탄소나노 지능형 복합소재의 스트레인 게이지로 이용을 위한 특성 연구

Abstract

A strain gauge is one of popular sensors since it can measure deformation and force with a simple processing data acquisition system. Since carbon materials have been studied to develop a strain sensor, this study experimentally characterized strain sensing performances of piezoresistive Carbon-Nano Composites Sensor (CNCS) and its application in the case of stress concentration on a beam to develop a novel strain gauge. The CNCS was made of multi-walled carbon nanotube (MWCNT)/epoxy composites by using nano-composite process. The sensing characteristics were experimentally evaluated with tests of linearity, zero drift, hysteresis, thermal effect, free vibration and impact. The CNCS showed fairly good strain sensing performances compared with a conventional strain gauge. This study also examined geometrical parameters of the CNCS such as width and length to design the strain gauge. The design parameters determine the strain sensitivity and that can be explained by a piezoresistive model. This study presume that the electrical conductive paths of the fillers in the matrix may dominate the piezoresistive changes and that can be designed by the parameters as well. For the application of the CNCS fabricated by brushing process, this study tested its sensing performance in the case of stepped beam which brings stress concentration to the structure. A stress concentration evaluation at the discontinuous region was conducted with experiments and ANSYS analysis. The experimental and analytical results showed wide discrepancies and that may be caused by imperfect boundary conditions due to the experimental setup.