Research Papers

Load Recovery in Components Based on Dynamic Strain Measurements

[+] Author and Article Information
Anoop K. Dhingra

e-mail: dhingra@uwm.edu

Deepak K. Gupta

Department of Mechanical Engineering,
University of Wisconsin,
Milwaukee, WI 53201

1Corresponding author.

2Currently President, Wolf Star Technologies, 3321 N. Newhall St., Milwaukee, WI 53211, e-mail: tim.hunter@wolfstartech.com.

Contributed by the Design Engineering Division of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received March 5, 2012; final manuscript received April 26, 2013; published online June 18, 2013. Assoc. Editor: Jean Zu.

J. Vib. Acoust 135(5), 051020 (Jun 18, 2013) (8 pages) Paper No: VIB-12-1056; doi: 10.1115/1.4024384 History: Received March 05, 2012; Revised April 26, 2013

This paper presents a modeling approach for estimating time varying loads acting on a component from experimental strain measurements. The strain response of an elastic vibrating system is written as a linear superposition of strain modes. Since the strain modes, as well as the normal displacement modes, are intrinsic dynamic characteristics of a component, the dynamic loads exciting a component are estimated by measuring induced strain fields. The accuracy of the estimated loads depends on a number of factors, such as the placement locations and orientations of the gauges on the instrumented structure, as well as the number of retained modes from strain modal analysis. A solution procedure based on the construction of D-optimal designs is implemented to determine the optimum locations and orientations of strain gauges such that the variance in load estimates is minimized. A numerical as well as an experimental validation of the proposed approach through two example problems is also presented.

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Fig. 1

Flow chart of the overall solution process

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Fig. 2

Bent beam with its four modes

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Fig. 3

Optimum gauge locations and orientations

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Fig. 4

Load-time history applied at the tip of the beam

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Fig. 5

Recovered mode participation factors

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Fig. 6

Cantilevered beam with optimum gauge placement

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Fig. 7

Clamped cantilevered beam mounted on the shaker

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Fig. 8

MPF for a 28 Hz base excitation

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Fig. 9

Recovered MPF for a 28 Hz input

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Fig. 10

Actual and reconstructed strains in gauge 1

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Fig. 11

Actual and reconstructed strains in gauge 3



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