| 41. |
- Radovan, Drazumeric, et al.
(författare)
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Truing of diamond wheels - Geometry, kinematics and removal mechanisms
- 2018
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Ingår i: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 1726-0604 .- 0007-8506. ; 67:1, s. 345-348
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Tidskriftsartikel (refereegranskat)abstract
- An investigation is made into traverse truing of diamond grinding wheels using various truing grit types, grit sizes and truing parameters. Geometry and kinematics of the truing contact are modeled. Specific energies are found to depend on truing-grit size but not on truing parameters, indicating little to no size effect. Removal mechanisms are analyzed via SEM examination of diamond- and truing-wheel swarf. A fundamental relationship is established relating the truing compliance number to the truing efficiency, which encompasses truing parameters and truing- and diamond-grit sizes. Recommendations are made for optimum conditions to minimize force-constrained truing time.
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| 42. |
- Söderberg, Rikard, 1963, et al.
(författare)
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An information and simulation framework for increased quality in welded components
- 2018
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Ingår i: CIRP Annals - Manufacturing Technology. - : Elsevier BV. - 1726-0604 .- 0007-8506. ; 67:1, s. 165-168
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Tidskriftsartikel (refereegranskat)abstract
- The recent trend toward using simulation models with real-time data as digital twins is rapidly increasing in industry. In this paper, a digital framework supporting real-time geometrical quality control of welded components, is presented. The concept is based on a structured process model for all operations included in typical welding, strategies for selective assembly, automatic adjustment of fixtures and optimization of weld sequence. The concept utilizes recently developed algorithms for fast welding simulation and in-line scanning to be used in the optimization loop of an automated welding station—a digital twin for a welding cell.
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| 43. |
- Paik, Jeom Kee, et al.
(författare)
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Full-scale collapse testing of a steel stiffened plate structure under axial-compressive loading at a temperature of −80°C
- 2021
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Ingår i: Ships and Offshore Structures. - : Informa UK Limited. - 1754-212X .- 1744-5302. ; 16:3, s. 255-270
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the paper was to develop a test database of the ultimate strength characteristics of full-scale steel stiffened plate structures under axial compressive loading at a temperature of −80°C. This paper is a sequel to the authors’ articles (Paik et al. 2020a, https://doi.org/10.1016/j.istruc.2020.05.026 and Paik et al. 2020b, https://doi.org/10.1080/17445302.2020.1787930). In contrast to the earlier articles associated with room temperature or cryogenic condition, this paper investigated the effect of a low temperature at −80°C which is within the boundary range of temperature of the ductile-to-brittle fracture transition for carbon steels. A material model representing the test conditions was also proposed to capture the characteristics of carbon steels at low temperatures both in tension and in compression, and it was used in finite element method simulations of the full-scale experiment. A comparison between numerical analyses and experiments showed that the proposed model could successfully predict the failure modes and ultimate strength characteristics at low temperatures for stiffened plate structures under axial compressive loading conditions.
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| 44. |
- Shetty, Sandeep
(författare)
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Optimization of Vehicle Structures under Uncertainties
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advancements in simulation tools and computer power have made it possible to incorporate simulation-based structural optimization in the automotive product development process. However, deterministic optimization without considering uncertainties such as variations in material properties, geometry or loading conditions might result in unreliable optimum designs. In this thesis, the capability of some established approaches to perform design optimization under uncertainties is assessed, and new improved methods are developed. In particular, vehicle structural problems which involve computationally expensive Finite Element (FE) simulations, are addressed.The first paper focuses on the evaluation of robustness, given some variation in input parameters, the capabilities of three well-known metamodels are evaluated. In the second paper, a comparative study of deterministic, reliability-based and robust design optimization approaches is performed. It is found that the overall accuracy of the single-stage (global) metamodels, which are used in the above study, is acceptable for deterministic optimization. However, the accuracy of performance variation prediction (local sensitivity) must be improved. In the third paper, a decoupled reliability-based design optimization (RBDO) approach is presented. In this approach, metamodels are employed for the deterministic optimization only while the uncertainty analysis is performed using FE simulations in order to ensure its accuracy.In the fifth paper, two new sequential sampling strategies are introduced that aim to improve the accuracy of the metamodels efficiently in critical regions. The capabilities of the methods presented are illustrated using analytical examples and a vehicle structural application.It is important to accurately represent physical variations in material properties since these might exert a major influence on the results. In previous work these variations have been treated in a simplified manner and the consequences of these simplifications have been poorly understood. In the fourth paper, the accuracy of several simple methods in representing the real material variation has been studied. It is shown that a scaling of the nominal stress-strain curve based on the Rm scatter is the best choice of the evaluated choices, when limited material data is available.In this thesis work, new pragmatic methods for non-deterministic optimization of large scale vehicle structural problems have been developed. The RBDO methods developed are shown to be flexible, more efficient and reasonably accurate, which enables their implementation in the current automotive product development process.
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| 45. |
- Forsman, Fredrik, 1973, et al.
(författare)
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Teamwork as joint activity in sailing
- 2016
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Konferensbidrag (refereegranskat)abstract
- Sailing is a sport and activity that takes a long time both to learn and to master, as much of its competence-based knowledge is acquired through experience. Experiencebased learning is very important, time-intensive, and the factors for success are often tacit and hidden. Should these success factors become explicit and salient, learning would occur faster and produce obvious competitive advantages. This research was conducted by embedding on-going research results into two competitive sailing teams racing in different classes, one offshore keelboat racing with a crew of eight, and a one-design Star-class racing yacht with a crew of two. The data collection consisted of observations, interviews, and video recordings. The results were also verified with the crews to catch biases in the analysis process. A jibe, a specific but common maneuver was analyzed from the perspective of Common Ground within Joint Activity. Maneuvering a competitive offshore sail racer or a previously Olympic Star-class yacht are tasks that fulfill the requirements for Joint Activity. A high level of Common Ground is required for the effective coordination needed in order to perform at a high level and maintain the safety of the crew and equipment. Breakdowns in the coordination of maneuvers were observed, although they must be recorded on video for higher analysis reliability. To achieve greater validity, more and different maneuvers should be considered within the analysis. By better understanding the factors for success, sail racing teams can more quickly gain competence and thus competitive advantages. The research analyzes the teamwork found in sailing from the perspective of Joint Activity and Common Ground and provides insight into how to achieve performance improvements more efficiently.
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| 46. |
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| 47. |
- Johannisson, Wilhelm, et al.
(författare)
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Multifunctional performance of a carbon fiber UD lamina electrode for structural batteries
- 2018
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Ingår i: Composites Science And Technology. - : Elsevier. - 0266-3538 .- 1879-1050. ; 168, s. 81-87
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Tidskriftsartikel (refereegranskat)abstract
- In electric transportation there is an inherent need to store electrical energy while maintaining a low vehicle weight. One way to decrease the weight of the structure is to use composite materials. However, the electrical energy storage in today's systems contributes to a large portion of the total weight of a vehicle. Structural batteries have been suggested as a possible route to reduce this weight. A structural battery is a material that carries mechanical loads and simultaneously stores electrical energy and can be realized using carbon fibers both as a primary load carrying material and as an active battery electrode. However, as yet, no proof of a system-wide improvement by using such structural batteries has been demonstrated. In this study we make a structural battery composite lamina from carbon fibers with a structural battery electrolyte matrix, and we show that this material provides system weight benefits. The results show that it is possible to make weight reductions in electric vehicles by using structural batteries.
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| 48. |
- Osvalder, Anna-Lisa, 1961, et al.
(författare)
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Children's attitudes towards comfort and safety of an extra seatbelt during car travelling
- 2014
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Ingår i: 46th Annual Nordic Ergonomics Society (NES), Aug 17-20, Copenhagen, Denmark.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this study was to identify and analyse children’s attitudes regarding comfort and safety of extra seatbelts in the car rear seat. Together with the existing three- point belt the extra seatbelt holds the child in a more upright and forward facing position, which is the desired sitting position for optimal protection. Focus groups were used to identify attitudes of 11 Swedish children between 8-10 years. First attitudes towards the standard three-point seat belt were discussed then two different extra seat belt concepts were introduced verbally with pictures. Finally the two concepts were tested in the rear seat of a car.The results showed that the children were much aware of car safety issues but also influenced by their parents’ attitudes regarding safety. They said the seat belt is good since it provides a feeling of safety and protection, even though it sometimes makes it uncomfortable to travel. The children reacted positively on the extra seat belts and considered them as nicer, simpler, more comfortable and cooler to use than solely the three- point belt. They also wished to have extra seat belts in their own car due to increased safety. However they were also much annoyed by discomfort. For some children the extra seat belt caused chafing to the neck or unpleasant pressure on their upper body. They also felt trapped because it reduced the possibility to move freely.To conclude the children showed high acceptance of extra seat belts based on their first impression, much due to that their parents want them to be safe. However, after testing the concepts for only a couple of minutes, some concerns arose regarding comfort and handling aspects. The children believed that if the extra seat belt would cause discomfort or be troublesome to handle, it would result in decreased usage.
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| 49. |
- Bergsjö, Dag Henrik, 1980, et al.
(författare)
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A Model to Evaluate Efficiency,Quality, and Innovation through User Satisfaction with Information Management Systems
- 2007
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Ingår i: Proceedings of CSER'07.
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Konferensbidrag (refereegranskat)abstract
- A statistical model for measuring user satisfaction in information management systems is presented. An evaluation of the model is made, based on previous qualitative studies as well as preliminary results of a quantitative data collection. A discussion is made of the fulfilment of statistical assumptions regarding the model. The model is tested by performing an exploratory factor analysis.Further, the future possibilities to perform a partial least squares (PLS) analysis in order to study how the proposed variables relate to user satisfaction, efficiency, information quality and innovation is discussed. The aim of this paper is to evaluate the questionnaire and statistical model by one case study.
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| 50. |
- Bergsjö, Dag Henrik, 1980
(författare)
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The PLM user perspective: identification of user needs and their organisational impacts
- 2015
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Ingår i: International Journal of Product Lifecycle Management. - 1743-5129 .- 1743-5110. ; 8:2, s. 172-187
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the user perspective when implementing and improving PLM in anorganisation. The main issues investigated are how to efficiently identify, collect andprioritise the engineers' need towards PLM. This paper presents results from one qualitativeand one quantitative case study performed at one independent automotive OEM, in Sweden.The case studies show that there are means to collect user-requirements efficiently thatrepresent both the management and the engineering needs of the organisation
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