engleski

Experimental and Numerical Stress Analysis of some Plane Stress Problems beyond Yield Point

The paper deals with experimental and numerical stress and strain analysis in a membrane with different geometrical discontinuities, such as central circular hole, semicircular side notches etc., loaded beyond yield point. The experimental method of birefringent coatings is used for the determination of the initiation and spreading of plastic region. Two ways of application of birefringent coatings to specimens were investigated. In sevsral models a thin layer of birefringent material was cemented to the specimen. As cement, epoxy resin with hardener was used. For other models epoxy resin (trade name Araldit F) was directly moulded on the specimen. This second procedure gave better results, because it was possible to make experiment with very thin coatings, with smaller influence of coating effects. There weren't any problems with sensitivity of birefringent coatings, because large strains and the quite enough fringe order was obtained. The experimental results were compared whit those obtained by the numerical method. The numerical analysis was performed on the base of finite element method calculation. The theory of small elasto-plastic deformations was used. Due to the non-linearity of the problem the computation was performed incrementaly.

Experimental methods; method of birefringent coatings; spreading of plastic region; cemented coatings; moulded coatings; numerical methods; finite element method

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