engleski

Reduced stress concentration factors in tension and bending

The main objective of this contribution is to introduce the idea of reduced stress concentration factors for flat orthotropic bars with different geometrical discontinuities such as central holes, side notches and fillets, loaded in tension, compression and pure bending. In such bars maximum stress occurs at the free boundary of the geometrical discontinuity. The fracture or failure of the isotropic bar will start at a point of maximum stress. However, if the bar is made of an orthotropic material, failure will start at a point where the ratio of normal stress to local strength is a maximum rather than at point of maximum stress. Thus, the stress concentration factors should be defined in a different way in order to be of use to designers and engineers. The experimental method of birefringent coatings was utilized to establish stress distribution around the geometrical discontinuities namely around elliptical holes. After all experiments for the determination of stress distribution by means of birefringent coatings have been completed, and then loaded in tension. The load was gradually increased untils, finally fracture of the models occured. The photographs of three broken models with corresponding diagrams are presented.

Stress concentration factors; Orthotropic bars; Birefringent coatings

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