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The conversion design strategy, and emissions and performance results for a dedicated propane, vapour injected, 1995 Dodge Dakota truck are reported. Data is obtained from the University of Waterloo entry in the 1997 Propane Vehicle Challenge. A key feature of the design strategy is its focus on testing and emissions while preserving low engine speed power for drivability. Major changes to the Dakota truck included the following: installation of a custom shaped fuel tank, inclusion of a fuel temperature control module, addition of a vaporizer and a fuel delivery metering unit, installation of a custom vapour distribution manifold, addition of an equivalence ratio electronic controller, inclusion of a wide range oxygen sensor, addition of an exhaust gas recirculation cooler and installation of thermal insulation on the exhaust system. A competition provided natural gas catalyst was used.

The benefits of deliberately modulating air-to-fuel ratio over a three-way catalyst are disputed. In this work, engine test cell experiments were carried out to assess the performance of a warmed-up Pd/Rh three-way catalyst. The objectives were threefold: first, to determine the best mode of operation; second, to determine if air-to-fuel ratio modulation enhances robustness to transient air-to-fuel ratio disturbances; third, to determine if the conversion efficiency can be manipulated by controlling the shape of the air-to-fuel ratio oscillation. It was observed that the highest conversion efficiency is obtained using a steady air-to-fuel ratio just rich of stoichiometric; however, this mode of operation lacks robustness with respect to transient disturbances and UEGO sensor errors. Robustness can be improved using an oscillating air-to-fuel ratio, but with a sacrifice in peak conversion efficiency.

This paper examines the application of damage models in tube bending and subsequent hydroforming of AlMg3.5Mn aluminum alloy tubes. An in-house Gurson-based damage model, incorporated within LS-DYNA, has been used for the simulations. The applied damage model contains several void nucleation and growth parameters that must be determined for each material. A simpler straight tube hydroforming process was considered first to check the damage parameters and predicted ductility. Then the model was applied to a sequence of bending and hydroforming. The damage history from pre-bending was mapped to the hydroforming stage, to allow prediction of the overall ductility. The applied forming parameters in the simulation were based on data extracted during the experimental tests. Finally, the numerical results were compared to the experimental data.

Life Cycle Assessment (LCA) is commonly used to measure the environmental and economic impacts of engineering projects and/or products. However, there is some uncertainty associated with any LCA study. The LCA inventory analysis generally relies on imperfect data in addition to further uncertainties created by the assessment process itself. It is necessary to measure the effects that data and process uncertainty have on the LCA result and to communicate the level of uncertainty to those making decisions based on the LCA. To accomplish this, a systematic and rigorous means to assess the overall uncertainty in LCA results is required. This paper demonstrates the use of Monte Carlo Analysis to track and measure the propagation of uncertainty in LCA studies. The Monte Carlo technique basically consists of running repeated assessments using random input values chosen from a specified probable range.

TiCP/Ni coating has been deposited onto the electrodes by electro-spark deposition to improve electrode life during resistance welding of Zn-coated steels. However, welding results revealed that molten Zn penetrates into coating through the cracks and then reacts with substrate copper alloy to form brasses. In the present work, laser treatment was performed on the TiCP/Ni coated electrodes to eliminate cracks formed in the as-deposited TiCP/Ni coating. In addition, a multi-electro-spark deposition of Ni, TiCP/Ni and Ni has also been carried out to improve coating quality. On the other hand, a TiB2 coating was also investigated. those coatings were characterized by electro-microscopy, energy-dispersive X-ray analysis, X-ray diffraction and micro-hardness tests. The results showed that cracks within the as-deposited TiCP/Ni coating could be eliminated with the use of laser treatment or a multi-layer deposition process.

Fatigue crack initiation and propagation models predict the fatigue life of welded "T" specimens tested by the Fatigue Design and Evaluation (FDE) Committee of SAE under constant and variable amplitude load histories. The crack propagation equations stipulated by British Standard BS-7910 have been incorporated in a material memory model for cyclic deformation. The simulations begin with the crack initiation model and show how it is used to account for cyclic mean stress relaxation and the effects of periodic overloads. After the cracks initiate the BS-7910 model is applied to predict the crack advance due to either constant or variable amplitude histories. Simulation results correspond to the experimental results with good accuracy.

The performance of a commercial Cu-zeolite SCR catalyst after differing degrees of hydrothermal aging (aged for 72 hours at 500, 700 and 800°C with 10% moisture balanced with air) was studied by spatially resolving different key reactions using gas-phase FTIR measurements. Gases were sampled along a channel at different positions and analyzed using FTIR, which overcomes the interference of water and nitrogen on ammonia concentration detection encountered in standard mass spectrometer-based spatial resolution measurements. The NO:NO₂ concentration ratio was changed so that the standard (NO:NO₂ = 1:0), fast (NO:NO₂ = 1:1) and NO₂ (NO:NO₂ = 0:1) SCR reactions could be investigated as a function of the catalyst's hydrothermal aging extent. In addition, the effects of hydrothermal aging on the activity of NH₃ and NO oxidation were also investigated. Hydrothermal aging had little effect on NO oxidation activity.

Tessellation methods have been applied to characterize second phase particle fields and the degree of clustering present in AA 5754 and 5182 automotive sheet alloys. A model of damage development within these materials has been developed using a damage percolation approach based on measured particle distributions. The model accepts tessellated particle fields in order to capture the spatial distributions of particles, as well as nearest neighbour and cluster parameter data. The model demonstrates how damage initiates and percolates within particle clusters in a stable fashion for the majority of the deformation history. Macro-cracking leading to final failure occurs as a chain reaction with catastrophic void linkage triggered once linkage beyond three or more clusters of voids takes place.

This work outlines the evaluation of static and dynamic dent resistance of medium scale structural assemblies fabricated using AA6111 and AA5754. The assemblies fabricated attempt to mimic common automotive hood designs allowing for a parametric study of the support spacing, sheet thickness and panel curvature. Closure panels of AA6111, of two thicknesses (0.8, and 0.9mm), are bonded to re-usable inner panels fabricated using AA5754 to form the structural assemblies tested. While normal practice would use the same alloy for both the inner and the outer, in the current work, AA5754 was adopted for ease of welding. Numerical simulations were performed using LS DYNA. A comparison of experimental and numerically simulated results is presented. The study attempts to establish an understanding of the relationship between structural support conditions and resulting dent depths for both static and dynamic loading conditions.

Fracture characterization of automotive metals under simple shear deformation is critical for the calibration of advanced fracture models employed in forming and crash simulations. In-plane shear fracture tests of high ductility materials have proved challenging since the sample edge fails first in uniaxial tension before the fracture limit in shear is reached at the center of the gage region. Although through-thickness machining is undesirable, it appears required to promote higher strains within the shear zone. The present study seeks to adapt existing in-plane shear geometries, which have otherwise been successful for many automotive materials, to have a local shear zone with a reduced thickness. It is demonstrated that a novel shear zone with a pocket resembling a “peanut” can promote shear fracture within the shear zone while reducing the risk for edge fracture. An emphasis was placed upon machinability and surface quality for the design of the pocket in the shear zone.

The characterization of sheet metals under in-plane uniaxial bending is challenging due to the aspect ratios involved that can cause buckling. Anti-buckling plates can be employed but require compensation for contact pressure and friction effects. Recently, a novel in-plane bending fixture was developed to allow for unconstrained sample rotation that does not require an anti-buckling device. The objective of the present study is to design the sample geometry for sheared edge fracture characterization under in-plane bending along with a methodology to resolve the strains exactly at the edge. A series of virtual experiments were conducted for a 1.0 mm thick model material with different hardening rates to identify the influence of gage section length, height, and the radius of the transition region on the bend ratio and potential for buckling. Two specimen geometries are proposed with one suited for constitutive characterization and the other for sheared edge fracture.

Strict environmental regulations are driving the automotive industry toward electric vehicles as they offer zero emissions. A key component in electric vehicles is the electric motor, where the stator and rotor are manufactured from stacks of thin electrical steel sheets. The electrical steel sheets can be cut in different ways, and the cutting methods may significantly affect the fatigue strength of the component. It is important to understand the effect of the cutting processes on the fatigue properties of electrical steel to ensure there is no premature failure of the electric motor resulting from an improper cutting process. This investigation compared the effect of three different edge preparation methods (stamping, CNC machining, and waterjet cutting) on the fatigue performance of 0.27mm thick electrical steel sheets. To investigate the effect of the edge finish on fatigue behavior, surface roughness was measured for these different samples.

The effects of bead surface roughness on friction, die pickup, and sheet surface damage in the drawbead test were investigated. Beads of HRC 58 hardness were prepared from centerless-ground rod by circumferential honing to 0.05 μm roughness, followed by finishing with 100, 400, or 600 grit SiC paper in the axial direction. Paraffinic base oils with viscosities of 4.5, 30, and 285 mm2/s were used neat and in conjunction with stearic acid. The effects of bead roughness depended on the nature of metal transfer, especially its distribution and firmness of attachment. The presence of a boundary additive increased, decreased, or had no effect on friction depending on the particular coating and bead finish.

The Extended Stress-Based Forming Limit Curve (XSFLC) failure criterion has been shown to provide good qualitative and quantitative predictions of failure (necking) in straight tube hydro forming when the on the level of end-feed (EF) used during hydro forming, the failure criterion has a tendency to over predict failure pressure at low Keeler-Brazier (K-B) approximation is used to define the XSFLC failure curve. Depending EF and under predict failure pressure for high EF. The over/under predictions suggest that the strain-space εFLC, which the XSFLC is based on, has too high of a plane-strain intercept (FLCo), when it is obtained using the K-B approximation (developed for sheet metal).

This paper investigates the application of standard formability testing results for aluminum alloy tailor welded blanks (TWB) to full size stampings. The limit strains obtained from formability testing are compared to measured strains in a larger scale part. The measured strains in the full scale part are also compared to predictions from finite element simulation.

The presence of residual stresses affects the fatigue response of welded components. In the present study of thick welded cantilever specimens, residual stresses were measured in two A36 steel samples, one in the as-welded condition, and one subjected to a short history of bending loads where substantial local plasticity is expected at the fatigue hot-spot weld toe. Extensive X-Ray Diffraction (XRD) measurements describe the residual stress state in a large region above the weld toe both in an untested as-welded sample and in a sample subjected to a short load history that generated an estimated 0.01 strain amplitude at the stress concentration zone at the weld toe. The results show that such a test will significantly alter the welding-induced residual stresses. Fatigue life prediction methods need to be aware that such alterations are possible and incorporate the effects of such cyclic stress relaxation in life computations.

Electrical steels are silicon alloyed steels that possess great magnetic properties, making them the ideal material choice for the stator and rotor cores of electric motors. They are typically comprised of laminated stacks of thin electrical steel sheets. An electric motor can reach high temperatures under a heavy load, and it is important to understand the combined effect of temperature and load on the electrical steel’s performance to ensure the long life and safety of electric vehicles. This study investigated the fatigue strength and failure behavior of a 0.27mm thick electrical steel sheet, where the samples were prepared by a stamping process. Stress-control fatigue tests were performed at both room temperature and 150°C. The S-N curve indicated a decrease in the fatigue strength of the samples at the elevated temperature compared to the room temperature by 15-25 MPa in the LCF and HCF regimes, respectively.

The paper describes the fabrication and testing of thin sheet metal uniaxial fatigue specimens that have been laminated to prevent buckling. When hot or cold rolled metal thicknesses are below 5 mm, the usual fatigue specimens, having a uniform gauge length of 7.5 mm or more, buckle in the short life region (∼10000 cycles) of strain-life testing. For thinner materials, non-standard specimen designs or anti-buckling guides have been used, but each of these solutions requires additional instrumentation. The results presented in this paper show that laminating multiple sheets of material together to increase the specimen's effective thickness raises the strain level for the onset of buckling of the standard uniaxial specimen. Constant and variable amplitude fatigue tests extending into the high-strain short-life region were performed. Fatigue life data for multiple layer specimens were in good agreement with those obtained for single layer specimens.

The objective of this study was to assess the formability of two 3rd generation advanced high strength steels (3rd Gen AHSS) with ultimate strengths of 980 and 1180 MPa and evaluate their applicability to a structural B-Pillar for a mid-sized sport utility vehicle. The constitutive behavior including strain-rate effects and formability were characterized to generate the material models for use within AutoForm R8 software to design the B-pillar tooling and forming process. An extended Bressan-Williams instability model was able to deterministically predict the forming limit curves obtained using Marciniak tests. The tooling for the representative B-pillar was designed and fabricated with Bowman Precision Tooling and forming trials conducted for both 3rd Gen steels that had a thickness of 1.4 mm.

Porous silicon as gas/chemical sensing material has been widely investigated in recent years. In this paper, the humidity sensing property of n-type porous silicon with ordered structure is studied for the first time. The ordered porous silicon used in this experiment has uniform pore size, pore shape and distribution. Both the membrane and closed bottom samples were studied. The resistance change of the porous silicon was measured. A 22-28% decrease of resistance was observed when relative humidity was changed from 1% to 100%. Both the response time and the recovery time were within 10 minutes, and 90% of the response can be reached in 6 minutes for the PS membrane sample. The possible sensing mechanism and future work are also discussed in this paper.