Experimental Bench for the Analysis of Belt Deformation in Belt–Pulley Systems by Digital Image Correlation

Abstract

Belt–pulley transmissions are a classical topic in mechanical engineering, usually studied following two approaches: the creep theory (Euler or Grashof model) and the shear theory. Recently, the authors introduced a new theory to study the belt–pulley contact mechanics, which is inspired to the brush model used for pneumatic tires. Basing on this theory, the belt is considered as an almost axially rigid tension member connected to a series of bristles, which are, at the other end, in contact with the pulley. In this paper, a test bench is presented and designed to experimentally validate the brush model. The bench is made up of two pulleys connected to two shafts driven by independently controlled motors; a belt is installed between the pulleys, and the shafts are equipped with sensors measuring the angular velocity and the transmitted torque. The belt preload, which is measured by a load cell, can be varied by changing the distance between the two shafts. The belt was painted creating a suitable texture (random speckle pattern) to be interpreted using the Digital Image Correlation (DIC) technique. The first results obtained by carrying out tests at low speed with different transmitted torque values are discussed, appreciating the variation in the tension of the belt along the winding arc and the dependence of the radial compression of the belt from the transmitted torque. The tangential deformation of the belt under the action of different torque values and direction of rotation of the pulleys is also presented, which is consistent with that foreseen by the brush model.