RHEOLOGY

PHENOMENOLOGICAL ASPECTS ARE DISCUSSED OF RHEOLOGY DEFINED AS THE STUDY OF THE PROPERTIES OF MATTER THAT DETERMINE ITS RESPONSE TO MECHANICAL FORCE. THE CONCEPTS OF LINEAR VISCOELASTIC BEHAVIOR WERE DEVELOPED IN THE PERIOD 1947 TO 1952. IT WAS DEMONSTRATED THAT, FOR MANY MATERIALS WITHIN REASONABLE RANGES OF DEFORMATIONS AND DEFORMATION RATES, INADEQUATE DESCRIPTION OF MECHANICAL PROPERTIES CONSISTED OF THE SPECIFICATION OF TWO FUNCTIONS (OF EITHER TIME OR FREQUENCY) THAT ARE EXACTLY ANALOGOUS TO THE SHEAR AND BULK MODULI OF CLASSICAL ELASTICITY. THE FOLLOWING RELATIONS BETWEEN THE VARIOUS REPRESENTATIONS OF THESE FUNCTIONS THAT CAN BE MEASURED DIRECTLY AND OBTAINED FROM THE LAPLACE TRANSFORM ARE: (1) THE CREEP FUNCTION, THE RESPONSE TO A CONSTANT FORCE, (2) THE STRESS RELAXATION FUNCTION, (3) THE RESPONSE TO A CONSTANT DEFORMATION, AND (4) THE DYNAMIC MODULUS OR COMPLIANCE, THE RESPONSE TO A SINUSOIDAL FORCE OR DEFORMATION. IT WAS DEMONSTRATED THAT THE INFLUENCE OF TEMPERATURE ON THESE VISCOELASTIC FUNCTIONS COULD BE EXPRESSED QUITE ACCURATELY IN TERMS OF ITS EFFECT ON (STEADY-FLOW) VISCOSITY. A NONLINEAR THEORY MUST BE BASED ON A THREE-DIMENSIONAL DESCRIPTION OF MATERIALS, RATHER THAN THE ESSENTIALLY ONE-DIMENSIONAL LINEAR FORMULATION IN TERMS OF SHEAR AND BULK MODULI. FORMULATIONS NOW AVAILABLE ARE LIMITED IN TWO WAYS: THEY ASSUME THAT ONLY THE FIRST GRADIENT OF DEFORMATION NEED BE CONSIDERED, AND ALL THEORIES DEVELOPED TO THE POINT PERMITTING EXPERIMENTAL EVALUATION ASSUME INCOMPRESSIBILITY. EXPERIMENTS SUGGESTING A BETTER DESCRIPTION ARE BEING INITIATED.

• Supplemental Notes:
  • Vol 21, No 5, PP 52-53
• Authors:
  • Marvin, R S
• Publication Date: 1968-5

Media Info

• Serial:
  • Physics Today

Subject/Index Terms

• TRT Terms: Bulk modulus; Creep; Deformation; Dynamic modulus of elasticity; Elasticity (Mechanics); Force; Laplace transforms; Materials; Mechanical properties; Mechanical relaxation; Rheology; Shear strength; Theory; Viscoelasticity
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00216401
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 8 1994 12:00AM