Stiff and strong yet lightweight cellular structures have become widely designed and used as cores for the construction of sandwich panels to reach high stiffness and strength to weight ratios. A low-density pyramidal cellular core has been proposed for investigation in this work. The novel core is manufactured from stainless steel sheet type 304 through a mechanical expansion procedure which is described in detail. The out-of-plane stiffness and strength performance is estimated by an analytical model which is successfully validated through experimental tests. A comparative study with other existing cellular core configurations made from other materials indicates an average performance behavior for the investigated structure. However, potential for a further structural performance increase is observed and discussed

The use of sandwich panels in industries such as aerospace, naval and automotive is extending nowadays, due to their high mechanical performances with respect to low-weight ratios. In this regard, the concept of 'lightweight structures' has been already acknowledged as the alternative solution in addressing one of the major issues when it comes to the future vehicle design and construction. This paper aims to present a novel cellular structure used as core in sandwich structures, obtained through a mechanical expansion process. A topological study is carried out, proving the competitive relative density of this new structure compared to the already existing ones.