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摘要: 分析了汽车制动过程前、后轮受力状况, 建立了汽车制动距离与路面附着系数的数学模型。在冰雪路面和使用融雪剂路面上进行了制动试验, 应用MATLAB软件仿真计算了汽车在不同制动初速度下的制动距离。试验结果表明: 在冰雪路面上, 当汽车制动初速度分别为10.8、24.4、31.4km·h-1时, 制动距离分别为2.959、18.378、26.264m;在使用融雪剂路面上, 当汽车制动初速度分别为11.0、22.9、31.0km·h-1时, 制动距离分别为2.430、13.766、18.860m。使用融雪剂后, 附着系数明显提高, 测试制动距离减小了25%~28%, 仿真计算制动距离减小了约30%, 两者接近, 因此, 计算模型可靠。Abstract: The forces conditions of front and rear wheels during automobile braking process were analyzed, and a mathematical model of automobile braking distance and road adhesion coefficient was established.Braking tests on ice-snow-covered pavement and the pavement after using deicing salt were carried out, and the braking distances under different primary braking speeds were calculated by using MATLAB software.Test result shows that on ice-snow-covered pavement, when the primary braking speeds are 10.8, 24.4, 31.4 km·h-1 respectively, the braking distances are 2.959, 18.378, 26.264 m respectively.On the pavement after using deicing salt, when the primary braking speeds are 11.0, 22.9, 31.0 km·h-1 respectively, the braking distances are 2.430, 13.766, 18.860 m respectively.After using deicing salt, the adhesion coefficient of the pavement increases significantly, and the test braking distance decreases by 25%-28%, the simulation braking distance decreases by about 30% and is close to the test value.So the calculation model is feasible.
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表 1 车辆参数
Table 1. Vehicle parameters
试验车辆型号 轮胎型号 制动器类型 宝来 195/65R15 盘式 表 2 试验环境1
Table 2. Test environment 1
试验日期 试验地点 天气 气温 道路状况 载荷情况 2011-01-07 东北林业大学林场 多云 -12℃ 冰雪压实路面 空载 表 3 试验环境1下的制动参数
Table 3. Braking parameters under test environment 1
方向 v0/(km·h-1) Bmax /(m·s-2) s/m 正 10.3 10.8 2.26 2.28 2.860 2.959 反 11.6 2.30 3.058 正 23.6 24.4 2.08 2.25 17.569 18.378 反 25.1 2.41 19.186 正 32.6 31.4 2.12 2.23 27.151 26.264 反 30.2 2.33 25.376 表 4 试验环境2
Table 4. Test environment 2
试验日期 试验地点 天气 气温 道路状况 载荷情况 2011-01-09 东北林业大学林场 多云 -10 ℃ 融雪剂作用后的路面 空载 表 5 试验环境2下的制动参数
Table 5. Braking parameters under test environment 2
方向 v0/(km·h-1) Bmax /(m·s-2) s/m 正 11.2 11.0 3.91 3.84 2.470 2.430 反 10.8 3.76 2.390 正 22.0 22.9 4.01 3.79 13.241 13.766 反 23.7 3.57 14.291 正 30.9 31.0 3.91 3.71 17.551 18.860 反 31.0 3.50 20.168 表 6 2种试验环境下的φ1和φ2
Table 6. φ1andφ2under two test environments
冰雪压实路面 v0/(km·h-1) φ1 φ2 10.8 0.152 0.228 24.4 0.150 0.225 31.4 0.149 0.223 融雪剂作用后的路面 11.0 0.256 0.384 22.9 0.253 0.379 31.0 0.247 0.371 表 7 基本参数
Table 7. Basic parameters
M/kg L/m a/m b/m h/m β t21/s t22/s 1 305 2.610 1.259 1.351 0.526 0.6 0.1 0.3 -
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