How do application-related issues influence the reliability of fiber optic strain measurements?

Abstract

Fibre optic strain sensors are increasingly used and sensor systems are provided with specifications. Even if the performance is well specified, the strain characteristics of the sensor, strain transfer factor, mechanical stability under thermal influences, the performance of applied strain sensors can seriously differ from virgin sensor's the performance. The contribution will focus on issues that can deteriorate the sensor function or reduce the reliability of measurement results. Aspects are considered how to come to reliable strain measurements and how to validate strain measurements of applied sensors. Related to this topic, European activities like the recently started European COST TD1001 action, called (OfSeSa) will be presented.

Fiber-optic strain sensors are making the leap from lab to industrial use: reliability and validation as precondition for standards

“…The small fibers around the optical fiber are reinforcing glass fibers. [15] The observed delamination of the sensing fiber due to shrinkage of the hosting material (Fig. 6, left) as well as the deformation of the coating due to increased thermal strain during curing (Fig.…”

Theoretical Analysis on Strain Transfer Error of FBG Sensors Attached on Steel Structures Subjected to Fatigue Load

“…Taking the Laplace transformation of Equation 12 and adopting Equation 13 and Equation 14, it yields…”

“…This explains the strain directly read from the sensor cannot entirely represent the actual strain of the host material, and the accurate interpretation of the collected data addresses further discussion. The different material properties and thicknesses of the adhesive layer affect the relationship between the sensor output and the strain of the host material [13][14][15][16]. To eliminate the strain transfer error and improve the measurement accuracy of FBG sensors, strain transfer analysis is developed to establish the quantitative relationship of strains between the host material and the optical fibre [17].…”

Fibre-optic strain sensors are making the leap from lab to industrial use—reliability and validation as a precondition for standards

“…Strain transfer problems arise when inappropriate fibre coatings were selected or integration process was bad. The small fibres around the optical fibre are reinforcing glass fibres[28].…”