Adhesiveless honeycomb sandwich structures of prepreg carbon fiber composites for primary structural applications

This study presents a comparative study of adhesiveless honeycomb sandwich structures of carbon fiber prepreg composites while assessing the structure with an adhesive film at the skin-to-core interface. Laminate and honeycomb sandwich panels were fabricated and tested with consistent layup, curing, and testing processes. Adhesive sandwich panels were produced using the CYCOM 977-2 prepreg system, while adhesiveless sandwich panels were constructed with the MTM45-1 prepreg system. Laminate panels were also fabricated using the two different prepregs. Specimens from the panels were tested for physical and mechanical properties as well as moisture-absorption performance. Test results obtained from non-destructive testing and experimental work confirmed that physical properties of the self-adhesive prepreg mainly met the component and void-content recommendations for use in primary structures. Mechanical tests were performed at room (24 degrees C), hot (82 degrees C), and cold (-55 degrees C) temperatures, as well as under dry (low moisture) and wet (852% humidity) conditions. In all environments tested, the adhesiveless sandwich panel with MTM45-1 exhibited a 14-16% higher tensile strength than the sandwich panel with 977-2 prepreg and AF191 adhesive film, testifying to the stronger bond at the skin-to-core interface. The short-beam shear strengths of the dry laminates above 58 MPa were also suitable indicators of polymeric composite materials for primary structural purposes in aircraft. The average short-beam shear strength of the 977-2 laminate was 28% higher than that of the MTM45-1 laminate, hence displaying a tougher and stronger epoxy resin. These experiments suggest that an aramid honeycomb sandwich structure with a self-adhesive carbon prepreg system compared to a similar structure using additional adhesive demonstrates the ability of these configurations for use as primary structures in aircraft. This study also confirms using adhesiveless composite panels for different industrial applications (e.g., wind turbine, automotive, ship, defense, and space).Adhesiveless honeycomb sandwich structures with prepreg while assessing the structure with an adhesive film at the skin-to-core interface.