Edge damageability and fracture resistance of elements made of brittle and semibrittle materials
Journal Title: Вісник Тернопільського національного технічного університету - Year 2015, Vol 77, Issue 1
Abstract
Technical approach for evaluation of the fracture resistance and damageability of edge areas for structural elements made of brittle and quasibrittle materials, which avoids drawbacks arising from the use of sharp indenter and enables to determine continuous and discrete characteristics of the edge resistance is developed. To implement the test of the parts edge a special arrangement is developed. The testing method is that a loading element with cylindrical surface is moving along the edge of the specimen and scanning one. As the load element carbide or polycrystalline superhard material plate is suggested. The test subjects were edges of flat glass plates and cemented carbide cutting tool. As the parameters of damageability maximum and mean sizes of chips on the front surface and the flank one and their ratio, as well as square of chips are used. As the indicator of local resistance to fracture of edges the ratio of load to the size of chips is proposed. The features of mechanical behavior of acute glass edge at a local discrete load and in continuous scanning are determined. Two mechanisms for local fracture of glass: chipping with the predominant influence of the breaking-off mechanism and microchipping and crushing of edge fragments with the predominant influence of mechanisms of scattered fracture were detected. The experimental evaluation of the nature and degree of damage and fracture resistance for cemented carbide cutting tool in its original condition and with wear-resistant PVD - coating TiAlN is obtained. It is shown that the application of brittle wear-resistant coating reduces cutting edge fracture under the local loading. The mechanisms of edge fracture of brittle and quasibrittle materials are revealed. It is proved that the ratio of mean sizes of chips on the front surface and the flank one as well as the indicator of local resistance to fracture of edges characterize brittleness of the material under the local loading. It is shown that the results of continuous scanning allow estimating the behaviour of elements’ edge under the local loading with the considering of level and nature of defects. Complex of characteristics obtained by the proposed method can be used to improve the load carrying capacity of brittle and quasibrittle elements by improving design solutions, edge technology and surface modification of materials.
Authors and Affiliations
Yuriy Rodichev
Keywords
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