Importance of tread inertia and damping on the tyre/road contact stiffness

Predicting tyre/road interaction processes like roughness excitation, stick-slip, stick-snap, wear and traction requires detailed information about the road surface, the tyre dynamics and the local deformation of the tread at the interface. Aspects of inertia and damping when the tread is locally deformed are often neglected in many existing tyre/road interaction models. The objective of this paper is to study how the dynamic features of the tread affect contact forces and contact stiffness during local deformation. This is done by simulating the detailed contact between an elastic layer and a rough road surface using a previously developed numerical time domain contact model. Road roughness on length scales smaller than the discretisation scale is included by the addition of nonlinear contact springs between each pair of contact elements. The dynamic case, with an elastic layer impulse response extending in time, is compared with the case where the corresponding quasi-static response is used. Results highlight the difficulty of estimating a constant contact stiffness as it increases during the indentation process between the elastic layer and the rough road surface. The stiffness-indentation relation additionally depends on how rapidly the contact develops; a faster process gives a stiffer contact. Material properties like loss factor and density also alter the contact development. This work implies that dynamic properties of the local tread deformation may be of importance when simulating contact details during normal tyre/road interaction conditions. There are however indications that the significant effect of damping could approximately be included as an increased stiffness in a quasi-static tread model

The contribution of air-pumping to tyre/road noise

It is generally accepted that there are at least two tyre/road noise generation mechanisms commonly referred to as tyre vibrations and air-pumping. While the modelling of tyre vibrations is rather mature, the modelling of air-pumping is still on a basic stage and unsatisfactory in many aspects. Applying the fact that tyre vibrations and air-pumping have different vehicle speed dependency allows for identifying the contribution from each mechanism in field measurements of tyre/road noise. This paper presents an analysis of controlled pass-by measurements and simulations with the tyre/road simulation model at Chalmers. Results show that air-pumping is a major contributor to tyre/road noise. The question arises which physical mechanisms are behind the air-pumping noise observed in measurements and simulations. The analysis indicates that tyre vibrations in the contact may lead to air-pumping noise. This suggestion deviates from generation mechanisms usually assumed in the air-pumping context

Mechanisms of light energy harvesting in dendrimers and hyperbranched polymers

Since their earliest synthesis, much interest has arisen in the use of dendritic and structurally allied forms of polymer for light energy harvesting, especially as organic adjuncts for solar energy devices. With the facility to accommodate a proliferation of antenna chromophores, such materials can capture and channel light energy with a high degree of efficiency, each polymer unit potentially delivering the energy of one photon-or more, when optical nonlinearity is involved. To ensure the highest efficiency of operation, it is essential to understand the processes responsible for photon capture and channelling of the resulting electronic excitation. Highlighting the latest theoretical advances, this paper reviews the principal mechanisms, which prove to involve a complex interplay of structural, spectroscopic and electrodynamic properties. Designing materials with the capacity to capture and control light energy facilitates applications that now extend from solar energy to medical photonics. © 2011 by the authors; licensee MDPI, Basel, Switzerland

Luminescent Properties of a Water-Soluble Conjugated Polymer Incorporating Graphene-Oxide Quantum Dots

Marie Curie. Grant Number: MRTN-CT-2006-036040, Higher Education Funding Council for England, China Scholarship Council, Centre for Advanced Structural Ceramics, Royal Societ

International Production Networks in the Automotive Industry:Drivers and Enablers

The automotive industry was one of the earliest to internationalise, with overseas production by US companies already happening in the early 1900s. However, the arrangement for overseas automotive production at that time was quite different from the idea of international production networks in the contemporary sense. There were few linkages between international locations and overseas operations were designed either as largely self-sufficient, vertically integrated, replications of their domestic factories or as CKD/SKD assembly plants with little local technical content. By comparison, our current understanding of international production networks is that they are dispersed, collaborative, high value adding and centrally coordinated. This paper uses global company case analysis to identify the drivers and enablers that shape the international production networks of two automotive companies, BMW and Volvo Cars. The methodology contrasts with previous network studies of the automotive industry that have concentrated their analysis at the country and regional level. /320191409_International_Production_Networks_in_the_Automotive_Industry_Drivers_and_Enablers [accessed Oct 18 2017]

Research Results Improve Learning and Understanding in Master Courses - The use of a manufacturing strategy tool

The analytical STRATEGO-tool has been used in total 48 project groups in master courses at Chalmers University of Technology from spring term of 2015. The project trains the students in applying theoretical tools at real organizations with a specific interest in analyzing their use of operations strategy. This paper presents the outcome from these courses and specifically discusses its usability as a pedagogic tool in different contexts, even though the intention with the tool initially was to constitute a tool for SMEs who wanted to develop their manufacturing strategies

Modulating the charge injection in organic field-effect transistors: fluorinated oligophenyl self-assembled monolayers for high work function electrodes

Financial support from the ERC project SUPRAFUNCTION (GA-257305), the EC Marie-Curie projects IEF-MULTITUDES (PIEF-GA-2012-326666) and ITN iSwitch (GA no. 642196), the Agence Nationale de la Recherche through the LabEx project Chemistry of Complex Systems (ANR-10-LABX-0026_CSC), and the International Center for Frontier Research in Chemistry (icFRC). The computational work was supported by the Interuniversity Attraction Pole Programme (P7/05) initiated by the Belgian Science Policy Office, and by the Belgian National Fund for Scientific Research (FNRS). J.C. is an FNRS research director. Colin Van Dyck is a recipient of a Gustave Boël – Sofina Fellowship of the Belgian American Educational Foundation (BAEF). K.M., F.R. and M.M. acknowledge financial support by the Swiss National Science Foundation (SNF) and the Swiss Nanoscience Institute (SNI)