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Accessory belt “chirp” noise is a major quality issue in the automotive and truck industry. Chirp noise control is often achieved by very tight pulley alignment, a guideline being .33 degree maximum belt entry angle into each grooved pulley. Occasionally belts will chirp at pulleys where the system alignment is this good or better. This study offers an explanation for such occurrences. This is a study to see if fundament groove side sticking theory correlates with the belt entry angle, and how the coefficient of friction relates to this entry angle. The study combines theory with lab data. In summary, the study fundamentally links the coefficient of friction of the belt to the belt chirp noise phenomenon, and allows the projection of a belt's general tendency to chirp to be predicted by the measurement of belt coefficient of friction on a test stand.

A geometrical set of closed form trigonometric equations are developed as a simplified alternative to the complex numerical computations required for determining lateral belt tracking locus due to pulley misalignment tolerances. Solutions are validated by a comprehensive statistically designed database. Further, analytical verification is obtained from ABAQUS/Explicit results based on a nonlinear hyperelastic Ogden finite element model. Three-dimensional geometric equations form the basis of a computer tool developed to predict belt displacement across a flat backside pulley, as well as angles of entering and exiting spans. Predictions are performed for the critical combination of a grooved-flat-grooved pulley arrangement typically found in automatically tensioned front-end automotive serpentine accessory drives. Excellent correlation is found between the three-dimensional finite element analysis, experimental data, and the simplified geometrical model.

Serpentine accessory belts are commonly used in industries such as automotive and general machinery. The purpose of this analytical tool is to provide design engineers the capability to model belt drive systems using ADAMS (Automated Dynamic Analysis of Mechanical Systems). The generated ADAMS models can be used to analyze several different characteristics concerning V-Ribbed belt drive systems. The general solution of the governing nonlinear equations provides the coupled longitudinal and transverse response of the translating belt drive system. Typical simulation outputs include pulley hubloads, belt impact dynamic forces, and belt slip rates at the pulleys.

This paper reviews a test procedure and some empirical and theoretical insights related to V-ribbed belt accessory drive system belt alignment. The paper focuses on the effects of backside pulleys, or the smooth pulleys, which can generate significant belt misalignment. The test procedure has been recently introduced to determine the belt alignment sensitivities of accessory drive belt system variables such as belt tension, belt wrap, belt span length, belt backside surface, and backside pulley crown. The test procedure is described in detail, and some examples of results are provided. The advantages of generating real-time data are also discussed.