Fibre-based magneto-optic layer-sensor (FAMOS²)

复合材料嵌入式光纤应变传感器在安全相关结构的长期监测中发挥着重要作用，例如海上风力涡轮机发电厂或飞机的机翼或机身部件。到目前为止，还没有针对嵌入式传感器的验证程序，可以在安装后和结构运行期间评估传感器的行为。因此，需要嵌入式传感器的自诊断能力，以向用户提供关于可靠和长期稳定的传感器功能的信息。为了满足要求，磁致伸缩层将被施加到应变敏感光纤上，以评估嵌入后和结构操作期间的功能。光纤中的敏感元件通过施加磁场而产生应变。外加磁场与传感器的光学响应信号之间的关系决定了特性校准曲线。嵌入材料中的传感器的校准曲线的变化对应于嵌入条件的变化（例如界面分层、传感器在材料内的滑动）。通过这种方式，传感器的可靠功能可以被确定，并与待评估材料的变化（例如材料老化）分离。该项目的主要目标是磁致伸缩FBG元件（光纤布拉格光栅）的自诊断特性的表征和性能证明。在本项目期间，应开展有关磁致伸缩元件的再现性、校准曲线稳定性、精度和长期稳定性的基础研究。如果这一概念被证实是成功的，则嵌入式光纤传感器的功能性证据将成为可能，并且可以最佳地规划用于确定结构完整性的维护周期。这导致维护成本和人员能力的降低。FBG元件可以用作安全相关在线监测系统中的应变传感器，只有当传感器显示出关键信号时，才需要对结构进行维护。当维护成本非常高（例如海上风力涡轮机发电厂、海上石油平台）或必须高效地组织维护中断（例如飞机维护）时，这种基础研究对于在安全相关结构和设施中使用测量系统至关重要。

Composite-embedded fibre optic strain sensors play an important role for long-term monitoring of safety relevant structures, such as offshore wind turbine power plants or wing or fuselage parts of aircrafts. Until now, no validation procedure for embedded sensors exists that allows the evaluation of the sensors behaviour after installation and during operation of the structure. Therefore, self-diagnostic capability of embedded sensors is required to provide the users information about reliable and long-term stable sensor function. In order to fulfil the requirements, a magnetostrictive layer is to be applied onto the strain-sensitive optical fibre to evaluate the functionality after embedment and during operation of the structure. The sensitive element in the optical fibre is strained by applying a magnetic field. The relation between applied magnetic field and optical response signal of the sensor determines the characteristic calibration curve. Changes in the calibration curve of sensors embedded in materials correspond to changes in the embedment condition (e.g. interface delamination, sliding of the sensor inside the material). This way, the reliable functionality of the sensor can be determined and separated from changes of the material to be evaluated, e.g. material aging.The main goal of this project is the characterisation and performance proof of the self-diagnostic feature of magnetostrictive FBG-elements (Fibre Bragg Grating). Fundamental investigations concerning reproducibility, stability of the calibration curve, precision and long-term stability of the magnetostrictive element should be carried out during this project.If this concept is confirmed to be successful, the evidence of functionality of embedded fibre optic sensors will be possible, and the maintenance periods for the determination of the structures integrity can optimally be planned. This leads to a reduction of maintenance costs and personnel capacity. FBG-elements can then be used as strain sensors in safety-relevant online-monitoring systems, and maintenance of structures is only necessary when the sensor shows a critical signal. This basic research is of principal importance for the use of measurement systems in safety-relevant structures and facilities, when the maintenance costs are very high (e.g. offshore wind turbine power plants, offshore oil platforms), or where the maintenance break must highly efficiently be organized (e.g. maintenance of aircrafts).