EM-120 | Polari Scope Apparatus

Photoelasticity is a proven method of analysing and recording mechanical stresses and strains in components. It is used both for quantitative measurements and for demonstrating complex stress states. The components used are models made of a transparent, photoelastically sensitive plastic, which becomes optically birefringent under mechanical load. It is used to conduct photoelastic experiments on plane, transparent plastic models. The models are subjected to load by external forces, and they are radiated by circular polarised light. An analyser analyses the light penetrating the body. The experimental setup comprises the separate components: a light source, two linear polarising filters (polariser and analyser), and two quarter-wave filters and a frame in which the models are attached and subjected to load. The light source optionally permits coloured stress patterns with white light or a light/dark representation with monochromatic light. The polariser includes a polarising filter and a quarter-wave plate and generates circular polarised light. Behind the model is a second quarter-wave plate (perpendicular to the first one), which is combined with a second polarising filter. These form the analyser. The filters are mounted on rotating bearings and fitted with angle scales. Various polycarbonate models are mounted inside the frame. A load application device applies bending, tensile or compressive load to the model through a spindle. Stresses and strains occurring in the model are identifiable as bright spots, visualising the distribution of stress. The order of the dark isochromats is analysed to determine the principal stress differential. A wide selection of models such as notched bars, a wrench and a model-roller bearing or a rack-and-pinion is available as accessories. These ensure the implementation of comprehensive experiments. It is also possible to investigate your own models.