Photoelasticity is one of the most recognized and reliable methods to detect the stress distribution in the materials and products.
What is Photoelasticity?
Photoelasticity is one of the most recognized and reliable methods to detect the stress distribution in the materials and products. It is an experimental method which enables the users to determine the stress distribution in the specimen with great accuracy as compared to the analytical methods. The method of photoelasticity gives an accurate and accurate stress distribution analysis along with some discontinuities present in the materials. The method is also very efficient in finding the stress concentration in the materials with irregular geometry.
Working Principle of Photoelasticity
The method of photoelasticity works on the basic principle of birefringence which is exhibited some of the materials. In birefringent materials, there are two refractive indices present due to the application of stress to the crystal structure of material. When a ray of light passes through a material with birefringence, the electromagnetic components of the light are resolved into two components along the directions of principal stress. Each component of the light has to go through a different refractive index. This different causes the phase difference in the two resolved components of the light. The magnitude of this difference is determined the following expression in two-dimensional photoelasticity.
Where ? is the induced phase difference, the C is the coefficient of stress optics, t is the thickness of the specimen, λ is the wavelength of the light in vacuum and σ1 & σ2 are the principle stress 1 and 2. The Polariscope strain viewer is an instrument that is used for combining the different polarization states of the light waves after and before they pass through the specimen. Due to the process of interference, there are patterns of fringes formed on the screen. The number of fringes is demoted by the expression
Use of Polariscope in Photoelasticity
A plane polariscope strain viewer is used for studying photo-elasticity in different materials such as glass, polymers, PET, etc. The instrument consists of two linear polarizers along with a light source. Either monochromatic or white light can be used for the experiment method. The light ray first passes through the first polarizer that converts the light ray into a plane polarized light. The setup of the apparatus is done in such a way that the plane polarized light is passed through the specimen to be tested. The light follows the direction of the principle stress in every point of the specimen. The light is then passed through the second polarizer or analyzer which finally causes the formation of fringes.
The Polariscope strain viewer is used in many industries such as PET and preforms, glass, gemology and many others to determine any structural flaws in the crystals. With the help of this instrument, the manufacturers can quickly detect the flaws in the initial stage of manufacturing hence, can discard the defective materials to save time, money and resources.
Polariscope Manufacturers in India
When it comes to choose a polariscope for your laboratory, it is essential that you choose the best. One such instrument is offered by Presto who is a prominent manufacture of high efficiency testing instruments. The polariscope offered by Presto is one of the most efficient device that is provided with a wider viewing area which allows testing bigger samples along with easy placement of the sample. There are three different versions of the instrument offered by Presto namely Polariscope strain viewer, Illuminator Polariscope and Polariscope strain viewer for glass.
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