Experimental Mechanics

, Volume 5, Issue 6, pp 167–176 | Cite as

The moiré-fringe method of displacement measurement applied to indirect structural-model analysis

Authors indicate that the results of experimental model-analysis technique compare satisfactorily with those derived from theoretical analysis
  • R. Shepherd
  • L. Mc D. Wensley


The production of moiré fringes when one grid of equally spaced lines is moved relative to a second similar grid is a well known phenomenon. These fringes may be used to measure the displacements of a transparent structural model if one set of lines is attached to the model and a second set is fixed to a transparent reference screen.

The indirect method of model analysis of structures entails the determination of the influence line for a force or moment at a section in the structure from accurate observations of the displacements of the model which occur when a chosen deformation is applied at the particular section under consideration.

This paper describes the successful application of the moiré-fringe method of displacement measurement to indirect structural-model analysis.


Mechanical Engineer Fluid Dynamics Indirect Method Displacement Measurement Accurate Observation 
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List of Symbols


fringe order


span ratio


horizontal force Subscripts refer to position of application


moment Subscripts refer to position of application


vertical force Subscripts refer to position of application


distance between adjacent line


distance between adjacent fringes


applied horizontal displacement


applied vertical displacement

\(\delta _\phi \)

applied rotational displacement


acute angle between two sets of lines


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Copyright information

© Society for Experimental Mechanics, Inc. 1965

Authors and Affiliations

  • R. Shepherd
    • 1
  • L. Mc D. Wensley
    • 2
  1. 1.Civil EngineeringUniversity of CanterburyChristchurchNew Zealand
  2. 2.Moir, New & Jenkins, Consulting EngineersInvercargillNew Zealand

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