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Stress relaxation behavior after cyclic preloading in polypropylene
Author(s) -
Ariyama Takashi
Publication year - 1993
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.760332209
Subject(s) - viscoelasticity , materials science , polypropylene , stress relaxation , relaxation (psychology) , amplitude , stress (linguistics) , composite material , constitutive equation , tension (geology) , finite element method , structural engineering , physics , creep , engineering , optics , psychology , social psychology , linguistics , philosophy , ultimate tensile strength
The viscoelastic behavior of polypropylene before and after cyclic preloading was investigated by stress relaxation tests. The relaxation tests were performed after a simple uniaxial tension (number of cycles N = 0) and after the cyclic preloading ( N = 50) by use of a closed loop, electrohydraulic, servocontrolled testing machine. The tests were conducted under different sets of strain rate, number of cycles, and strain amplitude. The experimental data were compared with theoretical results analyzed by use of a linear viscoelastic model. The three‐element model consists of a Maxwell unit and a Hookean spring in parallel. The calculated results agree well with the experimental ones; in particular, in the relaxation tests after the cyclic preloading ( N = 50), the calculated results agree very well with the experimental ones at both the predetermined strain rates of 1,000 μ/s and 10,000 μ/s, at a strain amplitude of ±5%. It can be seen that the linear viscoelastic model explains the viscoelastic characteristics of polypropylene despite the solution of the constitutive equation constructed by the simple three‐element model.