Characterization of Creep Curves Using Fuzzy Set Theory

A creep constitutive equation is important for estimating creep deformation for structural designs under high temperatures. We can formulate the creep constitutive equation by characterizing a large number of creep curves. The characterization of a creep curve involves dividing the creep curve into three regions : transient, steady state and accelerating creep regions. Such characterization cannot be performed manually because of the massive amount of numerical data. This paper proposes a new algorithm for the characterization of the creep curve using fuzzy set theory. We use the fuzzy set theory for determining threshold levels between each region, because those levels have high fuzziness. The new algorithm enables us to mechanically characterize the creep curve without manual computation as well as to deal with massive amount of numerical data in a short time.