Some considerations on specimen types for small sample creep tests

Abstract

Commonly used small creep specimen types (i.e. conventional sub-size uniaxial specimens, impression creep specimens and small punch specimens) and test methods, are briefly described, including their capabilities and the methods used to process the data from these tests. The performances of these test types are compared and their relative advantages and disadvantages, for specific practical applications, are assessed. An alternative, novel, “more flexible”, small ring-type specimen test method is described. A significant advantage of the ring-type specimen is that it has a much greater equivalent gauge length (EGL), compared with those of other small specimen types. This specimen type allows small strains to be related to relatively large deformations; it is particularly suitable for creep tests at relatively low equivalent uniaxial stresses. Possible future exploitation of the small specimen test techniques is briefly addressed.