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Technical Paper

An Electronically Tunable Resonator for Noise Control

Many engineering systems create unwanted noise that can be reduced by the careful application of engineering noise controls. When this noise travels down tubes and pipes, a tuned resonator can be used to muffle noise escaping from the tube. The classical examples are automobile exhaust and ventilation system noise. In these cases where a narrow frequency band of noise exists, a traditional engineering control consists of adding a tuned Helmholtz resonator to reduce unwanted tonal noise by reflecting it back to the source (Temkin, 1981). As long as the frequency of the unwanted noise falls within the tuned resonator frequency range, the device is effective. However, if the frequency of the unwanted sound changes to a frequency that does not match the tuned resonator frequency, the device is no longer effective. Conventional resonators have fixed tuning and cannot effectively muffle tonal noise with time-varying frequency.
Technical Paper

The Effect of Loading Rate on the Degree of Acute Injury and Chronic Conditions in the Knee After Blunt Impact

Lower extremity injuries due to automobile accidents are often overlooked, but can have a profound societal cost. Knee injuries, for example, account for approximately 10% of the total injuries. Fracture of the knee is not only an acute issue but may also have chronic, or long term, consequences. The criterion currently used for evaluation of knee injuries in new automobiles, however, is based on experimental impact data from the 70''s using seated human cadavers. These studies involved various padded and rigid impact interfaces that slightly alter the duration of contact. Based on these data and a simple mathematical model of the femur, it appears fracture tolerance increases as contact duration shortens. In contrast, more recent studies have shown mitigation of gross fractures of the knee itself using padded interfaces. The use of padded interfaces, however, result in coincidental changes in contact duration and knee contact area.
Technical Paper

A Demonstration of Simultaneous Infrared and Visible Imaging Techniques with Pressure Data in an Optically Accessible Diesel Engine Operating at Part Load with High EGR

This work presents a method for simultaneously capturing visible and infrared images along with pressure data in an optical Diesel engine based on the International 4.5L VT275 engine. This paper seeks to illustrate the merits of each imaging technique for visualizing both in-cylinder fuel spray and combustion. The engine was operated under a part load, high simulated exhaust gas recirculation operating condition. Experiments examining fuel spray were conducted in nitrogen. Overlays of simultaneously acquired infrared and visible images are presented to illustrate the differences in imaging between the two techniques. It is seen that the infrared images spatially describe the fuel spray, especially fuel vapors, and the fuel mixing process better than the high-speed visible images.
Technical Paper

Quantification of primary flows of a torque converter using laser doppler velocimetry

All modern automotive automatic transmissions require the use of a torque converter to allow for the transmission of torque from the engine to the drivetrain. Although they are commonly used throughout the automotive industry, there is little understanding of the internal flows within the torque converter. An experimental study has been conducted to reveal the internal flow characteristics within a production torque converter using Laser Doppler Velocimetry (LDV) under the operating conditions. LDV measurements were conducted on the planes between impeller blades, and the gap between the impeller and turbine blades. The study showed that the internal flow is highly complex and the difference in rotor speeds between the impeller and turbine compound the flow effects. Transmission oil flows in the planes at the impeller exit and gap region were affected by the turbine blade as it passed.
Technical Paper

Numerical Optimization of Ring-Pack Behavior

The ring-pack behavior in a modern gasoline engine represent complicated phenomena. The process of ring pack design consists of two stages: understanding the physical behavior and design synthesis on the systematic manner. Computer models give an inside on the physical processes associated with the ring-pack behavior. Mathematical optimization techniques provide the tools for design synthesis on the systematic way based on an optimal criteria. The mathematical optimization technique was developed and applied to ring pack design synthesis. When applied to the existing engine ring-pack designs, the optimized results indicated the potential for significant reduction in blow-by through the ring-pack by optimizing ring pack geometry. The optimization results were compared with the original ring pack designs for two gasoline engines for a wide range of operating conditions.
Technical Paper

A Life Cycle Comparison of Alternative Transportation Fuels

The paper analyzes energy use and emissions per GJ of various fuels delivered to the vehicle fuel tank, covering extraction, fuel production, transportation, storage, and distribution phases of the life cycle of alternative fuels. Drawing on a number of existing studies, the modeling issues and approaches, main results and insights are summarized. The range of estimates in various studies is large; however, common patterns can be observed. The analysis indicates, that conventional gasoline fuel cycle has robust advantages with respect to energy efficiency, conventional pollutant emissions, and most importantly, existing infrastructure compared to alternative fuels. Fossil fuel based alternatives like CNG, NG–Methanol, NG–FTL do not result in significant improvement in fuel cycle environmental performance. Biofuels offer the benefits of lower and even negative GHG emissions, sustainability, and domestic fuel production.
Technical Paper

Development of a Comparison Index and a Database for Sea Model Results

This study analyzes methods of comparing SEA model results with experimental results for key traits. These qualitative traits provide the basis for correlation of model results with experimental results through the development of a comparison index. This paper formulates a comparison index and illustrates the application to SEA models. A customized data structure was designed around the comparison index to store all necessary aspects of the modeling, experiment and comparison results. This data structure was then implemented using relational database software. These new tools; the comparison index and the SEA database, will create a common language and a forum for SEA model results that will aid and stimulate dialog in the SEA modeling community and in tern, advance the science of SEA modeling.
Technical Paper

Modeling the Lower Torso of Hybrid III Dummy

A finite element model for hybrid III dummy's lower torso is presented. All details of the dummy's knee structure are carefully considered. In order to justify the finite element model, numerical results are made to compare with the experimental results from both knee impact test and knee slider impact test. It is found that the finite element results agree very well with their experimental counterparts.
Technical Paper

An Evaluation of Turbulent Kinetic Energy for the In-Cylinder Flow of a Four-Valve 3.5L SI Engine Using 3-D LDV Measurements

A better understanding of turbulent kinetic energy is important for improvement of fuel-air mixing, which can lead to lower emissions and reduced fuel consumption. An in-cylinder flow study was conducted using 1548 Laser Doppler Velocimetry (LDV) measurements inside one cylinder of a 3.5L four-valve engine. The measurement method, which simultaneously collects three-dimensional velocity data through a quartz cylinder, allowed a volumetric evaluation of turbulent kinetic energy (TKE) inside an automotive engine. The results were animated on a UNIX workstation, using a 3D wireframe model. The data visualization software allowed the computation of TKE isosurfaces, and identified regions of higher turbulence within the cylinder. The mean velocity fields created complex flow patterns with symmetries about the center plane between the two intake valves. High levels of TKE were found in regions of high shear flow, attributed to the collisions of intake flows.
Journal Article

Stress Analysis of the Separator in a Lithium-Ion Battery

A separator is a membrane that prevents the physical contact between the positive and negative electrodes while enabling ionic transport. The integrity of the separator is vital to the performance and reliability of a battery. This paper presents finite element stress analysis for the separator in a lithium-ion battery using a macro-scale battery cell model. In this model, the porous electrodes were treated as homogenized media and represented with the effective properties estimated using the rule of mixtures. To compute the deformation due to lithium (Li) intercalation & deintercalation and temperature variation, the Li concentration distribution and temperature change due to electrochemical reactions must be known. These parameters were computed using a multi-physics model in COMSOL and mapped to the macro-scale model in ANSYS. Numerical simulations were conducted to identify the locations and magnitudes of the maximum strain and stress of the separator in the pouch cell.
Technical Paper

The Effect of Fuel Injection Pressure on Spray and Combustion Characteristics in a Gasoline Direct-Injection Engine

A single-cylinder gasoline direct-injection engine was used for fuel spray and combustion visualizations with optical access to the combustion chamber. Experiments were conducted to investigate the effect of fuel injection pressure on spray and combustion characteristics inside the engine cylinder. A multi-hole high-pressure production injector was used with fuel pressures of 5 and 10 MPa. A Mie scattering technique was used to image the liquid phase of the fuel dispersion. The obtained spray images were then used to study the macroscopic spray characteristics such as spray structure, spray tip penetration and spray angle. Combustion visualization tests were performed to evaluate the effect of fuel injection pressure on combustion characteristics. In-cylinder pressure signals were recorded for the combustion analyses and synchronized with the high-speed combustion imaging recording.
Journal Article

High-Speed Flow and Combustion Visualization to Study the Effects of Charge Motion Control on Fuel Spray Development and Combustion Inside a Direct-Injection Spark-Ignition Engine

An experimental study is performed to investigate the effects of charge motion control on in-cylinder fuel-air mixture preparation and combustion inside a direct-injection spark-ignition engine with optical access to the cylinder. High-pressure production injector is used with fuel pressures of 5 and 10 MPa. Three different geometries of charge motion control (CMC) device are considered; two are expected to enhance the swirl motion inside the engine cylinder whereas the third one is expected to enhance the tumble motion. Experiments are performed at 1500 rpm engine speed with the variation in fuel injection timing, fuel pressure and the number of injections. It is found that swirl-type CMC devices significantly enhance the fuel-air mixing inside the engine cylinder with slower spray tip penetration than that of the baseline case without CMC device. Combustion images show that the flame growth is faster with CMC device compared to the similar case without CMC device.
Technical Paper

Design and Analysis of a Hybrid Electric Vehicle Chassis

Design of a hybrid electric vehicle chassis for the 1993 and 1994 HEV Challenge is presented. Computer finite element modeling and solid modeling techniques were used in developing the chassis. The main design parameters are presented and described. Final chassis design was tested, using finite element analysis, to ensure overall structural integrity and occupant safety. The chassis proved to be safe and reliable, under the rigors of competition driving, in the 1993 and 1994 HEV Challenges.
Technical Paper

Assessment of Alternative Strategies for Reducing Hydrocarbon and Carbon Monoxide Emissions from Small Two-Stroke Engines

Five small two-stroke engine designs were tested at different air/fuel ratios, under steady state and transient cycles. The effects of combustion chamber design, carburetor design, lean burning, and fuel composition on performance, hydrocarbon and carbon monoxide emissions were studied. All tested engines had been designed to run richer than stoichiometric in order to obtain satisfactory cooling and higher power. While hydrocarbon and carbon monoxide emissions could be greatly reduced with lean burning, engine durability would be worsened. However, it was shown that the use of a catalytic converter with acceptably lean combustion was an effective method of reducing emissions. Replacing carburetion with in-cylinder fuel injection in one of the engines resulted in a significant reduction of hydrocarbon and carbon monoxide emissions.
Technical Paper

The Effects of Subfracture Impact Loading on the Patellofemoral Joint in a Rabbit Model

This study showed that subfracture impact loading to a joint creates stresses in cartilage and bone which can initiate a chronic osteoarthrosis. The magnitude and location of the impact induced stresses are dependent on the orientation and the intensity of loading. Impact loading produced lesions on retro-patellar cartilage and their depths increased as the thickness of subchondral bone increased with time post-impact. Mechanical tests of cartilage indicated significant softening twelve months post-impact. These alterations are similar to those documented clinically as early OA. In vitro impacts of isolated limbs, together with mathematical models, showed that high mean stress generated during impact may help protect joint tissues from acute injury. This study and others are being used to develop stress-based tissue failure criteria for predicting an osteoarthrosis following subfracture impact loading.
Technical Paper

New Biomechanical Models for Automobile Seat Design

New models are being developed to represent the geometry and movements of people in seated postures. The positions and motions of the torso skeletal structures for different amounts of lumbar curvature have been studied and represented in side view, two dimensional computer models of the average man, small woman, and large man. Some further developments for the average man include: 1. two dimensional, articulated drafting template, 2. three dimensional computer model of the skeletal system with soft tissue thicknesses added to represent the external body contours on the back of the torso, and 3. model of forces and moments between body segments based on seated posture, body segment masses, and seat surface forces. This paper describes these new biomechanical models and their potential uses in designing seats that more comfortably fit and move with people.
Technical Paper

Identification of Internal Loss Factors During Statistical Energy Analysis of Automotive Vehicles

Statistical Energy Analysis (SEA) is a useful tool for predicting the transmission of noise and vibration through the structures of automotive vehicles. This work discusses the identification of SEA internal loss factor parameters from experimental measurements of vehicle sound pressure levels and structural accelerations. A simple automotive vehicle SEA model can be constructed from elements idealized as uniform beams, flat plates and acoustic volumes. Such an SEA automotive vehicle model can accurately predict the vibro-acoustic response of an automotive vehicles when appropriate equivalent SEA parameters are identified from in situ experimental data. This paper will present an algorithm for identifying internal loss factors for SEA models. The paper will include an example of the application of the algorithm to identification of automotive vehicle internal loss factors from measured vehicle response data.
Technical Paper

Use of Expert Systems for Life Cycle Analysis

As environmental regulations become more stringent, manufacturers are confronted with the task of product-design considering environmental impacts. Life Cycle Analysis (LCA) is a developing technique that attacks this problem. LCAs provide environmental information for decision making by consumers, manufacturers, and governments. These decisions significantly affect the ability to maximize source reduction, re-use, recyclability, and recycled content. LCAs can aid in diminishing the negative impact a product has on the environment and can be utilized as a partial solution of our nations' (worlds') growing waste management problem. To date, the application of LCAs has varied from product comparison to process development and improvement. The results from these analyses have differed because of differing assumptions and differing choices of boundary conditions. An appropriate Life Cycle Analysis should be consistent across products, locations, and especially across experimenters.