Fig. 4: Quantification of entanglement in carbon fibre tows.

Measurements of the half-crack length \(a\) versus pin diameter \(d\) for tows A and B. The error bars show the range (and mean indicated by the markers) of the 70 measurements conducted for each pin diameter. For both tows we include a best linear fit to the data of the form \(a=\alpha d+\lambda\) where \(a\), \(d\) and \(\lambda\) are in millimetre and \(\alpha \equiv 0.5\sqrt{\mu t/{G}_{c}}\,\) is dimensionless.