Imtiaz Haque

The effect of up‐armoring of the high‐mobility multi‐purpose wheeled vehicle (HMMWV) on the off‐road vehicle performance

Purpose – A parallel finite‐element/multi‐body‐dynamics investigation is carried out of the effect of up‐armoring on the off‐road performance of a prototypical high‐mobility multipurpose‐wheeled vehicle (HMMWV). The paper seeks to investigate the up‐armoring effect on the vehicle performance under the following off‐road maneuvers: straight‐line flatland braking; straight‐line off‐angle downhill braking; and sharp left turn.Design/methodology/approach – For each of the above‐mentioned maneuvers, the appropriate vehicle‐performance criteria are identified and the parameters used to quantify these criteria are defined and assessed. The ability of a computationally efficient multi‐body dynamics approach when combined with a detailed model for tire/soil interactions to yield results qualitatively and quantitatively consistent with their computational counterparts obtained using computationally quite costly finite element analyses is assessed.Findings – The computational results obtained clearly reveal the comp...

Optimization and integration of ground vehicle systems

This article deals with the optimal design of ground vehicles and their subsystems, with particular reference to ‘active’ safety and comfort. A review of state-of-the-art optimization methods for solving vehicle system design problems, including the integration of electronic controls, is given, thus further encouraging the use of such methods as standard tools for automotive engineers. Particular attention is devoted to the class of methods pertaining to complex system design optimization, as well as approaches for the optimal design of complex systems under uncertainty. Some examples of design optimizations are given in the fields of vehicle system dynamics, powertrain/internal combustion engine design, active safety and ride comfort, vehicle system design and lightweight structures, advanced automotive electronics, and smart vehicles.

Evaluation of On-Board Photovoltaic Modules Options for Electric Vehicles

This paper presents an overview of different commercial photovoltaic (PV) module options to power on-board electric vehicles (EVs). We propose the evaluation factors, constraints, and the decision-making criteria necessary to assess the suitability of this PV module for this application. The incorporation of quality function deployment (QFD) and the analytical hierarchy process (AHP) is the decision-making methodology used in this study. Our approach is innovative and robust in that the evaluation depends upon data collected from PV manufactures datasheets. Unlike traditional research, a hybrid AHP and QFD innovative decision-making methodology has been created, and current commercial PV market data for all pairwise comparisons are used to show that methodology. Using both cooled and uncooled PV modules, best, intermediate, and worst-case scenarios were used to estimate the driving ranges of lightweight EVs powered exclusively by bulk silicon PV modules. Results showed that the available daily driving ranges were between 25 and 60 km and that the CO2 emissions were reduced between 3 and 6.5 kg, compared with internal combustion vehicles of a similar type. We found that mono-Si PV modules were most suited to power low-speed, lightweight, and aerodynamically efficient EVs.

Transient Dynamics of the Metal V-Belt CVT: Effects of Pulley Flexibility and Friction Characteristic

A continuously variable transmission (CVT) offers a continuum of gear ratios between desired limits. The present research focuses on developing a continuous one-dimensional model of the metal V-belt CVT in order to understand the influence of pulley flexibility and friction characteristics on its dynamic performance. A metal V-belt CVT falls under the category of friction-limited drives as its performance and torque capacity rely significantly on the friction characteristic of the contact patch between the belt element and the pulley. Since the friction characteristic of the contact patch may vary in accordance with the loading and design configurations, it is important to study the influence of the friction characteristic on the performance of a CVT. Friction between the belt and the pulley sheaves is modeled using different mathematical models which account for varying loading scenarios. Simple trigonometric functions are introduced to capture the effects of pulley deformation on the thrust ratio and slip behavior of the CVT. Moreover, since a number of models mentioned in the literature neglect the inertial coupling between the belt and the pulley, a considerable amount of effort in this paper is dedicated towards modeling the inertial coupling between the belt and the pulley and studying its influence on the dynamic performance of a CVT. The results discuss the influence of friction characteristics and pulley flexibility on the dynamic performance, the axial force requirements, and the torque transmitting capacity of a metal V-belt CVT drive.

A Critical Review of Optimization Methods for Road Vehicles Design

[Abstract] The paper deals with the optimal design of road vehicles and their subsystems. The highly competitive nature of the automotive industry demands constant product innovation and reduction in product development both in time and cost while satisfying performance and legal requirements. Optimization procedures provide a scientific approach to automatically determine the most efficient designs under the target operating environment. Particular attention is devoted to the class of methods pertaining to complex system design optimization, as well as the approaches for the optimal design of complex systems under uncertainty. A critical review of the optimization methods used for solving road vehicle system design problems is reported. Some examples of design optimization are given in the field of vehicle system dynamics, powertrain design, internal combustion engine design, active and passive safety, vehicle system design and lightweight structures, advanced automotive electronics.

Using Genetic Algorithms to Identify Initial Operating Conditions for a Transient CVT Model

A Continuously Variable Transmission (CVT) provides a continuum of gear ratios between desired limits. CVT is a promising automotive technology and a sundry of models has been researched to realize the potential benefits of a CVT. CVT, being a highly nonlinear system, has a definite operating regime where it is able to maximize the torque transmission. The numerical model presented in this paper is difficult to solve because of its sensitivity with respect to the initial operating conditions such as initial belt tension, axial forces, and driven preload. The present research focuses on using Genetic Algorithms (GA) to identify these operating conditions and to understand the various dynamic interactions in a metal pushing V-belt CVT. This paper uses continuous Coulomb friction approximation theory to model friction between the belt and the pulleys. The computational scheme, the mathematical models, and the results corresponding to different loading scenarios are discussed.Copyright

A finite element analysis of pneumatic‐tire/sand interactions during off‐road vehicle travel

Purpose – The purpose of this paper is to carry out a series of transient, non‐linear dynamics finite element analyses in order to investigate the interactions between a stereotypical pneumatic tire and sand during off‐road vehicle travel.Design/methodology/approach – The interactions were considered under different combined conditions of the longitudinal and lateral slip as encountered during “brake‐and‐turn” and “drive‐and‐turn” vehicle maneuvers. Different components of the pneumatic tire were modeled using elastic, hyper‐ and visco‐elastic material models (with rebar reinforcements), while sand was modeled using the CU‐ARL sand models developed by Grujicic et al. The analyses were used to obtain functional relations between the wheel vertical load, wheel sinkage, tire deflection, (gross) traction, motion resistance and the (net) drawbar pull. These relations were next combined with Pacejka magic formula for a pneumatic tire/non‐deformable road interaction to construct a tire/sand interaction model sui...

Quality function deployment as a tool for including customer preferences in optimising vehicle dynamic behaviour

Expert simulation can solve difficult problems that are beyond the power of even the most insightful designers. However, it also suggests the potential for equipping designers with tools that enhance their insight. This paper proposes a combined application of the Quality Function Deployment (QFD) design technique and a Genetic Algorithm-based (GA) optimisation method to a multi-criteria optimisation design problem to reduce the dimensionality of the problem and, most importantly, to help make choices based on customer preference because the success of the design depends on how well it addresses the wants and needs of the consumers - both internal and external. To illustrate that, a complex vehicle multi-body model that has a significant number of design variables is used. Vehicle performance is assessed using a number of different performance measures calculated over a number of different scenarios. Results show excellent improvements in the vehicle handling performance over three open loop manoeuvres.

An assessment of a genetic algorithm-based approach for optimising multi-body systems with applications to vehicle handling performance

Simulation is seen as a way to develop an excellent understanding of vehicle dynamic behaviour and the utilisation of this understanding in designing vehicles. An essential component of this approach is the use of mathematical optimisation methods as a means of synthesising complex mechanical systems such as vehicles. Complex vehicle multi-body models have a significant number of design variables. Vehicle performance is assessed using a number of different performance measures calculated over a number of different scenarios. The resulting problem is one of significant complexity and deterministic optimisation methods are not suitable for this type of problem because of their propensity to lead to local minima. Stochastic Optimisation methods are not as sensitive to local minima and frequently yield better results. This paper presents the use of a Genetic Algorithm-based (GA) approach to vehicle handling design problems and compares the results obtained with other methods such as Simulated Annealing and Monte-Carlo. The results show that the Genetic-Algorithm approach shows distinct advantages over the other two methods. Results obtained using GAs show superior improvements in the vehicle handling performance over three manoeuvres.

On configurations of symbolic equations of motion for rigid multibody systems

An algorithmic procedure for generating symbolic equations of motion for rigid multibody systems based on a Matrix-Vector approach is presented in this paper. The ease of computation and power inherent in this approach are demonstrated through a series of illustrative examples. Various techniques such as simultaneous generation of second order differential equations of motion and conversion to first order differential equations of motion in Hamiltonian variables, generalized coordinates transformation, order reduction using holonomic and nonholonomic constraint equations and block construction of equations of motion for the compound system from the equations of motion of the sub-systems are described.