Composite Structures, Volume 98, April 2013, Pages 153-159.
Sha Yin, Linzhi Wu, Steven Nutt.
Center for Composite Materials, Harbin Institute of Technology, Harbin 150001, China and
Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-0241, USA.
Hierarchical composite pyramidal lattice (CPL) cores with foam-core sandwich struts were designed, and two stacking patterns were fabricated and tested in out-of-plane compression. Analytical expressions for five possible failure modes were derived considering not only stretching and bending deformation but also shear deformation of struts. Core shear failure was absent from collapse mechanism maps for both Patterns-I and II CPL cores. Optimized Pattern-I hierarchical CPL cores were more efficient than Pattern-II cores. The following comparison with almost all competing composite sandwich cores revealed that the hierarchical CPL structures here, the assembly of both stretch- and bend-dominated constructions, could perform among the most efficient sandwich cores. Meanwhile, the construction concept can also enable multifunctionality by judicious selection of strut core materials without compromising structural efficiency.
In this work, bend-dominated foams are incorporated into highly efficient lattice construction. The stretch-bend-hybrid hierarchical structures, with designing parameters at two different length scales, can greatly increase performance of conventional lattice structures at relatively low densities. Also, the simple and cost-effective fabrication approach will enable those structures to be more popular for engineering application.
Structural efficiency of stretch-bend-hybrid hierarchical CPL cores compared with other competing constructions. Note that the sketches inside the figure represent different cross-sections of lattice trusses.