National Repository of Grey Literature 3 records found  Search took 0.01 seconds. 
Influence of surface hardening on fracture behaviour of steels
Dlouhý, Ivo ; Chlup, Zdeněk ; Hadraba, Hynek
The paper is focused on the phenomena associated with fracture in surfaře layer produced by three different procedures. Standard cementing, nitriding and surface hardening were applied onto surfaces of six low alloy structural steels. For fracture behaviour evaluation Charpy type specimen with U notch were applied the surface of the notch radius was hardened too. The samples were loaded by means of an instrumented impact pendulum. The evaluation and classification of different fracture behaviour modes have been based on evaluation of load . flexure tracen supported by fractographic analysis. Knowledge obtained were summarised into general schematics of failure modes. As the most detrimental for the fracture resistance the surface cementing was found. The surface hardening showed the minimal negative effect on crack initiation and relatively small fracture resistence decrease.
Methods for evaluation of stability of crack between two isotropic/orthotropic materials
Damborský, Petr
This article deal with problems of cracks in bodies with bimaterial interface. The approaches based on the stress intensity factor (SIF) and the energy release rate (ERR) concepts are presented for isotropic and orthotropic materials. A relation between the mixity of the two fracture modes (I and II) in accordance with the two approaches mentioned is presented. The last part deals with the use two states ψ- integral to determine generalized stress intensity factor.
Effect of coating on fracture behaviour of ceramic foams under tensile loading
Řehořek, Lukáš ; Dlouhý, Ivo ; Chlup, Zdeněk
Cellular structures are promising type of architecture for a lot of materials whether made of metals, plastic or ceramic. Target applications are those where lightweight, damping and and/or stiff properties are required. With combination of different kinds of materials the foamed composites with favourable mechanical properties can be developed. In case of ceramic foams the main disadvantage – brittleness – can be reduced. For straight forward application of this materials all types of mechanical properties have to be known. The tensile properties of open cell ceramic foam material based on alumina coated by various materials are presented in this paper.

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