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  • 1.
    Erikson, Martin G
    et al.
    University of Borås, Sweden.
    Eriksson, Anita
    University of Borås, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Nagy, Agnes
    University of Borås, Sweden.
    Richards, Tobias
    University of Borås, Sweden.
    A conceptual model of how research can influence student development2017In: Connecting Higher Education International perspectives on research-based education BOOK OF ABSTRACTS. Tues 27 June to Wed 28 June 2017. London, United Kingdom, 2017, p. 71-72, article id 86Conference paper (Refereed)
  • 2.
    Hedberg, Claes M.
    et al.
    Blekinge Institute of Technology, Sweden.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Sara A.K.
    Blekinge Institute of Technology, Sweden; Acoustic Agree AB, Sweden.
    Haller, Kristian C.E.
    Acoustic Agree AB, Sweden.
    Kjell, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Hellbratt, Sven Erik
    Kockums AB, Sweden.
    Ultrasonic monitoring of a fiber reinforced plastic: Steel composite beam during fatigue2012In: Proceedings of the 6th European Workshop - Structural Health Monitoring 2012, EWSHM 2012, 2012, Vol. 2, p. 1254-1260p. 1254-1260Conference paper (Refereed)
    Abstract [en]

    The use of composite superstructures on current or newly built steel hulls is a recently emerged technology. The economic estimations predict that the extra costs for putting composite superstructures, with the present safety margins, on steel ships will be paid back in only 2-3 years. This also makes the ships having smaller ecological footprints with less fuel consumption and CO2 emissions. In this stage of development it is needed to ensure the durability of the joints between the steel and glass fiber reinforced plastic. The first step is that the joints must first be proven to withstand fatigue. In this test a 4-meter beam, which represents the joint, were investigated for fatigue progression by a four-point-bending fatigue test. In order to show that ultrasonic material monitoring techniques can be used to monitor the damage progression, the beam was measured during the tests until failure. The test was successful both in showing that the joint could withstand high levels of mechanical exposure, and in that the ultrasonic techniques accompanied the damage progression which means that they may be used on vessels during operation.

  • 3.
    Holmgren, Magnus Andreas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Kjell, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Lundh, Karin
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Misalignment in Fatigue Testing Machines, a Nordic Laboratory Intercomparison NICe project 041492006Report (Refereed)
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  • 4.
    Holmgren, Magnus
    et al.
    RISE - Research Institutes of Sweden.
    Johansson, Klas
    RISE - Research Institutes of Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden.
    Svensson, Thomas
    RISE - Research Institutes of Sweden.
    Inter-laboratory comparison of a fatigue test2005In: Materialprüfung, Vol. 47, p. 529-533Article in journal (Refereed)
  • 5.
    Håkansson, Måns
    et al.
    Saab Kockums, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Cost and weight ofcomposite ship structures: A parametric study based on Det Norske Veritasrules?2017In: IMechE Part M - Journal of Engineering for the Maritime Environment, Vol. 232, no 3, p. 331-350Article in journal (Refereed)
    Abstract [en]

    A wider use of composites in larger, commercial vessels has been limited by initial costs and fire regulations, but both of these obstacles are diminishing. Increasing fuel costs and more stringent emission requirements have heightened the value of lightweight structures. Due to the higher acquisition costs and other entry barriers, composite designs must be as cost efficient as possible in order to compete with traditional steel or aluminium designs. The purpose of this article is to investigate which fibre-reinforced polymer materials and types of structures are most suitable for different parts of a ship design in order to minimize weight or cost. This is done by designing and comparing individual composite panels while varying a wide range of input parameters and strictly following the ‘Det Norske Veritas (DNV) Rules for Classification of High Speed, Light Craft and Naval Surface Craft’. The results are presented as weight and cost comparisons between materials and structures and also degree of utilization for the different design criteria; carbon fibre structures are on the average 20%–30% lighter than glass fibre structures but are consistently more expensive. The results also indicate that sandwich panels in most cases are lighter than single-skin panels, and that for sandwich structures, the mechanical properties of the core material are commonly the critical design criterion. The minimum amount of reinforcement stipulated by the rules is also found to be a critical factor.

  • 6. Högström, P
    et al.
    Ringsberg, J
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    An experimental and numerical study of the effects of length scale and strain state on the necking and fracture behaviours in sheet metals2009In: International Journal of Impact Engineering, Vol. 36, p. 1194-1203Article in journal (Refereed)
  • 7. Högström, P
    et al.
    Ringsberg, J
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Analysis of a struck ship with damage opening - influence from model and material properties uncertainties.2010Conference paper (Refereed)
  • 8. Högström, P
    et al.
    ringsberg, J
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Experimental verification of finite element failure criteria with respect to strain state and element size2009Conference paper (Refereed)
  • 9.
    Johannesson, Pär
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Lang, X.
    Chalmers University of Technology, Sweden.
    Yang, S. -H
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Ringsberg, J. W.
    Chalmers University of Technology, Sweden.
    Mechanical reliability of flexible power cables for marine energy2021In: Proceedings of the European Wave and Tidal Energy ConferencePages 2146-1 - 2146-102021, European Wave and Tidal Energy Conference Series , 2021, p. 2146-1-2146-10Conference paper (Refereed)
    Abstract [en]

    Marine power cables play a crucial role to utilize energy in marine areas, such as offshore wind, wave energy and tidal energy. Marine energy devices are typically grouped into arrays to increase the economic viability, and power cables transfer the energy from the devices to a central hub which is then transmitted ashore. Cables connected to moving devices may experience millions of load cycles per year, and thus they need to be flexible and designed for mechanical loads due to the movements of the cable. In this study, the focus is on the mechanical life of flexible cables connecting devices to hubs, and thus lowand medium voltage power cables is the focus. The reliability design method Variational Mode and Effect Analysis (VMEA) is applied that is based on identifying and quantifying different types of uncertainty sources, such as scatter, model uncertainties and statistical uncertainties. It implements a load-strength-approach that combines numerical simulations to assess the loads on the cable and experimental tests to assess the strength of the cable. The VMEA method is demonstrated for an evaluation of bending fatigue, and it has been found to be a useful tool to evaluate uncertainties in fatigue life for cables in WEC (Wave Energy Converter) systems during the design phase. The results give a firm foundation for evaluation of safety against fatigue and are also helpful for identifying weak spots in the reliability assessment that can motivate actions  in the improvement process. Uncertainties in terms of scatter, statistical uncertainty and model uncertainty have been evaluated with respect to the WaveEL 3.0, a WEC designed by the company Waves4Power, and deployed in Runde, Norway. A major contribution to the overall uncertainty is found to originate from the fatigue life model, both in terms of scatter and model uncertainty. 

  • 10.
    Johannesson, Pär
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Lang, Xiao
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics. Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W
    Chalmers University of Technology, Sweden.
    Mechanical Reliability Analysis of Flexible Power Cables for Marine Energy2022In: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 10, no 6, article id 716Article in journal (Refereed)
    Abstract [en]

    Marine power cables connected to moving devices at sea may experience millions of load cycles per year, and thus they need to be flexible due to the movements of the cable and designed for mechanical loads. In this study, the focus is on the mechanical life of flexible low-and medium voltage power cables connecting devices to hubs. The reliability design method Variational Mode and Effect Analysis (VMEA) is applied, based on identifying and quantifying different types of uncertainty sources, including scatter, model and statistical uncertainties. It implements a load–strength approach that combines numerical simulations to assess the loads on the cable and experimental tests to assess the strength of the cable. The VMEA method is demonstrated for an evaluation of bending fatigue, and is found to be a useful tool to evaluate uncertainties in fatigue life for WEC (Wave Energy Converter) system cables during the design phase. The results give a firm foundation for the evaluation of safety against fatigue and are also helpful for identifying weak spots in the reliability assessment, thereby motivating actions in the improvement process. Uncertainties in terms of scatter, statistical uncertainty and model uncertainty are evaluated with respect to the WaveEL 3.0, a WEC designed by the company Waves4Power, and deployed in Runde, Norway. A major contribution to the overall uncertainty is found to originate from the fatigue life model, both in terms of scatter and model uncertainty. © 2022 by the authors. 

  • 11. Johansson, J
    et al.
    Leisner, Peter
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Elektronik.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Belov, Ilja
    An approach to life consumption monitoring of solder joints in operating temperature environment2012Conference paper (Refereed)
  • 12.
    Johansson, Jonas
    et al.
    Saab, Sweden; Jönköping University, Sweden.
    Belov, Ilja
    Jönköping University, Sweden.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Dudek, Rainer
    Fraunhofer, Germany.
    Leisner, Peter
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Elektronik.
    Investigation on thermal fatigue of SnAgCu, Cu100C, and SnPbAg solder joints in varying temperature environments2014In: Microelectronics Reliability, Vol. 54, no 11, p. 2523-2535Article in journal (Refereed)
    Abstract [en]

    Thermal cycling tests have been performed for a range of electronic components intended for avionic applications, assembled with SAC305, SN100C and SnPbAg solder alloys. Two temperatureprofiles have been used, the first ranging between -20 °C and +80 °C (TC1), and the second between -55 °C and +125 °C (TC2). High level of detail is provided for the solder alloy composition and the component package dimensions, and statistical analysis, partially supported by FE modeling, is reported. The test results confirm the feasibility of SAC305 as a replacement for SnPbAg under relatively benign thermomechanical loads. Furthermore, the test results serve as a starting point for estimation of damage accumulation in a critical solder joint in field conditions, with increased accuracy by avoiding data reduction. A computationally efficient method that was earlier introduced by the authors and tested on relatively mild temperature environments has been significantly improved to become applicable on extended temperature range, and it has been applied to a PBGA256 component with SAC305 solder in TC1 conditions. The method, which utilizes interpolated response surfaces generated by finite element modeling, extends the range of techniques that can be employed in the design phase to predict thermal fatigue of solder joints under field temperatureconditions.

  • 13.
    Johansson, Jonas
    et al.
    Saab, Sweden.
    Belov, Ilja
    Jönköping University, Sweden.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Leisner, Peter
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Elektronik. Jönköping University, Sweden.
    A computational method for evaluating the damage in a solder joint of an electronic package subjected to thermal loads2014In: Engineering computations, ISSN 0264-4401, E-ISSN 1758-7077, Vol. 31, no 3, p. 467-489, article id 17110717Article in journal (Refereed)
    Abstract [en]

    Purpose-The purpose of this paper is to introduce a novel computational method to evaluate damage accumulation in a solder joint of an electronic package, when exposed to operating temperature environment. A procedure to implement the method is suggested, and a discussion of the method and its possible applications is provided in the paper. Design/methodology/approach- Methodologically, interpolated response surfaces based on specially designed finite element (FE) simulation runs, are employed to compute a damage metric at regular time intervals of an operating temperature profile. The developed method has been evaluated on a finite-element model of a lead-free PBGA256 package, and accumulated creep strain energy density has been chosen as damage metric. Findings-The method has proven to be two orders of magnitude more computationally efficient compared to FE simulation. A general agreement within 3 percent has been found between the results predicted with the new method, and FE simulations when tested on a number of temperature profiles from an avionic application. The solder joint temperature ranges between +25 and +75 °C. Practical implications-The method can be implemented as part of reliability assessment of electronic packages in the design phase. Originality/value-The method enables increased accuracy in thermal fatigue life prediction of solder joints. Combined with other failure mechanisms, it may contribute to the accuracy of reliability assessment of electronic packages.

  • 14.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    A method for assessment of the survival time of a ship damaged by collision2011In: Transactions - Society of Naval Architects and Marine Engineers, ISSN 0081-1661, Vol. 119, p. 603-619Article in journal (Refereed)
  • 15.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Measurement of forces and neutral temperatures in railway rails - an introductory study2004Report (Refereed)
    Abstract [sv]

    Railway business (both in Sweden and internationally) is in need of efficient and non-destructive methods for convenient measurements of the neutral temperature. Banverket has hitherto made some investigations of different such methods and this analysis aims in this perspective to · Identify different techniques and methods that are possible to use for measuring the neutral temperature and sort out those that are not useful for rail applications. · Give the theoretical basis for each method in order to obtain a firm base for further investigations and judgements. · Perform critical examinations of the development potential, cost and time consumption for each of the methods and identifying those methods and equipments that are of most interest for further investigations. · Identify additional actions to be taken in combination with efficient neutral temperature determinations for reduction of the heat distortion risk in CWR-tracks. The following methods are possible candidates for further investigations: Ultrasonic methods Based on either the longitudinal wave principle or the birefringence principle with methods developed by, for example, NIST and RIPL. Deformation methods Based on measurements of either strains or of positions with commercial methods as the Pfender device, the MS-02 device, the MP method or the geodesic method. Magnetic methods The Barkhausen noise principle seems to be more promising than the magnetic parameter method with developed testing methods by Railscan, Railtest and Rollscan. X-ray diffraction method Based on diffraction of X-rays in crystal planes, portable equipment exists although the method has traditionally been used under laboratory conditions. Rail vibration techniques method Based on the relation between stiffness and force in combination with an accurate laser measurement system, this method is a promising alternative. In parallel to improved measurement techniques for neutral temperature, a list of possible additional actions has been identified. These are additional logical ways to reduce the risk for rail heat distortions and they do not have any technical solutions today. The author is currently not aware of all possible efforts that have been made regarding these issues but they should be kept in mind during future work. For example: · Could rail cooling be performed by heat conduction to the cooler regions below the track? · Should the neutral temperature be increased (cf. chapter 3)? · Could rail grinding improve the mechanical integrity? · Are there possible modifications of the CWR-concept itself that could reduce the thermal stress build up? · One obvious action is to improve the lateral resistance of the track region. This is the main focus of the accompanying report within this preliminary study. This preliminary study shows that there exist promising methods that would improve the measurements of neutral temperature. When this preliminary study is completed, it is therefore proposed that actions are taken for more detailed investigations of the one or two most promising methods. This should be done through field studies and laboratory studies in Sweden but also, where appropriate, through visits to places in Europe where the methods have been evaluated. It would also be of interest to study additional ways of reducing the risk for rail heat distortions.

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  • 16.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Modelling approaches for reliability estimations of fibre-reinforced plastic laminates2014In: Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE 2014, 2014Conference paper (Refereed)
    Abstract [en]

    Numerous methodologies for estimating the reliability of composites have been published in the past few decades. This paper presents the experiences and findings by the authors regarding an assessment of different mechanical and probabilistic models for the calculation of reliability estimates of fibre-reinforced plastic laminates. The assessment was performed to determine the manner by which the models influence the reliability estimations. This knowledge is used to determine the most suitable combination of models for reliability-based design optimization of marine structures made out of fibre-reinforced plastics. The assessment consists of a brief overview of a number of probabilistic and mechanical models as well as the computation of reliability estimates for a number of fibre-reinforced laminates through Monte Carlo simulations. Among some of the findings, it was found that the definition of matrix cracking and the choice of mechanical model (description of damage initiation and development) influence significantly the reliability estimations of fibre-reinforced plastic laminates.

  • 17.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Strukturer och Komponenter.
    Optimization of composite maritime structures - effects of uncertainties on design criteria limits.2011In: Proceedings of the Third International Conference on Marine Structures (MARSTRUCT2011), 2011, , p. 707-714Conference paper (Refereed)
  • 18.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Simulations of microcracking in the process region of ceramics with a cell model2001In: International journal of fracture, Vol. 111, no 4, p. 36-380Article in journal (Other academic)
  • 19.
    Johnson, Erland
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Högström, P
    Schreuder, M
    Jansson, E
    A method for assessment of the survival time of a ship damaged by collision.2011In: Journal of Ship Research, Vol. 55, no 2, p. 86-99Article in journal (Refereed)
  • 20.
    Johnson, Erland
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Högström, P
    Schreuder, M
    Jansson, E
    Survivability analysis of a struck ship with damage opening - influence from model and material properties uncertainties2011In: Ships and Offshore Structures, ISSN 1744-5302, E-ISSN 1754-212X, Vol. 6, no 4, p. 339-354Article in journal (Refereed)
  • 21.
    Johnson, Erland
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Johansson, Klas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Svensson, Thomas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Holmgren, Magnus
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Reflections regarding uncertainty of measurement, on the results of a Nordic fatigue test interlaboratory comparison2005In: Accreditation and Quality Assurance, ISSN 0949-1775, E-ISSN 1432-0517, Vol. 10, no 5, p. 208-213Article in journal (Refereed)
  • 22.
    Johnson, Erland
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Svensson, Thomas
    Choice of Complexity in Constitutive Modelling of Fatigue Mechanisms.2009In: Robust Design Methodology for Reliability: Exploring the Effects of variation and uncertianity / [ed] edited by redigerad av Bo Bergman,Jacques de Mare,Thomas Svensson,Sara Loren, 2009, p. 133-144Chapter in book (Other academic)
  • 23.
    Johnson, Erland
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Svensson, Thomas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Choice of complexity in constitutive modelling of fatigue mechanisms2005Report (Refereed)
    Abstract [en]

    The uncertainties in the virtual design stages of the product development chain are considered. The current computer capacity enables the processing of complex models to handle these steps. However, in the present work it is shown that the prediction capacity is not always favoured by an increased model complexity. In fact, it is observed that the prediction capacity deteriorates when the complexity exceeds a certain level. An example is shown and its implication for fatigue design are discussed. Key words: fatigue, model complexity, prediction uncertainty

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    FULLTEXT01
  • 24.
    Johnson, Erland
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut. Chalmers University of Technology, Sweden.
    Yang, Shun-Han
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    The influence of biofouling on power capture and the fatigue life of mooring lines and power cables used in wave energy converters2016In: Progress in Renewable Energies Offshore - Proceedings of the 2nd International Conference on Renewable Energies Offshore (RENEW2016) / [ed] Guedes Soares, 2016, p. 711-722Conference paper (Other academic)
    Abstract [en]

    This study presents an analysis of a wave energy converter (WEC) system consisting of a buoy, a mooring system and a power cable connected to a hub. The investigated WEC system is currently under full-scale testing near Runde in Norway. The purpose of the study was to investigate the characteristics of the entire system, primarily with regard to energy performance and the fatigue life of the mooring lines and power cable, considering the effects of marine biofouling and its growth on the system’s components. The energy performance of the system and the fatigue life of the mooring lines and the power cable were systematically studied via parameter variation analysis, considering different mooring configurations, biofouling conditions, and environmental loads (current and sea state conditions), among other factors. Hydrodynamic and structural response simulations were conducted in a coupled response analysis using the DNV-GL software SESAM. Energy performance analyses and stress-based rainflow counting fatigue calculations were performed separately using an in-house code. The results show that, for a WEC system which has been deployed for 25 years, biofouling can reduce the total power absorption by up to 10% and decrease the fatigue life of the mooring lines by approximately 20%.

  • 25. Karlsson, U
    et al.
    Ringsberg, J
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Hoseini, M
    Ulfvarsson, A
    Experimental and numerical investigation of bulb impact with a ship side-shell structure.2009In: Marine Technology, Vol. 46, p. 16-26Article in journal (Refereed)
  • 26. Karlsson, U
    et al.
    Ringsberg, J
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Hoseini, Mohammed
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Ulfvarsson, A
    Experimental and numerical investigation of bulb impact with a ship side-shell structure2009In: Marine Technology, ISSN 0025-3316, Vol. 46, no 1, p. 16-26Article in journal (Refereed)
  • 27. Karlsson, U
    et al.
    Ulfvarsson, A
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Kjell, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Stress and Fatigue Analysis of a Bow-Door Arm2007In: Journal of Engineering for the Maritime Environment, no 221, p. 125-136Article in journal (Refereed)
  • 28.
    Kjell, Gunnar
    et al.
    RISE - Research Institutes of Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden.
    Measuring axial forces in rail by forced vibrations - experiences from a full scale laboratory experiment2009In: IMechE, Part F: Journal of Rail and Rapid Transit., Vol. 223, no 3, p. 241-254Article in journal (Refereed)
    Abstract [en]

    The longitudinal load in rail caused by thermal expansion must be regularly monitored in order to avoid buckling or rail fracture. Different methods of monitoring with benefits and drawbacks are used or suggested. In this paper one of the proposed methods is investigated by a full-scale experiment. The aim is to measure the change in wavelength of the bending wave caused by the longitudinal load. In contrast to other vibration methods, this method does not require knowledge of the boundary conditions. However, it requires very accurate measurements, advanced finite element (FE) calculations, and sophisticated data analyses. The full-scale experiment shows that this is a method with potential. On the basis of the results of the full-scale experiment the required accuracy of the different steps in the method are clarified. Influence of measurement accuracy, loosened clamps at the sleepers, FE mesh size, degree of wear of the rail, and inaccuracy in the material parameters is considered.

  • 29.
    Kuznecovs, Artjoms
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics. Chalmers University of Technology, Sweden.
    Yamada, Yasuhira
    National Institute of Maritime, Japan.
    Ultimate limit state analysis of a double-hull tanker subjected to biaxial bending in intact and collision-damaged conditions2020In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 209, article id 107519Article in journal (Refereed)
    Abstract [en]

    This study presents a comparison between nonlinear finite element analysis (FEA) and the Smith method of Fujikubo et al. (2012). The objective was to compare the accuracy and computation effort of the two methods for a double-hull tanker under biaxial bending and various ship conditions: intact hull structure, collision-damaged hull structure, newly built condition, and ship hull aged due to corrosion. The results for the non-corroded and intact ship hull structures showed good agreement between FEA, the Smith method and IACS CSR-H for vertical bending loading conditions. For all other bending load combinations, FEA always gave lower ultimate bending moments than the Smith method. The differences between the two methods were larger for the corroded and damaged ship hull structure than for other conditions. Results from ultimate strength analyses of the collision-damaged hull structures showed that both methods captured the expected asymmetric ultimate strength response due to asymmetric damage. A residual strength index calculation showed that the reduction was larger for the FEA than for the Smith method. A procedure is proposed that combines results of a few FEAs with the advantages of the Smith method to generate accurate biaxial bending load interaction curves for different ship conditions. © 2020 Elsevier Ltd

  • 30.
    Kuznecovs, Artjoms
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Mallaya Ullal, Anirudh
    Chalmers University of Technology, Sweden.
    Janardhana Bangera, Pavan
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics. Chalmers University of Technology, Sweden.
    Consequence analyses of collision-damaged ships — damage stability, structural adequacy and oil spills2023In: Ships and Offshore Structures, ISSN 1744-5302, E-ISSN 1754-212X, Vol. 18, no 4, p. 567-Article in journal (Refereed)
    Abstract [en]

    A ship collision accident may pose a threat to human lives, the environment and material assets. A damaged ship can suffer from the loss of ship stability, reduced global structural strength, and the loss of the integrity of internal tanks carrying polluting liquids. This study presents a methodology as a framework that can be used to analyze the related consequences of ship-ship collision events using simulations and evaluations. The methodology includes nonlinear finite element analyses of the collision event, a METOCEAN data analysis module, damage stability simulations, analyses of the damaged ship’s ultimate strength and structural integrity, oil spill drift simulations, and finally, an evaluation of the three abovementioned consequences. A case study with a chemical tanker subjected to collision demonstrates the methodology. The collision event was assumed to occur in the Kattegat area (between Sweden and Denmark) at a ship route intersection with high ship traffic density. © 2022 The Author(s).

  • 31.
    Kuznecovs, Artjoms
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Yang, Shun Han
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Anderson, Andreas
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    A methodology for design and fatigue analysis of power cables for wave energy converters2019In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 122, p. 61-71Article in journal (Refereed)
    Abstract [en]

    The recent development of subsea power cables for various offshore marine renewable energy technologies has identified the need for new cables that have low structural stiffness properties. This type of cable is referred to as dynamic cable because of its high bending flexibility compared to static cables. The current study presents a cable design model and simulation models that were developed for the design and fatigue analysis of dynamic cables. These models were applied on a subsea dynamic power cable with a design that is suitable for a floating point-absorbing wave energy converter (WEC), where the cable must withstand cyclic loads imposed by the motions of the WEC, the waves and the ocean currents. The cable design model is presented with its detailed design and dimensioning methodology for cables with multiorder helical structures, with respect to desired (target) mechanical properties. The cable design model is verified against a verification study in the literature. A simulation model of a fatigue test rig for accelerated rotational bending is presented. The results from the numerical simulations and the subsequent fatigue analyses are compared against results from experiments using the test rig. The influence of the dynamic effects and mechanical properties on the fatigue life of the cable is discussed. This study contributes to a better understanding of the fatigue failure mechanisms of the cable, and it also highlights the importance of further development of numerical models.

  • 32.
    Lang, Xiao
    et al.
    Chalmers University of Technology, Sweden.
    Yang, SH
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Rahm, Magnus
    Chalmers University of Technology, Sweden.
    Guedes Soares, Carlos
    Univerisity of Lisbon, Portugal.
    Comparison betweenfull-scale measurements and numerical simulations of mooring forces in afloating point-absorbing WEC system.2018In: Advances in Renewable Energies Offshore - Proceedings of The 3rdInternational Conference on Renewable Energies Offshore (RENEW 2018),, 2018, p. 865-876Conference paper (Refereed)
  • 33.
    Larsson, Jörgen
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Flansbjer, Mathias
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Williams Portal, Natalie
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Johansson, F
    KTH Royal Institute of Technology, Sweden.
    Mas Ivars, D
    KTH Royal Institute of Technology, Sweden; SKB Swedish Nuclear Fuel and Waste Management Co, Sweden.
    Geometrical Quality Assurance of Rock Joint Replicas in Shear Tests – Introductory Analysis2020Conference paper (Other academic)
    Abstract [en]

    The presence of joints in rock masses influences the structural integrity of geotechnical structures. A critical failure mode is shearing, thus making the shearing process of importance to understand. Historically, studies have been mainly executed on the basis of laboratory experiments, since full-scale in situ tests are seldom performed due to technical and economic considerations. Since each rock joint is unique by nature, the utilization of replicas is applied to carry out controlled experimental parameter studies. However, the manufacturing process of replicas introduces many sources of uncertainty. Therefore, in this work the influence of geometrical variations in replicas on the shear strength characteristics is evaluated, mutually as well as in relation to the mother rock specimen of the replicas. The joint surfaces were 3D scanned and the contact area of the joint was measured using pressure sensitive film before direct shear tests. Deviations in morphology were evaluated by surface comparisons between the joint surfaces of the mother rock and replicas. The initial matching of the joints was evaluated by calibrating the scanning data with respect to the contact area measurements. It could be visualized that geometrical deviations were caused by rock fragments coming off during mould production, positioning of the moulds and pores resulting from replica casting. These factors were found to influence the shear strength characteristics of the replicas. The influence of the deviations originating from morphology on the joint matching is demonstrated. In summary, it is shown that replicas with similar shear strength characteristics as rock can be manufactured, but even small deviations affect the characteristics, in particular the peak strength. Therefore, parameters relevant for geometrical quality assurance should be identified along with required value ranges. Selected introductory results on quantified parameters for geometrical quality assurance are presented, serving as a basis for continued work.

  • 34.
    Larsson, Jörgen
    et al.
    KTH Royal Institute of Technology, Sweden.
    Johansson, F
    KTH Royal Institute of Technology, Sweden.
    Ivars, D. Mas
    KTH Royal Institute of Technology, Sweden; SKB Swedish Nuclear Fuel and Waste Management Co, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Flansbjer, Mathias
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Williams Portal, Natalie
    RISE Research Institutes of Sweden, Materials and Production, Corrosion.
    A novel method for geometric quality assurance of rock joint replicas in direct shear testing : Part 2: Validation and mechanical replicability2023In: Journal of Rock Mechanics and Geotechnical Engineering, ISSN 1674-7755Article in journal (Refereed)
    Abstract [en]

    Each rock joint is unique by nature which means that utilization of replicas in direct shear tests is required in experimental parameter studies. However, a method to acquire knowledge about the ability of the replicas to imitate the shear mechanical behavior of the rock joint and their dispersion in direct shear testing is lacking. In this study, a novel method is presented for geometric quality assurance of replicas. The aim is to facilitate generation of high-quality direct shear testing data as a prerequisite for reliable subsequent analyses of the results. In Part 1 of this study, two quality assurance parameters, σmf and VHp100, are derived and their usefulness for evaluation of geometric deviations, i.e. geometric reproducibility, is shown. In Part 2, the parameters are validated by showing a correlation between the parameters and the shear mechanical behavior, which qualifies the parameters for usage in the quality assurance method. Unique results from direct shear tests presenting comparisons between replicas and the rock joint show that replicas fulfilling proposed threshold values of σmf < 0.06 mm and < 0.2 mm have a narrow dispersion and imitate the shear mechanical behavior of the rock joint in all aspects apart from having a slightly lower peak shear strength. The wear in these replicas, which have similar morphology as the rock joint, is in the same areas as in the rock joint. The wear is slightly larger in the rock joint and therefore the discrepancy in peak shear strength derives from differences in material properties, possibly from differences in toughness. It is shown by application of the suggested method that the quality assured replicas manufactured following the process employed in this study phenomenologically capture the shear strength characteristics, which makes them useful in parameter studies.

  • 35.
    Larsson, Jörgen
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics. KTH Royal Institute of Technology, Sweden.
    Johansson, F.
    KTH Royal Institute of Technology, Sweden.
    Ivars, DM
    KTH Royal Institute of Technology, Sweden; SKB Swedish Nuclear Fuel and Waste Management Co, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Flansbjer, Mathias
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Williams Portal, Natalie
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    A novel method for geometric quality assurance of rock joint replicas in direct shear testing – Part 1: Derivation of quality assurance parameters and geometric reproducibility2023In: Journal of Rock Mechanics and Geotechnical Engineering, ISSN 1674-7755Article in journal (Refereed)
    Abstract [en]

    Since each rock joint is unique by nature, the utilization of replicas in direct shear testing is required to carry out experimental parameter studies. However, information about the ability of the replicas to simulate the shear mechanical behavior of the rock joint and their dispersion in direct shear testing is lacking. With the aim to facilitate generation of high-quality direct shear test data from replicas, a novel component in the testing procedure is introduced by presenting two parameters for geometric quality assurance. The parameters are derived from surface comparisons of three-dimensional (3D) scanning data of the rock joint and its replicas. The first parameter, σmf, captures morphological deviations between the replica and the rock joint surfaces. σmf is derived as the standard deviation of the deviations between the coordinate points of the replica and the rock joint. Four sources of errors introduced in the replica manufacturing process employed in this study could be identified. These errors could be minimized, yielding replicas with σmf ≤ 0.06 mm. The second parameter is a vector, VHp100, which describes deviations with respect to the shear direction. It is the projection of the 100 mm long normal vector of the best-fit plane of the replica joint surface to the corresponding plane of the rock joint. |VHp100| was found to be less than or equal to 0.36 mm in this study. Application of these two geometric quality assurance parameters demonstrates that it is possible to manufacture replicas with high geometric similarity to the rock joint. In a subsequent paper (part 2), σmf and VHp100 are incorporated in a novel quality assurance method, in which the parameters shall be evaluated prior to direct shear testing. Replicas having parameter values below established thresholds shall have a known and narrow dispersion and imitate the shear mechanical behavior of the rock joint.

  • 36.
    Larsson, Jörgen
    et al.
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics. KTH Royal Institute of Technology, Sweden.
    Johansson, F
    Mas Ivars, D
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Flansbjer, Mathias
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Williams Portal, Natalie
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Rock joint replicas in direct shear testing – Part 1: Extraction of geometrical quality assurance parameters.Manuscript (preprint) (Other academic)
  • 37. Li, Z
    et al.
    Mao, W
    Ringsberg, J
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Storhaug, G
    A comparative study of fatigue assessment of a container ship structure using various direct calculation approaches2012In: Proceedings of the International Conference on Maritime Technology (ICMT2012) in Harbin, Heilongjiang, P. R. China, June 25-28, 2012, 2012, p. 405-409, article id H95Conference paper (Refereed)
    Abstract [en]

    Today, it is common practice to carry out fatigue assessments of ship structures using direct calculation procedures. Many numerical codes are available for these types of analyses. They could yield different values in a fatigue life prediction due to the different degrees of complexity as well as the large number of uncertainties in the computation of the ship’s response. In this investigation, a comparative study is carried out on a Panamax container ship in oblique waves using different typical direct calculation methods. The results of fatigue life prediction using these methods are compared with results obtained from full-scale measurements. It is found that the nonlinear time-domain method shows the best agreement with the full-scale measurements, and therefore, it is recommended to be used in fatigue predictions.

  • 38.
    Li, Zhiyuan
    et al.
    Chalmers University of Technology, Sweden.
    Mao, Wengang
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Storhaug, Gaute
    Det Norske Veritas, Norway.
    A comparative study of fatigue assessments of container ship structures using various direct calculation approaches.2014In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 82, p. 65-74Article in journal (Refereed)
    Abstract [en]

    It is common practice today to carry out fatigue assessments of ship structures using direct calculation procedures to compute fatigue loads. Many numerical codes are available for use in such fatigue load analyses. In addition to the various degrees of computation complexity associated with fatigue estimation methods, such methods also have large inherent uncertainties. In this investigation, a comparative study was carried out for two container ships using various typical direct fatigue calculation methods. The fatigue damage amounts calculated using these methods were compared with those obtained from full-scale measurements. Most of the direct calculation approaches investigated yielded similar fatigue damage estimates. The approach that employs nonlinear time-domain hydrodynamic analysis and the finite element method yields reasonable and conservative fatigue damage results and is therefore recommended. In addition, the results of this study confirm that various measures of wave environments and of the variation in wave models are important sources of uncertainty in fatigue life prediction.

  • 39.
    Li, Zhiyuan
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Performance assessment of the crashworthiness of corroded ship hulls.2017In: Proceedings of the Sixth International Conference on Marine Structures (MARSTRUCT2017), Lisbon, Portugal, May 2017, 2017, p. 523-532Conference paper (Refereed)
  • 40.
    Li, Zhiyuan
    et al.
    Chalmers Univeristy of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers Univeristy of Technology, Sweden.
    Serdyuk, Y
    Chalmers Univeristy of Technology, Sweden.
    Svensson, Daniel
    Chalmers Univeristy of Technology, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Andersson, Christian
    NKT A/S, Sweden.
    Predicting failure of dynamic subsea cables by electrical insulation breakdown due to water treeing2023In: Proceedings of the Ninth International Conference on Marine Structures (MARSTRUCT2023)  / [ed] C. Guedes Soares and Ringsberg J.W., 2023, p. 477-484Conference paper (Refereed)
  • 41.
    Li, Zhiyuan
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas W.
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE Research Institutes of Sweden, Materials and Production, Applied Mechanics.
    Serdyuk, Yuriy
    Chalmers University of Technology, Sweden.
    Crack Propagation in Dynamic Power Cables2022In: Proceedings of the ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering (OMAE2022) , 2022, article id OMAE2022‑79467Conference paper (Refereed)
  • 42.
    Lillbacka, Robert
    et al.
    SP.
    Ekh, Magnus
    Chalmers.
    Johnson, Erland
    RISE - Research Institutes of Sweden.
    Runesson, Kenneth
    Chalmers.
    Fatigue crack initiation based on simulations at the mesoscopic scale2003In: Proceedings of the 5th International Conference of the Engineering Society, Cambridge, UK 7-9 April 2003, 2003, p. 475-484Conference paper (Refereed)
  • 43.
    Lillbacka, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Ekh, Magnus
    Chalmers.
    Runesson, Kenneth
    Chalmers.
    Johnson, Erland
    RISE - Research Institutes of Sweden (2017-2019).
    Anisotropic damage modelling based on mesoscopic simulations2002In: Proceedings of the 5th World Congress on Computational Mechanics. July 7-12, 2002., 2002Conference paper (Refereed)
  • 44.
    Lillbacka, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Cyclic Stress-Strain Behavior and Load-sharing in duplex Stainless Steels - Aspects on Modeling and Experiments2007In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 55, no 16, p. 5359-5368Article in journal (Refereed)
  • 45.
    Lillbacka, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Bellander, Magnus
    Rubber component fatigue life evaluation based on FE-modelling and material testing2009Conference paper (Other academic)
  • 46.
    Lillbacka, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Ekh, Magnus
    A model for short crack propagation in polycrystalline materials2005In: Engineering Fracture Mechanics, Vol. 73, no 73, p. 223-232Article in journal (Refereed)
  • 47.
    Lillbacka, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Ekh, Magnus
    A model for short crack propagation in polycrystalline materials.2006In: Engineering Fracture Mechanics, Vol. 73, no 2, p. 223-232Article in journal (Refereed)
    Abstract [en]

    A model for microstructurally short crack propagation in a grain structure of a polycrystalline material is developed. The crack propagation model is based on a crystal plasticity model and a microstructurally short crack propagation model in the spirit of the model by Navarro and de los Rios [A model for short fatigue crack propagation with an interpretation of the short–long crack transition. Fatigue Fract Eng Mater Struct 1987;10:169–86]. Numerical examples, where the combined crystal plasticity and crack propagation model is implemented in a model of a microstructure representing a duplex stainless steel, concludes the paper. Results showing how the misorientation of the crack- and slip-directions between two adjacent austenitic grains influences the crack propagation rate, as the crack propagates across their common grain boundary, are given.

  • 48.
    Lillbacka, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Johnson, Erland
    RISE - Research Institutes of Sweden (2017-2019).
    Ekh, Magnus
    Chalmers.
    Runesson, Menneth
    Chalmers.
    Modelling growth of small cracks in a polycrystal2004In: Proceedings of the 15th European Conference of Fracture, Stockholm, Sweden, 11-13 August 2004., 2004Conference paper (Refereed)
  • 49.
    Rahm, Michael
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Evegren, Franz
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Johnson, Erland
    RISE - Research Institutes of Sweden (2017-2019), Built Environment.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Structural Fire Integrity Testing of Lightweight Multiple Core Sandwich Structures2017In: Proceedings of the 6th International Conference on Marine Structures - MARSTRUCT. Progress in the Analysis and Design of Marine Structures, 2017, p. 869-878Conference paper (Refereed)
    Abstract [en]

    Lightweight structures become increasingly important to reduce environmental impact and to improve payload/deadweight ratio of ships. Significant weight savings can be accomplished by replacing steel with fiber reinforced polymer (FRP) sandwich panels. An assessment is then necessary to ensure that equivalent fire safety is provided, since the structures are combustible. To support such assessments, this paper presents results from vertically loaded fire resistance tests of two structures: (1) a “conventional” FRP sandwich bulkhead with thermal insulation (providing load carrying fire resistance for 60 minutes) and (2) a multiple core FRP sandwich bulkhead without insulation. Both bulkheads were constructed for and tested with the same design load. The multiple core sandwich bulkhead demonstrated structural fire integrity performance well beyond 60 minutes whilst having a significantly lower structural weight and thickness. The new type of multiple core sandwich structure thus provides great potential, both from a weight-savings and a fire safety perspective.

  • 50. Ringsberg, J
    et al.
    Johnson, Erland
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Schreuder, M
    Högström, P
    Examples of selected research efforts made on characteristics of material, ship side structure response and ship survivability in ship collisions.2010Conference paper (Refereed)
12 1 - 50 of 81
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