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

组件集成传感器技术可以在铝铸件的整个使用寿命内对生产和运行中的组件进行监控。在铸造过程中现场采集的传感器数据的可用性使描述铸造过程的现有模型得以进一步发展。这些模型将使人们能够更好地理解铸造过程及其开环控制的优化。此外，使用组件集成传感器技术，可以在铸造过程中的早期阶段检测到偏离设定值的情况，并可以在质量保证的背景下评估组件可能的功能损害，并为下一次铸造提供适当的建议。对于服务监控，内置应变传感器检测组件在运行过程中的应力历史，并可能检测关键的、危险的应力条件。这可用于提高操作安全性，例如在误用负载情况下。类似于光纤复合材料中的相应概念，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。因此，光纤传感器在铸造过程中与部件一起浇铸。高温稳定和漂移减小的FBG的使用使得可以研究高温下凝固过程中的应变发展。这一点的基础是对高温下FBG的应变灵敏度和其他传感器特性的实验测定。这一主题在本研究项目中是第一次涉及到。利用高温下确定的传感器参数，建立了有限元传感器模型。利用该模型，可以从传感器数据中推算出铝的原状应变状态和可能的残余应力。铸造过程中所确定的基于FBG的应变值应通过Heinz Maier-Leibnitz中子源的中子衍射仪参考测量进行验证。此外，还将演示传感器方法在实际复合材料铸件残余应力检测中的应用。

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.