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The primary function of automotive windscreen wipers is to remove excess water and debris to secure a clear view for the driver. Their successful operation is imperative to vehicle occupants’ safety. To avoid reliance on experimental testing there is a need to develop physics-based models that can quantify the effects of design-based decisions on automotive wipers. This work presents a suite of evaluative tools that can provide quantitative data on the effects of design decisions. We analyse the complex non-linear contact interaction between the wiper blade and the automotive screen using finite element analysis, assessing the impact of blade geometry on the contact distribution. The influence of the evolution of normal applied load by the wiper arm is also investigated as to how it impacts the contact distribution evolution. The dynamics of the blade are subsequently analysed using a multiple connected mass spring damper system. Additionally, we apply hydrodynamic lubrication theory to study the residual film thickness post wipe and assess the effect of wiper blade geometry and lubricant composition. Finally, the complete wiper system is studied using a lump dynamic model, and bifurcation analysis is applied to determine areas of instability due to friction induced vibrations. Additionally, the wiper dynamics modelling shows peak frequencies occurring at 30-50Hz, which agrees well with a documented range of chatter frequencies. The friction coefficients calculated within the hydrodynamic model fall within experimentally documented ranges of lubricated sliding friction, μ ≈ 0.1. Furthermore, the areas of operational stability predicted by our bifurcation model coincide with current experimentally determined optimal operational regions for automotive wipers.

A novel semi-analytical solution has been developed for the calculation of the static and dynamic response of an off road tire interacting with a deformable terrain, which utilizes soil parameters independent of the size of the contact patch (size-independent). The models involved in the solution presented, can be categorized in rigid and/or pneumatic tires, with or without tread pattern. After a concise literature review of related methods, a detailed presentation of the semi-analytical solution is presented, along with assumptions and limitations. A flowchart is provided, showing the main steps of the numerical implementation, and various test cases have been examined, characterized in terms of vertical load, tire dimensions, soil properties, deformability of the tire, and tread pattern. It has been found that the proposed model can qualitatively capture the response of a rolling wheel on deformable terrain.

Recent data show that 35% of fatal crashes in sport utility vehicles included vehicle rollover. At the same time, experimental testing to improve safety is expensive and dangerous. Therefore, multi-body simulation is used in this research to improve the understanding of rollover dynamics. The majority of previous work uses low-fidelity models. Here, a complex and highly nonlinear multi-body model with 165 degrees of freedom is correlated to vehicle kinematic and compliance (K&C) measurements. The Magic Formula tyre model is employed. Design of experiment methodology is used to identify tyre properties affecting vehicle rollover. A novel, statistical approach is used to link suspension K&C characteristics with rollover propensity. Research so far reveals that the tyre properties that have the greatest influence on vehicle rollover are friction coefficient, friction variation with load, camber stiffness and tyre vertical stiffness. Key K&C characteristics affecting rollover propensity are front and rear sus...

The behaviour of tyres under transient handling manoeuvres is studied with the aid of a newly developed model. The model consists of a discretized flexible belt with damping and inertia, connected to the rim by viscoelastic elements representing the carcass. In the neighbourhood of the contact patch, the belt is connected to a separate discretized viscoelastic tread with inertia. A separate algorithm taking into account the radial deflection of the carcass elements is used for the calculation of the contact pressure distribution along the contact patch. Friction follows a stick—slip law taking into consideration the velocity of tread elements, the normal force and the unequal coefficients of friction in the lateral and longitudinal directions. The model seems capable of generating transient forces and moments including the phase lags observed under time-varying kinematic excitations.

The aim of this project is to improve the lateral stability of a motorcycle via active control. A simplified nonlinear motorcycle model forms the plant. The control goals are defined as roll angle tracking and minimal control effort. The control has to cooperate with the rider, and this achieved using two different approaches: using a parallel reference model for the ideal behavior, or using the reaction wheel purely to improve the stability of challenging poles. Two different control design methodologies (linear optimal and H ∞ control) are tested on the nonlinear model. The designs are tested in simulation and verified against a plant formulation containing lumped uncertainties. Further work will concentrate on finding the most suitable controller and testing it on a prototype vehicle.