桥梁设计外文翻译--wim系统中以光纤为基础的动态压力传感装置-桥梁设计(编辑修改稿)

桥梁设计外文翻译--wim系统中以光纤为基础的动态压力传感装置-桥梁设计(编辑修改稿)内容摘要：

different loading rates and magnitudes are chosen as dynamic loads to simulate the weight loads caused by moving vehicles on road. Fullsize image (45K) Fig. 2. Experimental setup. Fig. 3 shows a typical loading profile and fringe output of the interferometer during the duration of the applied ramp function load. As can be seen, the number of fringes at left corner of Fig. 3 is so great that it is hard to distinguish each fringe. Thus, another figure on the right is used. The figure is the enlargement of the circled area to show clearly the fringes. Because of the polarization effect, the amplitudes of fringes slightly vary. But will not influence the fringe count and period, thus neglected in this paper. In the experiment, the pressure load is applied to the chamber at MPa increments up to the maximum pressure level of 30 MPa, corresponding to load increments from kN to a maximum of 178 kN. The loading time is applied starting from 1 to 6 s with an increment of 1 s. Fullsize image (46K) Fig. 3. Typical loading procedure and fiber optic sensor output waveform. . Experimental data Fig. 4 shows the experimental results of the fringe number and fringe period readouts of the sensor output under different loads. Lines with different signs represent relations between the sensor39。 s outputs and the maximum amplitudes of the load under different loading rates. Fullsize image (33K) Fig. 4. The experimental results: the fringe numbers and fringe periods vs. loads. The fringe number has a linear relationship with the static load, while the fringe period has a nonlinear one. Note that, the relationship differs under different loading rates, since with increasing loading rate, the same maximum amplitude load will turn out to a bigger dynamic load, which causes the increase in fringe number and the decrease in fringe period. Though both the fringe number and the fringe period are sensitive to the dynamic load, their sensitive ranges are different. The sensitivity of the fringe number to load is a constant in the whole testing range. When load is low, the small change of dynamic load may not be recognized by the fringe number. On the other hand, the sensitivity of the fringe period to load is not a constant. When the load is low, the small change of dynamic load corresponds to big change of fringe period. These two parameters can be used together to give a more precise indication of the load tested. Considering Eqs. (5) and (6), the functions between loads and fringe number and fringe period can be approached as Eqs. (7) and (8), respectively: (7) Ls=ksn1Nf+ksn2 (8) where ksn1, ksn2, kst1 and kst2 are the parameters approached. . Repeatability of the sensor Three experimental results under the same loading conditions are pared in Fig. 5 demonstrating that the dynamic fiber optic pressure sensor has good repeatability. Fullsize image (21K) Fig. 5. Illustration of the repeatability of the optic fiber sensor. . Calibration of the sensor According to the fringe number and period of the optic fiber sensor output, the dynamic load and static load of the vehicle passed can be obtained from the calibration process. . Calibration of the static weight The function approach method was adopted to calibrate the static weight measured. It should be mentioned that the load duration time t should also be gained by the sensor system in order to get the static weight. Usually it is easy to get. The following steps are taken to calibrate the static weight: Step 1: Using the function approach method to approach the measured data when the sensor experienced the different static applied load with the same loading rate. Linear function and power function are adopted for the fringe number data and fringe period data. The approached results are shown in Table 1. Table 1. Step 1 approached results Loading time Approached ksn1, ksn2 for relation between the largest static load (Ls) an。