Eventos Anais de eventos
CONEM 2018
X Congresso Nacional de Engenharia Mecânica
Caracterização térmica e mecânica de uma célula auxética 2D obtida por micro-soldagem TIG de fios de LMF Ni-Ti
Submission Author:
Pedro Luiz Lima dos Santos , PE
Co-Authors:
Pedro Luiz Lima dos Santos, Paulo César Sales da Silva, Carlos Jose de Araujo
Presenter: Paulo César Sales da Silva
doi://10.26678/ABCM.CONEM2018.CON18-0921
Abstract
The mechanical behavior of architected structures can be tailored by changing the morphology of their unit cells. Auxetic materials are a novel type of material that exhibits a counter-intuitive behavior; due to their negative Poisson's ratio (NPR), they expand laterally when stretched longitudinally and vice-versa. This study assesses the thermal and mechanical behavior of a 2D planar auxetic unit cell manufactured by means of TIG micro welding of Ni-Ti shape memory alloys (SMA) wires. Transformation temperatures of the wire and the cell were evaluated using differential scanning calorimeter (DSC) and electrical resistance as a function of temperature (RET) tests, respectively. Its mechanical behavior was studied through tensile tests and video extensometry. A thermal hysteresis of the order of 10º C between the cooling and heating peaks was found, which indicates the presence of the austenite to R-phase transformation upon cooling. Furthermore, there was a small deviation on temperatures found on DSC and RET, hence showing the minor role that micro welding plays on changing transformation temperatures of the alloy, since welded joint dimensions are negligible compared to the size of the cell. A maximum deformation of 52% prior failure was observed, besides modification Poisson's ratio of the cell, which increased from - 0,09 to 0,04 corroborating the fact that auxeticity also relies on the magnitude of deformation of the cell.
Keywords
Auxetic Materials, Shape memory alloys (SMA), Micro welding, TIG
