Piezoresistivity in Micro Carbon Fiber Silicone Composites for Electrical Resistance to Strain Sensing

Abstract

In order to develop a cost-effective carbon fiber reinforced polymer sensor for compressive strain monitoring, a study was carried out to assess electrical and piezoelectric properties of samples containing five different carbon fiber weight percentages. Testing focused on sensing ability throughout measurement of resistivity: (1) when submitted to uniaxial variable compressive strain; (2) to time prolonged relaxation at constant strain; (3) and influence of environment temperature on measurements. Results enabled the possibility of usage for live monitoring of samples by determining sensitivity values of each sample being tested. Electrical resistance measurements assessment test results, show real time resistivity change in respect to experienced strain. Further piezoelectric properties where determined. An exponential decay function was found in fractional resistance in respect to relaxation due to constant strain testing. The total amount of time needed for measurements to present an error less than 1% at the probes was determined and found to vary up to seven days. Strain reversibility of resistivity measurements varied according weight percentages of carbon fibers used in composite sample being tested. Samples were tested in situ for monitoring of displacement on foundations of a dwelling to be built, placed on foundation’s soil. The main objective here was to assess practical questions such as handling and how measurements could be made safely. Results demonstrated successful monitoring during construction phase with easy deployment on site, sensing each construction phase loading.