Fabricating Multifunctional Composites via Transfer of Printed Electronics Using Additively Manufactured Sacrificial Tooling

Multifunctional composites have gained significant interest as they enable the integration of sensing and communication capabilities into structural, lightweight composites. Researchers have explored additive manufacturing processes for creating these structures through selective patterning of electrically conductive materials onto composites. Thus far, multifunctional composite performance has been limited by the conductivity of functional materials used, and the methods of integration have resulted in compromises to both structural and functional performance. Integration methods have also imposed limitations on part geometry due to an inability to adequately deposit conductive material over concave surfaces. Proposed methods of integrating functional devices within composites have been shown to negatively affect their mechanical performance. This work presents a novel method for integrating printed electronics onto the interior surfaces of closed, complex continuous fiber composite structures via the transfer of selectively printed conductive inks from additively manufactured sacrificial tooling to the composite surface. The process is demonstrated by creating multifunctional composites via embossing printed electronics onto structural composites without negatively affecting the mechanical performance of the structure. Additionally, this process expands the ability to pattern devices onto complex surfaces and demonstrates that the transferred functionality is well integrated (adhered) with the composite surface. The process is further validated through the successful completion of two separate case studies. The first is the integration of a functioning strain gauge onto an S-glass/epoxy composite, while a second process demonstration shows a composite surface featuring a band stop filter at the X-band, otherwise known as a frequency selective surface (FSS), to show the process' suitability for high performance, aerospace grade multifunctional composites.