Inclusion of Rotational Inertial Effects in Power Consumption Calculations for Vibratory Pile Equipment Presented at the Chattanooga Development Symposium

The paper Inclusion of Rotational Inertial Effects in Power Consumption Calculations for Vibratory Pile Equipment was presented last Tuesday at the Chattanooga Development Symposium. You can view this presentation in the YouTube video below.

The abstract–and a clarification–are below.

Abstract: Virtually all treatments of power consumption and modelled performance for vibratory pile driving equipment assume a constant rotational speed of the eccentrics. In reality this is not possible due to the inertial effects of the eccentrics themselves and the necessity that, without inertia, the power output of the motor for the eccentrics must follow the instantaneous power requirements, which continuously vary. In this paper the rotational inertial effects of the eccentrics are included in the calculations. Because of the non-linear nature of the equations, a numerical model was developed to estimate the dimensionless torque required to turn the eccentrics at a target rotational speed. The results track closely with those of the continuous torque model described by Warrington (2006) for a wide variety of inertia/eccentric moment ratios, although there are exceptional cases if the peak acceleration is increased and the frequency decreased. As an excursus, the method of computing the inertia/eccentric moment ratio and its corresponding pendulum frequency is described in detail for those who can apply this to other problems.

One thing I need to clarify: The Tr is the torque ratio, not the speed. The study aimed to determine the torque ratio at a given speed, soil and vibratory configuration. That doesn’t come through as clearly as I would like, it is certainly featured in the monograph.

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