MonStrain

Development of a novel spatially resolved carbon fiber-based strain measurement system for real-time structural health monitoring and validation of load assumptions

Within the project MonStrain, TUD-ILK aimed to conduct further research into a new type of carbon fiber sensor for strain measurement (CF strain sensor) and its integration into an airfoil demonstrator. The measuring principle of the CF strain sensor is based on the spatially resolved determination of the resistance of a pre-damaged carbon fiber (CF) roving by electrical time domain reflectometry (ETDR). Due to the deliberate introduction of fiber breaks, the sensor achieves a very high sensitivity and a strain measurement range of up to 3 % with a spatial resolution in the single-digit millimeter range. However, the sensor length was limited to 15 cm at the beginning of the research project, which is why the project focused on scaling up to longer measuring lengths. First, the sensor properties were extended. For this purpose, a laser treatment process for CF was developed as part of a subcontract, which makes the sensitivity adjustable through targeted pre-damage. A reduction in resistance was achieved by applying a metallic coating to the CF, which enabled the development of longer CF strain sensors. An evaluation strategy based on artificial neural networks was developed to calculate the strain from the ETDR data in order to enable real-time structural monitoring. The final wing demonstrator shows the potential of the sensor technology.

Photo of an aircraft wing in the outdoor area. People stand in the background and unload something from a means of transport. — Wing demonstrator with integrated CF strain sensor after delivery.

Two photos side by side. Left: People grasp an elongated, metallic component with their gloved hands. Right: Elongated component, cables are integrated into the component. — Members of Akaflieg Dresden e.V. and the ILK integrating the CF strain sensor into the wing demonstrator (left) and scaled CF strain sensor with additional measuring point (right).

Period

01.01.2021 – 30.06.2024

Project partners

Associated partner

Akaflieg Dresden e.V.

Funding

Federal Ministry for Economic Affairs and Climate Action (BMWK): Federal Aviation Research Programme LuFo VI-1
Fundingline 'Ökoeffizientes Fliegen und disruptive Technologien'
Funding code: 20E1904