The paper by ZHIGANG SUO and JOHN W. HUTCHINSON addresses the analysis of a semi-infinite interface crack between two infinite isotropic elastic layers under general edge loading conditions. The problem is solved analytically, with a single real scalar independent of loading being extracted from the numerical solution for a specific loading combination. Two applications of the basic solution are discussed: interface cracking driven by residual stress in a thin film on a substrate, and an analysis of a test specimen proposed for measuring interface toughness. The mathematical formulation involves a semi-infinite crack along the negative $x_1$-axis, with the uncracked bimaterial layer considered as a composite beam. The overall equilibrium constraints reduce the number of independent load parameters to four, and the singular fields for the problem are shown to be the same as those for a simpler configuration when certain conditions are met. The paper also explores the practical implications of the solution through two sample problems, demonstrating how the stress intensity induced by residual stress can be simulated and how the proposed test specimen can be used to measure fracture toughness over a range of mixed-mode interface intensity factors.The paper by ZHIGANG SUO and JOHN W. HUTCHINSON addresses the analysis of a semi-infinite interface crack between two infinite isotropic elastic layers under general edge loading conditions. The problem is solved analytically, with a single real scalar independent of loading being extracted from the numerical solution for a specific loading combination. Two applications of the basic solution are discussed: interface cracking driven by residual stress in a thin film on a substrate, and an analysis of a test specimen proposed for measuring interface toughness. The mathematical formulation involves a semi-infinite crack along the negative $x_1$-axis, with the uncracked bimaterial layer considered as a composite beam. The overall equilibrium constraints reduce the number of independent load parameters to four, and the singular fields for the problem are shown to be the same as those for a simpler configuration when certain conditions are met. The paper also explores the practical implications of the solution through two sample problems, demonstrating how the stress intensity induced by residual stress can be simulated and how the proposed test specimen can be used to measure fracture toughness over a range of mixed-mode interface intensity factors.