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Physical properties of multi-component slag systems are of great importance for metallurgical processes, thereby many studies have shown that properties such as density, surface tension or viscosity can be predicted using previously developed models. However, nowadays there is no such framework integrating published models for calculation of slag properties and allowing for user-friendly post-processing of data. In this study, a web-based application for calculation of slag properties both in solid and liquid state was developed in Python. The web-application predicts density, heat capacity, surface tension and other properties from temperature and slag composition provided by the user and subsequently the user has the possibility to interact with and visualize data, and compare results from various models. The architecture of the web-application was designed to address interoperability and data security concepts. In addition, the modularity of the web-application was based on standardized web architectural styles to facilitate the addition of new models or functions in the future. The current work is aimed at demonstrating the key functionality of the application and initiating discussion and further collaboration for its development.

In geothermal energy, a huge energy potential lies in hydrothermal reservoirs close to magma where ultra-high temperature fluids (>450 ° C) can be harnessed. Well casing system needs to be properly designed to ensure its integrity during its service lifetime. There currently exist neither any commonly accepted design tools nor standards regulating geothermal well design under such conditions. In this study a novel tool, Casinteg, was developed for structural analyses of geothermal wells. The tool is intended to bridge the gap between simplified analytic solutions and complex FE-based commercial software. The reliability and efficiency of the constitutive models implemented in Casinteg were verified in comparison with Abaqus. Casinteg's capability for structural analyses of full geothermal wells was preliminarily investigated, using IDDP-1 well as a case study. The calculated stress in the production casing was in a good agreement between Casinteg and Ansys models, while the computational time of Casinteg simulations was within minutes. Further developments are still needed. However, preliminary results were encouraging and have demonstrated the benefit of Casinteg for efficient structural analyses of full geothermal wells.

Discrete yield surfaces for several generic texture components, including randomness, found in aluminium alloys have been generated and used to calibrate the yield function Yld2004-18p. It is generally observed that the roundness of the corners of the yield surface increases, and the stress and strain ratios flatten towards isotropic values, as the ratio of random component increases. A short investigation on the effect of number of points and homogenization approach on calibration of the yield function seems to indicate that the number of points used in the calibration has a stronger effect than the homogenization approach. Furthermore, it is also shown that setting the exponent as a free parameter in calibrating the yield function could lead to better fits. This is the authors’ accepted and refereed manuscript to the article. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in (citation of published article) and may be found at https://doi.org/10.1063/1.5112746

Sheet metal formability is traditionally described by the forming limit curve (FLC). Experimental FLCs are obtained by performing formability tests and determining failure strains. The strains are usually measured either by etching a grid on the sheet surface or by digital image correlation (DIC). Ductile metal sheets fail primarily by local necking which introduces a severe strain gradient in the failure region. This makes accurate detection of the failure strains challenging. An international standard (ISO12004-2:2008) was introduced in 2008 to unify the procedure of FLC detection; prior to this large discrepancies were observed between the results reported by different laboratories. The main limitation of the standard method for detection of forming limits is that its application is limited to cases where a single local neck is formed in the metal sheet prior to fracture. In the case of multiple local necks, the samples are simply discarded. Furthermore, the standard method does not include any guidelines to distinguish the failure by local necking and direct failure by fracture. One of the advantages of DIC over the traditional etched-grid technique is that the former allows us to obtain not only the strain distribution but also its history. This allows for alternative methods for detection of forming limit strains. This paper introduces a DIC-based method which was specially developed to handle the case of multiple local necks and to distinguish failure by local necking from direct fracture automatically. The method is not confined to a single test type and can be used in combination with different formability tests as long as DIC is used to measure strains. © 2015. This is the authors’ accepted and refereed manuscript to the article. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

The present study investigated experimentally and numerically the structural behaviour of two chamber extruded profiles in AA6060-T7 alloy subjected to axial crushing under quasi-static loading conditions. Experimental tests were performed (including uniaxial tests, in-plane shear test and plane strain tension tests) to characterize the elastic–plastic, anisotropy and fracture behaviour of the investigated material. The material under investigation exhibited anisotropic properties and isotropic yield models such as von-Mises were not able to predict correctly the shear and plane strain test behaviour. It depicted that the advanced material model with anisotropic Yld2004-18p yield function and ECL criterion was necessary to predict the material tests results (UT, ISS and PST) both in terms of force–displacement curves and ductile fracture. Axial crushing tests were also conducted to investigate the energy absorption capacity of two chamber profiles made of this alloy. A solid element-based numerical model of these component tests was established in the commercial finite element code LS-DYNA, and simulations were run with the calibrated material models and fracture criterion. The predicted force–displacement curves, the energy absorption and fracture were in a good agreement with the experimental results. These results demonstrate that numerical models can be used as a reliable design tool for optimizing aluminium profiles for automotive applications.

Smoothed particle hydrodynamics (SPH) simulations are often initialized on a regular Cartesian grid. Ten SPH kernels were analyzed numerically with respect to their ability to correctly reproduce a uniform density distribution. Three types of kernels were identified. The number of neighboring particles required to represent the density with an accuracy of 0.1% was obtained for the 10 kernels in 1, 2 and 3 dimensions. The effect of random particle displacements from grid nodes on the error was investigated. The results of the study are important for correct application of initial conditions in SPH simulations.

The effects of prestrain by rolling on the formability of AA6016 sheets in the biaxial stretching region are studied in this paper. An experimental program including formability experiments has been carried out for as-received and prestrained sheets. Forming limit strains are determined by the digital image correlation technique and then mapped into stress space using an anisotropic plasticity model in order to assess the pathindependence of forming limit stresses. Different diagrams for description of formability such as the traditional strain-based forming limit diagram (FLD), the forming limit stress diagram (FLSD) and various equivalent plastic strain based (EPS-based) diagrams are applied in order to study the effect of prestrain. It is shown that prestrain by rolling has the same effect on the forming limit strains as prestrain by plane strain tension. Furthermore, the forming limits of the virgin material nearly coincide with the forming limits of the prestrained material in the FLSD and EPS-based diagrams, serving as a conservative estimate for the prestrained material. Due to the roping phenomenon, the material displays significant anisotropy in forming limit strains. At the same time, the presence of roping does not affect the path-independence of the forming limits in the FLSD and EPS-based diagrams. © Springer-Verlag France SAS 2017. This is the authors' accepted and peer-reviewed manuscript, locked until 22 June 2018 due to copyright restrictions.The final authenticated version is available online at: http://dx.doi.org/10.1007/s12289-017-1363-6

Forming limit diagrams (FLDs) are widely used to assess metal sheet formability. Experimental FLDs are obtained by performing formability tests and determining failure strains. The standard method for detection of forming limits is based on the spatial distribution of the strains and requires formation of a single local neck. Some aluminium alloys, such as AA6016, have a tendency to form multiple strain localizations in formability tests, which can be interpreted as multiple local necks. Thus, use of the standard method is questionable for these aluminium alloys. The present paper presents an alternative, digital-image-correlation-based method for experimental detection of the onset of local necking in an aluminium sheet. The method is based on monitoring the sheet-thickness evolution, and is developed to be user independent and resistant to noise in the measurements. The method can be used in combination with different types of formability tests. The main requirement is that digital image correlation is used for strain measurements. Here, the method is initially tested on uniaxial tension tests of AA6016 aluminium alloy sheets and then extended to formability tests.

The thesis is focused on quasi-static ductile fracture in the low range of stress triaxiality of the dual-phase steel Docol 600DL. The study includes mechanical testing, theoretical aspects of ductile fracture and numerical simulations. Ductile fracture in the low range of stress triaxiality is an interesting topic since experimental data from various studies suggests that the ductility of the material is not only governed by the hydrostatic stressstate, but is also influenced by the deviatoric stress-state.The thesis consists of four journal articles bound together by a synopsis, where the introduction gives the motivation for the work and a state-of-the-art of the topics examined in this study. After the introduction, the objectives for the study are given followed by a summary of the work, conclusions and suggestions for further work. Finally the four articles are given. The articles are referred to as parts as they give detailed information of the different parts of the study.In Part I and Part II the experimental side of the study is described. These parts give detailed information regarding the material, test set-ups, specimen geometries and optical measurement procedures. The results from the experiments in form of the minor versus major principal strain as well as the stress triaxiality, the Lode parameter, and the equivalent strain at fracture are presented and used to describe the material’s fracture characteristics. Macroscopically the material displayed typical ductile behaviour with large strains before fracture. This was confirmed by scanning electron microscopy of selected specimens since all showed ductile dimples. Further, the material displayed a significant drop in ductility when exposed to plane-strain loading; an observation that suggests that the material’s fracture properties are Lode dependent.In Part III several uncoupled criteria for ductile fracture which explicitly take into account the effect of the Lode dependence were assessed. One of the criteria, the modified Mohr-Coulomb criterion, was taken from literature, while two of the criteria, the extended Cockcroft-Latham criterion and the extended Rice-Tracey criterion are augmented versions of existing criteria. The data given in Part I and II were used in evaluating the various criteria and it was found that the proposed extended Cockcroft- Latham criterion managed to give accurate predictions on the equivalent strain at fracture, while a somewhat larger spread was observed for the modified Mohr-Coulomb criterion and the extended Rice-Tracey criterion.Part IV focuses on numerical modelling of ductile crack propagation. Here the experimental tests from Part I were used in assessing the extended Cockcroft-Latham and modified Mohr-Coulomb criteria on crack propagation. Additionally the effects of using a high-exponent yield surface and material softening were investigated. It was found that the different fracture criteria as well as a change of yield function had little effect on the crack propagation. By including material softening through damage coupling, slant shear fracture as observed in some of the experiments was captured, but this did not alter the global response in form of the force-displacement curves.

Forming limit strains are used to construct a forming limit diagram (FLD), which is a diagram in the principal strain space, traditionally used for designing forming operations of sheet metals. A line indicating the boundary between safe and unsafe strains is often called the forming limit curve (FLC). FLDs are also used to evaluate results from finite element simulations. Therefore consistency and reproducibility are important. This paper deals with the experimental determination of forming limit strains from Marciniak-Kuczynski (MK) tests. The material tested is AA6016 aluminum alloy in three different conditions: virgin material and material subjected to 5% and 8% deformation by rolling. Strains were measured by the use of digital image correlation (DIC) technique. Forming limit strains were determined by the use of two automated methods. The results from the two methods are compared and evaluated regarding their applicability to the Marciniak-Kuczynski test and ability to capture actual forming limit strains.

This paper presents experimental tensile test results obtained on flat aluminum magnesium alloy samples on a hard machine. The mechanical response, kinematic fields and acoustic emissions were simultaneously obtained in an experimental setup. Propagation instabilities associated with the Portevin-Le-Châtelier effect were observed as localized intense strain increment bands. Depending on the strain rate, A, B or C types were studied on the basis of stress drops, acoustic emission and strain fields. Then the band characteristics (position, orientation, width, thickness reduction, intensity, acoustic emission, principal strain direction) were presented in various strain rate conditions.