Vibration and Acoustics Research Journal (VARJ)

Research Article

Repeated Vibrational Motion Using an Inertial Drive

Christopher G. Provatidis

Mechanical Engineering Department, National Technical University of Athens, Zografou Campus, 9, Iroon Polytechniou str, 15780 Zografou, Greece.

Submitted: August 6, 2019; Accepted: December 21, 2019

Abstract

The primary purpose of this paper is to demystify the vibrational motion caused by a typical inertial (Dean) drive when is attached to a heavier object (vehicle). A Dean drive consists of two symmetric eccentric masses which are rigidly connected to rotating rods and driven by (say electric) motors. Therefore, the force components along the line l which joins them are cancelled and thus the two rotating masses operate together as a single equivalent driving mass which vibrates along the perpendicular midline to l passing through the object. Hence the system “vehicle + drive” reduces to a “two-body” problem. The contra-rotation of the two eccentrics is shown to cause a unidirectional displacement of the connected object for which closed-form analytical equations of motion are obtained in terms of the conservation of linear momentum. A first novel feature of the paper is that it discusses alternative design configurations. Within this context, the Dean-drive itself is shown to be almost equivalent to a spring-mass system attached above the vehicle whereas a similar vehicle’s motion is obtained when a single spring is put below the vehicle. In the hitherto published classical version of the air-operated mechanism, the vehicle performs a reduced travel distance until it reaches the upper point of its trajectory. A second novel feature of this work is to demonstrate that repeated (endless) unidirectional motion of the vehicle is ensured when external support forces are exerted periodically during specific short time intervals at the end of each cycle of the travel.

Keywords

Vibrational motion; Dean drive; Inertial propulsion; Support force; Transportation.

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