EVALUATION OF THE TENSILE STRESS RELAXATION TEST,

Abstract

The tensile stress relaxation test is widely used to measure the mechanical properties of viscoelastic materials. For certain combinations of test conditions and materials the interpretation of data from this test will be influenced by sample inertia, test apparatus elasticity, and/ or internal heat generation. Sample inertia causes longitudinal waves to be generated within the sample upon application of a prescribed end displacement. Wave propagation in viscoelastic materials is described as it relates to the tensile-stress-relaxation experiment. This behavior is contrasted with quasi-static behavior. A nonrigid test apparatus modifies the measured relaxation time of the material. At high strain rates, the testapparatus elasticity permits the existency of transmitted as well as reflected waves at the boundary between sample and test machine. The effect of internal heat generation consists of thermodynamic coupling and heat dissipation terms which alter the material response. Thermal stresses are produced and relaxation times are modified. The behavior of a thermorheologically simple material is discussed. Quantitative calculations are made for a two-parameter Maxwell material. Limitations of the theory are noted. (Author)

Document Details

Document Type
Technical Report
Publication Date
Sep 01, 1964
Accession Number
AD0609336

Entities

People

  • J. H. Thacher

Tags

DTIC Thesaurus Topics

  • Boundaries
  • Demographic Cohorts
  • Elastic Properties
  • Materials
  • Mechanical Properties
  • Relaxation Time
  • Strain Rate
  • Stresses
  • Tensile Properties
  • Tensile Stress
  • Thermal Stresses
  • Wave Propagation

Readers

  • Electromagnetic Wave Scattering and Antenna Radiation Engineering
  • Mechanical Engineering/Mechanics of Materials.