Steady mechanics of layered, multi-band belt drives used in continuously variable transmissions (CVT)

The steady mechanics of multi-layered metal belts used in metal-pushing continuously variable transmissions (CVT) are examined where the thin individual bands are modeled as axially moving strings. For each band, the main characteristics of classic flat belt models, such as band inertia, tension/speed constitutive law and elastic extension, are retained. Relative speeds between the layered bands and between the innermost band and the pulleys transfer the driving torque via friction between the contacting surfaces. The friction, tension and speed distributions in the individual bands are obtained by a boundary value problem (BVP) solver-based method. Load sharing among the multiple bands is investigated. This model is useful for belt fatigue life analysis and to guide the design of such multi-layered belts, given that one of the main failure modes of metal-pushing CVT is premature breakage of one or more of the layered steel bands.