Fig. 1. Coupling particles model with broken friction symmetry.

Fig. 2. The average velocity of coupled particles varying with the free length l, where , , , , .

Fig. 3. The average velocity of coupled particles varying with the strength of coupling k, the insert figure described the average velocity curve when , where , , , , .

Fig. 4. The average velocity of coupled particles varying with the amplitude A of external force, where , , , , .

Fig. 5. The average velocity of coupled particles varying with the frictional damping coefficient ratio , the insert figure described the average velocity curve when , where , , , , .