Viewing 1 to 30 of 22539
Journal Article
Michael J. Lance, C. Scott Sluder, Samuel Lewis, John Storey
Exhaust gas recirculation (EGR) cooler fouling has become a significant issue for compliance with nitrogen oxides (NOx) emissions standards. In order to better understand fouling mechanisms, eleven field-aged EGR coolers provided by seven different engine manufacturers were characterized using a suite of techniques. Microstructures were characterized using scanning electron microscopy (SEM) and optical microscopy following mounting the samples in epoxy and polishing. Optical microscopy was able to discern the location of hydrocarbons in the polished cross-sections. Chemical compositions were measured using thermal gravimetric analysis (TGA), differential thermal analysis (DTA), gas chromatography-mass spectrometry (GC-MS), x-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and x-ray diffraction (XRD). Mass per unit area along the length of the coolers was also measured.
Journal Article
Michael Marr, James S. Wallace, Silvio Memme, Sanjeev Chandra, Larry Pershin, Javad Mostaghimi
Surface temperature and heat flux were measured in a single cylinder SI engine piston when uncoated and with two different surface coatings: a metal TBC and YSZ. Average heat flux into the piston substrate was 33 % higher with the metal TBC and unchanged with the YSZ relative to the uncoated surface. The increase with the metal TBC was attributed to its surface roughness. However, the metal TBC and YSZ reduced peak heat flux into the substrate surface by 69 % and 77 %, respectively.
Journal Article
Krishna Prasad Balike, Subhash Rakheja, Ion Stiharu
The larger chassis space requirements of hybrid vehicles necessitates considerations of the suspension synthesis with limited lateral space, which may involve complex compromises among performance measures related to vehicle ride and handling. This study investigates the influences of suspension linkage geometry on the kinematic and dynamic responses of the vehicle including the wheel load in order to facilitate synthesis of suspension with constrained lateral space. A kineto-dynamic half-car model is formulated incorporating double wishbone suspensions with tire compliance, although the results are limited to kinematic responses alone. An optimal synthesis of the suspension is presented to attain a compromise among the different kinematic performance measures with considerations of lateral space constraints. In the kineto-dynamic model, the struts comprising linear springs and viscous dampers are introduced as force elements.
Journal Article
Dongfang Jiang
To get a sequence retainable rainflow cycle counting algorithm for fatigue analysis, an alternate equivalent explanation to rainflow cycle counting is introduced, based on which an iterative rainflow counting algorithm is proposed. The algorithm decomposes any given load-time history with more than one crest into three sub-histories by two troughs; each sub-history with more than one crest is iteratively decomposed into three shorter sub-histories, till each sub-history obtained contains only one single or no crest. Every sub-history that contains a single crest corresponds to a local closed (full) cycle. The mean load and alternate load component of the local cycle are calculated in parallel with the iterative procedure.
Journal Article
Robert V. Petrach, David Schall, Qian Zou, Gary Barber, Randy Gu, Laila Guessous
Coatings have the potential to improve bearing tribological performance. However, every coating application process and material combination may create different residual stresses and coating microstructures, and their effect on bearing fatigue and wear performance is unclear. The aim of this work is to investigate coating induced residual stress effects on bearing failure indicators using a microstructural contact mechanics (MSCM) finite element (FE) model. The MSCM FE model consists of a two-dimensional FE model of a coated bearing surface under sliding contact where individual grains are represented by FE domains. Interactions between FE domains are represented using contact element pairs. Unique to this layered rolling contact FE model is the use of polycrystalline material models to represent realistic bearing and coating microstructural behavior. The MSCM FE model was compared to a second non-microstructural contact mechanics (non-MSCM) model.
Journal Article
Terrill B. Atwater, Paula Tavares
The benefits of lithium battery systems lie within their high energy density (Wh/L) and high specific energy (Wh/kg). Manganese dioxide (MnO2) is an attractive active cathode material because of its high energy density and low material cost. Manganese dioxide is an intercalating compound for lithium that functions by solvating and desolvating lithium cations from the electrolyte in solid state. The lithium cations are deposited into the vacancies of the MnO2 cathode crystal structure. The objective of this effort focuses on the limited cycle life of rechargeable lithium manganese-based electrochemical systems, most importantly capacity fading of the cathode. These two characteristics are considered the major technology hurdles in rechargeable lithium battery technology.1, 2, 3, 4
Journal Article
Dennis P. Shay, Clive A. Randall
Mn and/or rare earth-doped xCaTiO₃ - (1-x)CaMeO₃ dielectrics, where Me=Hf or Zr and x=0.7, 0.8, and 0.9 were developed to yield materials with room temperature relative permittivities of Εr ~ 150-170, thermal coefficients of capacitance (TCC) of ± 15.8% to ± 16.4% from -50 to 150°C, and band gaps of ~ 3.3-3.6 eV as determined by UV-Vis spectroscopy. Un-doped single layer capacitors exhibited room temperature energy densities as large as 9.0 J/cm₃, but showed a drastic decrease in energy density above 100°C. When doped with 0.5 mol% Mn, the temperature dependence of the breakdown strength was minimized, and energy densities similar to room temperature values (9.5 J/cm₃) were observed up to 200°C. At 300°C, energy densities as large as 6.5 J/cm₃ were measured. These observations suggest that with further reductions in grain size and dielectric layer thickness, the xCaTiO₃ - (1-x)CaMeO₃ system is a strong candidate for integration into future power electronics applications.
Journal Article
Patricia Manning, Jerome Manning, Chadwyck Musser, George Peng
The contribution of wind noise through the glasses into the vehicle cabin is a large source of customer concern. The wind noise sources generated by turbulent flow incident on the vehicle surfaces and the transmission mechanisms by which the noise is transmitted to the interior of the vehicle are complex and difficult to predict using conventional analysis techniques including Computational Fluid Dynamics (CFD) and acoustic analyses are complicated by the large differences between turbulent pressures and acoustic pressures. Testing in dedicated acoustic wind tunnel (AWT) facilities is often performed to evaluate the contribution of wind noise to the vehicle interior noise in the absence of any other noise sources. However, this testing is time-consuming and expensive and test hardware for the vehicle being developed is often not yet available at early stages of vehicle design.
Journal Article
Lindsay J. Miller, Susan Sawyer-Beaulieu, Edwin Tam
Polyurethane (PU) foam is used for many automotive applications with the benefits of being lightweight, durable, and resistant to heat and noise. Applications of PU foams are increasing to include non-traditional purposes targeting consumer comfort. An example of this is the use of PU foam between the engine and engine cover of a vehicle for the purpose of noise abatement. This addition will provide a quieter ride for the consumer, however will have associated environmental impacts. The additional weight will cause an increase in fuel consumption and related emissions. More significant impacts may be realized at the end-of-life stage. Recycling PU foams presents several challenges; a lack of market for the recyclate, contamination of the foams, and lack of accessibility for removal of the material.
Journal Article
Ala Qattawi, Mahmoud Abdelhamid, Ahmad Mayyas, Mohammed Omar
1 The manufacturing of Origami based sheet metal products is a promising technology, mostly in terms of reducing the tooling and process complexity. This procedure can also be called fold forming, as it depends on exclusively shaping the required geometry via sequence of bends. However, the design analysis and modeling of folded sheet metal products are not fully mature, especially in terms of determining the best approach for transferring the analysis from a three-dimensional (3D) to a two-dimensional (2D) context. This manuscript discusses the extension of the Origami technique to the fold forming of sheet metal products represented in modeling approach and design considerations for the topological variations, the geometrical validity, and the variance of stress-based performance. This paper also details the optimization metrics that were developed to reflect the design and manufacturing differences among the possible topological and geometrical options for a single part design.
Technical Paper
Swapnil Pawar, Sandip Patil, Suhas Joshi, Rajkumar Singh
Abstract Tapping is an important process in assembly of aircraft structures because on an average one millions of tapped holes are made on an aircraft structure. However, sudden breakage of the tap is the most undesirable event frequently encountered during the tapping process. In particular, this can mostly occur when small diameter internal threads are made in a ‘difficult-to-cut’ material like titanium. For this reason, it has been a topic of industrial interest in the manufacturing sector for many years. The ultrasonic vibrations assisted tapping (UVAT) is a novel manufacturing technology, where ultrasonic vibrations are provided to the work piece in the axial direction. The present work is a comprehensive study involving experimental characterization. The experimentation shows that UVAT reduces the torque during tapping as compared to that of in conventional process. There is a 19.1% reduction in torque and about 20.3% reduction in cutting temperature in UVAT over that of in CT.
Journal Article
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.
Journal Article
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.
Journal Article
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.
Journal Article
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.
Journal Article
Sayed A. Nassar, Xianjie Yang, Saravanan Ganeshmuthy
In this paper, an emphasis is put on describing the elastic and plastic deformation behavior of the bolted joint. The bolt material is assumed to be plastic hardening. A nonlinear combined stress model is established for a typical bolted joint for the purpose of studying its behavior under a yield tightening. The combined effect of axial and torsional stresses in the tightened threaded fastener is considered. A new approach for yield tightening under ideal plastic bolt was proposed, and the effects of the thread and bearing frictional coefficients on the clamp load prediction are evaluated. The prediction precision of deformation behavior of the bolted joint under yield tightening for the strain hardening bolt material are studied experimentally.
Types of aircraft passenger-escape systems An overview of existing and potential new methods for assuring aircraft occupant safety. SAE Skill India Initiative: S2I2 A new SAEINDIA collaboration aims to help young engineers acquire "industry-ready" skills. A technology-driven sustainable-agriculture solution Pumping more air into the cylinder is key to solving the CAFE puzzle, and engineers are hard at work figuring out the best ways to do it with turbocharger and supercharger innovation. Rotorcraft icing computational tool development 3D printing machines can't be built fast enough In the additive-manufacturing world, the costs of components are dropping, the technology is becoming more reliable and parts are fabricated faster, allowing industries beyond aerospace to adopt additive technologies, says Oak Ridge Lab's Ryan Dehoff.
Focus on advanced safety systems and human-factor interventions The impact of REACH on the aviation sector Considered the most comprehensive chemical-regulation legislation to date, REACH presents serious ramifications for the aircraft industry. Lightweighting: What's Next? Experts weigh in on the challenges and future enablers in the battle to reduce vehicle mass. The best of COMVEC 2016 Autonomous vehicles and improved fuel efficiency via advanced powertrain solutions are pressing topics detailed in this select group of technical papers from the SAE Commercial Vehicle Engineering Congress. Optimizing waste heat recovery for long-haul trucks Autonomous solutions in agriculture Downsizing a HD diesel engine for off-highway applications Zero-emissions electric aircraft: Theory vs. reality
New resins, new attributes The past decade has seen an explosion of new engineering plastics that have, inch by inch, penetrated into tougher and tougher aerospace applications.
Automation leads advances in aerospace composites usage Increased productivity is the focus of today's automation for composites made of carbon-fiber reinforced plastics.
Taking a deeper look at NDT Rapid adoption of composties in aircraft has accelerated the need for newer and faster nondestructive testing methodologies. We look at some of the issues.
Inside information on lightweight materials While plenty of engineering effort is being made to change materials on the outside, there is as much going on with aircraft interiors to cut weight.
Tolling for large, light composite parts Aerospace engineers use carbon-fiber composites to create larger, unified parts to replace many smaller parts fastened together. As composite parts get larger, tooling to make them is evolving.
New materials-new tests material development calls for new testing techniques to be used, aided by key service suppliers.
Bright outlook for glass cockpits Cockpits are adopting larger screens and touch input, using modularity to ease upgrades. Composites give copters a lift Design, fabrication, and analysis of a tail rotor blade made of composite laminated materials for a heavy transport helicopter. Taming overruns with simulation For aerospace projects, cost overruns and program delays start in the concept and proposal stage. How could using today's advanced CAE simulations earlier reduce that risk? Going modular with airborne radar Innovative approaches to solving the affordability challenge posed by too many specialist airborne surveillance systems. Efficient & effective leadership Frank O. Klegon, a 30-year SAE member and former product development VP at Chrysler, brings 'customer first' approach to term as SAE International's chief elective officer.
UAVs shrink as missions, and emerging technologies, grow Remotely piloted air vehicles are getting smaller in size as technology permits previously unattainable performance from smaller packages.
The big boys go for plastic While it is true that the latest developments in advanced alloy manufacturing techniques can deliver structures and components that meet all the product requirements that aerospace primes need for new aircraft, there can be no escaping the fact that there is now an unstoppable momentum building up for the plastic airplane.
ETS Baja parts failure analysis: Geared for success When the ETS Baja team had to withdraw from the Baja Auburn 2012 event due to abnormal gear failure, an extensive analysis was required to ensure that problems of this nature would not surface again. After some serious investigation, the conclusion of almost 30 hours of research was unexpected and proved surprisingly simple. Body and soul rule at 2012 Formula SAE Months before the Formula SAE Michigan competition in May, teams were hashing out product development decisions. The end-game was presenting a racecar that had the right stuff for earning high points in the challenge's vehicle design evaluation as well as the acceleration, skid pad, endurance, and autocross dynamic performance events.
Electrochemical reactions Students from the Department of Automotive Engineering at the NED University of Engineering and Technology build the first onboard fuel-cell vehicle of Pakistan. The Baja balance How to combine heavy homework load with your CDS team responsibilities. Embraer progresses on clean-sheet military program It has been over two years since Embraer announced that it would be developing the KC-390 military airlift and tanker jet under a contract with the Brazilian Air Force (FAB), which established the requirements for the aircraft as it did with other Embraer military programs. Calling all recruiters Lack of response to distributed resumes leaves many wondering, is anyone out there?
The Nano in retrospect A senior graduate student in the Department of Mechanical Engineering at the Indian Institute of Technology looks at the development of the world's cheapest car and its effect on Indian car users. A different riff on your basic two-seat electric car Markus Lienkamp, Chair of Automotive Engineering at the Technical University of Munich, is leading the Visio.M project, a German government-supported R&D effort to produce a low-cost, high-utility electric car that might attract the interest of the middle European mass market. Materials lead the way to vehicle mass reduction Reducing a vehicle's mass opens the door for a downsized engine and transmission, a lighter cradle and body structure, smaller wheels and brakes, as well as a weight-slimmed suspension. The start point for this ripple effect is materials.
Viewing 1 to 30 of 22539


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