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D. A. Hills et alii, Frattura ed Integrità Strutturale, 25 (2013) 27-35; DOI: 10.3221/IGF-ESIS.25.05 34 are in the range II r f g   , the process zone is implied to be as large as the slip zone in the mode I dominated region, but a second slip zone is implied to extend past the mode II dominated region. These dotted lines are included in the figure to distinguish between cases in which the slip zone in the mode I dominated region is fully enveloped by plasticity at a coefficient of friction below II r g  , which implies that for coefficients of friction greater than II r g  there will be no slip, from the cases in which the magnitude of load required to envelop the slip zone in the mode I dominated region does not appear on the plot, which implies that, for the range of load shown in the figure, the slip zone is larger than the process zone and that the contact will slip. The curves in Fig. 5 corresponding to the case 120    (shown in blue) illustrate these two distinct possibilities; when I K and II K are both positive (Left) neither dotted nor solid lines appear on the plot and the slip zone is implied to be larger than the plastic zone in the range of f and 0 G / k shown in the figure, but when I K is negative and II K is positive (Right) a dotted line appears on the plot and thus if II rθ f g  no slip is implied. Figure 5 : Plots showing the strength of load 0 / G k , above which the process zone and frictional slip zone at the edge of contact are implied to be of equal size when II r f g   (solid lines), and when II r f g   (dotted lines), for punch angles of   60 , 90 ,120      , plotted in red, black, blue, respectively. This is done for the case when both I K and II K are positive (Left) and when I K is negative and II K is positive (Right). Also shown are the values of II r g  for each punch angle (horizontal dotted lines), using the same colour scheme as for the other lines. C ONCLUSIONS his paper develops further our physical understanding of the physical implications of the asymptotic form given by Williams, allowing not only mode mixity but also the competing effects of frictional and plastic slip to be treated; the former, but not the latter, is independent of the magnitude of the load. The ‘output’ of this paper is therefore a specific answer to the question ‘When is a sharp contact corner rigorously notch-like?’ and equally ‘When is frictional slip likely to be important?’. Space limitations preclude the application of the results to real problems, which requires calibrations for I K and II K in terms of the applied loads. This last step then permits these results to be applied directly to any complete fretting (or potentially fretting) contact, by simply ‘pasting in’ this asymptotic form. A CKNOWLEDGEMENTS . C. Flicek thanks Rolls Royce plc for financial support for his studentship and David Hills thanks the Zilkha Trust for the award of a travel grant permitting these results to be presented. 60° 90° 121° g r II 60° g r II 90° g r II K I ,  K II 0.0 0.2 0.4 0.6 0.8 1.0 1.2 G 0 k 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 f 60° 90° 120° 121° g r II 60° g r II 90° g r II K I ,  K II 0.0 0.2 0.4 0.6 0.8 1.0 1.2 G 0 k 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 f T R