Modeling/defining Loop of blocks of different load amplitude

Dear all

In the experiment setup, the fatigue loading spectrum has a loop of 2 blocks of load amplitude. First load amplitude the higher applied for 2X time period followed by lower load amplitude for X time period then the loop repeated till failure. the load sequence was High-Low and Low-High in this loop.X was in thousands so might be suggested as the cyclic response will be stabilized in the first 10 cycles, the first block will dominate the fatigue behaviour at least till fracture, or damage initiation.

The case here is the repetition of the few load amplitude blocks, is it still variable, is there a way to analyse such a load, please

How to model such a load in damage model

如何输入这样的加载在有限元分析中,

can it be reduced to fewer cycles ( 2 H, 1 L, 2H) to include the sequence effect

or do I have to use static load, the higher amplitude, then find a way to include the sequence effect in the damage model

I saw in the literature, some just assumed it as constant amplitude with the higher, I know it looks far from acceptance

If you can guide me to some papers or article, will be appreciated