An experimental characterization of nanocomposite strain and damage sensing in support of development of CNT-polymer nanocomposites for structural health monitoring (SHM) applications was conducted. As such, effort here is focused towards examining the piezoresistive behavior of poly(dimethyl-siloxane) (PDMS) and epoxy filled with acid treated single walled carbon nanotubes (COOH-SWNTs) under quasi-static compression and tension. Precision LCR Meter with two terminal method, in conjunction with mechanical testing and data acquisition system were used to measure instantaneous resistance values. Given the emphasis on SHM applications which correlate changes in electrical resistivity to deformation and damage, 0.1 wt% COOH-SWCNTs concentration below the nanocomposite electrical percolation threshold was considered for PDMS and epoxy. Measurements confirmed the onset of damage prior to noticeable effects in the stress-strain response. The resistance measurements were able to both detect strain for PDMS nanocomposites and damage initiation and provide continuous assessment of the damage state between damage initiation events for epoxy nanocomposites. Digital Image Correlation (DIC) System was used to observe the crack propagation on notched epoxy nanocomposite compact tension samples.

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