Test Methods and Performance of Structural Core Materials -1. Static Properties

The first in a series, this presentation describes the static mechanical test methods and response of structural core materials used in sandwich construction. The concept of sandwich construction is introduced wherein high strength facings are lami nated around lightweight cores. Benefits of this method of fabrication include higher strength and stiffness per unit weight compared with more traditional, homogeneous materials. A series of standardized test methods for characterizing the performance of structural cores is presented and the procedures, apparatus and relevance of each is dis cussed in detail. The core compressive, tensile, shear and flexural properties thus gener ated are necessary to the proper design of sandwich panels which may be subjected to static loading conditions. Three of the more prominent core types are compared on the basis of micro-structure and composition. These include end-grain balsa, hexagonal honeycombs constructed of aluminum or aramid fiber-paper and the polyvinyl cellular plastic cores. The results of our testing, performed on end-grain balsa core samples over a range of densities, are offered and compared with literature values of the other core materials. In subsequent presentations of this series, the time-dependent behavior and thermal response of structural cores will be addressed.