Evaluation and discussion of material strength of flat bar in TETRIX for design and manufacture of demonstration equipment for automatic control theory

In this paper, we focus on the strength of a flat bar made of the aluminum alloy in expansion kit TETRIX of LEGO MindStorms, in order to design and manufacture a demonstration equipment for an automatic control theory. The tensile and bending tests were carried out to investigate the mechanical properties of the flat bar. And, the strength design of the demonstration equipment was discussed when the flat bar is subjected to compression in long axis direction, and to combined load of bending and torsion. 0 2% proof stress and Young's modulus of flat bar obtained by tensile test were 174[MPa] and 76[GPa], respectively. Two 0.2% proof stresses obtained by bending tests were depend on bending direction (203[MPa] and 340[MPa]). The critical buckling load and the yield criterion of the flat bar subject to the combined load of bending and torsion were discussed based on the actual mechanical properties.