| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 6 / 6
Na začetekNa prejšnjo stran1Na naslednjo stranNa konec
1.
High-cycle fatigue behaviour of the aluminium alloy 5083-H111
Branko Nečemer, Franc Zupanič, Tomaž Vuherer, Srečko Glodež, 2023, izvirni znanstveni članek

Ključne besede: aluminium alloys, rolling direction, high-cycle fatigue, fracture analysis
Objavljeno v DKUM: 04.04.2024; Ogledov: 84; Prenosov: 5
.pdf Celotno besedilo (8,97 MB)
Gradivo ima več datotek! Več...

2.
Razvoj modela za spremljanje degradacije površine materiala med dinamičnim obremenjevanjem : doctoral disertation
Marijana Milković, 2023, doktorska disertacija

Opis: The study focuses on the behavior of the AA7075-T6 material, widely used in the aerospace industry, under dynamic loadings. The material undergoes processing, including cold rolling and stretching, resulting in residual stress compressive stresses on its surface. The research centers on monitoring changes in the surface condition during dynamic loaidngs using Fiber Bragg Grating (FBG) sensors and numerical simulations. The dissertation includes experimental testing of AA 7075-T6 material samples, numerical simulations of optical fiber responses to tensile loads, and an investigation of surface condition changes using techniques such as focused ion beam engraving and scanning electron microscope observation. The study has shown that the surface condition of the material changes even under low dynamic loads, including variations in surface roughness, residual stresses, and FBG response. Despite low load levels, changes in FBG sensor spectra are observable. The dissertation concludes that the surface condition of the material changes during dynamic loadings, detectable through FBG sensors. It underscores the effectiveness of FBG sensors in monitoring stress levels throughout the material’s service life, particularly on the side lobes of the spectral response. In summary, the research on the dynamic behavior of the AA7075-T6 alloy offers valuable insight into surface condition changes that can impact the integrity and durability of materials in the aerospace industry.
Ključne besede: fatigue, high cycle load, Fiber Bragg grating
Objavljeno v DKUM: 05.01.2024; Ogledov: 298; Prenosov: 32
.pdf Celotno besedilo (10,61 MB)

3.
Effect of residual stresses on fatigue strength on the smooth and splined parts of spring torsion bars
Vinko Močilnik, Jožef Predan, Nenad Gubeljak, 2023, izvirni znanstveni članek

Opis: The article discusses the effect of residual stresses on the fatigue strength of torsion bars by using the Dang Van fatigue criterion, at the stress concentration at the root of the tooth and at the smooth part of the torsion bar. Residual compressive stresses were induced on the surface during the technological processes by cold surface rolling and torsional pre-strain (pre-setting) to the plastic range, to increase the elastic linear range and to reduce the stress state during torsional loading. Normally, the stress reduction in the torsion bar at the mounting point is provided by the increased diameter of the splined part, compared to the smooth part of the torsion bar. In the case of a small difference between the diameter of the splined and the smooth parts of the torsion bar, a fatigue crack can be initiated in the notch, which causes the torsion bar to break during operation after a few hundred loading cycles. FEM stress analysis of a torsion bar was performed in the article. The actual residual stresses were measured by the non-destructive X-ray method at the place of stress concentration on the smooth and splined parts with a notch of the torsion bar, and Dang Van’s failure criterion was used to determine the fatigue behavior during torsional loading. Therefore, in the paper, the three methods were combined to determine the optimum lifetime of a torsion bar exposed to the required cyclic torque. The results of the analysis showed that the residual compressive stresses are useful up to a certain limit where the retarded fatigue crack initiation occurred, but a further increase of compressive stress caused an increase of the maximum shear stresses, which, in turn, caused the initiation of fatigue and failure at the splined part of the torsion bar before achieving the required number of cycles.
Ključne besede: Dang Van fatigue criterion, torsion bars, pre-setting, high-cycle fatigue, residual stress
Objavljeno v DKUM: 30.11.2023; Ogledov: 317; Prenosov: 23
.pdf Celotno besedilo (7,29 MB)
Gradivo ima več datotek! Več...

4.
Experimental determination of fatigue parameters of high chromium steel under different loading and temperature conditions
Matej Drobne, Nenad Gubeljak, Srečko Glodež, 2014, izvirni znanstveni članek

Opis: Fatigue investigation of high chromium steel (HCS) at different loading ratios (R = 0, R = -1) and different temperatures (20 °C, 600 °C) is presented in this paper. Before fatigue testing, monotonic mechanical properties (ultimate compressive and ultimate tensile strength) are determined at different temperatures, using standardized testing procedures according to DIN 50125 standard. Moreover Charpy impact tests at different temperatures were done with specimens that comply with the standard ISO 14556. Fatigue testing is performed on a servo - hydraulic testing machine with consideration of different loading conditions as described above. On the basis of the experimental results the S - N curves are constructed from which typical fatigue parameters (the fatigue strength coefficient 0'f and the fatigue strength exponent b) are determined. After fatigue testing a comprehensive investigation of fracture surfaces is performed using the Scanning Electron Microscope (SEM). Experimental results presented in this paper will serve as a basis for further investigations related to fatigue behaviour of real working rolls in hot strip mills made of HCS.
Ključne besede: experiments, high chromium steel, high cycle fatigue, fracture mechanics
Objavljeno v DKUM: 12.07.2017; Ogledov: 1089; Prenosov: 133
.pdf Celotno besedilo (2,88 MB)
Gradivo ima več datotek! Več...

5.
Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material
Matej Drobne, Tomaž Vuherer, Ivan Samardžić, Srečko Glodež, 2014, izvirni znanstveni članek

Opis: Fatigue crack growth and fracture mechanics analysis of a working roll surface layer material is presented in this paper. The research is done on a hot strip mill working roll where High Chromium Steel is used for roll’s shell material. To obtain corresponding parameters, a rectangular single edge notched bend specimens – SENB, according to standard BS 7448, were used. The fatigue crack growth analysis was done on a resonant testing machine with use of special crack gauges, while for fracture mechanics parameters the electro–mechanical testing machine was used.
Ključne besede: fracture mechanics, fatigue crack growth, metal forming, rolling process, high chromium steel
Objavljeno v DKUM: 03.07.2017; Ogledov: 1192; Prenosov: 121
.pdf Celotno besedilo (1,11 MB)
Gradivo ima več datotek! Več...

6.
An integrity analysis of washing machine holders
Nenad Gubeljak, Matej Mejač, Jožef Predan, 2007, izvirni znanstveni članek

Opis: The paper deals with structure integrity analysis of the holder for the carrying cross of a washing machine drum. Premature fracture of the holder occurred between mechanical sustainable tests of washing machine in the factory. In order to prevent fracture, the task was to determine the reasons for premature fracture of the holder and to estimate the suitability of the new design of the holder cross. Input data for structure integriry analysis were obtained by material by mechanical testing of used materials. Stress and strain analysis of holder limit load was performed by finite element modeling of holder. Dynamic tests of holders with two different thicknesses were done on a servo-hydraulic machine in order to find dynamical strength and endurance of holder. Fracture behaviour of holders is defined as initiation and propagation of crack. The obtained behaviour confirmed that the new design of holders reduces stress concentration in the critical region. Consequently, the new holder subjected to the same dynamic load can endure a higher number of cycles until breakage. The total number of cycles overcomes industrial testing requirements.
Ključne besede: lomna mehanika, visokociklično utrujanje, preizkušanje lomne žilavosti, nosilci kadi pralnega stroja, mejna obremenitev, ocena celovitosti konstrukcije, fracture mechanics, high cycle fatigue, fracture toughness testing, washing machine holders, washing machine drums, structure integrity assessment, limit load
Objavljeno v DKUM: 10.07.2015; Ogledov: 1749; Prenosov: 109
.pdf Celotno besedilo (517,04 KB)
Gradivo ima več datotek! Več...

Iskanje izvedeno v 5.77 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici