A non-linear model of screen panel for dynamics analysis of a flip-flow vibrating screen

By taking advantage of periodic high-frequency flexure deformation of screen panels, flip-flow vibrating screens (FFVSs) can achieve outstanding sieving performance. As the amplitude of the relative displacement between the main frame and the floating frame of a FFVS exceeds the relaxing length of screen panel, the tensile stress generated from the deformation of screen panel can considerably affect the dynamics and the screening per-formance of the FFVS. However, there is a research gap in understanding the mechanical properties (especially the stiffness and damping) of screen panels. To address this research issue, the dynamic tests are first conducted to investigate the dynamic behavior of screen panels under harmonic excitations. Then the Kelvin-Voigt (KV) model is adopted to represent the hysteresis feature of the tension force. Furthermore, to characterize the me-chanical properties of the screen panels under different stretching lengths, a nonlinear mechanical model is introduced and incorporated into the dynamic model of the FFVS. The effects of the stiffness, damping and relaxing length of screen panel, the shear springs and the eccentric mass moment on the vibration characteristics of the FFVS are numerically studied using a genetic algorithm and Newmark-beta algorithm. The obtained results show that the panel tension force can induce the hardening nonlinearity in the relative displacement response of FFVS and the soft type of nonlinearity in the displacement response of the main screen frame in a certain fre-quency region. Furthermore, at the second-order resonance peak, a small change in frequency can cause a substantial increase in the vibration amplitude of the main frame and a significant decrease in the relative amplitude. This nonlinear phenomenon would induce a large alternating stress on the main frame structure and thus reduce the service life of the FFVS.