Interest of cellular materials for structural applications is mainly focusing on foams and more recently on entangled materials and truss structures On the other hand, in the last decade, randomly crumpled materials as polymerized membranes, biological cells and thin paper or metallic sheets, became a subject of great interest for physicists because of their fascinating topological properties and scaling laws.

Despite this literature, it was not possible to find experimental data for a complete comparison between crumpled materials and other cellular solutions for structural applications. This is the reason why this contribution proposes a more complete characterization and analysis of the mechanical behavior of crumpled aluminum thin foils in a wide range of relative density. The results are discussed in regard to the knowledge concerning opened cell and closed cell foams and entangled metals as well. Our experiments seem to highlight that crumpled materials can present a hybrid mechanical behavior, between foams and entangled fibrous materials. They exhibit a clear plasticity and a low hysteresis as foams but no plateau beyond the yield stress. Instead, a strain hardening occurs directly after reaching the yield stress.
As this aspect is scientifically intriguing and as crumpled materials can have potential use for structural applications due the good combination between properties, density and an easy way to process.
In a second part, a new kind of composite were manufactured by densification of co-crumpled aluminium and tantalum thin foils using close die compression. It was shown by optical micrography that its microstructure is highly interlocked. The morphology was analysed quantitatively in terms of the following three parameters: the area of the foil interface per unit volume, the interface tortuosity, and a characteristic of the local orientation of the foil surface. Based on these parameters, co-crumpled material studied has been compared with conventional laminates. A fractal nature of its self-similar structure was revealed.