LAUSR

Bilinear delamination failure criteria proposed by Reeder for mixed-mode (I–II) fracture of composite laminates has four limitations: require mixed-mode (I–II) fracture data by the more complex MMB test; determination of bilinear constants by two independent curve fits; failure of bilinear equations to intersect at $$\hbox {G}_{\mathrm{I}}^{\mathrm{m}}/\hbox {G}_{\mathrm{II}}^{\mathrm{m}}=1$$ G I m / G II m = 1 ; and the data representation by $$\hbox {G}_{\mathrm{I}}^{\mathrm{m}}$$ G I m versus $$\hbox {G}_{\mathrm{II}}^{\mathrm{m}}$$ G II m instead of the conventional $$\hbox {G}_{\mathrm{c}}^{\mathrm{m}}$$ G c m versus $$\hbox {G}_{\mathrm{II}}^{\mathrm{m}}/\hbox {G}_{\mathrm{T}}$$ G II m / G T . Some of these limitations were overcome by limited input bilinear criteria (LIBC) proposed by Davidson and Zhao by replacing the MMB test data by DCB, ENF, and SLB (single leg beam) test data. But the LIBC retained the two discontinuous forms of the equations for no specific reason in a continuous material system. This paper eliminates the two equations by a single power law equation that covers the whole domain of fracture as in Benzeggagh and Kenane’s empirical equation. This simplified mixed-mode delamination fracture criterion we call “Limited Input B–K (LIBK) criterion in recognition of the works of Davidson and Zhao, and Benzeggagh and Kenane. The criterion was validated by a large number of test data in the literature.