Measuring mechanical properties of micro- and nano-fibers embedded in an elastic substrate: Theoretical framework and experiment

We propose to measure the elastoplastic properties of micro- and nano-fibers by a normal indentation technique in which the vertically aligned fibers are embedded in an elastic matrix. Measurements are taken at two different indentation depths, which represent different levels of the matrix effects and lead to the establishment of two independent equations that correlate the fiber/matrix properties with the indentation responses. Effective reverse analysis algorithms are proposed, and by following which the desired fiber properties can be determined from a sharp indentation test. Comprehensive analysis is also carried out to verify the effectiveness and error sensitivity of the presented method. The extracted material properties agree well with those measured from the parallel experiments on human hair and glass fibers.