1. Physical regularities in the cracking of nanocoatings and a method for an automated determination of the crack-network parametersP. O. Maruščak, Vladimir Gliha, Igor Konovalenko, Tomaž Vuherer, Sergey Panin, 2012, strokovni članek Opis: The regularities and spatial distribution of multiple cracking of a nanocoating are investigated. It is found that in the cracking zones the relaxation of the stresses accumulated in the coating takes place; moreover, the intensity of its failure is determined by the structural level of defect accumulation. A new algorithm for a digital identification of the elements of a crack network in a nanocoating is proposed, and its adequacy is checked.
Ključne besede: nanocoatings, cracks, materials testing
Objavljeno: 10.07.2015; Ogledov: 705; Prenosov: 79
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2. Fracture toughness of heterogeneous energy componentsZdravko Praunseis, 2012, izvirni znanstveni članek Opis: The presence of different microstructures along pre-crack fatigue fronts has important effects on the critical crack tip opening displacement (CTOD). This value is the relevant parameter for the safe servicing of energy components (penstocks). In the case of specimens with a through thickness notch partly in the weld metal, partly in the heat affected zone and partly in the base material, i.e. using the composite notched specimen, the fracture behaviour strongly depends on the portion of ductile base material, its size and the distribution of the mismatching factor along the vicinity of the crack front.
Ključne besede: fracture toughness, energy materials, experimental testing
Objavljeno: 10.07.2015; Ogledov: 1147; Prenosov: 43
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3. Calculation model for pre-stressed bolted joints of slewing bearingsPéter Göncz, Srečko Glodež, 2009, izvirni znanstveni članek Opis: The presented paper describes a calculation model for pre-stressed bolted joints used to connect slewing bearings to the adjacent structures. A classical pre-stressed bolted joint calculation model is described and its insufficiencies for direct application on slewing bearings are pointed out. Finally, the suggested stress analysis is done by modelling the most loaded single bolt segment of the slewing bearing assembly, applying the preload and the working load on it. The stress determination in the bolt is done by finite element analysis.
Ključne besede: preiskava materialov, vijačne zveze, aksialni ležaji, dimenzioniranje, matematični modeli, materials testing, bolted joints, slewing bearings, dimensioning, calculation models
Objavljeno: 10.07.2015; Ogledov: 1219; Prenosov: 40
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6. Behaviour of cellular materials under impact loadingMatej Vesenjak, Zoran Ren, Andreas Öchsner, 2008, izvirni znanstveni članek Opis: The paper describes experimental and computational testing of regular open-cell cellular structures behaviour under impact loading. Open-cell cellular specimens made of aluminium alloy and polymer were experimentally tested under quasi-static and dynamic compressive loading in order to evaluate the failure conditions and the strain rate sensitivity. Additionally, specimens with viscous fillers have been tested to determine the increase of the energy absorption due to filler effects. The tests have shown that brittle behaviour of the cellular structure due to sudden rupture of intercellular walls observed in quasi-static and dynamic tests is reduced by introduction of viscous filler, while at the same time the energy absorption is increased. The influence of fluid filler on open-cell cellular material behaviour under impact loading was further investigated with parametric computational simulations, where fully coupled interaction between the base material and the pore filler was considered. The explicit nonlinear finite element code LS-DYNA was used for this purpose. Different failure criteria were evaluated to simulate the collapsing of intercellular walls and the failure mechanism of cellular structures in general. The new computational models and presented procedures enable determination of the optimal geometric and material parameters of cellular materials with viscous fillers for individual application demands. For example, the cellular structure stiffness and impact energy absorption through controlled deformation can be easily adapted to improve the efficiency of crash absorbers.
Ključne besede: mechanics, porous materials, cellular materials, impact loading, mechanical testing, fluid-structure interaction, failure mechanism
Objavljeno: 31.05.2012; Ogledov: 1334; Prenosov: 68
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