Physical modeling of dynamic phenomena in the operation of rotor excavators

Abstract

1. The results of the first model investigations of the dynamics of RE operation indicate the effectiveness and high resolving power of this new (as applied to RE) experimental technology. 2. When ϕ≥30°, with both sharp and blunt teeth, sections of negative slope are seen on the curves of Pls(vm), indicating the possibility of self-excitation of the dynamic system, and instability of horizontal motion of the working element of self-oscillatory type is reproduced in the theoretically expected conditions. 3. Depending on the setting angle of the teeth at the buckets ψ and the frequency ratio ωτ/ωfr, the self-oscillations take different forms—from low-frequency relaxational oscillations to quasiharmonic oscillations close in frequency to ωfr. With relaxational oscillations, the system loses its sensitivity to external periodic perturbation and resonance: the induced and resonant oscillations are captured by the self-oscillation. 4. When ψ=0, regardless of the other structural parameters and operating conditions, the characteristic Pls(vm) has a positive slope at all points; self-oscillations are suppressed, and induced oscillations with the frequency of the external perturbation occur in the system; their amplitude is limited as a result of the formation, in the working process, of geodynamic damping forces which intensified the damping of the oscillations. Taking account of the possibility of sharp reduction in level of the dynamic phenomena in the working process, the condition ψ=0 must be recommended as the basic condition in synthesizing a rational structure of RE working elements.