| 1. |
- Dettmann, Tobias, 1987, et al.
(författare)
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Startup Methodology for Production Flow Simulation Projects Assessing Environmental Sustainability
- 2013
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Ingår i: Proceedings of the 2013 Winter Simulation Conference. - 9781479920761 ; , s. 1926-1937
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Konferensbidrag (refereegranskat)abstract
- Environmental impact assessments for companies and products are important to increase sales and reduceenvironmental impact. To support improvements and detailed analyses, researchers have extended the useof simulation of production flows to include sustainability performance indicators. The research casesperformed until recently lack standardized methodology and thus have comparability issues and an increasenumber of common faults. By using a common methodology and gathering best practice, futurecases can gain a lot. Especially noted by the authors is that the project startup phase is critical for success.This paper proposes a methodology to support the startup phases of simulation projects with sustainabilityaspects in production flows. The methodology is developed and applied in an automotive industry studypresented in this paper. Using a rigid project startup, such as the proposed methodology, reduces iterationsduring modeling and data collection and decreases time spent on modeling.
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| 2. |
- Johansson, Björn, 1975, et al.
(författare)
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Power Level Sampling of Metal Cutting Machines for Data Representation in Discrete Event Simulation
- 2015
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 53:23, s. 7060-7070
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Tidskriftsartikel (refereegranskat)abstract
- An extension to the application area for discrete event simulation (DES) has been ongoing since the last decade and focused only on economic aspects to include ecologic sustainability. With this new focus, additional input parameters, such as electrical power consumption of machines, are needed. This paper aim at investigating how NC machine power consumption should be represented in simulation models of factories. The study includes data-sets from three different factories. One factory producing truck engine blocks, one producing brake disc parts for cars and one producing forklift components. The total number of data points analysed are more than 2,45,000, where of over 1,11,000 on busy state for 11 NC machines. The low variability between busy cycles indicates that statistical representations are not adding significant variability. Furthermore, results show that non-value-added activities cause a substantial amount of the total energy consumption, which can be reduced by optimising the production flow using dynamic simulations such as DES.
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| 3. |
- Johansson, Björn, 1975, et al.
(författare)
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Evaluation and Calculation of Dynamics in Environmental Impact Assessment
- 2013
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Ingår i: IFIP Advances in Information and Communication Technology. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1868-4238 .- 1868-422X. - 9783642403514 ; 397:1, s. 135-141
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Konferensbidrag (refereegranskat)abstract
- In ten years customers will select products not only based on price and quality but also with strong regard to the product value environmental footprint, including for example the energy consumed. Customers expect transparency in the product realization process, where most products are labeled with their environmental footprint. Vigorous companies see this new product value as an opportunity to be more competitive. In order to effectively label the envi-ronmental impact of a product, it is pertinent for companies to request the envi-ronmental footprint of each component from their suppliers. Hence, companies along the product lifecycle require a tool, not only to facilitate the computing of the environmental footprint, but also help reduce/balance the environmental impact during the lifecycle of the product. This paper proposes to develop a procedure that companies will use to evaluate, improve and externally advertise their product’s environmental footprint to customers.
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| 4. |
- Ståhle, Alexander, et al.
(författare)
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Designguide för Smarta gator
- 2022
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Designguiden för smarta gator konkretiserar hur de fyra megatrenderna urbanisering, digitalisering, samhällsförändringar och miljöförändringar leder till nya krav och utformningsprinciper för framtidens gator. Guiden är tänkt att fungera som en inspiration och ett underlag för att förnya svensk gatupolicy på nationell, regional och kommunal nivå.Guiden innehåller utöver en inledning följande kapitel: en historisk tillbakablick (gatans utveckling), gatans användning, gatans delar, gatans design, designprocessen, guidens genomförande.
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| 5. |
- Andersson, Björn, 1989
(författare)
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Thermo-Mechanical-Metallurgical Modelling of Pearlitic Steels and Railhead Repair Welding
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The efficiency of rail transport is attributed to low rolling resistance, which comes at the cost of high contact pressures between rail and wheel. Consequently, both the rail and wheel can be susceptible to fatigue crack initiation and propagation due to the resulting high stresses and large number of load cycles in service. Therefore, the mechanical performance of the rail and wheel material is critical for safe operation. Thermal loading, such as that caused by wheel locking or railhead repair welding, can cause gradual or drastic changes in local material behaviour, resulting in significant detrimental effects to the rail and wheel. This thesis presents a phenomenological modelling framework for numerical simulations of the thermo-metallurgical-mechanical behaviour of pearlitic railway steels during and after high-temperature thermal loading. The framework consists of a material model that incorporates cyclic hardening plasticity, phase transformation kinetics, transformation-induced plasticity, multi-phase homogenisation, and recovery of the virgin material state after cyclic melting and solidification. The ability of the model to simulate intricate thermo-metallurgical-mechanical behaviour is demonstrated in quasi-static material point simulations. The material model is implemented in a finite element framework to obtain a simulation-based tool that balances computational efficiency, simulation fidelity, and engineering applicability. Several simulations demonstrate the effectiveness of this tool, including simulations of a wheel flat, laser-induced martensitic patches on the rail surface, and railhead repair welding processes. The simulation-tool is also validated against experimental data, in terms of residual material states after high-temperature processes. The thesis provides insights into the evolution of material phases and stresses under thermal loading in high-temperature railway processes, as well as the redistribution of residual stresses during subsequent operational loading conditions. For instance, simulations of the railhead repair welding process indicate that pre-heating has a minor impact on the quality of the repair, while the welding build-up paths have a significant impact. The simulations also highlight the critical region for fatigue crack initiation by showing how residual tensile stresses are reduced near the surface of the rail or wheel and increased at some distance below during operation for the repaired rail.
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| 6. |
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| 7. |
- Jain, Sanjay, et al.
(författare)
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A Hierarchical Approach for Evaluating Energy Trade-offs in Supply Chains
- 2013
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Ingår i: International Journal of Production Economics. - : Elsevier BV. - 0925-5273. ; 146:2, s. 411-422
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Tidskriftsartikel (refereegranskat)abstract
- Supply chain design and operational decisions may impact the energy needed to keep the products flowing through to the customers. It is a challenge to determine the energy consumption and even more challenging to understand the impact of design and operational decisions on the energy consumption along the supply chain. This paper presents a hierarchical simulation based approach for estimating the energy consumption to keep the products flowing through a supply chain. System dynamics simulation is used at a high abstraction level to understand the major factors that may affect the energy consumption. Discrete event simulation is then used to delve down in detail for evaluating the critical stages in the supply chain. A case study for a closed loop supply chain of forklift brakes is used as an example of application of the approach. (C) 2013 Elsevier B.V. All rights reserved.
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| 8. |
- Svensson, Magnus, et al.
(författare)
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Unsupervised deviation detection by GMM - A simulation study
- 2011
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Ingår i: SDEMPED 2011. - Piscataway, N.J. : IEEE Press. - 9781424493036
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Konferensbidrag (refereegranskat)abstract
- A new approach to improve fault detection of electrical machines is proposed. The increased usage of electrical machines and the higher demands on their availability requires new approaches to fault detection. In this paper we demonstrate that it is possible to detect a certain fault on a PMSM (Permanent Magnet Synchronous Machine) by using multiple similar motors, or a single motor, to build a norm of expected behavior by monitoring signal relations. This means that the machine is monitored in an unsupervised way. Four levels of an increased temperature in the rotor magnets have been investigated. The results are based on simulations and the signals used (for relation measurements) are available in a real motor installation. The method shows promising results in detecting two of the temperature faults. © 2011 IEEE.
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| 9. |
- Andersson, Björn, 1989, et al.
(författare)
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Homogenization based macroscopic model of phase transformations and cyclic plasticity in pearlitic steel
- 2022
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Ingår i: Journal of Thermal Stresses. - : Informa UK Limited. - 0149-5739 .- 1521-074X. ; 45:6, s. 470-492
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Tidskriftsartikel (refereegranskat)abstract
- In this contribution macroscopic modeling of phase transformations and mechanical behavior of low alloy steels are developed and investigated. Such modeling is of importance in simulations of transient thermo-mechanical processes which can cause phase transformations, examples from the railway industry include train braking induced frictional heating as well as rail grinding and welding operations. We adopt a modeling approach which includes phase transformation kinetics and individual constitutive models for the phases in combination with different homogenization methods. Algorithmic implementations of the isostrain, isostress and self-consistent homogenization methods are presented and demonstrated in finite element simulations of a laser heating experiment. Stress field results from the different homogenization methods are compared against each other and also against experimental data. The importance of including transformation induced plasticity in the modeling is highlighted, as well as the multi-phase stages of the heating and cooling.
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| 10. |
- Andersson, Björn, 1989
(författare)
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Modeling of phase transformations and cyclic plasticity in pearlitic steels
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The low rolling resistance in railway transportation is a key factor for its high efficiency, but it comes at the price of very high contact pressure between the rail and wheel. Due to the high stresses and the large number of load cycles during railway operation, both the rail and the wheel can be susceptible to fatigue crack initiation and propagation. Furthermore, thermal loads due to frictional heating can generate high temperature in the material surface layers leading to gradual or drastic changes in material behavior. Other events that may cause such high temperatures include welding or grinding of the rail. In this thesis, a modeling framework for phase transformations and cyclic plasticity of pearlitic steel is developed. The framework allows for modeling of the thermo-mechanical behavior of the individual phases. The implemented phase transformation kinetics in heating events include austenitization and possible tempering of martensite, and in cooling events the formation of pearlite, bainite, and martensite. Cyclic plasticity is incorporated in the model by using a Chaboche plasticity model with a von Mises yield function, non-linear isotropic and kinematic hardening. The capability of the modeling framework is demonstrated by studying the development of residual stresses during a double wheel flat scenario on the tread of a railway wheel followed by rolling contact loadings. Further, the modeling framework is extended and improved by accounting for transformation induced plasticity (TRIP). To further improve the model, the influence of the choice of homogenization method is evaluated. Four methods are considered; iso-strain, iso-stress, self-consistent method and the linear mixture rule. These show different behavior during the multi-phase stages in simulations of a laser heated rail surface, which in turn affects the residual stress states. Although the conclusions are not entirely clear, comparison with experimental data indicates that the iso-strain and the self-consistent method are the most promising, with a slight advantage to the latter. The thesis also presents an attempt at using the developed material model and the linear mixture rule in a simple butt-weld simulation, which can be seen as a first step towards simulation of repair welding of rails. The simulation includes a moving heat source and continuous addition of filler material. Preliminary results show that residual stress fields found for similar examples in the literature can be reproduced. Therefore, it is believed that the simulation methodologies developed in Papers A and B can be used as a basis for future developments towards simulations of repair welding of rails.
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