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The energetics of two unequal-length collinear cracks is considered in Mode I, II,III loadings. The material force, i.e., the energy change accompanying thetranslation of each crack, the expanding moment accompanying their isotropicexpansion, and the total potential energy of the system are evaluated. The analysisis performed for remote uniform load normal to the cracks plane using theconcept of the J and M path-independent integrals. The closed form exact solutionto this interaction problem is obtained as a function of cracks dimensions andtheir spacing. While both the material force and the moment tend to infinity as thedistance between the inner crack tips approaches zero, the total strain energy ofcracks converges to the limit. The material force decays rapidly to zero as the twocracks become a few lengths apart. Comparisons of the obtained results withthose for two equal cracks and with other available solutions are considered anddiscussed