The Anisotropic Yield Surface of Cellular Materials

Conway, Kaitlynn M.
Romanick, Zachary
Cook, Lea M.
Morales, Luis A.
Despeaux, Jonathan D.
Ridlehuber, Marcus L.
Fingar, Christian
Doctor, Daquan
Pataky, Garrett J.
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University of Texas at Austin

Mechanical metamaterials are often limited in engineering applications because of uncertainty in their deformation behavior. This uncertainty necessitates large factors of safety and behavior assumptions to be included in mechanical metamaterial designs, detracting from the largest benefit of metamaterials: their ultralight weight. In this study, a yield envelope was created for both a bending dominated and a stretching dominated cellular material topology to improve the understanding of the response of cellular materials under various load types and orientations. Experimental studies revealed that the shear strength of a cellular material is significantly less than that predicted by the Mohr’s criterion, necessitating a modification of the Mohr’s yield criterion for cellular materials. Both topologies experienced tension-compression anisotropy and anisotropy dependent on the topology orientation during loading with the stretching dominated topology experiencing the largest anisotropies.