Abstract: The paper deals with the strength and the yield (failure) ofmaterials in generalized Mohr space and finds out the transformations offailure criterions represented in the principal stress space and in thegeneralized Mohr space. A universal compatibility relations for the failurestress and the failure plane, which is independent of the failurecriterions, is also discovered. For double shearing strength theory, owingto its representation in the generalized Mohr space, the theory isconsidered the equivalent of the maximal deviator stress.