Influence of distance between the first sensor and support in determining tension of fixed-end cable using multiple synchronized vibration measurement

Non-destructive evaluation has been developed to identify cable tension for any end-rotational stiffness condition. One of the existing methods uses multiple vibration measurements. This paper aims to study the effect of shifting the closest sensor to the support in multiple vibration measurements through numerical simulation. A cable fixed at both ends vibrates under artificial random excitation is simulated. Three cases of five synchronized signal recording arrangements are applied to the cable, where the distance from the support to the first recorder (d1) is different for each case. The distance d1 of Case 1, Case 2, and Case 3 are d, 2d, and 3d, respectively, where d is the distance between the recorder, and d is taken as 7% of the total length and the same for all cases. Cable dynamical properties are analyzed using a stochastic subspace identification method, and effective lengths are figured out by curve fitting. Under the same frequency range, seven effective lengths are obtained in Case 1, while eight are detected in Cases 2 and 3. Besides, it can be concluded that Case 1 generates larger errors in predicting tension compared to other cases.