NOTCHED TENSILE CREEP TESTING OF CERAMICS

The use of axisymmetric tensile creep specimens containing semicircula r notches is shown to provide important data which complement results of the common smooth tensile creep test. The notch provides a stress a nd strain concentration which can represent the non-uniform state of a ctual components in service. Finite element analysis confirms that the initial concentration of stress redistributes during creep to yield a more uniformly loaded cross-section. Additionally, it is shown that t he stress follows a highly non-proportional loading path during creep. The first experiments of notched tensile creep of a ceramic (silicon nitride) are examined in the light of finite element simulations of th e transient deformation. The implications of notched tensile creep are discussed as an important test for the evaluation of constitutive mod els.