Accession Number : AD0609336

Title :   EVALUATION OF THE TENSILE STRESS RELAXATION TEST,

Corporate Author : ALLEGANY BALLISTICS LAB HERCULES POWDER CO CUMBERLAND MD

Personal Author(s) : THACHER,J. H.

Report Date : SEP 1964

Pagination or Media Count : 12

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)

Descriptors :   (*TEST METHODS, TENSILE PROPERTIES), (*TENSILE PROPERTIES, TEST METHODS), MATERIALS, VISCOELASTICITY, MECHANICAL PROPERTIES, RELAXATION TIME, THERMAL STRESSES, THERMAL CONDUCTIVITY, STRESSES, EQUATIONS

Distribution Statement : APPROVED FOR PUBLIC RELEASE