Blar i NTNU Open på forfatter "Holmedal, Bjørn"
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Plasticity of solid solution Al-Mn and Al-Mn-Si alloys
Holmedal, Bjørn; Kula, Anna; Niewczas, marek (Journal article, 2024)The influence of Mn and Si on the mechanical properties of solid solution Al-Mn and Al-Mn-Si alloys have been studied at 4 K, 78 K, and 298 K. The solute strengthening potency of the yield strength increases with decreasing ... -
Possibilities of Improving the Structural Properties of Welded Al-Mg-Si Alloys Through Automated Local Induction Heat Treatments
Bugten, Andreas Voll (Master thesis, 2021)Det er et kjent fenomen at materialet i den varmepåvirkede sonen (HAZ) hos Al-Mg-Si-legeringer blir svekket etter sveising. Østhus et al. har designet et dataprogram som simulerer strekkprøving av sveiste Al-Mg-Si ... -
Precipitation and strengthening modeling for disk-shaped particles in aluminum alloys: Size distribution considered
Li, Yue; Holmedal, Bjørn; Li, Hongxiang; Zhuang, Linzhong; Zhang, Jishan; Du, Qiang (Journal article, 2018)For an ICME (Integrated Computational Material Engineering) modeling framework used for the age-hardening aluminum alloy design and heat treatment parameters optimization, it is critical to take into account the geometric ... -
Precipitation of Non-Spherical Particles in Aluminum Alloys Part I: Generalization of the Kampmann–Wagner Numerical Model
Holmedal, Bjørn; Osmundsen, Elisa; Du, Qiang (Journal article, 2015)Particles precipitated during aging treatments often have non-spherical shapes, e.g., needles or plates, while in the classical Kampmann–Wagner Numerical (KWN) precipitation model, it is assumed that the particles are of ... -
Precipitation, mechanical properties and early slant ductile fracture in cyclic and naturally aged Al-Zn-Mg(-Cu) alloys
Shah, Sohail; Gopal, Akash; Thronsen, Elisabeth; Hatzoglou, Constantinos; Holmedal, Bjørn (Peer reviewed; Journal article, 2022)Natural and artificial ageing treatments are compared with ageing by cyclic deformation at room temperature. Atom probe tomography and transmission electron microscopy revealed that a fine distribution of GP-zones, was ... -
Precipitation, strength and work hardening of age hardened aluminium alloys
Ryen, Øyvind; Holmedal, Bjørn; Marthinsen, Knut; Furu, Trond (Journal article; Peer reviewed, 2015)The strength and work hardening of age hardened AA6063 and AA6082 alloys have been investigated in terms of a detailed characterization of precipitate and dislocation structures obtained by TEM and SEM. Tensile and compression ... -
Press Form Hardening of Aluminium - The influence of hot forming, quench interruption and direct artificial aging on the mechanical properties of AA6082
Myrold, Benedikte Jørgensen (Master thesis, 2018)The automotive industry is in need of new lightweight solutions to meet stricter regulations regarding reduction in greenhouse gas emissions. Replacing steel components with age-hardenable high-strength aluminium alloys ... -
Regularized Yield Surfaces for Crystal Plasticity of Metals
Holmedal, Bjørn (Peer reviewed; Journal article, 2020)The rate-independent Schmid assumption for a metal crystal results in a yield surface that is faceted with sharp corners. Regularized yield surfaces round off the corners and can be convenient in computational implementations. ... -
Relationship between Al-Ni intermetallic Phases and Bond Strength in Roll Bonded Steel-Aluminum Composites with Nickel Interlayers
Arbo, Siri Marthe; Bergh, Tina; Holmedal, Bjørn; Vullum, Per Erik; Westermann, Ida (Journal article; Peer reviewed, 2019)In this work, the interface characteristics and resulting bond strength were investigated for roll bonded steel-aluminum composites with nickel interlayers, both after rolling and after post-rolling heat treatments at 400 ... -
Return-mapping algorithm for rate-independent crystal yield surface
Moradi Asadkandi, Hassan (Master thesis, 2020)Hovedmålet med dette arbeidet var å utvikle en stabil og hurtig numerisk algoritme for krystallplastisitet med vilkårlige slip systemer og krystallelastisitet. Ved å bruke en regularisert flyteflate blir metodene for ... -
A robust algorithm for rate-independent crystal plasticity
Manik, Tomas; Moradi Asadkandi, Hassan; Holmedal, Bjørn (Peer reviewed; Journal article, 2022)A new stable return-mapping algorithm enables crystal-plasticity solutions by using a regularized yield surface with very large exponents, for which the rate-independent limit of the Schmid assumption in practice is reached. ... -
A Robust Image Processing Algorithm for Optical-Based Stress–Strain Curve Corrections after Necking
Lu, Feng; Manik, Tomas; Andersen, Ida Lægreid; Holmedal, Bjørn (Peer reviewed; Journal article, 2021)To determine the stress–strain curve of a ductile material up to the fracture from a tensile test, the necking contour is measured by an optical measurement technique. The radius of the minimal cross-sectional area and the ... -
A simple method enabling efficient quantitative analysis of the Portevin–Le Chatelier band characteristics
Xu, Jianbin; Liu, Lei; Hopperstad, Odd Sture; Holmedal, Bjørn; Manik, Tomas; Marthinsen, Knut (Peer reviewed; Journal article, 2022)Localized deformation bands are often observed in materials exhibiting the Portevin–Le Chatelier (PLC) effect. However, efficient quantitative analysis of PLC bands remains challenging. A novel method is thus proposed in ... -
Spin and vorticity with vanishing rigid-body rotation during shear in continuum mechanics
Holmedal, Bjørn (Journal article; Peer reviewed, 2020)A long-standing challenge in continuum mechanics has been how to separate shear deformation and corresponding shape changes from the rotation of a continuum. This can be obtained by a new decomposition of the spin tensor, ... -
Strain-path change induced transients in flow stress, work hardening and r-values in aluminum
Mánik, Tomás; Holmedal, Bjørn; Hopperstad, Odd Sture (Journal article, 2015)Commercially pure aluminum with random texture was prestrained either by rolling or by uniaxial compression, and then tested in uniaxial tension to study the transients in flow stress, work hardening and r-value induced ... -
Strain-Path Changes in Brass (Cu-20Zn)
Hågensen, Tonje Asklund (Master thesis, 2017)Metals are often exposed to multi-path loading in the forming process. Plastic deformed in more than one direction can have significant effects on microstructural evolution and mechanical behaviour. These mechanisms and ... -
Strength contributions from precipitates
Holmedal, Bjørn (Journal article; Peer reviewed, 2015)A theory for the strength contribution from precipitates is developed based on the statistical particle-size and shape distributions and the corresponding obstacle strengths. The generic case of spherical precipitates and ... -
Stress corrections after necking using a two-parameter equation for the radius of curvature
Lu, Feng; Manik, Tomas; Holmedal, Bjørn (Peer reviewed; Journal article, 2021)Uniaxial tensile tests were conducted at room temperature, 100 °C and 150 °C, for obtaining necking-corrected stress–strain curves until fracture. The necking correction is based on specimen contours estimated from images ... -
Stress-strain relations for age hardened AlMgSi alloys, measured with necking corrections and modelled based on TEM characterization
Lu, Feng (Doctoral theses at NTNU;2021:182, Doctoral thesis, 2021)Age hardening Al-Mg-Si(-Cu) alloys, like other aluminium alloys, are increasingly utilized due to the combination of cost-saving, easy fabrication, and good mechanical properties. Yield strength and work hardening are ... -
Styrketapsreduksjon ved sveising av 6082 aluminiumlegeringer
Anderson, Magnus Johansen (Master thesis, 2022)Sveising av utfellingsherdede aluminiumlegeringer er forbundet med et betraktelig styrketap i materialet rundt sveiselinjen. Det viktigste herdebidraget i disse legeringene utgjøres av termodynamisk ustabile utfellinger. ...