Mechanical Properties of Optical Fiber Strain Sensing Cables under γ -Ray Irradiation and Large Strain Influence.

Optical fiber strain sensing cables are widely used in structural health monitoring; however, the impact of a harsh environment on them is not assessed despite the huge importance of the stable performances of the monitoring systems. This paper analyzes (i) the impact of the different constituent layers on the behavior of a strain sensing cable whose constitutive materials are metal and polyamide, (ii) the radiation influence on the optical fiber strain sensing cable response (500 kGy of gamma-rays), and (iii) the behavior of the cable under high axial strain (up to 1%, 10,000 mu epsilon). Radiation impact on strain sensitivity is negligible for practical application, i.e., the coefficient changes by 4% at the max. The influence of the composition of the cable is also assessed: the sensitivity differences remain under 15%, a standard variation range when different cable compositions and structures are considered. The elasto-plastic behavior is at the end evaluated, highlighting the residual strain (about 1600 mu epsilon after imposing 10,000 mu epsilon) of the cable (especially for metallic parts).