Figure 13.

(a) The coordinate system and ($\mathit{m}$, $\mathit{n}$, $\mathbf{t}$) vectors used to obtain estimates of the indentation modulus in equation (4.10). The variation of calculated indentation modulus $M_r$ with average microfibril orientation $\overline{\mu }$ is shown in (b). The indentation moduli obtained from nano-indentation experiments are superposed.