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Thermal cycling of plastics—relaxation and set in polycarbonate and polypropylene
Author(s) -
Fesko Donald G.
Publication year - 2000
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.11278
Subject(s) - materials science , polypropylene , polycarbonate , temperature cycling , composite material , stress relaxation , viscoelasticity , relaxation (psychology) , finite element method , thermal , modulus , thermal expansion , residual stress , structural engineering , thermodynamics , creep , psychology , social psychology , physics , engineering
The residual stress state or the amount of permanent set as a result of thermal cycling a plastic specimen white it is restrained can be estimated by a simple model using the thermal expansion coefficient, modulus vs. temperature data, stress relaxation data and knowing the time spent at elevated temperature. This offers the opportunity to model the end result of thermal cycling of plastic components by finite element analysis (FEA) without resorting to a viscoelastic FEA. The method combines the developed thermal strain with the relaxation taking place at the elevated temperature for the elapsed time and assumes the set is frozen in on cooling. Experimental data for polycarbonate and polypropylene show the method to be a good approximation. Data also show that it works for multiple cycles by simply treating the accumulated time at elevated temperature.