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Technical Paper

Eutectic Segregation and Cracking in AZ91 Friction Stir Spot Welds

2007-04-16
2007-01-1700
Friction stir spot welding of Mg-alloy AZ91 is investigated. The temperature cycles within the stir zone and in the TMAZ region are examined using thermocouples, which are located within the tool itself and also by locating thermocouples in drilled holes at specific locations relative to the bottom of the tool shoulder and the periphery of the rotating pin. The measured temperatures in the stir zone range from 437°C to 460°C (0.98Ts, where Ts is the solidus temperature in degrees Kelvin) in AZ91 spot welds produced using plunge rates from 2.5 and 25 mm/s. The thermal cycle within the stir zone formed during AZ91 spot welding could not be measured by locating thermocouples within the workpiece in drilled holes adjacent to the periphery of the rotating pin.
Technical Paper

Microcellular Ceramic Foams: Manufacturing and Study of Acoustical Properties

2007-05-15
2007-01-2187
A novel processing method for fabricating high porosity microcellular ceramic foams for sound absorption applications has been developed. The strategy for fabricating the ceramic foams involves: (i) forming some shapes using a mixture of preceramic polymer and expandable microspheres by a conventional ceramic forming method, (ii) foaming the compact by heating, (iii) cross-linking the foamed body, and (iv) transforming the foamed body into ceramic foams by pyrolysis. By controlling the microsphere content and that of the base elastomer, it was possible to adjust the porosity with a very high open-cell content (ranging between 43 - 95%), high microcellular cell densities (9 × 108 - 1.6 × 109 cells/cm3) and desired expansion ratios (3 - 6 folds). Sound absorption testing has been performed using ASTM C-384 standard test. The preliminary results show that ceramic foams are candidate sound absorption materials.
Technical Paper

Improving Flow Uniformity in a Diesel Particulate Filter System

2001-05-07
2001-01-1944
In this study, a simulation-based flow optimization of the diesel particulate filter (DPF) system is performed. The geometry and the swirl component of the inlet flow is optimized to improve flow uniformity upstream of the filter and to decrease overall pressure drop. The flow through the system is simulated with Fluent computational fluid dynamics (CFD) software from Fluent Inc. The wall-flow filter is modeled with an equivalent porous material. This study only investigates the clean flow. The DPF system is composed of three parts: the inlet diffuser, the filter and the outlet nozzle. In the original system a linear cone joins the inlet and outlet pipes to the cylindrical filter. Due to the large opening angle of this cone, flow separates and creates a recirculation zone between the inlet and the filter. The flow pattern reveals that a large area of the filter is not used: More than 88% of the air flow passes through less that 53% of the area.
Technical Paper

Wood Microfibres - Effective Reinforcing Agents for Composites

2006-04-03
2006-01-0106
This work is based on a process to develop novel cellulose microfibre reinforced composite materials, and to understand fundamental mechanical properties of these composites. Cellulose microfibres having diameters <1 μm were generated from bleached kraft pulp by a combination of high shear refining and subsequent cryocrushing under liquid nitrogen, followed by filtration through a 60 mesh screen. Through film casting in polyvinyl alcohol, theoretical stiffness of the microfibres was calculated as 69 GPa. Subsequently, these microfibres were successfully dispersed in the bioplastics thermoplastic starch and polylactic acid (PLA), using conventional processing equipments. The high aspect ratio of these microfibres coupled with their high tensile properties imparted superior mechanical strength and stiffness to the composites. These indicated that by suitably choosing the polymer, excellent reinforcement can be achieved for high end applications like automotive parts.
Technical Paper

Effect of Fungal Modification on Fiber-Matrix Adhesion in Natural Fiber Reinforced Polymer Composites

2006-04-03
2006-01-0006
Natural fiber reinforced polymer composites are beginning to find their way into the commercial automotive market. But, inadequate adhesion between hydrophilic natural fibers and hydrophobic matrix materials affects the performance of the resulting composites. In this study the effect of an environmental friendly fungal treatment on the adhesion characteristics of natural fibers is investigated. Firstly, changes in acid-base characteristics of the modified hemp fibers were studied using Inverse Gas Chromatography (IGC). Afterwards, composites were prepared using Resin Transfer Molding (RTM) process and the effect of modification on performance and durability of the composites was investigated.
Technical Paper

The Effect of Fiber Surface Treatment on the Performance of Hemp Fiber/Acrylic Composites for Automotive Structural Parts

2006-04-03
2006-01-0005
The use of natural fibers for polymer composite materials has increased tremendously in the last few years. This type of reinforcements offers many advantages such as low density, low cost, high specific strength and low environmental impacts. The performance of the natural fiber composites are affected by the fiber loading, the individual mechanical properties of each component (fiber and matrix), and the fiber and matrix adhesion. Concerning the interfacial interaction, natural fibers present a major drawback because of poor compatibility of fibers with most hydrophobic thermoplastic and thermoset matrix. Hemp fiber/acrylic composites were manufactured with sheet molding technique recently. Although mechanical tests give promising results, they exhibit low tensile strength resulting from a poor fiber/matrix adhesion. The moisture resistance property of the sheet molded composites also needs further improvement.
Technical Paper

The Effect of Surface Modification on the Mechanical Properties of Hemp Fiber/Polyester Composites

2004-03-08
2004-01-0728
In this work hemp fibers were chemically treated in order to improve the fiber/matrix interaction in hemp fiber/unsaturated polyester composites prepared by a Resin Transfer Molding (RTM) process. Chemicals used for paper sizing (AKD, ASA, Rosin Acid and SMA) as well as a silane compound and sodium hydroxide were used to modify the fibers' surface. The tensile, flexural and impact properties of the resulting materials were measured. A slight improvement in mechanical properties was observed for the SMA, silane and alkali treated specimens. However close analysis of these tests and of the fracture surface of the samples showed that there was no amelioration of the fiber/matrix adhesion. It was found that predicted tensile strengths using the rule of mixture were very close to the experimental values obtained in this work. Finally the properties of an hybrid glass fiber/hemp fiber composite were found to be very promising
Technical Paper

Model Identification and Analysis of a High Performance Hydrostatic Actuation System

2000-09-11
2000-01-2619
A hydrostatic actuation system referred to as the Electro Hydraulic Actuator (EHA) has been designed and prototyped. In this paper, a mathematical model of the EHA is reviewed and analyzed. This theoretical analysis is supported by open-loop experimental results that indicate the presence of nonlinearities but at a degree that is considerably less than that of conventional hydraulic systems with servo-valves. The behavior of the system can be approximated as piece-wise linear with the damping ratio and natural frequency changing according to a piece-wise operating region. The EHA model is used in conjunction with experimentation and numerical optimization for quantifying the influence of unknown parameters in this system. A parametric model for the EHA is subsequently proposed and validated.
Technical Paper

Injection Molded Hybrid Natural Fibre - Thermoplastic Composites for Automotive Interior Parts

2004-03-08
2004-01-0014
Eco-efficient and cost effective natural fibre - thermoplastic composites have gained attention to a great extent in the automotive industry. Most of the OEM specifications for automotive interior parts, for example, instrument panels, recommend the composite should have a minimum flexural modulus of 1900 MPa, a notched Impact strength greater than 150 J/m at room temperature and a melt flow index of 5 g/10min and above [1, 2 and 3]. The objective of this work was to develop a high performance hybrid composite by injection molding process of the composites made from natural fibre in combination with glass fibre or calcium carbonate in a thermoplastic matrix to meet the specifications required for automotive interior parts applications. Mechanical properties, such as tensile and flexural strengths and moduli of the composites prepared, were found to be highly promising.
Technical Paper

Concurrent Quantitative Laser-Induced Incandescence and SMPS Measurements of EGR Effects on Particulate Emissions from a TDI Diesel Engine

2002-10-21
2002-01-2715
A comparison of scanning mobility particle sizer (SMPS) and laser-induced incandescence (LII) measurements of diesel particulate matter (PM) was performed. The results reveal the significance of the aggregate nature of diesel PM on interpretation of size and volume fraction measurements obtained with an SMPS, and the accuracy of primary particle size measurements by LII. Volume fraction calculations based on the mobility diameter measured by the SMPS substantially over-predict the space-filling volume fraction of the PM. Correction algorithms for the SMPS measurements, to account for the fractal nature of the aggregate morphology, result in a substantial reduction in the reported volume. The behavior of the particulate volume fraction, mean and standard deviation of the mobility diameter, and primary particle size are studied as a function of the EGR for a range of steady-state engine speeds and loads for a turbocharged direct-injection diesel engine.
Technical Paper

The Effects of Nano-clay on Extrusion Microcellular Foaming of Nylon

2005-04-11
2005-01-1670
This paper demonstrates the effects of nano-clay on the microcellular foam processing of nylon. First, Nylon 6 nanocomposites with 1 wt% clay were prepared by a twin screw extruder. The nanocomposite structures were characterized by XRD and TEM. Nylon and its nanocomposites were foamed in extrusion using CO2. The cell morphologies of nylon and its nanocomposite foams were investigated. It appeared that the nano-clay not only enhanced cell nucleation, but also suppressed cell deterioration in the microcellular foaming of nylon.
Technical Paper

Effect of CO2 Content on Foaming Behavior of Recyclable High-Melt-Strength PP

2006-04-03
2006-01-0336
This paper presents an experimental study on the foaming behavior of recyclable high-melt-strength (HMS) branched polypropylene (PP) with CO2 as a blowing agent. The foamability of branched HMS PP has been evaluated using a tandem foaming extruder system. The effects of CO2 and nucleating agent contents on the final foam morphology have been thoroughly investigated. The low density (i.e., 12~14 fold), fine-celled (i.e., 107–109 cells/cm3) PP foams were successfully produced using a small amount of talc (i.e., 0.8 wt%) and 5 wt% CO2.
Technical Paper

Cell Nucleation and Growth Study of PP Foaming with CO2 in a Batch-Simulation System

2006-04-03
2006-01-0507
TPO is being used to make automotive parts for its number of advantages: i) low temperature flexibility and ductility, ii) excellent impact/stiffness/flow balance, iii) excellent weatherability, and iv) free-flowing pellet form for easy processing, storage, and handling. However, by foaming TPO, due to its higher rigidity-to-weigh ratio, it would offer additional advantages over the solid counterparts in terms of reduced weight, reduced material cost, and decreased fuel usage without compromising their performance. Since a major component in TPO is polypropylene (PP), understanding PP foaming behaviours is an important step towards understanding TPO foaming. For foam materials, cell density and cell size are two significant parameters that affect their material properties. In this research, we observed the cell nucleation and initial growth behaviours of PP foams blown with CO2 under various experimental conditions in a batch foaming simulation system.
Technical Paper

Energy Generation and Stir Zone Dimensions in Friction Stir Spot Welds

2006-04-03
2006-01-0971
Energy generation and utilization during friction stir spot welding of Al 6061-T6 and AM50 sheet materials are investigated. The dimensions of the stir zones during plunge testing are largely unchanged when the tool rotational speed increases from 1500 RPM to 3000 RPM (for a plunge rate of 1 mm/s) and when the rate of tool penetration increases from 1 mm/s to 10 mm/s (for a tool rotational speed of 3000 RPM). The energy resulting from tool rotation is also unaffected when higher tool rotational speeds are applied. The rotating pin accounts for around 70% and 66% of the energy generated when 6.3 mm thick Al 6061-T6 and AM50 sheet materials are spot welded without the application of a dwell period. In direct contrast, the contribution made by the tool shoulder increases to around 48% (Al 6061-T6) and to 65% (AM50) when a four second long dwell period is incorporated during spot welding of 6.3 mm thick sheets.
Technical Paper

Impact of Powertrain Type on Potential Life Cycle Greenhouse Gas Emission Reductions from a Real World Lightweight Glider

2017-03-28
2017-01-1274
This study investigates the life cycle greenhouse gas (GHG) emissions of a set of vehicles using two real-world gliders (vehicles without powertrains or batteries); a steel-intensive 2013 Ford Fusion glider and a multi material lightweight vehicle (MMLV) glider that utilizes significantly more aluminum and carbon fiber. These gliders are used to develop lightweight and conventional models of internal combustion engine vehicles (ICV), hybrid electric vehicles (HEV), and battery electric vehicles (BEV). Our results show that the MMLV glider can reduce life cycle GHG emissions despite its use of lightweight materials, which can be carbon intensive to produce, because the glider enables a decrease in fuel (production and use) cycle emissions. However, the fuel savings, and thus life cycle GHG emission reductions, differ substantially depending on powertrain type. Compared to ICVs, the high efficiency of HEVs decreases the potential fuel savings.
Technical Paper

Modelling and Optimization of Plug Flow Mufflers in Emission Control Systems

2017-06-05
2017-01-1782
Large-scale emergency or off-grid power generation is typically achieved through diesel or natural gas generators. To meet governmental emission requirements, emission control systems (ECS) are required. In operation, effective control over the generator’s acoustic emission is also necessary, and can be accomplished within the ECS system. Plug flow mufflers are commonly used, as they provide a sufficient level of noise attenuation in a compact structure. The key design parameter is the transmission loss of the muffler, as this dictates the level of attenuation at a given frequency. This work implements an analytically decoupled solution, using multiple perforate impedance models, through the transfer matrix method (TMM) to predict the transmission loss based on the muffler geometry. An equivalent finite element model is implemented for numerical simulation. The analytical results and numerical results are then evaluated against experimental data from literature.
Technical Paper

A Chemical-Kinetic Approach to the Definition of the Laminar Flame Speed for the Simulation of the Combustion of Spark-Ignition Engines

2017-09-04
2017-24-0035
The laminar burning speed is an important intrinsic property of an air-fuel mixture determining key combustion characteristics such as turbulent flame propagation. It is a function of the mixture composition (mixture fraction and residual gas mass fraction) and of the thermodynamic conditions. Experimental measurements of Laminar Flame Speeds (LFS) are common in literature, but initial pressure and temperature are limited to low values due to the test conditions: typical pressure values for LFS detection are lower than 25 bar, and temperature rarely exceeds 550 K. Actual trends in spark ignition engines are to increase specific power output by downsizing and supercharging, thus the flame front involves even more higher pressure and temperature since the beginning of combustion.
Technical Paper

Heavy Duty Diesel Engine Modeling with Layered Artificial Neural Network Structures

2018-04-03
2018-01-0870
In order to meet emissions and power requirements, modern engine design has evolved in complexity and control. The cost and time restraints of calibration and testing of various control strategies have made virtual testing environments increasingly popular. Using Hardware-in-the-Loop (HiL), Volvo Penta has built a virtual test rig named VIRTEC for efficient engine testing, using a model simulating a fully instrumented engine. This paper presents an innovative Artificial Neural Network (ANN) based model for engine simulations in HiL environment. The engine model, herein called Artificial Neural Network Engine (ANN-E), was built for D8-600 hp Volvo Penta engine, and directly implemented in the VIRTEC system. ANN-E uses a combination of feedforward and recursive ANNs, processing 7 actuator signals from the engine management system (EMS) to provide 30 output signals.
Technical Paper

Development and Calibration of One Dimensional Engine Model for Hardware-In-The-Loop Applications

2018-04-03
2018-01-0874
The present paper aims at developing an innovative procedure to create a one-dimensional (1D) real-time capable simulation model for a heavy-duty diesel engine. The novelty of this approach is the use of the top-level engine configuration, test cell measurement data, and manufacturer maps as opposite to common practice of utilizing a detailed 1D engine model. The objective is to facilitate effective model adjustments and hence further increase the application of Hardware-in-the-Loop (HiL) simulations in powertrain development. This work describes the development of Fast Running Model (FRM) in GT-SUITE simulation software. The cylinder and gas-path modeling and calibration are described in detail. The results for engine performance and exhaust emissions produced satisfactory agreement with both steady-state and transient experimental data.
Technical Paper

Application of Nonlinear Transformations to A/F Ratio and Speed Control in an IC Engine

1999-03-01
1999-01-0858
This paper presents the first application of the global feedback linearization method to an internal combustion (IC) engine. Through the application of this nonlinear control technique, the nonlinear coupled dynamics of the IC engine are globally linearized and decoupled. This represents a significant advance over previously published control approaches which rely on locally linearized dynamic models. With the IC engine dynamics globally linearized and decoupled, outer-loop controllers can be readily designed using simple linear tracking controller design methods, leading to very good dynamic response of three key IC engine outputs, air/fuel ratio, engine speed and manifold air pressure. In this paper, a standard IC engine model from the literature is first transformed to a controllable canonical form, required for the application of the global feedback linearization methods.
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