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Viewing 271 to 300 of 4689
2015-09-15
Technical Paper
2015-01-2513
Hans-Juergen Borchers, Kadir Akkuş, Cagatay Ucar
Abstract This paper will discuss the process of drilling large diameter holes within high quality requirements using a Robot positioning concept. This Robot end-effector system provides flexibility to handle different aircraft sections due to its Robot arm design. The material configuration that will be discussed in this paper is a mixed material stack of CFRP and Aluminum. The diameter range is from 7.9 mm to 15.9mm. This paper will focus on the largest diameter (Ø15.9mm). It addresses the process forces to be handled and the solutions. This paper will take an integrated look at the whole process including machine, spindle, cutting tool design and process conditions. Only this integrated view to all process related items enables running an innovative and effective process. The maximum stack size of 40 mm is another condition that requires a specific process to control the chip size to avoid an impact to the material. Here different concepts have been taken under consideration.
2015-09-15
Technical Paper
2015-01-2515
Adlai Felser, Peter B. Zieve, Bryan Ernsdorff
Abstract A new style of rivet injector is in production use on a variety of fastening machines used by major aircraft manufacturers. In this injector the opposing sides of the rivet guide blocks are attached to the arms of a parallel gripper. We have implemented the parallel gripper in both vertical axis and horizontal axis riveting applications. It is equally effective in both orientations. We have implemented the parallel gripper rivet injector on headed rivets, threaded bolts, ribbed swage bolts and unheaded (slug) rivets.
2015-09-15
Technical Paper
2015-01-2565
Nhan Nguyen, Sonia Lebofsky, Eric Ting, Upender Kaul, Daniel Chaparro, James Urnes
Abstract This paper summarizes the recent development of an adaptive aeroelastic wing shaping control technology called variable camber continuous trailing edge flap (VCCTEF). As wing flexibility increases, aeroelastic interactions with aerodynamic forces and moments become an increasingly important consideration in aircraft design and aerodynamic performance. Furthermore, aeroelastic interactions with flight dynamics can result in issues with vehicle stability and control. The initial VCCTEF concept was developed in 2010 by NASA under a NASA Innovation Fund study entitled “Elastically Shaped Future Air Vehicle Concept,” which showed that highly flexible wing aerodynamic surfaces can be elastically shaped in-flight by active control of wing twist and bending deflection in order to optimize the spanwise lift distribution for drag reduction.
2015-09-15
Technical Paper
2015-01-2570
Brandon Liberi, Praditukrit Kijjakarn, Narayanan Komerath
Abstract Loads slung under aircraft can go into divergent oscillations coupling multiple degrees of freedom. Predicting the highest safe flight speed for a vehicle-load combination is a critical challenge, both for military missions over hostile areas, and for evacuation/rescue operations. The primary difficulty was that of obtaining well-resolved airload maps covering the arbitrary attitudes that a slung load may take. High speed rotorcraft using tilting rotors and co-axial rotors can fly at speeds that imply high dynamic pressure, making aerodynamic loads significant even on very dense loads such as armored vehicles, artillery weapons, and ammunition. The Continuous Rotation method demonstrated in our prior work enables routine prediction of divergence speeds. We build on prior work to explore the prediction of divergence speed for practical configurations such as military vehicles, which often have complex bluff body shapes.
2015-09-15
Journal Article
2015-01-2594
Thomas G. Jefferson, Panorios Benardos, Svetan Ratchev
Abstract Current assembly systems that deal with large, complex structures present a number of challenges with regard to improving operational performance. Specifically, aerospace assembly systems comprise a vast array of interrelated elements interacting in a myriad of ways, resulting in a deeply complex process that requires a multi-disciplined team of engineers. The current approach to ramp-up production rate involves building additional main assembly fixtures which require large investment and lead times up to 24 months. Within Airbus Operations Ltd there is a requirement to improve the capacity and flexibility of assembly systems, thereby reducing non-recurring costs and time-to-market. Recent trends to improve manufacturing agility advocate Reconfigurable Assembly Systems (RAS) as a viable solution. Yet, adding reconfigurability to assembly systems further increases both the operational and design complexity.
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.
2015-06-15
Technical Paper
2015-01-2329
Paolo Di Francescantonio, Charles Hirsch, Piergiorgio Ferrante, Katsutomo Isono
Abstract A new method called Adaptive Spectral Reconstruction (ASR) for the stochastic reconstruction of broadband aeroacoustic sources starting from steady CFD analyses is presented and applied to the evaluation of the noise radiated by a model automotive side mirror. The new approach exploits some ideas from both SNGR and RPM, and for some aspects can be considered as a sort of mixing between the two methods since it permits to reconstruct both the frequency content of the turbulent field (as done by SNGR) and the spatial cross correlation (as done by RPM). The turbulent field is reconstructed with a sum of convected plane waves, but two substantial differences are introduced in respect of SNGR. The first difference concerns the spatial variation of the parameters that define each wave, that depends on the wavelength of each wave, rather than being kept constant or related to the CFD correlation length.
2015-06-15
Technical Paper
2015-01-2327
Hangsheng Hou, Wei Zhao, Jian Hou
Abstract Wind noise is one of the most influential NVH attributes that impact customer sensation of vehicle interior quietness. Among many factors that influence wind noise performance, the amount of dynamic door deflection under the pressure load due to fast movement of a vehicle plays a key roll. Excessive deflection could potentially lead to loss of sealing contact, causing aspiration leakage, which creates an effectual path through which the exterior aerodynamically induced noise propagates into the vehicle cabin. The dynamic door deflection can be predicted using CFD and CAE approaches which, in addition to modeling the structure correctly, require a correct pressure loading composed of external and internal pressure distributions. The determination of external pressure distributions can be fulfilled fairly straightforward by using commercial CFD codes such as Fluent, Star CCM+, Powerflow and others.
2015-06-15
Technical Paper
2015-01-2324
Hangsheng Hou, Guiping Yue
Abstract When a sunroof opens to let in fresh air while driving, there might be several noise issues associated with it. The most common and painful one is the wind throb issue, which is nevertheless largely resolved by implementing a sufficiently high wind deflector along the front edge of the sunroof. However, with the wind throb suppressed, other sound quality issues might emerge. The most notable one is the hissing noise issue, which becomes increasingly objectionable with the increase of vehicle speed. This work looks into the impact of sunroof deflector on interior sound quality with the consideration of wind throb, hissing noise and booming noise in terms of psychoacoustic attributes that could be felt subjectively. The goal is to achieve a better understanding of the sound quality associated with the sunroof deflector design, and inspire a balanced design, potentially targeting the most NVH demanding customers in the premium vehicle segment.
2015-06-15
Technical Paper
2015-01-2322
Bastien Ganty, Jonathan Jacqmot, Ze Zhou, ChanHee Jeong
Abstract At high cruising speed, the car A-pillars generate turbulent air flow around the vehicle. The resulting aerodynamic pressure applied on the windows significantly contributes to the total cabin noise. In order to predict this particular noise contribution, the physic of both the flow and the cabin needs to be accurately modeled. This paper presents an efficient methodology to predict the turbulent noise transmission through the car windows. The method relies on a two-step approach: the first step is the computation of the exterior aero-dynamic field using an unsteady CFD solver (PowerFLOW); the second step consists in the computation of the acoustic propagation inside the cabin using a finite element vibro-acoustic solver (ACTRAN). The simplified car cabin of Hyundai Motor Company, studied in this paper, involves aluminum skin, windows, sealant, inner air cavity and acoustic treatment inside the passenger compartment (porous material, damping layer).
2015-06-15
Technical Paper
2015-01-2079
Colin Hatch, Jason Moller, Eleftherios Kalochristianakis, Ian Roberts
Abstract The introduction of ice-phobic coatings promises to allow passive ice protection systems to be developed particularly for rotating systems such as propellers. The centrifugal force field combined with reduced adhesive strength can produce a self-shed capability limiting the amount of ice build-up. The size and shed time of ice shed from a propeller is predicted using a process that determines ice shape, ice growth rate and both internal and ice-structure interface stresses. A simple failure model is used to predict the onset of local failure and to propagate damage in the ice until local ice shedding is obtained. Recommendations are made on developing the model further.
2015-06-15
Technical Paper
2015-01-2127
Andrea Munzing, Franck Hervy, Stephane Catris
Abstract A helicopter blade profile was tested in the DGA Aero-engine Testing's icing altitude test facility S1 in Saclay, France during the winter of 2013/2014. The airfoil was a helicopter main rotor OA312 blade profile made out of composite material and with a metallic erosion shield. Dry air and ice accretion tests have been performed in order to assess the iced airfoil's aerodynamic behaviour. Several icing conditions were tested up through Mach numbers around 0.6. This paper presents the test setup, the test model and some of the test results. The test results presented in this paper include the ice shapes generated as well as dry air and iced airfoil lift and drag curves (polars) which were obtained with the real ice shapes on the airfoil.
2015-06-15
Technical Paper
2015-01-2163
Caio Fuzaro Rafael, Diogo Mendes Pio, Guilherme A. Lima da Silva
Abstract The present paper presents a validation of momentum boundary-layer integral solution and finite-volume Reynolds-Averaged Navier Stokes (RANS) Computational Fluid Dynamics (CFD) results for skin friction around airfoils NACA 8H12 and MMB-V2 as well as heat transfer around an isothermal cylinder with rough surface. The objective is to propose a two-equation integral model and compare its predictions to results from a robust CFD tool, to experimental data and to results from a one-equation integral solution. The latter is the mathematical model used by classic 2D icing codes. All proposed model predictions are compared to CFD results for verification and, whenever possible, to experimental data for validation. The code-to-code verification brings reliability to both the proposed code and the CFD tool when there is no test data available.
2015-06-15
Technical Paper
2015-01-2208
David Stotera, Scott Bombard
Abstract Both vehicle roof systems and vehicle door systems typically have viscoelastic material between the beams and the outer panel. These materials have the propensity to affect the vibration decay time and the vibration level of the panel with their damping and stiffening properties. Decay time relates to how pleasant a vehicle door sounds upon closing, and vibration level relates to how loud a roof boom noise may be perceived to be by vehicle occupants. If a surrogate panel could be used to evaluate decay time and vibration level, then a design of experiments (DOE) could be used to compare the effects of different factors on the system. The purpose of this paper is to show the effect of varying test factors on decay time and vibration level on a panel-beam system with viscoelastic material applied. The results were calculated using DOE software, and they were used to construct optimized systems for validation testing.
2015-06-15
Technical Paper
2015-01-2206
Glenn Yin, Alan Parrett, Nitish Wagh, Dennis Kinchen
Abstract In automotive noise control, the hood liner is an important acoustic part for mitigating engine noise. The random incidence absorption coefficient is used to quantify the component level acoustic performance. Generally, air gaps, type of substrate materials, density of the substrate materials and Air Flow Resistivity (AFR) of the cover scrim are the dominant control factors in the sound absorption performance. This paper describes a systematic experimental investigation of how these control factors affect flat sample performance. The first stage of this study is full factorial measurement based on current available solutions from sound absorber suppliers. The acoustic absorption of different hood liner constructions, with variations in materials, density, air gaps, and scrims was measured.
2015-06-15
Technical Paper
2015-01-2228
Kalyan Chakravarthy Addepalli, Natalie Remisoski, Anthony Sleath, Shyiping Liu
Abstract Drivelines used in modern pickup trucks commonly employ universal joints. This type of joint is responsible for second driveshaft order vibrations in the vehicle. Large displacements of the joint connecting the driveline and the rear axle have a detrimental effect on vehicle NVH. As leaf springs are critical energy absorbing elements that connect to the powertrain, they are used to restrain large axle windup angles. One of the most common types of leaf springs in use today is the multi-stage parabolic leaf spring. A simple SAE 3-link approximation is adequate for preliminary studies but it has been found to be inadequate to study axle windup. A vast body of literature exists on modeling leaf springs using nonlinear FEA and multibody simulations. However, these methods require significant amount of component level detail and measured data. As such, these techniques are not applicable for quick sensitivity studies at design conception stage.
2015-06-15
Journal Article
2015-01-2222
Nikos Zafeiropoulos, Marco Ballatore, Andy Moorhouse, Andy Mackay
Abstract Axle forces from tire-road interaction can excite different structural resonances of the vehicle hence a high number of sensors is required for observing and separating all the vibrations dynamics that are coherent with the cabin noise. Feed-forward road noise control strategies adopted so far rely mainly on capturing these dynamics and thus the number of sensors constitutes one major limitation of this approach. Therefore there is a necessity for reducing the number of sensors without degrading the performance of an ANC system. In the past coherence function analysis has been found to be a useful tool for optimizing the sensor location. In this case coherence function mapping was performed between an array of vibration sensors and the headrest microphones in order to identify the locations on the structure that are highly correlated with road noise bands in the compartment.
2015-06-15
Technical Paper
2015-01-2242
Ling Zheng, Zhanpeng Fang
Abstract The design optimization of vehicle body structure is addressed to reduce interior noise and improve customer satisfaction in this paper. The structural-acoustic model is established and the response of sound pressure in frequency domain is obtained by using finite element method. The minimization of sound pressure near the driver's right ear depends on the geometry of vehicle body structure and the layout of damping treatments. The panel participation analysis is performed to find out the key panels as design variables and improve the efficiency of optimization computation. Response Surface Method (RSM) is utilized to optimize the vibro-acoustic properties of vehicle body structure instead of complex structural-acoustic coupling finite element model. Geometric optimization problem of panels is described and solved to minimize the interior noise in vehicle.
2015-06-15
Technical Paper
2015-01-2262
Tom Knechten, Marius-Cristian Morariu, PJG van der Linden
Abstract Structural and vibro-acoustic transfer functions still form an essential part of NVH data in vehicle development programs. Excitation in the three DOFs at all body interface connection locations to target responses gives information on local dynamics stiffness and the body sensitivity for that specific path in an efficient manner. However, vehicles become more compact for fuel efficiency, production costs and to meet the market demand for urban vehicles. Alternative driveline concepts increase the electronic content and new mount locations. To achieve the optimum on road noise NVH, handling performance while conserving interior space and trunk volume requires a complex suspension layout. On top of that, customers put weight on safety and comfort systems which result to a higher packaging density. These trends imply ever limiting accessibility of the interface connections on the body structure.
2015-06-15
Journal Article
2015-01-2265
Murali Balasubramanian, Ahmed Shaik
Abstract Automotive manufacturers are being challenged to come up with radical solutions to achieve substantial (30-35%) vehicle weight reductions without compromising Safety, Durability, Handling, Aero-thermal or Noise, Vibration and Harshness (NVH) performance. Developing light weight vehicle enablers have assumed foremost priority amongst vehicle engineering teams in order to address the stringent Fuel Economy Performance (FEP) targets while facilitating lower CO2 emissions, downsizing of engines, lower battery capacities etc. Body sheet metal panels have become prime targets for weight reductions via gage reduction, high strength steel replacement, lighter material applications, lightening holes etc. Many of these panel weight reduction solutions are in sharp conflict with NVH performance requirements.
2015-06-15
Technical Paper
2015-01-2264
Rama Subbu, Baskar Anthonysamy, Piyush Mani Sharma
Abstract In India, demand for motorcycle with good comfort is increasing among the customers thereby the vibration reduction of two wheelers is key parameter for motorcycle manufacturers. In order to overcome the demand in the market, manufacturers are giving more importance to cost of the product by reducing the material. This results in the reduction of the life cycle of the vehicle models and drives the manufacturers to different product design philosophies and design tools, as one would expect. One of the performance factors that continue to challenge designers is that of vehicle vertical acceleration experienced by the motorcycle components. An essential tool in the motorcycle development process is the ability to quantify the durability of the component. This paper main objective is to increase the life of the motorcycle front fender through virtual simulation, on road testing and laboratory testing using NVH tool.
2015-06-15
Journal Article
2015-01-2263
Saeed J. Siavoshani, Prasad Vesikar
The intent of this paper is to document comprehensive test-based approach to analyze the door-closing event and associated sound using structural and acoustic loads developed during the event. This study looks into the door-closing phenomenon from the structural interaction point of view between the door and the body of the vehicle. The study primarily focuses on distributing the door and body interaction as discrete multiple structural and acoustic phenomena. It also emphasizes on the structural and acoustic loads developed by the discretized interactions at the interfaces between the door and the body frame. These interfaces were treated to be the load paths from the door to the body. The equivalent structural and acoustic loads were calculated indirectly using the well-known Transfer Path Analysis (TPA) methodology for structural loads and the Acoustic Source Quantification (ASQ) methodology for acoustic loads.
2015-06-15
Technical Paper
2015-01-2257
Ki-Chang Kim, Sang-Woo Lee, Seok-Gil Hong, Jay Kim, Gil-Jun Lee, Jae Min Choi, Yong-Jin Kim
Abstract Squeak and rattle (S&R) problems in body structure and trim parts have become serious issues for automakers because of their influence on the initial quality perception of consumers. In this study, various CAE and experimental methods developed by Hyundai Motors for squeak and rattle analysis of door systems are reported. Friction-induced vibration and noise generation mechanisms of a door system are studied by an intelligent combination of experimental and numerical methods. It is shown that the effect of degradation of plastics used in door trims can be estimated by a numerical model using the properties obtained experimentally. Effects of changes in material properties such as Young's modulus and loss factor due to the material degradation as well as statistical variations are predicted for several door system configurations. As a new concept, the rattle and squeak index is proposed, which can be used to guide the design.
2015-06-15
Technical Paper
2015-01-2267
Youngha Kim, Choonhyu Kim, Jaewoong Lee, Sunggi Kim
Abstract This paper describes a structure-borne noise reduction process that was developed using a combination of experimental and analytical methods. First, the major noise paths were identified using experimental Transfer Path Analysis (TPA). Next, FEA-Experimental modeling and forced response simulation were conducted using the Hybrid FEA-Experimental FRF method. The Hybrid FEA-Experimental FRF-Based Substructuring (FBS) model was used along with Operational Deflection Shape (ODS) and Modal Analysis. The Hybrid FEA-Experimental model consisted of an experimental FRF representation of the body and a finite element model of a sub-frame. The finite element of the sub-frame was created by using Altair HyperMesh from CATIA images and the dynamic analysis was carried out by using MSC Nastran. The natural frequency and frequency response function of the finite element sub-frame model were compared with that of a real sub-frame to determine the validity of applying the Hybrid FBS method.
2015-06-15
Technical Paper
2015-01-2302
Yuksel Gur, Jian Pan, David Wagner
Lightweighting of vehicle panels enclosing vehicle cabin causes NVH degradation since engine, road, and wind noise acoustic sources propagate to the vehicle interior through these panels. In order to reduce this NVH degradation, there is a need to develop new NVH sound package materials and designs for use in lightweight vehicle design. Statistical Energy Analysis (SEA) model can be an effective CAE design tool to develop NVH sound packages for use in lightweight vehicle design. Using SEA can help engineers recover the NVH deficiency created due to sheet metal lightweighting actions. Full vehicle SEA model was developed to evaluate the high frequency NVH performance of “Vehicle A” in the frequency range from 200 Hz to 10 kHz. This correlated SEA model was used for the vehicle sound package optimization studies. Full vehicle level NVH laboratory tests for engine and tire patch noise reduction were also conducted to demonstrate the performance of sound package designs on “Vehicle A”.
2015-06-15
Technical Paper
2015-01-2290
Sivanandi Rajadurai, Guru Prasad Mani, Kavin Raja, Sundaravadivelu Mohan
Abstract Bending moment is one of the strongest pursuits in resonator's structural validation. Eigen problems play a key role in the stability and forced vibration analysis of structures. This paper explains the methodology to determine the weak points in the resonator assembly considering the additional effects of the installation forces and temperature impacts. Using strain energy plots, weakest part of the product is identified in the initial stage. The solution comes in unique way of utilizing the worst case scenarios possible. As a consequence, the stress generated by these analyses will prove to be critical in concerning the durability issue of the system. These conditions are evaluated by a finite element model through linear approaches and results are summarized.
2015-06-15
Journal Article
2015-01-2321
Nicholas Oettle, Andrew Bissell, Sivapalan Senthooran, Mohammed Meskine
Abstract For the automotive industry, the quality and level of the wind noise contribution has a growing importance and therefore should be addressed as early as possible in the development process. Each component of the vehicle is designed to meet its individual noise target to ensure the wind noise passenger comfort level inside the vehicle is met. Sunroof broadband noise is generated by the turbulent flow developed over the roof opening. A strong shear layer and vortices impacting on the trailing edge of the sunroof are typical mechanisms related to the noise production. Sunroof designs are tested to meet broadband noise targets. Experimentally testing designs and making changes to meet these design targets typically involves high cost prototypes, expensive wind tunnel sessions and potentially late design changes.
2015-06-15
Technical Paper
2015-01-2103
Christian Bartels, Julien Cliquet, Carlos Bautista
Abstract In order to comply with applicable certification regulations, airframers have to demonstrate safe operation of their aircraft in icing conditions. Part of this demonstration is often a numerical prediction of the potential ice accretion on unprotected surfaces. The software ONICE2D, originally developed at the Office National d'Études et de Recherche Aérospatial (ONERA), is used at Airbus for predicting ice accretions on wing-like geometries. The original version of the software uses a flow solution of the 2D full-potential equation on a structured C-grid as basis for an ice accretion prediction. Because of known limitations of this approach, an interface was added between ONICE2D and TAU [6], a hybrid flow solver for the Navier-Stokes equations. The paper first details the approach selected to implement the interface to the hybrid flow solver TAU.
2015-06-15
Technical Paper
2015-01-2102
Guilin Lei, Wei Dong, Jianjun Zhu, Mei Zheng
Abstract The numerical simulation of ice melting process on an iced helicopter rotor blade is presented. The ice melting model uses an enthalpy-porosity formulation, and treats the liquid-solid mushy zone as a porous zone with porosity equal to the liquid fraction. The ice shape on the blade section is obtained by the icing code with a dynamic mesh module. Both of the temperature change and the ice-melting process on the rotor blade section surface are analyzed. The phenomenon of ice melting is analyzed through the change of temperature and liquid fraction on the abrasion/ice interface. The liquid fraction change as with time on the abrasion/ice surface is observed, which describes the ice-melting process well. The numerical results show that the ice melting process can be simulated effectively by the melting model. The de-icing process can be monitored by observing the change of the liquid fraction of the area around the abrasion/ice interface.
2015-06-15
Technical Paper
2015-01-2121
Yong Chen, Liang Fu
Abstract In helicopter, the icing rotor blades will decrease the effectiveness of the helicopter and endanger the lives of the pilots. The asymmetrical ice break-up and shedding could also lead to severe vibrations of the rotor blade. Ice break-up from the main rotor may strike the fuselage and tail rotor, even worse, find its way into the engine, which may cause serious aircraft accidents. An understanding of the mechanisms responsible for ice shedding process is necessary in order to optimize the helicopter rotor blade design and de-icing system to avoid hazardous ice shedding. In this paper, the ice shedding model is improved by introducing a bilinear cohesive zone model (CZM) to simulate the initiation and propagation of ice/blade interface crack. A maximum stress criterion is used to describe the failure occurred in the ice.
Viewing 271 to 300 of 4689