Effects of Temperature Fluctuation on the Creep Properties in Bending of a Linear Viscoelastic Column

Abstract

The creep properties in bending such as the lateral creep deflection versus time relations of a four-parameter model are investigated for the fluctuated temperature profile alongside the column length. The temperature fluctuation is assumed to be of asymmetric stepwise pattern, incessantly alternating around the average temperature just like an alternating current. The column considered is for simplicity, assumed to have an idealized section. The applied axial load is also assumed to be near an Euler load, and so the deflection curve has a single harmonic sine. The temperature fluctuation treated here is confined to be of small amplitude, so that the modulus of elasticity may be taken as left unchanged. The viscous term, representing the creep phenomenon, is expressed in terms of rate process to take account of temperature effects. The numerical example for polymethylmethacrylate shows a conspicuous degradation of life time even for a trifle amount of temperature fluctuation, say, about 30% reduction for only ±1.75% fluctuation. The temperature fluctuation amplitude therefore, should be exactly detected especially for such a linear viscoelastic column.