(a) Surface-rendering of 7.5×7.5×7.5mm3 sub-volume of TB from Figure 2b rotated CCW by 30°. (b) Uniform spherical sampling of mean-intercept-length in image coordinate system. (c) fabric ellipsoid with axes indicating TB’s principal material directions (axes are lengthened by 20% to extend outside of ellipsoid). (d–h) Steps in estimation of orthotropic mechanical constants (E11, E22, E33, G12, G13, G23, v12, v13, v23): (d) μFE simulation to compute S (e); (f) diagonalization (see text) of S leads to So; (g) compliance matrix C calculated as inverse of So; and (h) orthotropic compliance matrix Co used in determining mechanical constants.