Cork: Is It a Good Material for Aerospace Structures?

Cork is a natural material with remarkable energy absorption properties, which make it an ideal candidate material when thermal insulation or vibration suppression are major design requirements. However, little work has been done towards the use of cork based materials in structural components. This paper envisages assessing the feasibility of using cork composites with improved specific strength and damage tolerant properties for aerospace applications. A review of some results and conclusions about the mechanical behavior of cork composites will be done based on existing literature and other previous works of the authors on this subject. In particular, two types of materials were considered: 1) a sandwich structure with a cork-epoxy agglomerate core; 2) a carbon-epoxy laminate with embedded cork granulates. In both cases, a set of static and dynamic tests were carried out to characterize the mechanical behavior of the material with a special emphasis on its damage tolerant properties. These tests were replicated using a benchmark core material commonly used in aerospace applications in order to confirm the comparative benefits of cork based composites. A final part of this work seeks to evaluate the advantages of combining the natural damping characteristics of cork with high performance composites aiming at improving the aeroelastic behavior of aerospace components. In particular, the critical flutter speed of a cork based sandwich plate was compared with other conventional materials through a computational analysis. Regardless the type of application, results are encouraging about the use of cork based materials in aerospace components due to their noticeable damage tolerant and high energy absorption properties under different loading scenarios.