Course Content:

Introduction to stress and strain and need for experimental stress analysis. Localized measurement of deformation: Electrical resistance strain gages including bridge configurations and strain amplifiers used, optical displacement and strain sensors, LVDT and capacitance based sensors. Optical methods in strain analysis: Introduction to light, coherent light sources and coherence length of a light source, Interference, optical elements (lenses, prisms, beam splitters etc. used in optical setups); Principles of optical techniques such as photoelasticity in transmission and reflection including stress separation, Geometric Moiré and Moiré interferometry, Digital image correlation and Electronic Speckle Pattern Interferometry.

Lecture wise Breakup

I. Introduction (2 Lecture):

• Introduction to stress and strain and need for experimental stress analysis.

II. Localized measurements (8 lectures):

• Electrical resistance strain gages

• Bridge circuits and strain amplifiers used for conditioning strain measurements

• Optical displacement and strain sensors

• Linear voltage differential transducer and capacitance based displacement sensors

III. Introduction to optics (8 lectures):

• Representing light using electric field (plane and spherical wave fronts)

• Coherence, Coherence length and Interference

• Diffraction of light 

• Optical elements (lenses, prisms, beam splitters, front surface mirrors etc.)

IV. Photoelasticity (8 lectures):

• Stress optic law

• Analysis of plane and circular polariscope

• Fringe counting and calibration of optical constant

• Stress analysis using transmission and reflection photoelasticity

• Stress separation methods

V. Full field displacement measurement techniques (16 lectures):

• Geometric Moiré (3)

• Moiré Interferometry (5)

• Electronic Speckle Pattern Interferometry (4)

• Digital Image Correlation (4)

References:

1. Experimental Solid Mechanics, A Shukla and J.W. Dally

2. High Sensitivity Moiré, D. Post, B. Han and P. Ifju

3. Springer Hand Book of Experimental Solid Mechanics