Quantification of structural loading during off-road cycling.
Quantification of structural loading during off-road cycling.
复制标题
越野骑行期间结构载荷的量化。
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Maury L. Hull
中科院分区：
文献类型：
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作者：
D. S. D. Lorenzo;Maury L. Hull
为了提供越野自行车结构部件的疲劳寿命预测和测试数据，本文所述研究的目的是量化由于表面诱导载荷而输入到越野自行车的载荷。一辆全仪表化的测试自行车在踏板、车把和轮毂处配备了测力计，以测量通过自行车与骑手和地面之间的接触点作用的所有平面内结构载荷。站立骑手携带的便携式数据采集系统首次允许在延长的越野测试期间收集该负载信息。总之，七名经验丰富的车手骑下坡试验测试部分与测试自行车在前悬架和全悬架配置。通过计算平均值、标准差、幅值概率密度函数和功率谱密度函数，定量地使用载荷历史来描述载荷分量。对于站立位置，垂直于地面的载荷分量的变异系数分别大于1.2（踏板力）和0.3（踏板力）以及0.5-0.6（轮毂力）。因此，在平衡杆处动载荷的相对贡献比静载荷大得多，但在踏板和轮毂处的动载荷的相对贡献较小。如雨流计数所示，在前轮和后轮处分别产生接近测试对象重量的3倍和5倍的高振幅载荷。功率谱密度显示能量集中在0-50 Hz频段。通过应力计算和材料特性的知识，这些数据可以用于分析预测重要结构部件的疲劳寿命，例如转向系统。这些数据也可用于开发疲劳测试协议，以验证疲劳寿命的分析预测。
To provide data for fatigue life prediction and testing of structural components in off-road bicycles, the objective of the research described herein was to quantify the loads input to an off-road bicycle as a result of surface-induced loads. A fully instrumented test bicycle was equipped with dynamometers at the pedals, handlebars, and hubs to measure all in-plane structural loads acting through points of contact between the bicycle and both the rider and the ground. A portable data acquisition system carried by the standing rider allowed, for the first time, this loading information to be collected during extended off-road testing. In all, seven experienced riders rode a downhill trial test section with the test bicycle in both front-suspension and full-suspension configurations. The load histories were used quantitatively to describe the load components through the computation of means, standard deviations, amplitude probability density functions, and power spectral density functions. For the standing position, the coefficients of variation for the load components normal to the ground were greater than 1.2 for handlebar forces and 0.3 and 0.5-0.6 for the pedal and hub forces, respectively. Thus, the relative contribution of the dynamic loading was much greater than the static loading at the handlebars but less so at the pedals and hubs. As indicated by the rainflow count, high amplitude loading was developed approaching 3 and 5 times the weight of the test subjects at the front and rear wheels, respectively. The power spectral densities showed that energy was concentrated in the band 0-50 Hz. Through stress computations and knowledge of material properties, the data can be used analytically to predict the fatigue life of important structural components such as those for steering. The data can also be used to develop a fatigue testing protocol for verifying analytical predictions of fatigue life.