Critical Analysis of the Theory of the Double Cantilever Method of Measuring Fracture‐Surface Energies

This paper presents a critical discussion of the double cantilever method of measuring fracture‐surface energies. It was found that the equation developed by Gillis and Gilman is valid for crack lengths greater than 1.5 times the crack arm height. The constants in this equation were evaluated and were found to be practically independent of the elastic constants of the material for which they were evaluated, suggesting that the equation could be used on any material. The Gilman and Gillis approach to the double cantilever problem was found to be consistent with the approach used by Gross and Srawley.