INFLUENCE OF THE ROAD-SURFACE TEXTURE ON THE SPEED DEPENDENCY OF TIRE / ROAD FRICTION
Tire/wet road friction depends on two road-surface texture scales: the macrotexture (centimeterto millimeter dimensions) is responsible for the speed dependency of friction, and the microtexture (submillimeter dimensions) is responsible for the friction level at any speed. This paper deals firstly with the description of road-microtexture, the macrotexture scale being well documented. Considering the fact that rubber energy-loss controls tire/wet road friction and that angularity of road-surface asperities influences greatly tire deformation, the second author has proposed a description method derived from the motif-combination technique. This method defines two parameters related to the sharpness of asperity summits and the relative position of these summits. A model has been then proposed by the first author to describe the friction-speed curve from roadsurface macroand microtexture descriptors, tire-related characteristics (rubber properties, wear) and road wetness. The description is based on the Stribeck curve. The speed-dependency friction model is applied to the analysis of car-braking tests. Comparisons between calculated and measured friction-coefficients at different braking speeds are presented and discussed.
Multi-physical model for tyre–road contact – the effect of surface texture
ABSTRACT The purpose of this paper is to develop a multi-physical tyre model, which can take into account the influence of temperature and macro-texture of the road surface. The aim is to contribute to a better understanding and modelling of the tyre–road pavement interaction. This tyre–road interaction model can be used for friction estimation as well as rolling resistance estimation. Indeed, tyre–road friction has an undeniable influence on the rolling tyre; an accurate measurement of the tyre–road interaction is necessary for a better tyre design and simulations. The developed approach comprises mechanical and thermal models and gives dynamic forces and tyre temperatures as outputs. Comparison of simulations with experimental results to validate the model is presented and discussed. Special focus is given to the study of the impact of the macro-texture of road surface; numerical and experimental results are discussed. The experiments were done at IFSTTAR test tracks.
Capital Accumulation and Women's Labour in Asian Economies
* Contents * Foreword by Gerrit Huizer * 1. Feminism and the conceptualization of women's labour in Asian economies. * PART I: The Discourse on Women's Labour in Historical Perspective * 2. The patriarchal bias of working class theoreticians: Marx and Proudhon. 3. The proletarian women's movement in Germany and women's labour. 4. The legacy of the second feminist wave: the debate on household labour revisited. * PART II: The Industrial Work of Women in India and Bangladesh * 5. Home-based women labourers in the garment industry in West Bengal. 6. Wage slavery among women garment workers in the factory system in Bangladesh. 7. The German feminist school and the thesis of housewifization. * PART III: Women's Role as Agricultural Producers * 8. Developmental feminism and peasant women's labour in Bangladesh. 9. The ecofeminist discourse in India. 10. The German feminist school and the thesis of subsistence labour. * PART IV: Japanization and Women's Labour * 11. The Japanese style of management and Fordism compared. 12. Japanese women as a vast reserve army of Labour. 13. Conclusion: capital accumulation in contemporary Asia