today’s high volume production lacks a reliable production system that can handle carbon fibre with high efficiency and minimal material scrap, fibre placement is the only technology that reduces material scrap during the production process significantly, especially for shell shaped parts. Most of the technical applications for lightweight construction, such as in the automotive and aerospace industries are ‘shell’ type shaped parts. While textile production methods like in resin transfer moulding may cause a scrap rate of more than 50%, fibre placement would offer a total scrap rate of below 5%. Accordingly, fibre placement offers the design option to produce parts of variable wall thickness and local reinforcement.
2015-09-15
Technical Paper
2015-01-2592
Joao Pedro Malere, Wlamir Olivares Loesch Vianna
This paper presents a method to determine the root cause of an aircraft component failure by means of the aircraft fault messages history. The k-Nearest Neighbors (k-NN) and the Tree-Augmented naive Bayes (TAN) methods were used in order to classify the failure causes as a function of the fault messages (predictors). The contribution of this work is to show how well the fault messages of aircraft systems can classify specific components failure modes. The training set contained the messages history from a fleet and the root causes of a butterfly valve reported by the maintenance stations. A cross-validation was performed in order to check the loss function value and to compare both methods performance. It is possible to see that the use of just fault messages for the valve failure classification provides results that close to 2/3 and could be used for faster troubleshooting procedures.
2015-09-15
Technical Paper
2015-01-2497
George Nicholas Bullen
Abstract The introduction of composite materials onto air vehicles has complicated the traditional hole/countersink assessment criteria due its finished-part thickness variability; softer and dissimilar properties than the metallic substructure where it is mounted and attached; and the increased attention to other acceptance criteria such as fiber tear, fiber pull, and moisture propagation in the hole that degrades fastener capability. The addition of composite materials further complicates the assembly process by adding a boundary layer of liquid shim or sealant between the composite piece (usually a skin) and the substructure. Current hole inspection systems are absent the ability to assess the interior condition of the composite hole such as fiber tear, damage to the liquid shim, and debris or burrs between the multiple stacks of dissimilar material.
2015-09-15
Technical Paper
2015-01-2423
Samarth Jain, Soumya Roy, Dhruv Gupta, Vasu Kumar, Naveen Kumar
Abstract The art and science of thrust vectoring technology has seen a gradual shift towards fluidic thrust vectoring techniques owing to the potential they have to greatly influence the aircraft propulsion systems. The prime motive of developing a fluidic thrust vectoring system has been to reduce the weight of the mechanical thrust vectoring system and to further simplify the configuration. Aircrafts using vectored thrust rely to a lesser extent on aerodynamic control surfaces such as ailerons or elevator to perform various maneuvers and turns than conventional-engine aircrafts and thus have a greater advantage in combat situations. Fluidic thrust vectoring systems manipulate the primary exhaust flow with a secondary air stream which is typically bled from the engine compressor or fan. This causes the compressor operating curve to shift from the optimum condition, allowing the optimization of engine performance. These systems make both pitch and yaw vectoring possible.
2015-09-15
Technical Paper
2015-01-2453
Danilo Andreoli, Mario Cassaro, Manuela Battipede, Goodarz Ahmadi, Piergiovanni Marzocca
Abstract Flow control over aerodynamic shapes in order to achieve performance enhancements has been a lively research area for last two decades. Synthetic Jet Actuators (SJAs) are devices able to interact actively with the flow around their hosting structure by providing ejection and suction of fluid from the enclosed cavity containing a piezo-electric oscillating membrane through dedicated orifices. The research presented in this paper concerns the implementation of zero-net-mass-flux SJAs airflow control system on a NACA0015, low aspect ratio wing section prototype. Two arrays with each 10 custom-made SJAs, installed at 10% and 65% of the chord length, make up the actuation system. The sensing system consists of eleven acoustic pressure transducers distributed in the wing upper surface and on the flap, an accelerometer placed in proximity of the wing c.g. and a six-axis force balance for integral load measurement.
2015-09-15
Technical Paper
2015-01-2464
Anna Suñol Jiménez, Tao Yang, Dean Vucinic
Abstract Thrust vectoring is an interesting propulsion solution in aeronautic applications due to its fast response, improving aircraft's performance for take-off, landing and flight, and enabling Short/Vertical Take-Off and Landing (S/VTOL). In this context, an attempt to design a radically new concept of thrust vectoring nozzle is in current development. This novel nozzle, called ACHEON, bases the jet deviation control on the interaction of two primary jets of different velocities, where the one with higher velocity entrains the one with lower velocity. Two cylindrical walls are positioned after the two air jets mixing. If the inlet conditions are not symmetric, the Coanda effect on the walls forces the resulting air jet to divert from the symmetry axis. This paper shows the experimental pressure distribution along the Coanda wall for different inlet.
2015-09-15
Technical Paper
2015-01-2468
Rebecca Margetts, Chris Bingham, Tim Smith
Abstract Nonlinear Dynamic Inversion (NDI) has been previously reported for application to unmanned aircraft systems, due to the inherent attributes of allowing global co-ordinates to be used directly as control inputs. Here, the paper describes a model implementation of an ACHEON propulsion/thrust vectoring system that can be applied to a range of aircraft, with specific emphasis to thrust vectoring of a UAV. Results from the studies show the overall performance is shown to provide improved stability and dynamic characteristics when augmented with additional classical (PI based) control schemes.
2015-09-15
Technical Paper
2015-01-2512
Mark W. Sydenham, Tim Brown
Abstract Electroimpact has developed an automated solution for installing OSI-Bolts on the HStab for Boeing's 787-9 aircraft. This solution utilizes Electroimpact's existing accurate robotic system together with new hardware designed specifically for OSI-Bolts. In addition to automated drilling and fastener installation, this system performs numerous quality checks to insure the installed fastener meets engineering requirements. Before installing the fastener, the system measures actual stack thickness and the length of the fastener to ensure that the proper grip is installed. Torque and angle feedback are recorded during installation which can be used determine if the fastener was installed correctly. The system will also automatically shave the small protuberance on the fastener head left by the broken off fastener stem, which is inherent to the OSI-Bolt. Figure 1 Cell Overview
2015-09-15
Journal Article
2015-01-2416
Charles E. Oberly, Michelle Bash, Benjamin R. Razidlo, Travis E. Michalak, Fernando Rodriguez
Abstract An IPTMS hardware facility has been established in the laboratories of the Aerospace Systems Directorate of the Air Force Research Laboratory (AFRL) at Wright-Paterson Air Force Base (WPAFB). This hardware capability was established to analyze the transient behavior of a high power Electrical Power System (EPS) coupled virtually to a Thermal Management System (TMS) under fast dynamic loading conditions. The system incorporates the use of dynamic electrical load, engine emulation, energy storage, and emulated thermal loads operated to investigate dynamics under step load conditions. Hardware architecture and control options for the IPTMS are discussed. This paper summarizes the IPTMS laboratory demonstration system, its capabilities, and preliminary test results.
2015-09-15
Journal Article
2015-01-2491
Paul Haworth, Donald Peterson, Curtis Hayes
Abstract A new high speed forming process for fatigue rated index head rivets used in wing panel assembly using ball-screw based servo squeeze actuation has been developed. The new process is achieved using a combination of force and position control and is capable of forming to 40,000 lbs at rates of up to 200,000 lbs/second whilst holding the part location to within +/− 10 thousandths of an inch. Multi-axis riveting machines often have positioning axes that are also used for fastener upset. It is often the case that while a CNC is used for positioning control, another secondary controller is used to perform the fastener upset. In the new process, it has been possible to combine the control of the upset process with the machine CNC, thus eliminating any separate controllers. The fastener upset force profile is controlled throughout the forming of the rivet by using a closed loop force control system that has a load cell mounted directly behind the stringer side forming tool.
2015-09-06
Technical Paper
2015-24-2467
Alessandro Ferrari, Federica Paolicelli
Abstract A challenging task that is required to modern injection systems is represented by the enhanced control of the injected quantities, especially when small injections are considered, such as, pilot and main shots in the context of multiple injections. The propagation of the pressure waves triggered by the nozzle opening and closure events through the high-pressure hydraulic circuit can influence and alter the performance of the injection apparatus. For this reason, an investigation of the injection system fluid dynamics in the frequency domain has been proposed. A complete lumped parameter model of the high-pressure hydraulic circuit has been applied to perform a modal analysis. The visualization of the main vibration modes of the apparatus allows a detailed and deep comprehension of the system dynamics. Furthermore, the possible resonances, which are induced by the action of the external forcing terms, have been identified.
2015-09-06
Technical Paper
2015-24-2470
Daniel Pearce, Yannis Hardalupas, A.M.K.P Taylor
The measurement of the rate of fuel injection using a constant volume, fluid filled chamber and measuring the pressure change as a function of time due to the injected fluid (the so called “Zeuch” method) is an industry standard due to its simple theoretical underpinnings. Such a measurement device is useful to determine key timing and quantity parameters for injection system improvements to meet the evolving requirements of emissions, power and economy. This study aims to further the understanding of the nature of cavitation which could occur in the near nozzle region under these specific conditions of liquid into liquid injection using high pressure diesel injectors for heavy duty engines. The motivation for this work is to better understand the temporal signature of the pressure signals that arise in a typical injection cycle.
2015-09-06
Journal Article
2015-24-2472
Nikolaos Papadopoulos, Pavlos Aleiferis
The design of a Diesel injector is a key factor in achieving higher engine efficiency. The injector's fuel atomisation characteristics are also critical for minimising toxic emissions such as unburnt Hydrocarbons (HC). However, when developing injection systems, the small dimensions of the nozzle render optical experimental investigations very challenging under realistic engine conditions. Therefore, Computational Fluid Dynamics (CFD) can be used instead. For the present work, transient, Volume Of Fluid (VOF), multiphase simulations of the flow inside and immediately downstream of a real-size multi-hole nozzle were performed, during and after the injection event with a small air chamber coupled to the injector downstream of the nozzle exit. A Reynolds Averaged Navier-Stokes (RANS) approach was used to account for turbulence. Grid dependency studies were performed with 200k-1.5M cells.
2015-09-06
Journal Article
2015-24-2462
Fabio Auriemma, Heiki Tiikoja
The acoustic impedance exhibited by a new type of element for noise control, the Micro-Grooved Elements (MGEs), has been widely investigated in this paper. The MGEs are typically composed of two overlying layers presenting macroscopic slots and a number of micro-grooves on one of the contact surfaces. The micro-grooves result in micro-channels as the layers are assembled to form the element. Similarly to Micro-Perforated Elements (MPEs), the MGEs have been proved to provide effective dissipation of acoustic energy by the means of viscous losses taking place in the micro-channels. However, in contrast to the MPEs, the MGEs use the grooves, instead of the holes, in which the air is forced to pass through. It results in more cost effective elements, which have been found to represent an adequate alternative for fibrous materials, typically present in silencer units.
2015-08-28
Standard
AS5355/2A
SCOPE IS UNAVAILABLE.
2015-08-28
Standard
AS5355/3A
SCOPE IS UNAVAILABLE.
2015-08-28
Standard
AS5355/1A
SCOPE IS UNAVAILABLE.
2015-08-27
Standard
J2271M_201508
This SAE Parts Standard provides dimensional and quality assurance requirements for M6 through M36 metric sizes of studs in the following configurations in materials needed for ship system applications: 1. Continuous thread studs in M thread profile. b. Double end studs—clamping type (also called bolt-studs) where both ends are of the same thread series but different lengths (M thread profile). A complete inch companion to this document is provided in SAE J2271. These studs are primarily for use in ship systems and equipment. The continuous thread studs and the constant strength double end studs are configurations particularly suited to applications which are subject to high shock requirements.
2015-08-24
Standard
AS4393C
This specification establishes the requirements for the following types of self-locking nuts: a. Wrenching Nuts: i.e., hexagon and double hexagon nuts. b. Anchor Nuts: i.e., plate nuts, gang channel nuts, and shank nuts. The wrenching nuts, shank nuts, and nut elements of plate and gang channel nuts are made of corrosion and heat resistant precipitation hardenable iron base alloy of the type identified under the Unified Numbering System as UNS S66286 and of 160,000 psi axial tensile strength at room temperature, with maximum conditioning temperature of parts at 1200 °F prior to room temperature testing.
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