کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1468014 | 990127 | 2006 | 12 صفحه PDF | دانلود رایگان |
Compressive behavior of phenol–formaldehyde impregnated paper composites is studied in creep and strain recovery tests observing large nonlinear viscoelastic strains and irreversible strains, describing the latter as viscoplasticity. Stiffness reduction was not observed in experiments and therefore is not included in the material model. Schapery's nonlinear viscoelastic and nonlinear viscoplastic constitutive law is used as a material model and the stress dependent non-linearity functions are determined. First, the time and stress dependence of viscoplastic strains is described by Zapas et al. model and identified measuring the irreversible strains after creep tests of different length at the same stress and doing the same for creep tests of a fixed length but at different stress. Then, the determination of nonlinear viscoelastic stress dependent parameters is performed.
Journal: Composites Part A: Applied Science and Manufacturing - Volume 37, Issue 2, February 2006, Pages 344–355