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- Lundberg, Mattias, 1985-
(författare)
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Residual stresses, fatigue and deformation in cast iron
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The complex geometry of cylinder heads in heavy-duty diesel engines makes grey iron or compact graphite iron a preferred material choice due to its price, castability, thermal conductivity and damping capacity. Today’s strict emission laws have increased the demands on engine performance and engine efficiency. This means that material properties such as fatigue resistance need to be improved. Shot peening is often used to improve the fatigue resistance of components and the benefits of shot peening are associated with the induced compressive surface stresses and surface hardening. How different shot peening parameters can affect fatigue strength of grey and compact graphite iron has been investigated within the project underlying this thesis. To do this, X-ray diffraction (XRD) was utilized for residual stress measurements, scanning electron microscopy (SEM) for microstructural characterizations and mechanical fatigue testing for mechanical quantifications. The ultimate aim of this work has been to increase the fatigue resistance of cast iron by residual stress optimization.XRD measurements and SEM examinations revealed that the shot peening parameters shot size and peening intensity significantly influence residual stresses and surface deformation. Residual stress profiles, similar to the one general considered to improve the fatigue strength in steels, were obtained for both grey and compact graphite iron. Uniaxial push-pull fatigue testing on grey iron with these shot peening parameters reduced the fatigue strength with 15–20 %. The negative effect is likely related to surface damage associated with over peening and relatively high subsurface tensile residual stresses. With very gentle shot peening parameters, the uniaxial fatigue strength were unaltered from the base material but when subjected to bending fatigue an increase in fatigue strength were observed. An alternative way to increase the fatigue strength was to conduct a 30 min annealing heat treatment at 285 XC which increased the fatigue strength by almost 10 % in uniaxial loading. The improvement could be an effect of favourable precipitates forming during the annealing, which could hinder dislocation movement during fatigue.Measuring residual stresses using XRD and the sin2 -method demands accurate X-ray elastic constants (XEC) for meticulous stress analysis. The XEC referred to as 1~2s2 should therefore always be calibrated for the specific material used. The experiments conducted revealed that the XEC value is independent of the testing method used in this work. A small correction from the theoretical value should be applied when the material contains small amounts of residual stresses. The amount of residual stresses has a great impact on the XEC and thus on the stress analysis. Concluding that proper analysis of residual stresses in cast iron is not straight forward.
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| 4. |
- Allard, Bert, 1945-, et al.
(författare)
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Mining waste management in the Baltic Sea Region : Min-Novation project
- 2013
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Bok (refereegranskat)abstract
- Mining waste and what to do about it is a common challenge facing companies, local authorities, environmental organizations, policymakers and increasingly other stakeholders in several countries of the Baltic Sea Region. From 2011 to 2013, a network of scientific and regional expertise brought together in the Min-Novation project has put this topic in the spotlight. The importance of the management of waste from extractive industries is due to the substantial share this waste has in the overall stream of waste generated in the EU. In 2010, 672 Mt or 28.3% of the total waste generated in the EU was attributable to the mining and quarrying industry, second only to construction (34.4%) and ahead of manufacturing (11.0%) and households (8.7%)1. Apart from this, mining waste is the raw material for one of the more visible man-made landmarks that surround us, with waste heaps of various shapes and sizes dotting the landscape up and down the Baltic Sea Region. Despite this dual prominence, mining waste is most often seen only as an environmental problem and in no way a resource. To move away from a one-sided view of mining waste, a life-cycle approach, which recognises that value can be recovered from waste and re-introduced into the product cycle is of the essence. It cannot be stressed enough that mining waste is a source of secondary raw materials, the use of which helps to protect the natural mineral deposits for future generations. Equally important is an appreciation of how the waste can be re-cycled in the excavation process (preventionand recovery) and adapted to create value for local communities (reclamation and revitalisation). However, for there to be effective mining waste management, both in the prevention stage, as well as in the recovery stage, and finally during land reclamation many conditions must be fulfilled. Of these the most important are access to appropriate technologies and methods and common sense legislation. Another condition not without importance is social acceptance for the recovery of waste located in old landfills. The Min-Novation Network over a span of 3 years has worked to understand and appreciate mining waste both as a corporate, community, regulatory and strategic issue. Set against the background of mining activity and waste management in the partner countries: Estonia, Finland, Germany, Norway, Poland and Sweden, both good practices and problem areas, which need to be addressed have been presented in this monograph. The purpose of this monograph is to show a cross-section of topics that affect how mining waste management works today, and which will play a decisive role in whether management of mining waste remains – an issue of primarily local relevance or whether it becomes a growth opportunity of national and EU-wide importance. The monograph focuses primarily on issues related to the management of waste from extractive industries in the countries whose representatives were involved in the Min-Novation project. Examples from outside the Baltic Sea Region of the use of waste heaps as an industrial heritage of the mining regions and also as attractions for local communities are presented as well. Indeed, every experience is valuable for the environment and socio-economic development of the Baltic Sea Region.
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| 5. |
- Allard, Bert, 1945-, et al.
(författare)
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Neutralisation of an acidic pit lake by alkaline waste products
- 2014
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 21:11, s. 6930-6938
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Tidskriftsartikel (refereegranskat)abstract
- A former open pit where black shale (alum shale) was excavated during 1942-1965 has been water filled since 1966. The water chemistry was dominated by calcium and sulphate and had a pH of 3.2-3.4 until 1997-1998, when pH was gradually increasing. This was due to the intrusion of leachates from alkaline cement waste deposited close to the lake. A stable pH of around 7.5 was obtained after 6-7 years. The chemistry of the pit lake has changed due to the neutralisation. Concentrations of some dissolved metals, notably zinc and nickel, have gone down, as a result of adsorption/co-precipitation on solid phases (most likely iron and aluminium hydroxides), while other metals, notably uranium and molybdenum, are present at elevated levels. Uranium concentration is reaching a minimum of around pH 6.5 and is increasing at higher pH, which may indicate a formation of neutral and anionic uranyl carbonate species at high pH (and total carbonate levels around 1 mM). Weathering of the water-exposed shale is still in progress.
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| 9. |
- Angelstam, Per, et al.
(författare)
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Learning about the history of landscape use for the future : consequences for ecological and social systems in Swedish Bergslagen
- 2013
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 42:2, s. 146-159
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Tidskriftsartikel (refereegranskat)abstract
- Barriers and bridges to implement policies about sustainable development and sustainability commonly depend on the past development of social-ecological systems. Production of metals required integration of use of ore, streams for energy, and wood for bioenergy and construction, as well as of multiple societal actors. Focusing on the Swedish Bergslagen region as a case study we (1) describe the phases of natural resource use triggered by metallurgy, (2) the location and spatial extent of 22 definitions of Bergslagen divided into four zones as a proxy of cumulative pressure on landscapes, and (3) analyze the consequences for natural capital and society. We found clear gradients in industrial activity, stream alteration, and amount of natural forest from the core to the periphery of Bergslagen. Additionally, the legacy of top-down governance is linked to today's poorly diversified business sector and thus municipal vulnerability. Comparing the Bergslagen case study with other similar regions in Russia and Germany, we discuss the usefulness of multiple case studies.
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- Benyamine, Michelle, et al.
(författare)
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Multi-objective environmental management in constructed wetlands
- 2004
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Ingår i: Environmental Monitoring & Assessment. - 0167-6369 .- 1573-2959. ; 90:1-3, s. 171-185
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Tidskriftsartikel (refereegranskat)abstract
- We examined multi-objective environmental management as applied to pursuing concurrent goals of water treatment, biodiversity and promotion of recreation in constructed wetlands. A case study of a wetland established to treat landfill leachate, increase biodiversity, and promote recreation was evaluated. The study showed that attempts to combine pollution management with activities promoting biodiversity or recreation are problematic in constructed wetlands. This could be because the typical single-objective focus of scientific research leads to contradictions when planning, implementing and assessing the multi-objective use of wetlands. In the specific case of wetland filters for landfill leachate treatment, biodiversity, and recreation, there is a need for further research that meet practical needs to secure positive outcomes.
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