Photoelastisuus

Photoelastisuus, or photoelasticity, is an experimental method used to determine stress and strain distributions within transparent materials. It relies on the property of birefringence, where a material's refractive index changes depending on the polarization direction of light passing through it. When a transparent object is subjected to mechanical stress, it becomes birefringent. If polarized light is shone through the stressed object and then viewed through another polarizer (an analyzer), colorful patterns called fringe patterns are observed. These fringes are contours of equal stress or strain. The number and spacing of the fringes indicate the magnitude of the stress or strain, while the colors provide additional information about the stress state. Photoelasticity is particularly useful for analyzing complex geometries and stress concentrations where analytical solutions are difficult to obtain. It has applications in various engineering fields, including aerospace, automotive, and civil engineering, for designing and validating structures and components. The technique can be performed using either two-dimensional or three-dimensional models. In two-dimensional photoelasticity, thin flat models are used, while for three-dimensional analysis, models are often cast from birefringent resins and then subjected to temperature changes or stresses.