Abbas Niknejad - Mechanical Engineering Department, Yasouj University, P.O. Box: ۷۵۹۱۴-۳۵۳, Yasouj, Iran
Seyed Ahmad Taghizadeh - Mechanical Engineering Department, Yasouj University, P.O. Box: ۷۵۹۱۴-۳۵۳, Yasouj, Iran

In this paper, natural sandwich panels containing two flat balsa woods as faces and some cup-like structuresprepared from oak tree as the core are investigated, experimentally. The core is produced by routinely placing some cup-like structures called cupule in which the oak acorn is fixed. These structures are stuck to the faces by adhesiveglue. Four groups of cupules with different heights and diameters are prepared and three different arrangements of cupules include four, nine and sixteen numbers of cupules are selected. The specimens are compressed quasi-staticallyin the out of plane direction. Specific absorbed energy of specimens are calculated and compared to find the best cupules geometry and arrangement and finally to choose an optimized natural energy absorber structures. Resultsshow that the natural oak cupules can be used as sandwich core instead of other expensive and environmentally harmful cores such as foams, with a reasonable energy absorbing capacity.

sandwich panel, oak tree, cup-like structures, energy absorption