05 ��m. The sensing length of the FBGs was about 10 mm. The reflectivity of the resulting FBG was about 99%, and the peak wavelengths were between 1,550 and 1,551 nm. The full width half maximum (FWHM) of the FBGs was about 0.175 nm. Impacts were made at either of the two locations designated A and B in Figure 1b, using a 260 g aluminum weight falling from a height of 140 cm with an apparatus that conforms to ASTM D5628. B was the position of the FBG and position A was 30 mm from B. The fiber on the side that faced the impact was designated L1 and the one on the back surface L4. After impact the coupons were subjected to cyclic fatigue loading from 0.5 to 5 kN at a frequency of 5 Hz using an MTS servo-hydraulic testing system 810 (MTS Systems Corporation, Eden Prairie, MN, USA) for 200,000 cycles.
The reflected spectra from the FBGs were interrogated periodically using an optical spectrum analyzer (Anritsu MS9710C OSA, Anritsu Company Ltd., Kanagawa, Japan) under the load-free condition. The above tests have also been repeated on specimens without undergoing any impact to serve as control. Ultrasonic C-scan w
Inductive position sensors are widely used in modern automotive and industrial applications [1�C3]. They have various benefits such as low cost, good insensitiveness against temperature, and no wear-out [4�C6]. Several types of position sensors based on the inductive principle differ in their nonlinearity errors [7]. The grating eddy current position sensor not only has the function of resisting liquids, but it also prevents ferromagnetic particles from affecting measurement results.
However, measurement blind areas are not completely eliminated, so the linearity of the sensor is not satisfactory [8,9]. Inductive angle sensors are not susceptible to background electromagnetic interference, and they produce much greater output signal levels compared to other choices. However, there are usually higher order harmonic signals which lead to a considerable amount of nonlinearity AV-951 errors [10]. Inductive angle sensors provide a compact structure and a high degree of insensitivity to production and installation tolerances, but the weak linear relationships between position and output signal (near the zero crossings) often lead to significant nonlinearity errors for calculating the angular displacement [11,12].
In the inductive position sensor field, the nonlinearity error is around one percent [7,13,14]. To reduce the nonlinearity error, the sensor structure needs to be optimized.We previously presented an inductive angle sensor optimized using response surface methodology [15]. For simplicity the original paper did not discuss the influence of the sensor stator on the nonlinearity errors. However, it is found that the stator affects the behavior of electromagnetic fields within its rotor, which plays a key role in the linearity of the inductive angle sensor.