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Design of Multifunctional Films

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Technical Report,15 Sep 2018,14 Mar 2019

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University of Illinois Urbana United States

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In this reporting period, the use of a compliant interphase to reduce strain transfer from a composite laminate substrate to a fully bonded photovoltaic PV film was investigated. Research conducted in a prior AFOSR-sponsored project FA9550-12-1-0209 had shown that a thin film photovoltaic undergoes fragmentation and loss of its energy harvesting performance when the tensile strain in the underlying composite exceeds 0.8. In this study, a detailed analytical model was adopted from literature to determine the required thickness and elastic modulus of an interface material that would provide strain attenuation between a unidirectional carbon fiber composite laminate and a commercial PV film. For the given properties of the composite laminate and the PV films at hand, the model pointed to the need for a very compliant layer with tens of microns in thickness and modulus of the order of 0.1 MPa. These conditions could not be met by the nanospring films developed in earlier stages of this project, which are more appropriate for strain management in microelectronics devices. Instead, we employed a compliant PDMS interphase whose effective stiffness was controlled via its elastic modulus and thickness. It was shown that such an interphase guaranteed perfect bonding of the PV film onto the composite laminate while fully attenuating the strain applied from the composite to the PV film and also maintaining the original energy harvesting performance of the PV film until tensile failure of the composite

Subject Categories:

  • Laminates and Composite Materials
  • Mechanics
  • Electrical and Electronic Equipment

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