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Time‐dependent behavior of nylon‐6 under uniaxial and biaxial loadings at constant rate
Author(s) -
Mittal R. K.,
Singh I. P.
Publication year - 1986
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760260410
Subject(s) - materials science , torsion (gastropod) , viscoelasticity , power law , creep , strain rate , piecewise , composite material , exponent , nylon 66 , constant (computer programming) , uniaxial tension , mechanics , mathematical analysis , mathematics , polyamide , physics , computer science , ultimate tensile strength , medicine , linguistics , statistics , philosophy , surgery , programming language
The large deformation behavior of nylon‐6 when subjected to constant loading rate tests has been investigated experimentally. Three types of loadings—tension, torsion, and combined tension‐torsion—have been used and the strain histories for each type analyzed. It is shown that a piecewise power law in time can adequately describe the strain histories up to equivalent strains as high as 30 percent for all cases. This piecewise power law shows well‐defined transitions from one mode to the other while each mode is characterized by a power law exponent valid for all types of loading. On the basis of experimental results, it is also possible to establish the functional form of various kernels involved in the Green‐Rivlin representation of the non‐linear viscoelastic behavior of nylon‐6. This method of finding kernels is much simpler than the conventional method of carrying out a large number of multi‐step creep tests. A comparison is also made between the results of the present work and the well‐known Findley equation, particularly with respect to the instantaneous strain response of materials.