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Research Papers

Design Parameter Study of a New Test Apparatus Developed for Quantitative Rating of Squeak Propensity of Materials

[+] Author and Article Information
Gil Jun Lee

Department of Mechanical and
Materials Engineering,
College of Engineering and
Applied Science,
University of Cincinnati,
584D Rhodes Hall, 2600 Clifton Avenue,
Cincinnati, OH 45221
e-mail: leeg4@mail.uc.edu

Jay Kim

Fellow ASME
Department of Mechanical and
Materials Engineering,
College of Engineering and
Applied Science,
University of Cincinnati,
589 Rhodes Hall, 2600 Clifton Avenue,
Cincinnati, OH 45221
e-mail: jay.kim@uc.edu

1Corresponding author.

Contributed by the Noise Control and Acoustics Division of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received January 30, 2017; final manuscript received May 10, 2017; published online August 1, 2017. Assoc. Editor: Ronald N. Miles.

J. Vib. Acoust 139(6), 061006 (Aug 01, 2017) (12 pages) Paper No: VIB-17-1039; doi: 10.1115/1.4036926 History: Received January 30, 2017; Revised May 10, 2017

A novel, unique squeak test apparatus was developed to measure squeak propensity of a given pair of materials with a purpose to build a database for automotive engineers. The apparatus employs a sprag-slip mechanism to generate friction-induced, unstable sliding motion between the two materials that leads to a repeatable squeak noise to enable quantitative rating of the squeak propensity of a given pair of materials. An analytical model of the system was developed to study dynamic characteristics of the mechanism to gain insights to design the test apparatus. Stability analysis of the system identified unstable regions of the motion in parameter planes defined by the kinetic coefficient of friction and the attack angle. Furthermore, the effect of these system parameters on the amplitude of the limit cycle was investigated to obtain guidance to design the device. An automatic rating algorithm of squeak noises previously developed by authors was employed to calculate the squeak propensity of the material pairs. A practical engineering procedure is envisioned that can handle squeak problems in the design stage more effectively by taking advantage of such a squeak propensity database.

Copyright © 2017 by ASME
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References

Figures

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Fig. 1

(a) A squeak test apparatus and (b) the analytical model of the modified sprag-slip mechanism (k: stiffness of the linear spring, ξo: initial compression, ξ: dynamic displacement of spring from initial compression, ls: free length of the linear spring, K: stiffness of the torsional spring, l: length of a rigid bar, θa: angle of attack, θ: dynamic variation of angle, θT: total angle, Fn: normal force, and Ft = μFn: friction force)

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Fig. 2

Schematics of the modified sprag-slip mechanism (a) when there is no force applied and (b) when the initial compression is applied to obtain the attack angle (θa) (k: stiffness of the linear spring, ξo: initial compression, K: stiffness of the torsional spring, l: length of a rigid bar, θo: the angle of the bar when the linear spring is at free length, Fn: normal force, and Ft = μFn: friction force)

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Fig. 3

Free-body diagram of the modified sprag-slip mechanism shown in Fig. 1(a)

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Fig. 4

Unstable region with different values of K/kl2: (a) K/kl2 = 0, (b) K/kl2 = 0.05, (c) K/kl2 = 0.1, and (d) K/kl2 = 0.15

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Fig. 5

Unstable, transient responses of the system with θa = 15 deg, μ = 0.5, K = 100 N·m/rad, k = 105 N/m, and l = 0.2 m: (a) angular displacement, (b) angular velocity, and (c) phase portrait

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Fig. 6

Stable, transient responses of the system with θa = 45 deg, μ = 0.5, K = 104 N·m/rad, k = 105 N/m, and l = 0.2 m: (a) angular displacement, (b) angular velocity, and (c) phase portrait

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Fig. 7

The two eigenvalues of the system with respect to four parameters: (a) kinetic coefficient of friction μ, (b) angle of attack θa, (c) torsional stiffness K, and (d) linear stiffness k

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Fig. 8

Phase portraits of the limit cycles of the stable system with different values of mass (m) of the system and friction coefficient (μ): (a) μ = 0.1 and (b) μ = 0.7

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Fig. 9

Amplitude of the limit cycles with different values of mass (m): (a) displacement and (b) velocity

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Fig. 10

Phase portraits of the limit cycles of the stable system with different values of angle of attack (θa) of the system and friction coefficient (μ): (a) μ = 0.1 and (b) μ = 0.7

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Fig. 11

Amplitude of the limit cycles with different values of the angle of attack (θa): (a) displacement and (b) velocity

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Fig. 12

Phase portraits of the limit cycles of the stable system with different values of initial compression (ξo) and friction coefficient (μ): (a) μ = 0.3 and (b) μ = 0.7

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Fig. 13

Amplitude of the limit cycles with different values of the initial compression (ξo): (a) displacement and (b) velocity

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Fig. 14

Frequency spectra measured from aluminum-polymer A pair: (a) acceleration and (b) sound pressure level (line up the arrow to the highest peak)

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Fig. 15

Frequency spectra measured from aluminum-polymer B pair: (a) acceleration and (b) sound pressure level

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Fig. 16

(a) FE model of the squeak test apparatus and (b) setup of experimental modal analysis

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Fig. 17

Frequency response function of the bent beam of the test apparatus obtained from impact test

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Fig. 18

Time–frequency patterns of the generated squeak noise obtained from analytic wavelet transform: (a) aluminum-polymer A pair and (b) aluminum-polymer B pair

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Fig. 19

Objective rating curve of the generated squeak noises obtain from the automatic detection and rating algorithm: (a) aluminum-polymer A pair and (b) aluminum-polymer B pair

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