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The use of a predictive fatigue crack growth model to monitor progressive deterioration of initially small rib-tip flaws in automotive serpentine belts is presented in this paper. Model is based on computational fracture mechanics and fatigue coupon test data. A global-local finite element analysis procedure is used to compute the J-integral for a through-the-thickness crack in the rib tip. The three-dimensional global model is created with relatively coarse mesh using first order continuum elements in ABAQUS. The local model rib crack is constructed with significantly finer mesh utilizing second order continuum elements. Boundary conditions for the local model are driven by global displacements. Maximum and minimum J-integrals are calculated at two extreme configurations for a single belt running cycle. The range of the J-integral is input into the curve fitted power law to derive the fatigue crack growth rate and hence the fatigue life for the belt.

An automotive hydraulic system including pump, power steering gear, fan, and Active Hydraulic Suspension (AHS) is modeled and validated through bench testing. A Computer Aided Engineering (CAE) simulation capability is developed for design control of flow and pressure dynamics. The generated fluid-borne pump noise resulting from interaction with circuitry components is obtained from transfer matrix methods utilizing MATLAB and SIMULINK. Hose and tube components are modeled as continuous sections. Non-tubular components including fan, AHS, gear, and cooler are treated as lumped sections with point transfer functions. The reservoir is represented by low pressure termination points from entrance lines. Impedance at these points is defined as the pressure-flow ratio obtained from measurements at line entrance to the reservoir. Hydraulic fan and AHS are each considered to have branched flow with discharge to both high and low pressure lines.

In practical operation, serpentine belts are subjected to parametric excitation caused by tension and translation speed fluctuations from pulley rotations and crankshaft speed oscillations. Each of these excitation sources has spectral content at multiple frequencies and arbitrary phases. Stability boundaries for primary, secondary, and simultaneous primary/secondary parametric instabilities are determined analytically. The classical result that primary instability occurs when one of the excitation frequencies is close to twice a natural frequency changes as a result of multiple excitation frequencies. Unusual interactions occur for the practically important case of simultaneous primary and secondary instabilities.

A type of V-belt drive which shifts ratios in accordance with input speed and output torque has been successfully employed as the transmission for vehicles ranging from snowmobiles to compact automobiles. Increasing popularity of this kind of transmission has created the need for more reliable criteria to be used in its design. This paper presents a derivation of design equations for a symmetrical V-belt drive in which centrifugal control is governed by an expanding garter spring and torque control results from a helical cam. Experimental results are included which support the validity of these equations.