AN EXPERIMENTAL AND THEORETICAL INVESTIGATION OF THE RESPONSE OF BS11STEEL TO CYCLIC LOADING

This paper contains a detailed experimental investigation of the cycli c properties of a standard high-carbon pearlitic rail steel (BS11) sub jected to complex uniaxial cyclic loading. The experiments were design ed to be either load- or strain-controlled. It is found that the mater ial response strongly depends on the mean value of stress or plastic s train as well as its amplitude. In a strain-controlled process, the me an stress does not reduce to zero but to a value corresponding to the plastic mean strain assuming the amplitude is kept constant. The speci men ratchets in the direction of mean stress but the cyclic ratcheting rate greatly reduces during the cyclic process and ends at a constant value. There is no sign that the ratcheting would stop, which is a ne w observed feature different from Bower's observation. The constitutiv e description proposed by the authors is found to give a good correlat ion to the experimental observation.