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Experimental Mechanics

, Volume 44, Issue 4, pp 416–424 | Cite as

Luminescent photoelastic coatings

  • J. P. Hubner
  • P. G. Ifju
  • K. S. Schanze
  • Y. Liu
  • L. Chen
  • W. El-Ratal
Article

Abstract

In this paper we describe a new technique to measure the surface strain field on complex three-dimensional structural components under static load. It is cost-efficient to implement and suitable to be integrated in the product design cycle in conjunction with finite element analysis tools. The technique employs novel luminescent photoelastic coatings and digital imaging to map the in-plane strain field. The coatings consist of a binder, generally polymeric in nature, and luminescent dyes that are applied to the surface of a test part using conventional aerosol techniques. When excited with circular polarized ultraviolet or blue illumination, the corresponding emission intensity from the coating is measured via a digital camera. The relative change in emission magnitude and phase as measured after passing through an analyzing polarizer is related to the in-plane shear strain and its corresponding principal direction. Several basic test results are presented and discussed, showing quantitative, repeatable, and high spatial resolution measurements.

Key Words

Luminescent photoelastic coating strain full-field 

Nomenclature

E

electric field wave magnitude

h

coating thickness

I

measured emission intensity, proportional toE2

K

photoelastic optical sensitivity

r

luminescence anisotropy

t

time

α

analyzer angle

γ

shear strain

δ

optical strain response, φ p for a dual-layer coating

Δ

angular retardation

ɛ

normal strain

θ

principal direction

λ

wavelength of light

ν

Poisson constant

ϕ

efficiency or attenuation

σ

standard deviation

ω

angular frequency of light

avg

average

ex

excitation

c

combined

em

emission

f

fast axis

H

horizontal orientation

max

maximum

np

non-polarized

p

polarized or polarization

q

quantum

r

residual

s

slow axis

t

transmission or true

V

vertical orientation

1

primary in-plane principal direction

2

secondary in-plane principal direction

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References

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Copyright information

© Society for Experimental Mechanics 2004

Authors and Affiliations

  • J. P. Hubner
    • 1
  • P. G. Ifju
    • 1
  • K. S. Schanze
    • 2
  • Y. Liu
    • 2
  • L. Chen
    • 1
  • W. El-Ratal
    • 3
  1. 1.Department of Mechanical and Aerospace EngineeringUniversity of FloridaGainesvilleUSA
  2. 2.Department of ChemistryUniversity of FloridaGainesvilleUSA
  3. 3.Chassis Division, DSEVisteon CorporationSterling HeightsUSA

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