为避免减速度线性变化的假设造成制动距离计算值与实测值之间的偏差,回归了减速度与时间非线性关系式,并推导了减速度非线性变化时制动距离计算公式.建立轮胎-路面三维有限元模型,计算了在干燥与潮湿2种路表状况下制动减速度线性和非线性变化时的制动距离.结果表明:减速度线性和非线性变化计算所得制动距离,对于干燥路表差别不大,潮湿路表则差别十分明显;在潮湿路表状况下,相比于非线性变化,线性变化所得结果往往偏小,说明在分析水膜润滑导致制动距离延长方面,考虑线性变化的制动减速度是不合适的.
To avoid deviation of braking distance between theoretical calculated value and field measured results caused by the assumption of linearly varied braking deceleration, math formula of non-linear braking deceleration and braking time was regressed. Based on this formula, braking distance computation equation was deduced. Three dimensional finite-element model of tire-pavement was also established to investigate variation of braking distance using linear and non-linear deceleration. Results indicate that for dry pavement surface, the braking distance has little difference at low and high initial brake speed. As for wet pavement surface, the calculated braking distance varies significantly at a relative low initial brake speed, and this variation becomes more obvious with the increase of initial brake speed. It shows that to analyze the prolonged braking distance due to water film lubrication, linear variation of braking deceleration is not suitable.