CHARACTERIZATION AND PREDICTION OF THE COMPRESSIVE STRESS-STRAIN RELATIONSHIP OF LAYERED ARRAYS OF SPONGY BAKED GOODS

The sigmoid compressive stress-strain curves of crumbs from three types of bread, pound cake, and double-layered arrays of these materials (0-70% deformation) are described by two kinds of three-parameter mathematical models. The model structures were especially selected so that they could be transformed algebraically from stress-strain to strain-stress relationships or be determined directly from the strain-stress data by nonlinear regression. The model parameters enabled calculation of a specimen's deformation-force relationship with any given dimensions. When an in-series array of objects having the same cross-sectional area is deformed uniaxially, the force along the array is the same and the deformation the sum of that of its components. Since sponge compression is not accompanied by a significant lateral expansion, the effects of friction between the layers can be neglected. This enabled the prediction of the force-deformation and stress-strain relationships of double-layered arrays with reasonable accuracy from the compression parameters of the components' material,