Related Experiment Video
Updated: Jul 6, 2026
07:14
In situ Photo-rheology Monitors Viscoelastic Changes in Photo-responsive Polymer Networks
Published on: June 20, 2025
Multiple-reflection effects in photoelastic stress analysis
1Intel Corporation, 300 Enzo Drive, San Jose, California 95138, USA. achintya.k.bhowmik@intel.com
Applied Optics
|March 22, 2008
Summary
Multiple internal reflections significantly alter photoelastic stress measurements using laser light. These effects modify fringe patterns, shifting and changing intensity profiles, especially with reflective samples.
Area of Science:
- Optics
- Materials Science
- Solid Mechanics
Background:
- Photoelasticity uses light interference to measure stress in transparent materials.
- Coherent light sources like lasers can cause multiple internal reflections in slab specimens.
- These reflections are often ignored but can impact fringe interpretation.
Purpose of the Study:
- To analyze the impact of multiple internal reflections on photoelastic measurements.
- To investigate how these reflections affect fringe patterns in plane polariscope configurations.
- To understand the influence of sample reflectivity on fringe characteristics.
Main Methods:
- Theoretical analysis of light propagation within slab specimens.
- Modeling of interference effects from multiply reflected light waves.
- Examination of fringe intensity profiles and phase accumulations.
Main Results:
- Multiple internal reflections modify isochromatic fringes through wave interference.
- Multipass phase accumulations cause oscillatory changes in fringe intensity with thickness and wavelength.
- High reflectivity, such as with coatings, leads to fringe splitting.
Conclusions:
- Multiple reflections are a critical factor in laser-based photoelasticity, not negligible.
- Accurate stress interpretation requires accounting for these optical interference effects.
- Fringe splitting in highly reflective samples provides a distinct signature of multiple reflection impacts.
Related Concept Videos
01:18Transformation of Plane Stress
Studying stress transformation is essential in understanding how stress components within a material, like a cube under plane stress, change with rotation. This change is analyzed by considering a prismatic element within the cube. As the element rotates, the stress components acting on it—both normal and shearing stresses—change in magnitude and orientation. This change is quantified using trigonometric functions of the rotation angle, relating the forces acting on the rotated element's faces...
01:23Components of Stress
Stress analysis under multiple loading conditions is intricate, necessitating a comprehensive grasp of normal and shearing stresses. Consider a small cube at point O, subjected to stress on all six faces, visible or not. Normal stress components σx, σy, σz act perpendicularly to the x, y, and z axes. Shearing stress components τxy and τxz are exerted on faces perpendicular to these axes.
Interestingly, the hidden cube faces also experience these stresses, equal and opposite to those on the...
Interestingly, the hidden cube faces also experience these stresses, equal and opposite to those on the...
01:15Stress: General Loading Conditions
To grasp the intricacy of real-world conditions where multiple loads are applied simultaneously to a structure, one might visualize a section passing through a specific point within a body, aligned parallel to the xy plane. This section is subjected to various forces, including original loads, normal forces, and shearing forces.
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes.
The shearing force, possessing potential directionality within the plane of the section, is simplified into two component forces running parallel to the x and y axes.
01:20Elastic Strain Energy for Shearing Stresses
As discussed in previous lessons, strain energy in a material is the energy stored when it is elastically deformed, a concept crucial in materials science and mechanical engineering. This energy results from the internal work done against the cohesive forces within the material. When a material undergoes shearing stress and corresponding shearing strain, the strain energy density, which is the energy stored per unit volume, is calculated. Within the elastic limit, where the stress is...
01:15Relation between Poisson's ratio, Modulus of Elasticity and Modulus of Rigidity
Deformation occurs in axial and transverse directions when an axial load is applied to a slender bar. This deformation impacts the cubic element within the bar, transforming it into either a rectangular parallelepiped or a rhombus, contingent on its orientation. This transformation process induces shearing strain. Axial loading elicits both shearing and normal strains. Applying an axial load instigates equal normal and shearing stresses on elements oriented at a 45° angle to the load axis.
01:22Generalized Hooke's Law
The generalized Hooke's Law is a broadened version of Hooke's Law, which extends to all types of stress and in every direction. Consider an isotropic material shaped into a cube subjected to multiaxial loading. In this scenario, normal stresses are exerted along the three coordinate axes. As a result of these stresses, the cubic shape deforms into a rectangular parallelepiped. Despite this deformation, the new shape maintains equal sides, and there is a normal strain in the direction of the...