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Viewing 91 to 120 of 33395
2017-09-19
Technical Paper
2017-01-2047
Tyler Vincent, Joseph Schetz, K. Lowe
Analysis and design of total temperature probes for accurate measurements in hot, high-speed flows remains a topic of great interest in aerospace propulsion and a number of other engineering areas. Despite an extensive prior literature on the subject, prediction of error sources from convection, conduction and radiation is still an area of great concern. For hot-flow conditions, the probe is normally mounted in a cooled support, leading to substantial axial conduction along the length of the probe. Also, radiation plays a very important role in most hot, high-speed conditions. One can apply detailed computational methods for simultaneous convection, conduction and radiation heat transfer, but such approaches are not suitable for rapid, routine analysis and design studies. So, there is still a place for approximate methods, and that is the subject of this paper.
2017-09-19
Technical Paper
2017-01-2052
K Friedman, G Mattos, K Bui, J Hutchinson, A Jafri, J Paver PhD
Aircraft seating systems are evaluated utilizing a variety of impact conditions and selected injury measures. Injury measures like the Head Injury Criterion (HIC) are evaluated under standardized conditions using anthropometric dummies such as those outlined in 14 CFR part 25. An example would be a dummy seated in an upright position held with a two point belt decelerated from an impact speed and allowed to engage components that are in front of the dummy. Examples of head contact surfaces would include video monitors, a wide range of seat back materials, and airbags from which the HIC and other injury measures can be calculated. Other injury measures, such as Nij, are also of interest and can be measured with the Hybrid III dummy as well. A minimum deceleration pulse is defined as part of the regulations for a frontal impact. In this study the effect of variations in decelerations that meet the requirements is considered.
2017-09-19
Technical Paper
2017-01-2051
Vasanth Thanigaivelu, Samir Choksi
Testability addresses the extent to which a system or unit supports fault detection and fault isolation in a confident, timely and cost-effective manner. The incorporation of adequate testability, including Built-In Test (BIT), requires early end systematic management attention to testability requirements, design and measurement. Whilst the design of BIT has become a standard design practice for a complex control system, the process to measure the effectiveness of such circuitry (both hardware and software) remains qualitative. The Built-In Test Effectivity Analysis or BEA tries to quantify such analysis at each phase; identifying requirement gaps that help design safer products. The BEA modifies standard reliability programme to use Functional Failure Modes and Effects Analysis (FFMEA), and a reliability prediction of each functional group to generate a measure of how thoroughly the system can check itself.
2017-09-19
Technical Paper
2017-01-2115
Gilberto Burgio, Leonardo Mangeruca, Alberto Ferrari, Marco Carloni, Virgilio Valdivia-Guerrero, Laura Albiol-Tendillo, Parithi Govindaraju, Marcel Gottschall, Olaf Oelsner, Sören Reglitz, Jann-Eve Stavesand, Andreas Himmler, Lionel Yapi
This paper presents a demonstrator implemented in the project MISSION (Modelling and Simulation Tools for Systems Integration on Aircraft). This is a collaborative project being developed under the European Union Clean Sky 2 Program, a public-private partnership bringing together aeronautics industrial leaders and public research organizations based in Europe. The provision of integrated modelling, simulation, and optimization tools to effectively support all stages of aircraft design remains a critical challenge in the aerospace industry. In particular the high level of system integration that is characteristic of new aircraft designs is dramatically increasing the complexity of both design and verification. Simultaneously, the multiphysics interactions between structural, electrical, thermal, and hydraulic components have become more significant as the systems become increasingly interconnected.
2017-09-19
Technical Paper
2017-01-2060
Joseph Dygert, Patrick Browning, Magdalena Krasny
The dielectric barrier discharge (DBD) has seen significantly increased levels of interest for its applications to various aerodynamic problems. The DBD produces stable atmospheric-pressure non-thermal plasma with highly energetic electrons and a variety of ions and neutral species. The resulting plasma often degrades the dielectric barrier between the electrodes of the device, ultimately leading to actuator failure. Several researchers have studied a variety of parameters related to degradation and time-dependent dielectric breakdown of various polymers such as PMMA or PVC that are often used in actuator construction. Many of these studies compare the degradation of these materials to that of borosilicate glass in which it is claimed that there is no observable degradation to the glass. Recent research at West Virginia University has shown that certain actuator operating conditions can lead to degradation of a glass barrier and can ultimately result in failure.
2017-09-19
Technical Paper
2017-01-2058
Francesco Noziglia, Paolo Rigato, Enrico Cestino, Giacomo Frulla, Alfredo Arias-Montano
Innovative aircraft design studies have noted that uncertainty effects could become significant and greatly emphasized during the conceptual design phases due to the scarcity of information about the new aero-structure being designed. The introduction of these effects in design methodologies are strongly recommended in order to perform a consistent evaluation of structural integrity . The benefit to run a Robust Optimization is the opportunity to take into account uncertainties inside the optimization process obtaining a set of robust solutions. A major drawback of performing Robust Multi-Objective Optimization is the computational time required. The proposed research focus on the reduction of the computational time using mathematic and computational techniques. In the paper, a generalized approach to operate a Robust Multi-Objective Optimization (RMOO) for Aerospace structure using MSC software Patran/Nastran to evaluate the Objectives Function, is proposed.
2017-09-19
Technical Paper
2017-01-2064
Parvez Alam M, Dinesh Manoharan, Satheesh Chandramohan, Sabarish Chakkath, Sunil MAURYA
In the present market, multiple sophisticate and expensive Thrust Test Rigs for Brushless Motors (BLDC Motor) are available making it impossible to conduct such thrust analysis on a regular and cost effective basis. Moreover the present test rigs are incapable to measure high Thrust values. This needs specialized thrust testing rig which is more expensive. This paper aims at Design & Development of the Small Scale Test Rig Setup for measurement of the thrust of any Brushless DC motor and helps in refining the Selection of motor and propeller. This is a set up based on cost efficiency factor to implement such rigs, test and for comparing the static thrust produced by the BLDC motor. The fairly simple construction contains a weighing machine, a Tachometer and a Wattmeter to measure the Thrust, RPM and the Current Drawn respectively, and provide comprehensive, accurate and efficient data coming from the BLDC Motor including the Propeller and Electronic Speed Control (ESC).
2017-09-19
Technical Paper
2017-01-2062
Tushar Choudhary, Mithilesh Sahu, Shreya KRISHNA
Solid oxide fuel cell (SOFC) is the most promising candidate for utilization of waste generated from the GT based power system. By coupling SOFC with gas turbine (GT) based power system, a hybrid SOFC–GT power system has been developed and the thermal efficiency of the system can be enhanced upto 70-85%. This paper focuses of thermodynamic analysis of an internal reformed solid oxide fuel cell which is integrated with the gas turbine cycle to form a hybrid power generation system for an unmanned aerial vehicle (UAV) with a long range. Thermodynamic 1st and 2nd law, parametric analysis has been carried out and the effect of various parameters such as compressor pressure ratio, turbine inlet temperature, air flow rate has been examined. In order to validate the results, present work has been compared with the available literature and it shows good agreement.
2017-09-19
Technical Paper
2017-01-2059
Enrico Cestino, Giacomo Frulla, Renzo Duella, Paolo Piana, Francesco Pennella, Francesco Danzi
Future generations of civil aircrafts and unconventional unmanned configurations demand for innovative structural concepts to obtain the structural performance, and thus reduce the structural weight. For instance, one of the method to improve structural component is the material coupling used to alter static and dynamic aeroelastic stabilities. It is therefore useful to use an accurate and computationally efficient beam model during the preliminary design phase. In the present work, a numerical validation of equivalent homogeneous orthotropic material procedure, described in [1] and [2], is performed by the application of structural topology optimization technique [3] on a box beam made of isotropic material. The overall equivalent bending, torsional and coupled stiffness is derived by means of homogenization of the shell skin and of the stiffener plate stiffness. The optimum theoretical conditions of bending-torsion coupling was obtained when stiffeners were oriented at about 27°.
2017-09-19
Technical Paper
2017-01-2124
Violet Leavers
Within the aviation industry the analysis of wear debris particles recovered from magnetic plugs and lubricating fluids is an essential condition monitoring tool. However, in large organisations, high staff turnover in remote work environments often leaves dangerous gaps in on-site support and background knowledge. The current work seeks to bridge those gaps by developing interactive software dedicated to wear debris particle classification, root cause diagnosis and serviceability prognostics. During the research several hundred wear debris particle images were collected, analysed and classified. Each image was analyzed by a number of experts and at each stage of the analysis the experts were questioned about the knowledge and experience used to make their diagnoses and prognoses. The end result is the compilation of an extensive knowledge base representing the combined expertise of a number of highly trained engineers, each with decades of hands-on experience.
2017-09-19
Journal Article
2017-01-2036
William Schley
Abstract Of all aircraft power and thermal loads, flight controls can be the most challenging to quantify because they are highly variable. Unlike constant or impulsive loads, actuator power demands more closely resemble random processes. Some inherent nonlinearities complicate this even further. Actuation power consumption and waste heat generation are both sensitive to input history. But control activity varies considerably with mission segment, turbulence and vehicle state. Flight control is a major power consumer at times, so quantifying power demand and waste heat is important for sizing power and thermal management system components. However, many designers sidestep the stochastic aspects of the problem initially, leading to overly conservative system sizing. The overdesign becomes apparent only after detailed flight simulations become available. These considerations are particularly relevant in trade studies comparing electric versus hydraulic actuation.
2017-09-19
Technical Paper
2017-01-2125
Mohammad Barkat, Vivek Karan, Pradeep N
The exponential increase in the number of aircrafts and air travellers has triggered new innovations which aim to make airline services more reliable and consumer friendly. Quick and efficient maintenance actions with minimum downtime are the need of the hour. Areas that have a large potential for improvement in this regard are the real time use of diagnostic data, filtering/elimination of nuisance faults and machine learning capabilities with respect to maintenance actions. Although, numerous LRUs installed on the aircraft generate massive amounts of diagnostic data to detect any possible issue or LRU failure, it is seldom used in real time. The turnaround time for LRU maintenance can be greatly reduced if the results of the diagnostics conducted during LRU normal operation is relayed to ground stations in real-time. This enables the maintenance engineers to plan ahead and initiate maintenance actions well before the aircraft lands and becomes available for maintenance.
2017-09-19
Technical Paper
2017-01-2144
Michele Trancossi, Mohammad Hussain, Sharma Shivesh, Jose Pascoa
This paper is a preliminary step in the direction of the definition of a radically new wing concept that has been conceived to maximize the lift even at low speeds. It is expected to equip new aerial vehicle concepts that aim to compete against helicopters and tilt rotors. They are expected to achieve very good performance at very low speed (5 to 30 m /s) by mean of an innovative concept of morphing ducted-fan propelled wing that has been designed to maximize the lift force. This paper presents an effective bibliographic analysis of the problem that is a preliminary necessary step in the direction of the preliminary design of the wing and the vehicle.
2017-09-19
Technical Paper
2017-01-2159
Federico Cappuzzo, Olivier Broca, Jeremy Leboi
To answer the ever-increasing complexity of aircraft, it becomes of foremost importance to better and earlier assess the interactions among their systems and sub-systems. The study presents the Virtual Integrated Aircraft (VIA) methodology, which allows achieving the integration of aircraft systems with virtual means, complementing and preceding physical integration, which is usually completed at the end of the validation and integration phase. LMS Imagine.Lab platform provides the means for applying this methodology. A simulation architecture, integrating models from different platforms, is built and simulations are run on High Performance Computers (HPC) to cover multiple scenarios and therefore validate the selected architecture and pre-design in the early system development phases. Equipment, systems and subsystems are essential for the performance, safety, reliability and comfort.
2017-09-19
Technical Paper
2017-01-2070
Nicholas Anderson, Joseph Gao, Eric Whitman, Srikanth Gururajan
Recent advances in Small Unmanned Aerial Systems (SUAS) or drone technologies has resulted in their widespread use in a number of civilian applications, such as aerial imaging, infrastructure inspection, precision agriculture, among others. While this technology is accessible for everyone, it still requires a highly skilled operator to be able to successfully operate these drones in a safe and efficient manner. At the same time, the developments in Virtual/Augmented Reality (V/AR) technologies present opportunities for combining the two into novel applications and use cases, while providing an intuitive interface for interacting with the drones – this opens up possibilities for effective use of the drones by relatively untrained operators for civilian and military use.
2017-09-17
Technical Paper
2017-01-2509
Guirong Zhuo, Ruonan Xue, Subin Zhang, Cheng Wu, Kun Xiong
Abstract Electromechanical Braking System (EMB) stops the wheel by motor and related enforce mechanism to drive braking pads to clamp the friction plate. It is compact in sized as well as faster in response, which solves the issue of potential leakage and slows response of traditional hydraulic brake system. The institutions at home and abroad have put forward all kinds of new structural schemes of EMB. At present, there are various EMB structural schemes, but the analysis and evaluation of these schemes are relatively few. In this paper, on the basis of a large number of research, the EMB actuator is modular decomposed according to function ,then the parametric 3D model library of each function module is established. According to brake requirements of the target vehicle, a development platform is set up to match EMB actuator structure scheme quickly.
2017-09-17
Technical Paper
2017-01-2518
Thomas J. Hall
Abstract The Los Angeles City Traffic Brake Test Schedule has been an established procedure used almost universally for generations by vehicle manufacturers to evaluate and validate braking systems for the attributes of NVH and brake wear behavior. The Los Angeles driving route, commonly known as the Los Angeles City Traffic Test (LACT), has long been considered an effective and “quasi” extreme set of real world driving conditions representative of the US passenger vehicle market and have been covered in other analysis including SAE Technical Paper 2002-01-2600 [1] The performance of a vehicle, relative to braking, in LACT conditions is typically influenced by basic vehicle and brake system attributes including the ratios of vehicle mass to brake sizing attributes, friction material selection, and the acceleration, drag, and cooling behavior of the vehicle.
2017-09-17
Technical Paper
2017-01-2519
Sangbum Kim, Jae Seung Cheon, Inuk Park, Yongsik kwon
Abstract An Electrical Parking Brake (EPB) system is a device that operates to park the vehicle automatically with the push of a button instead of using conventional hand or foot levers which in some ways makes it the first by wire type of brake system. As such, it is being considered in some vehicle architectures as an automatic redundant backup for vacuum-less brake systems or autonomous cars. The EPB system is generally divided into cable puller and motor on caliper (MOC) types. Recently, the MOC type EPB is being more widely applied in the global market due to product competitiveness and cost effectiveness. The MOC type EPB is composed of the caliper body, torque member, pad assembly, nut assembly and actuator. Among them, the caliper body and torque member play a main role in the robustness of the EPB system and occupy more than 80% of the total weight.
2017-09-17
Technical Paper
2017-01-2531
Georg Peter Ostermeyer, Bastian Recke
Abstract In recent years, characteristic structures in the boundary layer of high-load contacts such as brakes have been reported, which have an important impact on the dynamics of the tribological contact. Usually, local assumptions concerning the friction of these patches are used to reach global conclusions about the brake system. Several numerical methods (e.g. Cellular Automata) have been developed which make use of such assumptions. The validation of these methods through measured data tends to be laborious and costly. Sprag-Slip elements are friction elements which are typically considered to exclusively undergo static friction. Such elements have been sporadically utilized towards describing friction in brake applications. In this paper, many locally distributed Sprag-Slip elements are used to model the global dynamics of braking friction. The results show good agreement with the measured characteristics of brakes.
2017-09-17
Technical Paper
2017-01-2499
Xianyao Ping, Meifang Wu, Gangfeng Tan, Yuxin Pang, Yu Tang, Di Wu
Abstract The engine brake is widely used as auxiliary braking device for its continuous braking torque. The engine brake performance is usually measured in the laboratory or proving ground as per relevant standards. The main purpose of this paper is to introduce an on-vehicle measurement system to measure the performance of the engine brake in the driving process, which can reduce the test times in the laboratory or proving ground and the test cost. Based on the vehicle longitudinal dynamics, the measurement system can match various vehicles without basic parameter calibration at installation. The measurement system can also estimate gross vehicle mass. First, the vehicle state information from CAN (Controller Area Network) bus and the road gradient from the gradient sensor are used to compute gross vehicle mass and relevant vehicle driving resistance coefficients by the vehicle longitudinal dynamics in the driving process.
2017-09-17
Technical Paper
2017-01-2489
Christian Ball, Li Lee, Weicherng Wang
Abstract The standard method for using FEA to predict and eliminate brake squeal has been to use complex eigenvalue analysis (CEA). Energy flow analysis has been adapted for use with FEA for brake squeal as an alternate mechanism for squeal prediction. This paper demonstrates an implementation of energy flow analysis with commercially available FEA software. The approach leverages the ability of commercial FEA solvers to obtain a quasi-static, pre-loaded brake model, as well as their eigenvalue extraction algorithms to create a modal space for energy flow calculations. The modal spaces as well as the pre-loaded stiffness matrix are then utilized to calculate energy flow values between nearby system modes. Three case studies are presented that compare the results of CEA and energy flow to different systems and countermeasures adopted to reduce noise occurrence in physical testing.
2017-09-17
Technical Paper
2017-01-2490
Qianjin Yang, Baozhi Zhang, Kangrong Ding, Liqiang Song
Abstract A brake disc is one of the most critical components in modern vehicle’s brake systems; hence, thorough validation of its performances in the development process by simulations, rig and vehicle tests is essential. In this paper, a disc brake system under a constant braking torque is analyzed using finite element method, and the stress and strain in a rotating ventilated brake disc employed are studied comprehensively. From detailed examination of the stress distribution and the cyclic stress history, it is found that the maximum stress in the rotating brake disc under the constant mechanical loading only occurs at some specified locations; and the stress history is multiaxial and non-proportional. These findings will help, as guidelines, to develop suitable evaluation tools for the strength and the fatigue of the brake discs; to setup proper laboratory test procedures and equipment; and to design strong and durable brake discs.
2017-09-17
Technical Paper
2017-01-2485
Tarun Teja Mallareddy, Peter Blaschke, Sarah Schneider, Daniel J. Alarcón
Abstract Brake squeal is an NVH issue experienced by brake systems and vehicle manufacturers for decades. This leads to customer dissatisfaction and the questioning of the quality of the brake system. Advanced testing tools, design modification, dynamometer testing, vehicle validation etc., are performed to study, analyze and eliminate this problem. But still it continues to exist nowadays. One of the most important reasons is the complexity of the brake pad having non-linear material properties. Therefore, it is imperative to understand the behavior of the brake pad in terms of its dynamic properties (eigenfrequencies, damping and mode shapes) under varying boundary conditions. Experimental Modal Analysis (EMA) is used to study the dynamic properties of any structure and is generally performed under free-free boundary conditions. An approach to study brake pads under pressure condition is a step towards reality, as brake pads squeal only during braking events.
2017-09-17
Journal Article
2017-01-2496
Enrico Galvagno, Antonio Tota, Alessandro Vigliani, Mauro Velardocchia
Abstract Brake systems represent important components for passenger cars since they are strictly related to vehicle safety: Anti-lock Braking Systems (ABS) and Electronic Stability Control (ESC) are the most well-known examples. The paper is focused on the characterization of the braking hydraulic plant and on the design of a pressure following control strategy. This strategy is aimed at pursuing performances and/or comfort objectives beyond the typical safety task. The low-level logic (focus of the paper) consists of a Feedforward and Proportional Integral controller. A Hardware In the Loop (HIL) braking test bench is adopted for pressure controller validation by providing some realistic reference pressure histories evaluated by a high-level controller. Results prove that innovative control strategies can be applied to conventional braking systems for achieving targets not limited to braking issues, i.e., comfort or NVH tasks.
2017-09-17
Technical Paper
2017-01-2494
Severin Huemer-Kals, Manuel Pürscher, Peter Fischer
Abstract Complex Eigenvalue Analysis (CEA) is widely established as a mid- to high-frequency squeal simulation tool for automobile brake development. As low-frequency phenomena like creep groan or moan become increasingly important and appropriate time-domain methods are presently immature and expensive, some related questions arise: Is it reasonable to apply a CEA method for low-frequency brake vibrations? Which conditions in general have to be fulfilled to evaluate a disk brake system’s noise, vibration and harshness (NVH) behavior by the use of CEA simulation methods? Therefore, a breakdown of the mathematical CEA basis is performed and its linear, quasi-static approach is analyzed. The mode coupling type of instability, a common explanation model for squeal, is compared with the expected real world behavior of creep groan and moan phenomena.
2017-09-17
Technical Paper
2017-01-2493
Sivakumar Palanivelu, Jeevan Patil, Ajit Kumar Jindal
Abstract Apart from being an active safety system the brake system represents an important aspect of the vehicle dynamics. The vehicle retardation and stopping distance completely depend upon the performance of brake system and the functionality of all components. However, the performance prediction of the entire system is a challenging task especially for a complex configuration such as multi-axial vehicle applications. Furthermore, due to its complexity most often the performance prediction by some methods is limited to static condition. Hence, it is very important to have equivalent mathematical models to predict all performance parameters for a given configuration in all different conditions This paper presents the adopted system modelling approach to model all the elements of the pneumatic brake system such as dual brake valve, relay valve, quick release valve, front and rear brake actuators, foundation brake etc.
2017-09-17
Technical Paper
2017-01-2492
Dejian Meng, Ziyi Wang, Lijun Zhang, Zhuoping Yu
Abstract In this paper, the initial disc thickness variation (DTV) of a ventilated disc in automotive brake system is modeled as sinusoidal function of the second order. The transient thermomechanical coupling properties of the brake system is simulated using finite element (FE) modeling. The system models and results were verified by a thermomechanical coupling test of a disc brake conducted on a brake dynamometer. By using varied evaluation indexes such as the temperature distribution, the normal stress and the elastic deformation of disc surfaces, the influences of the initial DTV and its direction as well as its amplitude on the thermomechanical coupling characteristics were analyzed.
2017-09-17
Technical Paper
2017-01-2491
Baskar Anthonysamy, Arun Kumar Prasad, Babasaheb Shinde
Abstract Automotive industry has led to constant production innovation among manufactures. This has resulted in the reduction of the life cycle of the design philosophies and design tools. One of the performance factors that have continues to challenge automotive designer is to design and fine tune the braking performance with low cost and short life cycle. Improvement in braking performance and vehicle stability can be achieved through the use of braking systems whosebrake force distribution is variable. Braking force distribution has an important and serious role in thevehicle stopping distance and stability. In this paper a new approach will be presented to achieve the braking forcedistribution strategy for articulated vehicles. For this purpose, the virtual optimization process has beenimplemented.
2017-09-17
Journal Article
2017-01-2527
Dejie Huang, Xu Zhou, Peiqing Qian, Chao Wen, Yu Liu
Abstract The seal structure and key parameters of wheel bearing were introduced. Research on sealing failure diagnosis, abrasive scratch analysis, residual interference, and abrasion reconstruction was carried out for a typical seal structure. Based on these methods of scientific failure analysis, eight causes of seal failure were summarized systematically, which were important for the guidance of seal design and failure analysis of wheel bearings.
2017-09-17
Journal Article
2017-01-2526
Robert G. Sutherlin
Abstract As material cleanliness and bearing lubrication have improved, wheel bearings are experiencing less raceway spalling failures from rotating fatigue. Warranty part reviews have shown that two of the larger failure modes for wheel bearings are contaminant ingress and Brinell damage from curb and pothole impacts. Warranty has also shown that larger wheels have higher rates of Brinell warranty. This paper discusses the Brinell failure mode for bearings. It reviews a vehicle test used to evaluate Brinell performance for wheel bearings. The paper also discusses a design of experiments to study the effects of factors such as wheel size, vehicle loading and vehicle position versus the bearing load from a vehicle side impact to the wheel. As the trend in vehicle styling is moving to larger wheels and low profile tires, understanding the impact load can help properly size wheel bearings.
Viewing 91 to 120 of 33395