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1.
Numerical analysis of the racking behaviour of multi-storey timber-framed buildings considering load-bearing function of double-skin façade elements
Miroslav Premrov, Erika Kozem Šilih, 2023, izvirni znanstveni članek

Opis: The paper presents an innovative approach in the modelling of multi-storey timber-framed buildings, where double-skin façade elements (DSF) are additionally considered as load-bearing wall elements against a horizontal load impact. The mathematical model with a fictive diagonal element developed for timber-framed wall elements with classical oriented strand boards (OSB) or fibre–plaster sheathing boards (FPB) is upgraded for DSF elements. The diameter of the fictive diagonal is determined with either experimental results or numerically obtained results using the time-consuming FEM model with elastic spring elements, which simulates the bonding line between the timber frame and both glazing panes. In the second part of the study, the numerical analysis of a specially selected three-storey timber-framed building was performed using the developed mathematical model with fictive diagonal elements. Two alternative calculations were performed with the DSF elements as non-resisting and racking-resisting wall elements. It was demonstrated on the selected case that the racking resistance (R) of a building can essentially increase up to 35% if DSF elements are considered as resisting wall elements. As a secondary goal of the study, it is also important to point out that by using DSF elements as racking-resisting elements, the distortion in the first floor essentially decreased. It is demonstrated on the selected numerical example that this torsional influence decreased notably (by almost 18%) when the load-bearing DSF elements were used for seismic excitation in the X direction. Therefore, such an approach can open new perspectives in designing multi-storey timber-framed buildings with a more attractive and dynamic floor plan and structure.
Ključne besede: sustainability, timber, structures, multi-storey, numerical analysis, DSF, racking resistance
Objavljeno v DKUM: 19.03.2024; Ogledov: 127; Prenosov: 19
.pdf Celotno besedilo (4,93 MB)
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2.
Numerical analysis of a wind turbine blade with different software
Gorazd Hren, 2019, izvirni znanstveni članek

Opis: The development of wind power generation technology recognises the wind turbine blade design and manufacturing as crucial for its performance. The laboratory size wind turbine blade was analysed, considering the 3D printing plastic material for blades. Applying the structural dynamic equations of blades, the aero-elastic model of the rotating rotor and the numerical simulation method of the deflections are presented under the aerodynamic loads and centrifugal forces. Based on the parameters of aerofoil and the geometrical parameters of blade, 3D model of the blade was established with the modelling software. Then the model was introduced into computational flow dynamics software to carry out the loads on the blade and further into numerical structural analysis. The analysis was performed in two different software packages. Design of wind turbine blades depends on high precision, reliable and robust numerical predictions of performance where the plug-in software is found to be inadequate for nontrivial problems.
Ključne besede: computational fluid dynamics, numerical analysis, structural analysis, wind turbine blade
Objavljeno v DKUM: 22.02.2024; Ogledov: 203; Prenosov: 14
.pdf Celotno besedilo (1,68 MB)
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3.
A fundamental study of the performance of X-section cast-in-place concrete single piles
Yu Wang, Yaru Lv, Dongdong Zhang, Jieying Zhou, 2016, izvirni znanstveni članek

Opis: X-section cast-in-place concrete (XCC) piles are used because they have a higher bearing capacity than circularsection cast-in-place concrete (CCC) piles of the same cross-sectional area. Although the bearing capacity of XCC piles has been studied, the performance of XCC single piles, especially for the stress-transfer mechanism dependent on the geometrical effects, is still not fully understood. This paper reports two comparative field static load tests on an XCC and a CCC single pile of the same cross-sectional area. In addition, corresponding threedimensional numerical back-analyses are performed to provide a fundamental understanding. The measured and computed results reveal that the XCC single pile has an approximately 25% higher ultimate bearing capacity than the CCC single pile. This is because the XCC single pile has an approximately 20% larger total side resistance, which is caused by a 60% larger pile perimeter and a slightly smaller unit side resistance. Lateral soil arching effects are developed, causing a non-uniform effective normal stress and a shear stress across the circumference of the XCC single pile. It is suggested that XCC single piles have a higher efficiency in terms of material saving compared with CCC single piles.
Ključne besede: X-section cast-in-place concrete pile, field static load test, three-dimensional numerical back-analysis, stresstransfer mechanism, side resistance, soil arching
Objavljeno v DKUM: 15.06.2018; Ogledov: 1366; Prenosov: 161
.pdf Celotno besedilo (485,57 KB)
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4.
Fatigue crack initiation and propagation in lotus-type porous material
Srečko Glodež, Sašo Dervarič, Janez Kramberger, Matjaž Šraml, 2016, izvirni znanstveni članek

Opis: The investigation of fatigue strength of lotus-type structure with nodular cast iron as a base material using computational model is analysed in present study. The irregular pores distribution in transversal and longitudinal direction, regarding the external loading, is considered in the computational models. The complete fatigue process of analyzed porous structure is then divided into the crack initiation (Ni) and crack propagation (Np) period where the total fatigue life (N) is defined as: N = Ni + Np. The crack initiation period is determined using strain life approach where elastic-plastic numerical analysis is performed to obtain the total strain amplitude in the critical stress fields around the pores. The simplified universal slope method is then used to determine the number of stress cycles, Ni, required for formation of initial cracks. The number of stress cycles, Np, required for crack propagation from initial to the critical crack length is also numerically determined using finite element (FE) models, in the frame of Abaqus computation FEM code. The maximum tensile stress (MTS) criterion is considered when analyzing the crack path inside the porous structure. The performed computational analyses show that stress concentrations around individual pores are higher when external loading is acting in transversal direction in respect to the pore distribution. Therefore, further computational analyses regarding crack initiation and crack propagation period have been done only for pores distribution in transversal direction.
Ključne besede: lotus-type porous structures, fatigue crack initiation, fatigue crack propagation, numerical analysis
Objavljeno v DKUM: 02.08.2017; Ogledov: 1330; Prenosov: 410
.pdf Celotno besedilo (4,75 MB)
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5.
Numerical analysis of temperature field during hardfacing process and comparison with experimental results
Vukić Lazić, Ivana Ivanović, Aleksandar Sedmak, Rebeka Rudolf, Mirjana Lazić, Zoran Radaković, 2014, izvirni znanstveni članek

Opis: The three-dimensional transient nonlinear thermal analysis of the hard facing process is performed by using the finite element method. The simulations were executed on the open source Salome platform using the open source finite element solver Code Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental results.
Ključne besede: welding simulations, numerical analysis, thermal analysis, simulations, transient heat conduction, moving heat source
Objavljeno v DKUM: 07.07.2017; Ogledov: 1383; Prenosov: 383
.pdf Celotno besedilo (975,43 KB)
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6.
The influence of surface coatings on the tooth tip deflection of polymer gears
Boštjan Trobentar, Srečko Glodež, Jože Flašker, Boštjan Zafošnik, 2016, izvirni znanstveni članek

Opis: When designing gear drives made of polymer, the tooth tip deflection is a crucial parameter in respect to the proper gear drive operation. Excessive tooth tip deflection can lead to serious disturbances of gear meshing and consequently to increased noise and wear of the teeth flanks. In such cases the tooth tip deflection can be reduced through the use of stiff surface coatings on the tooth flanks. In this paper the influence of different coating materials and thicknesses on the tooth tip deflection of polymer gears is analysed using comprehensive finite element computational analysis. The numerical results obtained are then used to define an approximate equation for the calculation of gear tooth tip deflection for the coating material used and the thickness of the surface coating layer. The results show that the tooth tip deflection decreases with large values of the coating material Young’s modulus and with the coating layer thickness.
Ključne besede: polymer gears, surface coatings, tooth deflection, numerical analysis
Objavljeno v DKUM: 27.03.2017; Ogledov: 1677; Prenosov: 395
.pdf Celotno besedilo (578,86 KB)
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7.
Investigations of pumped-storage hydro plants in the Alpine area
Umboro Lasminto, Roman Klasinc, 2011, izvirni znanstveni članek

Ključne besede: pumped storage, investigation, scale model, numerical analysis
Objavljeno v DKUM: 05.06.2012; Ogledov: 2296; Prenosov: 53
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8.
On new approach to rheological modeling of an electrostatic ash and water - quadratic law
Primož Ternik, 2002, objavljeni znanstveni prispevek na konferenci

Opis: In the paper a new rheological model for an electrostatic ash and water mixture is proposed. The fundamental equation of the rheological model was used to determine the relationship between the shear stress and the shear rate as well as the equation of a velocity profile for the flow through a straight pipe. Experimental results obtained from a capillary viscometer were used as the basis to determine the parameters for the proposed model by the non-linear regression analysis. With the Quadratic law a numerical analysis of a mixture flow through a capillary pipe with the finite volume method was performed. The derived equations for the velocity profile, shear stress and shear rate were validated through a comparison of numerically obtained and theoretical results. Finally, the compariosn between the Quadratic and the Power law is presented.
Ključne besede: fluid mechanics, non-Newtonian fluids, mixture of electrofilter ash and water, flow in pipes, capillary pipes, rheological model, velocity profile, shear stress, finite volume method, numerical analysis, quadratic law, power law, mehanika fluidov
Objavljeno v DKUM: 01.06.2012; Ogledov: 2343; Prenosov: 45
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9.
Numerical modelling of micro-pitting of gear teeth flanks
Gorazd Fajdiga, Jože Flašker, Srečko Glodež, Trevor K. Hellen, 2003, izvirni znanstveni članek

Opis: A two-dimensional computational model for simulation of contact fatigue of gear teeth flanks is presented. In the model, it is assumed that the initial crack of length 0.015 mm is initiated at the surface due to previous mechanical or heat treatment of the material as well as a consequence of the running in process. The discretized model with the initial crack is then subjected to normal contact pressure, which takes into account the elasto-hydro-dynamic (EHD) lubrication conditions, and tangential loading due to friction between contacting surfaces. The model also considers the moving contact of gear flanks, fluid trapped in the crack and residual stresses due to heat treatment of the material on crack propagation. The virtual crack extension (VCE) method, implemented in the finite element method, is then usedfor simulating the fatigue crack growth from the initial crack up to the formation of the surface pit. The computational results show that the initial surface crack of length 15 m and the considered boundary conditions lead to the appearance of very small surface pits, which can be termed as micro-pitting on gear teeth flanks. The numerical results correspond well withavailable experimental data.
Ključne besede: machine elements, gearing, fracture mechanics, numerical analysis, micro pitting, pitting simulation, matematical model, fatigue, contact mechanics, crack propagation
Objavljeno v DKUM: 01.06.2012; Ogledov: 2551; Prenosov: 0

10.
The re-characterisation of complex defects
Boštjan Bezenšek, John. W. Hancock, 2004, izvirni znanstveni članek

Opis: The re-characterisation of complex defects with re-entrant sectors has been addressed for cracks extending by fatigue, ductile tearing and cleavage. In Part I crack extension by fatigue and ductile tearing was discussed. In Part II cleavage data are presented for a family of complex defects with re-entrantsectors. Experimental tests on complex and re-characterised profilesare analysed using deterministic and probabilistic approaches. The work addresses the conservatism of re-characterisation procedures when appliedto cleavage failure on the lower shelf and in the ductile-brittle transition.
Ključne besede: fracture mechanics, structural elements, complex defects, recharacterisation, line-spring analysis, cleavage failure, constraint, statistical fracture mechanics, numerical analysis
Objavljeno v DKUM: 01.06.2012; Ogledov: 1392; Prenosov: 98
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