Printed Strain Sensor

In this paper, information is provided on a printed strain sensor that enables insitustrain measurements in an elastic fixture used for 3D molding of carbon fiber mats. The research is taking place as part of the DIREKT project (Digital Reconfigurable Manufacturing of Fiber Composite Components in an Elastic Production Environment) funded by the German Federal Ministry of Education and Research (BMBF).

The aim of DIREKT is to develop a reconfigurable, self-monitoring and sensor-supported production environment for components made of high-performance fiber composites. The basis is formed by low-consumption lay-up processes for carbon fiber-based semi-finished products as well as shape-adaptive tools that make the time-consuming and cost-intensive production of component-specific molding tools superfluous. Various sensors are integrated into the production environment at the Institute of Aircraft Design (IFB) in Stuttgart to continuously monitor the process.

The sensor presented here, which was developed by the HdM, is a single use (it will most likely be destroyed during the forming process), extremely low-cost strain sensor that can detect strains of up to 100 %. The sensor is screen printed on a TPU substrate and uses stretchable conductive silver tracks. A four-point resistance measurement is used to improve the measurement accuracy.