CONSIDERATIONS OF TRANSLATED STRESS DEVIATORS IN DESCRIBING YIELD SURFACES

Experiments have shown that initial yield surfaces reveal secondary effects. Subsequent yield surfaces are translated, rotated, or distorted, and the nature and extent of these effects are dependent on factors like prestrain, definition of yield point, and the manner in which (from partial or total unloading) a yield surface is determined. To be able to consider these effects, a function of second and third invariants of translated stress deviators is presented and its parameters are determined for variously obtained yield surfaces available in literature. The nature and extent of the variation of the parameters encountered in the formulation with the variation in prestrain is discussed.