Denise Morrey

Recent advances in antilock braking systems and traction control systems

Abstract Antilock braking systems (ABS) are closed-loop devices designed to prevent locking and skidding during braking. Traction control systems (TCS) limit the amount of traction force generated at the wheels to prevent loss of traction. Both systems contain an electronic control unit (ECU), which compares signals from each wheel sensor. In ABS systems, the pressure to one or more of the wheels is regulated, whereas in TCS systems, the drive torque to the wheels is reduced. Recent advances include the use of wireless accelerometers, developments in the control software that take into account the dynamics of the tyres and suspension, the estimation of parameters such as lateral acceleration and wheel slip and the use of adaptive control and fuzzy logic. More recently, these systems have been integrated into other vehicle systems, such as four-wheel steering and active suspension. Future improvements might include the use of smart materials for sensor development, and the use of roadside-to-vehicle control.

Automotive test drive cycles for emission measurement and real-world emission levels-a review

Abstract The emission levels produced by any vehicle are dependent on the mode of operation of the vehicle and technology behind the vehicle design. The test drive cycles employed to measure the emissions produced by vehicles should adequately represent the real-world driving pattern of the vehicle to provide the most realistic estimation of these levels. However, there is increasing concern about the representative drive cycles used by the various vehicle certification and regulatory authorities. This paper reviews the various drive cycles used for gasoline engine vehicles in Europe and the United States, and the impact of various factors and their influence on real-world emission levels. The proposed new drive cycles of the United States and Europe are considered. From the work reviewed, it can be concluded that the amount of pollutant levels from automotive vehicles are underestimated because of the characteristics of the existing drive cycles. While much work remains to be done with the development of new drive cycles to represent real-world driving patterns, some useful conclusions can be drawn regarding the impacts of the factors reviewed here. The impacts of the factors reviewed in this paper can be characterized to improve estimations and simulations of the real-world emission levels of the vehicle.

Real-world fuel economy and emission levels of a typical EURO-IV passenger vehicle

This paper presents the findings of research into real-world emission levels of a typical EURO-IV passenger car in the United Kingdom (UK). Four real-world drive cycles representing typical urban driving in the UK were used for the experiments. The work identified that the real-world emission levels of a EURO-IV vehicle in the UK are significantly higher than the certified legislative emission levels. The present work also identified that tailpipe-out carbon monoxide is the most affected emission specie in a gasoline-powered vehicle for real-world driving conditions.

The Most Significant Vehicle Operating Parameter for Real-World Emission Levels

The present work investigated the real-world emission performance of a typical light-duty gasoline vehicle to identify the most significant vehicle operating parameter responsible for excessive real-world emission levels. Based upon tailpipe-out emission levels, two distinct portions in the engine maps could be identified; a clean portion of the map, which covers the engine operating points within the European legislative drive cycle, and an unclean portion of the map that is outside the legislative testing. A systematic investigation of the tailpipe-out emission levels for the real-world drive cycle showed that the levels of vehicle speed and acceleration are immaterial if the vehicle operating points remain within the cleaner zone of the engine map. The methodical approach followed to identify the most significant vehicle operating parameter responsible for the real-world emission levels is given in this paper.

Real-world performance of catalytic converters

This paper investigates experimentally the performance of a three-way catalytic (TWC) converter for real-world passenger car driving in the United Kingdom. A systematic approach is followed for the analysis using a Euro-IV vehicle coupled with a TWC converter. The analysis shows that the real-world performance of TWC converters is significantly different from the performance established on legislative test cycles. It is identified that a light-duty passenger vehicle certified for Euro-IV emissions reaches the gross polluting threshold limits during real-world driving conditions. This result is shown to have implications for overall emission levels and the use of remote emissions sensing and on-board diagnostics (OBD) systems.

Dynamic analysis of rotationally flexible cam mechanisms

Abstract A novel mechanism for the actuation of valves in an internal combustion (IC) engine is described. Previous publications are reviewed and it is shown that the mechanism has received very little attention, in particular no dynamic analysis of it has been published. The mechanism features a shaft driving a cam through a coupling of sufficient rotational flexibility to permit significant angular offsets to develop during the cycle. A differential equation of motion of a simplified system is derived and solved using two methods. The theory requires a knowledge of twelve fundamental system dynamic parameters from which a prediction of angular offset of the camlobe throughout the cycle is produced. A dataset was obtained from a purpose built apparatus which recorded the angular offset of the camlobe with respect to the camshaft for a range of rotational speed values. Results graphs are presented and the level of agreement between theory and experiment is discussed. The work demonstrates for the first time that useful predictions of simplified mechanism performance can be obtained from the model developed. Recommendations for further work in this area are made.

Disbonding Technology for Adhesive Reversible Assembly in the Automotive Industry

Development of the automotive industry is currently driven by three fundamental considerations, i.e. environment, safety and cost, within a strong legislative framework. The reduction of material waste, production stages and weight have become key factors within this scope in the design of vehicles. Therefore, it is important to make greater use of non-conventional materials to take advantage of their recyclability, light weight and mechanical properties, for example new alloys and reinforced polymeric matrix composites (PMC). The dissimilar nature of the materials makes adhesive bonding the principal assembly technique for structural and semi-structural applications. Despite the enhanced performance and durability provided by the use of adhesives compared to that of more conventional joining technologies, bonded materials are very difficult to separate for recycling or reusing components at end of life. Currently, disassembly of adhesive bonded structures is conducted ineffectively by mechanical force, heat, and solvent or acid immersion. Previous research, to overcome these limitations has been mostly for applications other than automotive. Normally, reversible adhesive bonding is obtained through the development of engineered thermoplastic and/or thermosetting resins or incorporation of functional additives into commercial formulations. These technologies generally result in adhesive bonded joints with limited reliability, decreased adhesion strength and reduced resistance to higher temperature. Therefore, no effective disbonding technology has been developed for structural and semi-structural applications for the automotive industry. A comprehensive review will be presented on the adhesive disbonding technology which is currently or intended to be used by industry. This will highlight the advantages and limitations of the various techniques in order to develop an effective disbonding method for the next generation of vehicles at the end of life cycle (ELC).

Numerical Investigation of Real-World Gasoline Car Drive-Cycle Fuel Economy and Emissions

This paper investigates an approach to modelling real-world drive cycles for the prediction of fuel economy and emission levels. It demonstrates that a steady-state engine performance data based modelling approach can be used for real-world drive cycle simulation. It identifies and demonstrates that a steady-state performance data-based approach is the only current viable approach for real-world tailpipe-out CO level predictions. It also identifies quantitatively the difference between the modal emission measurements and constant volume sampling (CVS) bag values for emission modelling validation. A systematic validation and sensitivity analysis of the modelling approach is also described.

A comparison of one and two-sided Krylov-Arnoldi projection methods for fully coupled, damped structural-acoustic analysis

The two-sided second-order Arnoldi algorithm is used to generate a reduced order model of two test cases of fully coupled, acoustic interior cavities, backed by flexible structural systems with damping. The reduced order model is obtained by applying a Galerkin–Petrov projection of the coupled system matrices, from a higher dimensional subspace to a lower dimensional subspace, whilst preserving the low frequency moments of the coupled system. The basis vectors for projection are computed efficiently using a two-sided second-order Arnoldi algorithm, which generates an orthogonal basis for the second-order Krylov subspace containing moments of the original higher dimensional system. The first model is an ABAQUS benchmark problem: a 2D, point loaded, water filled cavity. The second model is a cylindrical air-filled cavity, with clamped ends and a load normal to its curved surface. The computational efficiency, error and convergence are analyzed, and the two-sided second-order Arnoldi method shows better efficiency and performance than the one-sided Arnoldi technique, whilst also preserving the second-order structure of the original problem.

A comparison between one‐sided and two‐sided Arnoldi‐based model order reduction (MORe) techniques for fully coupled structural‐acoustic analysis

Reduced order models are developed for fully coupled structural‐acoustic unsymmetric matrix models, resulting from Cragg’s displacement/pressure formulation, using Krylov subspace techniques. The reduced order model is obtained by applying a Galerkin and Petrov‐Galerkin projection of the coupled system matrices, from a higher dimensional subspace to a lower dimensional subspace, while matching the moments of the coupled higher dimensional system. Two such techniques, based on the Arnoldi algorithm, focusing on one‐sided and two‐sided moment matching, are presented. To validate the numerical techniques, an ABAQUS coupled structural‐acoustic Benchmark problem is chosen and solved using the direct approach. First, the physical problem is modeled using ANSYS FE package and compared with closed form solutions. Next, ANSYS results are compared with nodal velocities obtained by generating reduced order models via moment matching. The results show that the reduced order models give a very significant reduction in...