Topologically Optimized Graded Foams

The adoption of Nature‐inspired strategies to improve materials has fostered the introduction of cavities. But how to mass‐produce structures in which a complex architecture of cavities is point‐to‐point fine‐tuned to the local and global application requirements? To this aim, the use of a procedure based on topology optimization and gas foaming is herein reported. As an example case, a polymeric foamed beam whose density map is optimized in 3D for three‐point bending is designed and produced by gas foaming a purpose‐designed preform. The preform is produced with polypropylene and by a high pressure autoclave with CO₂ as blowing agent. Optical and scanning electron microscopy as well as X‐ray microscopy are used to analyze the 3D optimized foamed structures and show the effectiveness of the foaming design protocol in producing the finite element method‐optimized structures. A remarkable twofold increase in the stiffness of the optimized structures is measured with respect to that of the uniformly foamed counterpart with equal overall mass. With the use of a single recyclable material in a single processing step, this method allows one to conceive the mass production of optimized, therefore more sustainable, plastic parts.