14th World Congress on Computational Mechanics (WCCM) ECCOMAS Congress 2020) 19–24 July 2020, Paris, France F. Chinesta, R. Abgrall, O. Allix and M. Kaliske (Eds) COMPUTATIONAL MODELING OF THE EXPERIMENTAL RESPONSE OF MICROSCALE BISTABLE TENSEGRITY STRUCTURES ZACHARIAS VANGELATOS 1 , ANDREA MICHELETTI 2 , NARINDER SINGH 3 , COSTAS P. GRIGOROPOULOS 1 AND FERNANDO FRATERNALI 3 1 Department of Mechanical Engineering University of California, Berkeley, CA, USA zacharias vangelatos@berkeley.edu, cgrigoro@berkeley.edu 2 Department of Civil and Computer Science Engineering University of Rome Tor Vergata, Italy micheletti@ing.uniroma2.it 3 Department of Civil Engineering University of Salerno, Italy snarinder@unisa.it, f.fraternali@unisa.it Key words: Architected Metamaterials, Tensegrity Systems, Bistability, Multiphoton Lithography, In- dentation testing Abstract. We report about the analysis, design, and experimental testing of modular structures com- posed of bistable units derived from the classic triangular tensegrity prism. Tensegrity structures are pin- connected frameworks, composed by bars and cables, possessing internal mechanisms and self-stress states, and featuring a variety of structural responses depending on their prestress, edge connectivity, and geometry. When a tensegrity system has only one internal mechanism and one self-stress state, as in the triangular prism case, it is possible to associate to it a corresponding bistable unit, by replacing all cables with bars and changing their edge-lengths slightly. After presenting experimental results of compression tests carried out on microscale specimens fabricated through multiphoton lithography, we compare them with the numerical predictions obtained by our computational model. 1 INTRODUCTION In recent times, architected metamaterials, structural systems whose physical behavior depends on the way they are designed rather than from the bulk properties of the constituent material, are attracting more and more attention from the scientific community. In particular, metamaterials are designed so as to obtain extraordinary mechanical properties, such as exceptional strength-to-weight and stiffness-to- weight ratios, frequency bandgaps, negative overall elastic moduli, negative mass density, auxeticity, and solitary wave propagation [1] -[13]. Bistability is one of the difficult-to-find and most desired features in current studies on architected materials [14] - [19]. Tensegrity systems, pin-connected prestressed frameworks composed by bars and cables, constitute a particular structural class in that their response 1