Fig. 5a shows the model predicted σ n as a function of the elapsed time/cycle. The maximumσ n in each cycle is the sum of the relaxedσ n in pre-compression and the increment ofσ n induced by the load reversal. The maximumσ n starts from a value of 761 MPa in the 1st cycle, and then decreases cycle by cycle. After 40 cycles, the maximumσ n reaches its steady state with a value of 310 MPa, as highlighted by the hatched region in Fig. 5a. The evolution ofσ n during the 1st cycle is shown in Fig. 5b, where the magnitude change due to the load reversal from compression to tension appears to be the same as that from tension to compression. In addition, the inset shows that the magnitude of relaxedσ n in tensile hold (54 MPa) is larger than that in compressive hold (11 MPa). This stress difference is caused by the longer tensile hold time t t than the compressive time t c. Thus, the net σ nchange during the non-saturation cycle is negative (e.g. -42 MPa in the 1st cycle), leading to gradually decreased maximum value ofσ n (Fig. 5a).