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Lateral strain effects during the large extension of thermoplastics
Author(s) -
Stokes Vijay K.,
Nied Herman F.
Publication year - 1988
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.760281902
Subject(s) - materials science , polycarbonate , polyetherimide , lateral strain , composite material , auxetics , strain (injury) , poisson's ratio , plane stress , polymer , poisson distribution , structural engineering , finite element method , anatomy , medicine , statistics , engineering , mathematics
A noncontacting experimental procedure is used for characterizing lateral strain effects during the large‐strain uniaxial stretching of flat sheet‐like specimens of polycarbonate, polyetherimide, and poly(butylene terephthalate), both at room and elevated temperatures. It is shown that the in‐plane lateral stretch, λ 2 , is related to the longitudinal stretch, λ 1 , through the relation λ 2 = λ 1 −n . Depending on the temperature, the “Poisson's ratio” for incremental strains, n , is shown to lie between n = 0.4 and n = 0.5. While the lateral stretch in the thickness direction, λ 3 , is smaller than λ 2 at room temperature, it is shown that λ 3 = λ 2 at higher temperatures. Stretch data have been used to infer the volumetric strains in these materials.