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Computation of the creep behavior of thermoplastics
Author(s) -
Overath F.,
Menges G.
Publication year - 1978
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.760181211
Subject(s) - creep , dimensioning , superposition principle , exponential function , viscoelasticity , computation , materials science , logarithm , boltzmann constant , time–temperature superposition , constant (computer programming) , simple (philosophy) , deformation (meteorology) , stress (linguistics) , modulus , mechanics , computer science , mathematical analysis , composite material , algorithm , mathematics , thermodynamics , physics , engineering , programming language , aerospace engineering , linguistics , philosophy , epistemology
The dimensioning of structural parts made of plastics requires the knowledge of the material parameters which depend on the processing and, loading conditions. In this paper, the possibility of describing the stress‐, temperature‐, and time‐dependent deformation behavior of thermoplastics below the linear viscoelastic limit is presented, using simple exponential functions. The formal relationship of the systems of equations have been ascertained based on a large number of experimental results. They enable a mathematical description of the deformation behavior of the material considered with sufficient accuracy for engineering requirements. This is based on parameters for creep experiments with three different stresses, at constant temperature, extending to 10 2 h. One experimental series extended to 10 3 h. As shown in examples, based on these experimental results, the computation makes possible a predetermination of the deformations obtained with the time‐factors of 10 2 to 10 3 . The temperature can vary within the nearly linear region of the semi‐logarithmic shear modulus‐temperature curve. Within the variation of the stress, cyclic changes of the loading can also very simply be taken into account using Boltzmann's superposition principle. Principally, the computation can be carried out using any auxiliary means which contains the exponential function x y . Simple programmable pocket computers allow an automatic calculation.