On the Use of Power Laws in Stress Analysis Beyond the Elastic Range

In a recent paper A. A. Ilyushin drew attention to the remarkable simplicity which the theory of plastic deformation assumes when the secant shear modulus is taken as a power of the octahedral shearing stress. In the present paper Ilyushin’s results are discussed in connection with a specific example and it is shown that great caution is indicated in the use of such power laws.