L. Halász and O.C. Vorster
Technikon Pretoria, P.O. Box X680, Pretoria,
Republic of South Africa
The
cooling process used during the extrusion coating of cables causes a complex
temperature distribution in the polymer layer. A stress field is formed due to
temperature inhomogeneity in the polymer layer. A cooling and stress
distribution model has been developed and investigated. The material parameters
(heat conduction coefficient, specific heat, density and heat expansion
coefficient) depend on the temperature, while the shear modulus depends on both
the temperature and loading time. In the model a regression equation was used
to describe material parameters. Air and water-cooling methods were
investigated. The cooling rate has a significant effect on the radial stresses
formed in the polymer layer during cooling.