What are photoelastic materials?
A photoelastic material is one that has a stress dependent refractive index. When placed between crossed polarizers, the rotation of the polarized light by the stress field in the material generates a fringe pattern displaying contours of equal stress.
What are the requirements in selection of photoelastic materials?
1.0 Method of Plastic Application. Photoelastic coatings are available in two basic forms:
What are the properties of photoelastic material?
Photoelasticity, the property of some transparent materials, such as glass or plastic, while under stress, to become doubly refracting (i.e., a ray of light will split into two rays at entry).
What are the uses of Photoelasticity?
Photoelasticity describes changes in the optical properties of a material under mechanical deformation. It is a property of all dielectric media and is often used to experimentally determine the stress distribution in a material, where it gives a picture of stress distributions around discontinuities in materials.
How is Fringe order determined?
The central fringe is n = 0. The fringe to either side of the central fringe has an order of n = 1 (the first order fringe). The order of the next fringe out on either side is n = 2 (the second order fringe).
What causes birefringence?
Stress birefringence results when isotropic materials are stressed or deformed (i.e., stretched or bent) causing a loss of physical isotropy and consequently a loss of isotropy in the material’s permittivity tensor.
What are Isoclinic fringes?
Isoclinic fringes are lines of constant stress difference; isochromatic fringes are obtained when the principal stress direction coincides with the polarisation of the polariser.
What are fringes in Photoelasticity?
Isochromatic fringes are lines of constant principal stress difference, (σP – σQ). If the source light is monochromatic these appear as dark and light fringes, whereas with white light illumination coloured fringes are observed.
What are the different types of fringe benefits?
Examples of these fringe benefits include:
- Stock options. The employer allocates a percentage of the company’s shares to each eligible employee at no upfront cost.
- Disability insurance.
- Paid holidays.
- Education reduction.
- Retirement planning services.
- Life insurance.
- Paid time off.
- Commuter benefits.
What does it mean when a material undergoes photoelasticity?
Photoelasticity describes changes in the optical properties of a material under mechanical deformation.
Can a photoelastic tensor be expressed in terms of mechanical stress?
Although the symmetric photoelastic tensor is most commonly defined with respect to mechanical strain, it is also possible to express photoelasticity in terms of the mechanical stress . The experimental procedure relies on the property of birefringence, as exhibited by certain transparent materials.
How are polarizers used in a photoelastic analyzer?
A photoelastic analyzer consists of a pair of left and right polarizers (each with their quarter- wave plate facing inward towards the photoelastic materials). Polarized sunglasses are linear polarizers, and 3D movie glasses can be either linear or circular polarizers depending on the system.
How is photoelasticity used to validate the stiffener model?
Photoelastic model to validate the stiffener model. Isochromatic fringe patterns around a steel platelet in a photo-elastic two-part epoxy resin. Photoelasticity has been used for a variety of stress analyses and even for routine use in design, particularly before the advent of numerical methods, such as finite elements or boundary elements.