The moiré-fringe method of displacement measurement applied to indirect structural-model analysis
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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.
KeywordsMechanical Engineer Fluid Dynamics Indirect Method Displacement Measurement Accurate Observation
List of Symbols
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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