Effects of heating rate on the stress-strain state in a heat-protective fiberglass material

Abstract

1. These experimental and analytical studies have shown that there is a marked effect on the deformation laws due to the physicochemical transformations in the material under conditions simulating real ones, particularly as regards the state of strain in a rod or cylindrical shell made of fiberglass bonded with phenolformaldehyde resin. 2. In the range where αT is linearly dependent on temperature (T = 20–300 °C), an increase in heating rate causes a rise in the stress gradients; in the range where the behavior of αT is nonlinear (300–1000 °C), the relationship for the thermal stresses is the converse. For example, an increase in heating rate shifts the zone of maximum thermal stresses in a cylindrical shell under realistic conditions by more than 35% towards the heating surface; the maximum thermal stresses are then more than halved. 3. The stresses in a rod working under one-sided heating and subject to a load providing a constant shape increase by 15–30% at high heating rates (100 deg/min) and almost by a factor three at low rates (25 deg/min).