Behaviour of auxetic honeycomb angular stiffeners in cold formed steel upright section under buckling modes

Abstract

This work was carried out on the study of buckling instability in cold formed perforated steel upright column with and without lip. The study deals with the local, distortional and global buckling effects on the column with the inclusion of external auxetic stiffeners. The auxetic stiffener is designed based on two theories, with first order honey comb stiffener and hexa-chiral stiffener. The buckling studies of the cold formed perforated steel section were conducted on two categories as pre-buckling effects and post buckling effects. The pre- buckling studies include the effect of rotational moment and axial stiffness of the perforated column with and without lip under axial compressive load. These studies were further analysed by the inclusion of auxetic honey comb and hexachiral stiffeners. The second category deals with studies on post buckling modes under local, distortional and global buckling of cold formed perforated steel sections. newlineThe material used for the fabrication of cold formed steel was the ASTM A572. The perforations in the steel section were fabricated by using the Laser cutting process. The symmetrical web stiffened section was fabricated under sheet metal bending process with 500 KN load capacity. The process web stiffened cold formed perforated steel section with the inclusion of base plate under bolted connections was designed and fabricated for 10 combinations with variable dimensions. This was denoted from Specimen A to Specimen J. The auxetic stiffeners were designed based on two theories one with first order honeycomb model and second with the hexachiral model. This was fabricated using 3d printing with the Fused deposition modelling technique. A Thermoplastic polyurethane material was used to fabricate the auxetic stiffener. newline newline