Many machines in the world comprise gears, mostly made from steel. Nowadays, the share of polymeric gears is increasing rapidly. Such gears have several advantages and disadvantages. With gears, we transmit torque through small contact surfaces between two teeth. When carrying the load, various phenomena occur, e.g. elastic deformation of the tooth, heat generation and changes in geometry. The extent to which these phenomena occur heavily depends on the geometry and the gear material. In this work, we focus on deformation and the stress distribution. The deformation was calculated using the small deformation theory. Experiments were carried out on two identical gears made of transparent polymeric material, which allowed us to use photoelasticity. Due to the relatively large deflections, we have found out that the theory of small deformation was not the best choice. For good measurements of deflection, a sharp image and a clearly visible edge are necessary to reduce the error due to the subjective nature of the length measurement in the software. The tooth stress distribution gives us an overview of the most critical points in the tooth and shows that the maximum stress occurs in the point of contact.
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