In-situ strain measurement during solidification and cooling of aluminium alloys using regenerated fibre Bragg gratings

组件集成式传感器技术可以在整个使用寿命期间对生产和运行中的铝铸造组件进行监控。在铸造过程中原位采集的传感器数据的可用性允许进一步开发描述铸造过程的现有模型。这些模型将使人们能够更好地理解铸造过程及其通过开环控制进行的优化。除此之外，还可以使用组件集成的传感器技术在早期检测铸造过程中与设定值的偏差，并在质量保证的背景下评估组件可能的功能缺陷，并为下一次铸造提供合适的建议。对于服务监控，内置应变传感器可检测部件在运行期间的应力历史，并可检测关键的危险应力条件。这可以用于提高操作安全性，例如在误用负载情况之后。与光纤复合材料中的相应概念类似，基于光纤布拉格光栅（FBG）的光纤传感器网络被认为是一种组件集成的传感器技术。光纤传感器由此在铸造过程中与部件一起铸造。使用高温稳定和漂移减少的FBG允许在高温下的固化过程中的应变发展的调查。其基础是高温下FBG的应变灵敏度和其他传感器特性的实验测定。本课题是本研究项目中首次提出的。在高温下确定的传感器参数用于开发FE传感器模型。采用该模型，铝的未受干扰的应变状态和铝中可能的残余应力将从传感器数据推导出。应使用中子源海因茨迈尔-莱布尼茨的中子衍射参考测量值验证铸造过程中确定的基于FBG的应变值。此外，传感器方法的应用，检测残余应力在一个真实的复合材料铸造组件将在拟议的项目。

A component-integrated sensor technology can enable the monitoring of aluminum casting components in production as well as in operation during their entire service life. The availability of sensor data acquired in situ during the casting process allows existing models describing the casting process to be further developed. These models will enable a better understanding of casting processes and their optimization by means of open loop control. In addition to that, deviations from set points during the casting process can be detected at an early stage using component-integrated sensor technology, and possible functional impairments of the component can be evaluated in the context of quality assurance, and suitable recommendations for the next casting can be given. For service monitoring, the cast-in strain sensors detect the stress history of the component during operation and may detect critical, hazardous stress conditions. This can be used to improve the operational safety, for example after misuse load cases. Similar to corresponding concepts employed in fiber composites, fiber optic sensor networks based on fiber Bragg gratings (FBGs) are considered here as a component-integrated sensor technology. The fiber-optic sensors are thereby cast-in together with the component during the casting process. The use of high-temperature stable and drift-reduced FBGs allows the investigation of the strain development during the solidification process at high temperatures. The basis for this is the experimental determination of the strain sensitivity and other sensor characteristics of FBGs at high temperatures. This topic is addressed for the first time in this research project. The sensor parameters determined at high temperatures are used to develop an FE sensor model. Employing this model, the undisturbed strain state of the aluminum and possibly residual stresses in the aluminum will be deduced from the sensor data. The FBG-based strain values determined during the casting process shall be verified with neutron diffractometric reference measurements in the neutron source Heinz Maier-Leibnitz. In addition, the application of the sensor method for the detection of residual stresses in a real composite casting component will be demonstrated in the proposed project.