Comparative study of viscoelastic properties using virgin yogurt
| Autor: | Don Nelson, Sam Weaver, John R. Baumgardner, Robert Gore, Elane Flower-Maudlin, Manjit S. Sahota, Guy Dimonte, Marilyn Schneider |
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| Rok vydání: | 1998 |
| Předmět: |
Yield (engineering)
Materials science Mechanical Engineering Rheometer Young's modulus Condensed Matter Physics Viscoelasticity Physics::Fluid Dynamics Shear modulus symbols.namesake Rheology Mechanics of Materials Ultimate tensile strength symbols Shear stress General Materials Science Composite material |
| Zdroj: | Journal of Rheology. 42:727-742 |
| ISSN: | 1520-8516 0148-6055 |
| DOI: | 10.1122/1.550915 |
| Popis: | We describe six different tests used to obtain a consistent set of viscoelastic properties for yogurt. Prior to yield, the shear modulus μ and viscosity η are measured nondestructively using the speed and damping of elastic waves. Although new to foodstuffs, this technique has been applied to diverse materials from metals to the earth’s crust. The resultant shear modulus agrees with μ∼E/3 for incompressible materials, where the Young’s modulus E is obtained from a stress–strain curve in compression. The tensile yield stress τo is measured in compression and tension, with good agreement. The conventional vane and cone/plate rheometers measured a shear stress yield τos∼τo/3, as expected theoretically, but the inferred “apparent” viscosity from the cone/plate rheometer is much larger than the wave measurement due to the finite yield (τos≠0). Finally, we inverted an open container of yogurt for 106 s≫η/μ and observed no motion. This demonstrates unequivocally that yogurt possesses a finite yield stress rather... |
| Databáze: | OpenAIRE |
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