Design, fabrication, and testing of meso-scale cellular contact-aided compliant mechanisms

The design and fabrication of meso-scale cellular contactaided compliant mechanisms with micron sized features are presented in this paper. Cellular structures with internal contact mechanisms exhibit a reduction in stress during deformation and, thus, can be stretched further than they could without a contact mechanism. Fabricating such structures at a meso-scale can result in new high-strength, high-strain materials. Manufacturing at a meso-scale restrains the maximum aspect ratio and the initial contact gap of the mechanism. An analytical model is used to resolve the tradeoffs between these manufacturing constraints and to design suitable contact-aided cellular mechanisms. A lost mold rapid infiltration forming process is employed to fabricate meso-scale cellular mechanisms using either 316L stainless steel or a composite 316L stainless steel with nanoparticulate zirconia. A custom rig was developed to test meso-scale cellular mechanisms. The elastic modulus of 316L stainless steel was found to be about 110±40 GPa both from tensile testing of test bars and from model-matching of cellular mechanisms. The cellular mechanisms were observed to exhibit about 1.1% of overall strain before any local permanent deformation. This study validates the efficacy of the design and fabrication methodology for the meso-scale cellular mechanisms.