Mathematical Modeling of Phenomenological Material Properties – Differential Operator Forms of Constitutive Equations

The paper deals with rheological models and creep and relaxation tests on matters which are represented by models. Three models based on two fundamental components (Hooke’s elastic and Newton’s viscous compounds) are performed. The models originated from several fundamental matters by their parallel or serial connections. The corresponding constitutive equations are derived. The behavior of the models under the creep and relaxation tests is observed and is expressed by corresponding stress - strain formulas and illustrated in the figures.