Detachment Waves and Self-Oscillation in a Belt-Drive System Incorporating Tensile Cords

Abstract

Recent experimental studies have shown that tension transition via detachment waves (rather than via sliding, as commonly accepted) occurs at the belt–pulley interface for systems using simple homogeneous or textured flat belts operating under slow speeds. This raises the question of whether or not such detachment waves are universal—e.g., will they persist in systems incorporating belts with composite cross sections, such as those used in commercial applications? Herein, we experimentally explore the behavior of a belt-drive system incorporating a composite belt with tensile cords, with and without a patterned contact surface, and document the persistence of detachment waves. This then leads to a re-evaluation of the Firbank model of belt shear. We also explore the effect of tensile cords on (i) the amplitude and frequency of the observed detachment waves, (ii) the ensuing oscillations of the pulley, (iii) the evolution of belt shear strain, and (iv) the frictional losses of the system. We find that the detachment frequency increases and the pulley rotates steadier with inclusion of tensile cords. The corded belt undergoes shear deformation starting from the entry point due to a speed differential between the pulley envelope and the tension members, which is consistent with the classical Firbank shear model. However, the Firbank model cannot predict the rapid relaxation of the shear traction via detachment waves at the exit region. Additionally, accounting for shear and detachment events, we find that frictional losses in the belt-drive system decrease with inclusion of tensile cords.