where fcos (ωt) is the weak low-frequency excitation and Fcos (Ωt) is the high-frequency excitation, f ≪ 1 and ω ≪ Ω. The parameters a and b are positive coefficients of the linear and nonlinear terms, respectively. The paper is organized as follows. In Section 2, we will predict the potential frequency components in the response via the nonlinear frequency response theory. In Section 3, we discuss the VSubR at the frequencies ω/3 and ω/2, respectively. In Section 4, we discuss the VSupR at the frequencies 4ω/3 and 5ω/2 with some detail. Finally, the last section is devoted to some discussions and the main results of this work.