Nonlinear Viscoelastic Model Containing a Yield Element for Modeling a Food Material1

A series‐parallel model is introduced in which a yield element is incorporated in the parallel branch. Before the yield stress is reached, the stress‐strain behavior is determined by the series branch to exhibit the linear uiscoelasticity of the material. When the yield stress is reached, the stress in the model which was sustained by the yield element is suddenly transferred to the spring and dashpot in parallel. As a consequence, a stress rate discontinuity was created. It is this feature which makes possible the simulation of the yield behavior of the food material. Data from Instron tests on American cheese are used to illustrate the model.