On the preservation of the mechanical integrity of fiber reinforced composites with integrated functions

One main issue when adding extra functionalities to fiber reinforced composites is to preserve their mechanical integrity. A promising attempt with large degrees of freedom in terms of design of the integrated function displays the integration of printed structures. Examples shown here include wireless readable deformation elements, piezo sensors and heating structures. We can show that composite processing via vacuum infusion is possible without any larger adaptations in processing and that the resulting composites withstand comparable loads to the non-functionalized composites independently of the layer of integration into the composite. In contrast, integrated polymer layers of comparable size significantly decrease the apparent interfacial shear strength. The preservation of the mechanical integrity in the case of printed functionalization can be explained by good chemical compatibility of the matrix resin and the functional material (epoxy filled with metal particles). Hence, the results present a promising attempt for function-integrated composites for structural health monitoring and beyond.