Optical fibers with protective coatings have been used as distributed strain sensors for automated inspection in the construction, operation, and maintenance of various engineering structures. The presence of the protective coatings causes strain transfer effect, which can change the strain measurement of the distributed sensors. This study quantitatively evaluates the strain transfer for distributed fiber optic sensors subjected to an arbitrary strain field for the first time. Theoretical studies are performed to derive closed-form solutions for describing the strain transfer, and high-resolution (sub-millimeter) strain distributions were measured to validate the theoretical study. This study demonstrates that the strain transfer effect is dependent on the strain field in the host matrix, and the derived formulae enable correct interpretation of the strain measurement from the distributed sensor. This study provides theoretical foundations for using distributed fiber optic sensors to accurately measure strain distributions in engineering structures.

具有保护涂层的光纤已被用作分布式应变传感器，用于在各种工程结构的构造，操作和维护中进行自动检查。保护涂层的存在会引起应变传递效应，这会改变分布式传感器的应变测量。这项研究首次定量评估了分布式光纤传感器在任意应变场下的应变传递。进行理论研究以得出描述应变传递的封闭形式解，并测量了高分辨率（亚毫米）应变分布以验证理论研究。这项研究表明，应变传递效应取决于宿主基质中的应变场，导出的公式可以正确解释来自分布式传感器的应变测量。该研究为使用分布式光纤传感器准确测量工程结构中的应变分布提供了理论基础。