| A.R. Arutyunyan, |
|
Experimental creep curves and long-term strength curves for viscoelastic
compressible materials have been obtained at room temperature for a wide range of stresses.
The residual density change (loosening) of the material is considered as the main damage
factor. A modified creep equation for the loosening medium is proposed, which can describe
the second and third regions of the creep curve. Based on proposed equation the criterion of
long-term strength is formulated. It is shown that in the region of relatively high stresses and
under the assumption of incompressibility of the material, this criterion coincides with the
known Hoff law of viscous fracture.
Keywords: polymer materials, poly methyl methacrylate, pores, cracks, crazing, loosening, damage, creep, density changes, creep curve, fracture, long-term strength criterion |
full paper (pdf, 800 Kb)