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  • 51.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    Tightness of flange joints for large polyethylene pipes – Part 2 Full scale experimental investigations2011Report (Refereed)
    Abstract [en]

    Tightness of flange joints for large polyethylene pipes – Part 2 Full scale experimental investigations Leakage that sometimes occurs in flange joints in large size plastic pipelines for water supply is a serious problem. Research was undertaken in order to improve the knowledge about the function of such flange joints. The objectives were partly to find out the degree of sensitivity of the design, i e if small deviations from recommended practise is critical, partly to be able to suggest improved design and mounting procedures. One part of the investigation was a numerical (FEM) study of several geometries, which was reported in [2]. Use of a time-dependent material model made it possible to follow the development of deformations and flange surface pressures for long times. Although several important principal findings were made, the tightening procedure and exact material behaviour could not be modelled. Therefore a series of full-scale experiments were made on 630 mm pipes, for a number of combinations of flange dimension and gasket type. This second part of the research is reported here. Since four of the twenty bolts were instrumented, the bolt forces could be monitored and be related to the torque and to the pressure in the pipe over time. This resulted in novel, important information about the functioning of plastic flange joints. In short, the experiments were performed in the following way. First, the bolts were tightened in the recommended criss-cross fashion to pre-determined torque levels. Then the pressure in the pipe was increased until leakage occurred. For combinations of flanges, gaskets and torques where the joint was tight for pressures above 13 bars, the 13 bar pressure level was maintained for up to one week. The relationship between bolt force and torque does not agree at all with the frequently used rule of thumb formula, for the galvanized bolts used here. The bolt force was typically less than half the value obtained by the formula. Hence it is critical to verify the friction for the used combination of bolt material, surface treatment, and lubrication. The bolt forces also appear to be unevenly distributed, which is partly due to successive creep during the tightening procedure. For the high stresses in the flange creep is significant already for so short times as a few minutes, and the effect is increased by the fact that the bolts and backing rings are much stiffer than the plastic flange. For both the wide and the narrow (ISO) flange type used it appears that rubber gaskets perform better, in the sense that the joint is tight for lower applied torques. The hyper- elastic material properties help to smooth unevenness in the flange surface and to compensate for creep in the plastic. Use of SDR 17 pipes at pressure levels of 13 bars means considerable creep expansion of the pipe, although it is possible to obtain a tight joint. The expansion gives a wringing effect at the flange, also observed in [2], which contributes to concentrate the flange pressure to the outer parts of the flange surface. In summary, flange joints are possible to mount so that they are tight, also for 630 mm pipes. Since the design is a sensitive one it is vital to follow recommendations for 4 mounting of different combinations of flanges and gaskets. In particular, knowledge about the relationship between torque and bolt force is important.

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  • 52.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Vennetti, Daniel
    Tightness of flange joints for large polyethylene pipes – Part 1 Numerical simulations2011Report (Refereed)
    Abstract [sv]

    Tightness of flange joints for large polyethylene pipes – Part 1 Numerical simulations Leaks occasionally occur in flange joints in plastic pipelines, predominantly large dimension ones. Such pipelines are normally of importance for e g water supply, and repair is expensive. A better understanding is vital since a clear background is missing for the existing design and mounting recommendations, which also are differing. Analysis of plastic flanges is more complicated than for metal ones since the material is time dependent, and much softer than the backing rings and bolts. The aim of this work was to be able to assess on one hand if presently standardized flange geometries mean smaller safety margins when the size of the pipe is increased, and on the other hand if the instructions for mounting have to be improved. First, an analysis was made by manual calculations, without consideration of the time dependent properties of the material, in order to assess the stresses just after tightening of the joint but before pressurizing and start of service time of the pipeline. The manual analysis is of course misleading for assessment of the compression stresses in the flange surfaces over time, although it seems that such calculations often are used for design. The value of the manual analysis was mainly that it showed that the nominal stresses are similar for different sizes, except for the 630 mm pipe where they are significantly higher. Further it was established that pressurizing of the pipe means a moderate influence on the flange stresses and bolt forces, 10-15%, and that the bolt and backing ring are much stiffer than the plastic flange, meaning that it is mainly relaxation that is responsible for unloading of the joint over time. Computer simulations (FEM) were then made of both the tightening and the service phase for a set of geometries, and with a material model including time dependent properties of the plastic parts of the joint using material data from in-house experiments. Although the computer simulations are approximate too, they give a much better impression both of the principal function of the joint and of the magnitude of the stresses over time. It appears that the geometry of the flange joint means that the contact is lost over large parts of the flange surfaces already at pressurizing and that a triangular distribution of pressure covering a part of the flange surface corresponding to the width of the backing ring is developed over time which should be sufficient to keep the joint tight. The effects of gaskets and profiled, softer, backing rings are clarified, and it is indicated that re-tightening is an efficient way to improve the function of the joint over time. Further, it seems that there is no significant difference in behaviour, as regards flange pressure, between SDR 11 and SDR 17 geometries. So, the FEM investigation has revealed that intuitive thoughts about reasons for inferior functioning of large size flange joints in plastic pipes are not well founded. The most efficient way to improve the joint is to increase the bolt force and to keep it up, by re-tightening or by flexible backing rings. Gaskets, soft ones, may be beneficial for reducing unevenness of the plastic joint surfaces.

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  • 53.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Vennetti, Daniel
    Sällberg, Sven-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Göteborg (BMg).
    The functioning of flange joints – findings from full scale experiments and FEM analyses2012In: Proceedings of PPXVI, 2012Conference paper (Refereed)
  • 54.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Christiansson, Rolf
    Martin, Derek. C.
    Experimental determination of spalling initiation in hard rock2010In: Proceedings of Rock Mechanics in civil and Environmental Engineering, CRC press/Balkema , 2010, , p. 327-330Conference paper (Refereed)
    Abstract [en]

    Proceedings of the European Rock Mechanics Symposium (EUROCK) 2010, Lausanne, Switzerland, 15-18 June, 2010, Rock Mechanics in civil and Environmental Engineering, eds J Zhao, V Labiouse, J-P Dudt & J-F Mathier (Extern vetenskaplig bok)

  • 55.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Brzovic, Andres
    de los Santos, Carlos
    Direct shear and tensile test on cemented healed joints from El Teniente mine, Chile2011In: Proceedings of the 12th ISRM International Congress on Rock Mechanics, 2011, , p. 649-654Conference paper (Refereed)
  • 56.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Jansson, Thomas
    Christiansson, Rolf
    Measurement of micro crack volume in low porosity crystalline rock2007In: Proceedings of the 11th ISRM Congress, 2007Conference paper (Refereed)
  • 57.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Schouenborg, Björn
    RISE, SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Grelk, Bent
    Smits, Arwen
    Expert System for Dimensioning of Facade Cladding2010In: Proceedings of Global Stone Congress 2010, 2010, , p. 1-4Conference paper (Refereed)
    Abstract [en]

    Proceedings of the Global Stone Congress 2010, Alicante Spain, 2-5 March 2010 2010 (Extern vetenskaplig bok)

  • 58.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Glamheden, Rune
    Hakami, Eva
    Olofsson, Isabelle
    Rock mechanics laboratory testing in SKB site investigation program2012In: Proceedings of EUROCK 2012, 2012Conference paper (Refereed)
  • 59.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Karlsson, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Are methods for tightness testing fit for purpose?2012In: Proceedings of PPXVI, 2012Conference paper (Refereed)
  • 60.
    Jacobsson, Lars
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Runesson, Kenneth
    Computational modelling of high-cycle deformation of railway ballast2002In: Proceedings  5th World Congress on Computational Mechanics (WCCM V), 2002, p. 12 pp-Conference paper (Other academic)
  • 61.
    Jansson, Anette
    et al.
    Chalmers University of Technology, Sweden.
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Löfgren, Ingemar
    Chalmers University of Technology, Sweden.
    Lundgren, Karin
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Gylltoft, Kent
    Thomas Concrete Group AB, Sweden.
    Experimental investigation of surface crack initiation, propagation and tension stiffening in self-compacting steel–fibre-reinforced concrete2012In: Materials and Structures, ISSN 1359-5997, E-ISSN 1871-6873, Vol. 45, no 8, p. 1127-1143Article in journal (Refereed)
    Abstract [en]

    To investigate crack initiation and propagation in reinforced, self-compacting, steel–fibre-reinforced concrete (SCSFRC) members, tie elements were tested in tension. Strain and surface crack formation were monitored with an optical strain measurement system based on digital image correlation. In addition, to capture the softening behaviour (s–w) of the material, uni-axial tension testing was performed on SCSFRC cylinders. The results show that, with the optical strain measurement system, it was possible to detect different cracking modes and to follow the crack growth. It was especially of interest to recognize that high fibre amounts tend to change a sudden opening of a crack (as in non-fibrous concrete) into a more stable procedure. It was found that, for a given crack width, the SCSFRC specimens exhibited a noticeably higher tension stiffening than the specimens without fibres. Moreover, at a given load, the crack widths decreased by as much as 65% for the SCSFRC specimens with a nominal fibre content of 1%. For the uni-axial tension tests the results showed that with higher fibre content, for this type of fibre and concrete, both the peak stress and the residual tensile stress were increased. Additionally, it was noted for both specimen types that the scatter in fibre distribution decreased with increasing fibre content.

  • 62.
    Jansson, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research, Brandmotstånd.
    Flansbjer, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Albrektsson, Joakim
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Fire Research, Brandmotstånd.
    Lindqvist, Jan-Erik
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Brandteknik, material (BRm).
    Optisk mätmetod visar hur långt in betongen skadats2011In: Husbyggaren, ISSN 0018-7968, Vol. 53, no 2, p. 4 to 6-Article in journal (Other (popular science, discussion, etc.))
  • 63.
    Johannesson, Pär
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Rychlik, Igor
    Laplace models for describing road profiles.2014In: Proceedings of the 3rd International Commercial Vehicle Technology Symposium (CVT2014), 2014, , p. 99-108Conference paper (Refereed)
  • 64.
    Johannesson, Pär
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Rychlik, Igor
    Chalmers University of Technology, Sweden .
    Laplace processes for describing road profiles2013In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 66, p. 464-473p. 464-473Article in journal (Refereed)
    Abstract [en]

    The Gaussian model is frequently used for modelling environmental loads, e.g. sea elevation, wind loads and road profiles. However, the Gaussian model is often only valid for short sections of the load. For example, for roads profiles, short sections of roads, say 100 m, is well modelled by a Gaussian process, whereas longer sections of roads, say 10 km, typically contain shorter sections with high irregularity, and the variability between sections is higher than what can be explained by the stationary Gaussian model. This phenomenon can be captured by a Laplace process, which can be seen as a Gaussian process with randomly varying variance. Thus, the Gaussian process is a special case of the Laplace process. Further, the expected damage can be computed from the parameters of the Laplace process. We will give examples of modelling road profiles using Laplace models. Especially, it will be demonstrated how to reconstruct a road profile based on sparse road roughness measurements, such as a sequence of IRI (International Roughness Index) for 100 metre road sections. Further, IRI data from the Finnish road network will be evaluated.

  • 65.
    Johannesson, Pär
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Rychlik, Igor
    Modelling of road profiles using roughness indicators2012Report (Refereed)
    Abstract [en]

    The vertical road input is the most important load for durability assessments of vehicles. We focus on stochastic modelling of the road profile with the aim to find a simple by still useful model. The proposed non-stationary Laplace model with ISO spectrum has only two parameters, and can be efficiently estimated from a sequence of roughness indicators, such as IRI or ISO roughness coefficient. Thus, a road profile can be stochastically reconstructed from roughness indicators. Further, explicit approximations for the fatigue damage due to Laplace roads are developed. The usefulness of the proposed Laplace-ISO model is validated for eight measured road profiles. Keywords: Road surface profile, road roughness, road irregularity, Laplace process, non-Gaussian process, power spectral density (PSD), ISO spectrum, roughness coefficient, international roughness index (IRI), vehicle durability, fatigue damage.

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  • 66.
    Johannesson, Pär
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Rychlik, Igor
    Chalmers University of Technology, Sweden.
    Modelling of road profiles using roughness indicators2014In: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 66, no 4, p. 317-346Article in journal (Refereed)
    Abstract [en]

    The vertical road input is the most important load for durability assessments of vehicles. We focus on stochastic modelling of the road profile with the aim to find a simple but still useful model. The proposed nonstationary Laplace model with ISO spectrum has only two parameters, and can be efficiently estimated from a sequence of roughness indicators, such as IRI or ISO roughness coefficient. Thus, a road profile can be stochastically reconstructed from roughness indicators. Further, explicit approximations for the fatigue damage due to Laplace roads are developed. The usefulness of the proposed Laplace-ISO model is validated for eight measured road profiles.

  • 67.
    Johannesson, Pär
    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).
    Reliable fatigue design, by rigid rules, by magic or by enlightened engineering2013In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 66, p. 12-25p. 12-25Article in journal (Refereed)
    Abstract [en]

    This paper discusses some basic differences between engineering approaches to fatigue reliability assessment. The comparison is based on the fact that mechanical fatigue is a highly empirical science with large uncertainties in prior knowledge, both regarding observed data and model accuracy. It is claimed that the amount of available prior physical knowledge should decide the level of complexity in reliability tools, not computer resources nor mathematical theory. As a result the second moment statistics is put forward as a useful tool in fatigue reliability assessment, either in the regulated form like in Eurocode or in a free engineering form like through the Variation Mode and Effect Analysis. The latter method is outlined in certain detail and its practical usefulness demonstrated for some engineering reliability problems

  • 68.
    Johannesson, Pär
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh). Chalmers University of Technology, Sweden; Gothenburg University, Sweden.
    Svensson, Thomas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh). Chalmers University of Technology, Sweden; Gothenburg University, Sweden.
    Bergman, Bo
    Chalmers University of Technology, Sweden.
    Arvidsson, Martin
    Cochlear BAS, Sweden.
    de Maré, Jaques
    Chalmers University of Technology, Sweden; Gothenburg University, Sweden.
    Lönnqvist, Åke
    Volvo Cars, Sweden; Chalmers University of Technology, Sweden.
    Barone, Stefano
    Chalmers University of Technology, Sweden; University of Palermo, Italy.
    A Robustness Approach to Reliability2013In: Quality and Reliability Engineering International, Vol. 29, p. 17-32Article, review/survey (Refereed)
    Abstract [en]

    Reliability of products is here regarded with respect to failure avoidance rather than probability of failure. To avoid failures,we emphasize variation and suggest some powerful tools for handling failures due to variation. Thus, instead of technicalcalculation of probabilities from data that usually are too weak for correct results, we emphasize the statistical thinking thatputs the designers focus on the critical product functions.Making the design insensitive to unavoidable variation is called robust design and is handled by (i) identification andclassification of variation, (ii) design of experiments to find robust solutions, and (iii) statistically based estimations of propersafety margins.Extensions of the classical failure mode and effect analysis (FMEA) are presented. The first extension consists of identifyingfailure modes caused by variation in the traditional bottom–up FMEA analysis. The second variation mode and effect analysis(VMEA) is a top–down analysis, taking the product characteristics as a starting point and analyzing how sensitive thesecharacteristics are to variation.In cases when there is sufficient detailed information of potential failure causes, the VMEA can be applied in its mostadvanced mode, the probabilistic VMEA. Variation is then measured as statistical standard deviations, and sensitivities aremeasured as partial derivatives. This method gives the opportunity to dimension tolerances and safety margins to avoidfailures caused by both unavoidable variation and lack of knowledge regarding failure processes

  • 69.
    Johannesson, Pär
    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).
    Jacobsson, Lars
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik, Strukturer och Komponenter.
    Bokesjö, Mathias
    RISE, SP – Sveriges Tekniska Forskningsinstitut, AstaZero.
    Olsson, L
    VMEA-metoden för bedömning av osäkerheter i bergmekaniska tillämpningar. The VMEA-method for Assessing Uncertainties in Rock Engineering2013Report (Other academic)
  • 70.
    Johannesson, Pär
    et al.
    Chalmers, Goteborg,Sweden.
    Svensson, Thomas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Samuelsson, Leif
    Volvo Aero Corporation, Trollhattan, Sweden.
    Bergman, Bo
    Chalmers, Goteborg, Sweden.
    de Maré, Jaques
    Chalmers, Goteborg,Sweden ; Gothenburg University, Goteborg, Sweden.
    Variation mode and effect analysis: an application to fatigue life prediction2009In: Quality and Reliability Engineering International, ISSN 0748-8017, E-ISSN 1099-1638, Vol. 25, no 2, p. 167-179Article in journal (Refereed)
    Abstract [en]

    We present an application of the probabilistic branch of variation mode and effect analysis (VMEA) implemented as a first-order, second-moment reliability method. First order means that the failure function is approximated to be linear around the nominal values with respect to the main influencing variables, while second moment means that only means and variances are taken into account in the statistical procedure. We study the fatigue life of a jet engine component and aim at a safety margin that takes all sources of prediction uncertainties into account. Scatter is defined as random variation due to natural causes, such as non-homogeneous material, geometry variation within tolerances, load variation in usage, and other uncontrolled variations. Other uncertainties are unknown systematic errors, such as model errors in the numerical calculation of fatigue life, statistical errors in estimates of parameters, and unknown usage profile. By treating also systematic errors as random variables, the whole safety margin problem is put into a common framework of second-order statistics. The final estimated prediction variance of the logarithmic life is obtained by summing the variance contributions of all sources of scatter and other uncertainties, and it represents the total uncertainty in the life prediction. Motivated by the central limit theorem, this logarithmic life random variable may be regarded as normally distributed, which gives possibilities to calculate relevant safety margins

  • 71. 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)
  • 72.
    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.

  • 73.
    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.

  • 74.
    Johansson, Pernilla
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Byggnadsfysik och innemiljö (ETi ).
    Svensson, Thomas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Ekstrand-Tobin, Annika
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Byggnadsfysik och innemiljö (ETi ).
    Validation of critical moisture conditions for mould growth on building materials2013In: Building and Environment, Vol. 62, p. 201-209Article in journal (Refereed)
    Abstract [sv]

    Materials that are stored or used in damp conditions may be subject to mould growth. However, all materials are not equally susceptible; for each specific material, there is a critical moisture level for mould growth. If this is exceeded, there is a risk that mould fungi will develop on the material. This level can be determined in accelerated laboratory tests, at constant temperatures and relative humidity (RH) favourable to mould growth. Within a building however, these parameters are expected to vary from one part of the construction to another, and are seldom constant; there is fluctuation in temperature and RH due to seasonal or shorter-term variations. In this study, test pieces of the same materials tested in a laboratory environment were placed in three outdoor ventilated crawl spaces and three outdoor ventilated attics, where the temperature and RH varied, and mould growth on the test pieces was studied over 2.5 years. Material-specific mould growth curves were produced based on critical moisture levels, as determined in laboratory experiments under constant temperature and RH. When the actual conditions of RH and temperature exceeded these curves, there was mould growth on the test pieces if the time was sufficiently long. The conclusion from the study is that although conditions in laboratory studies are simplified and accelerated, the results serve well to indicate mould growth within a building construction.

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  • 75.
    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)
  • 76.
    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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  • 77.
    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.

  • 78.
    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)
  • 79.
    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)
  • 80.
    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)
  • 81.
    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)
  • 82.
    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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  • 83.
    Karlsson, Linda
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Grävskydd och djupförläggning som riskreducerande åtgärder vid förläggning av 10 bars PE-rörsystem2011Report (Refereed)
  • 84.
    Karlsson, Linda
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Andersson, Hans
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Metoder för täthetsprovning av trycksatta polyetenledningar2011Report (Refereed)
  • 85. 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)
  • 86. 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)
  • 87. 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)
  • 88.
    Kjell, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Jordbävningsprovning2008In: Electronics environment, Vol. 2, no 2, p. 28-31Article in journal (Other (popular science, discussion, etc.))
  • 89.
    Kjell, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Utbildning i miljötålighetsteknik2008In: Electronic environment, no 3Article in journal (Other (popular science, discussion, etc.))
  • 90.
    Kjell, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Vad menas med miljötålighet?2011In: electronic - environment, no 1, p. 8-11Article in journal (Other (popular science, discussion, etc.))
  • 91.
    Kjell, Gunnar
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Vibrationsprovning av batterier till el- och hybridbilar2011In: Electronic environment, no 3, p. 26-27Article in journal (Other (popular science, discussion, etc.))
  • 92.
    Kjell, Gunnar
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Lang, Jenny
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Elektronik, Miljötålighet.
    Comparing different vibration tests proposed for li-ion batteries with vibration measurement in an electric vehicle2014In: EVS 2014. 27th World Electric Vehicle Symposium and Exhibition, 2014, , p. 1-11article id 6914869Conference paper (Refereed)
    Abstract [en]

    Li-ion batteries are the most popular type of batteries in electric, EV, and hybrid vehicles, HV. During their life time the batteries will be subjected to vibrations and therefore vibration testing is demanded by several standards. Testing on different size levels of the batteries, i.e. cell, module or pack, are proposed. Depending on the standard random vibration tests or tests with sinusoidal excitation are required. To compare these standards with the measurements, Fatigue Damage Spectrum, FDS, and Shock Response Spectrum, SRS, have been used. The FDS is a tool to analyze and compare different types of vibration tests and vibration measurements with respect to the fatigue damage that the vibration will cause on a mechanic structure. The SRS is used to estimate the risk for functional disturbances in electric equipment subjected to shock and vibrations. The comparison shows that the FDS and SRS for different vibration tests proposed for li-ion batteries vary strongly. Both levels and frequency ranges differ. One of the compared standards prescribes testing only in the vertical direction. The measurement done in this study was done during rather hard driving on a test track, this means high but not unrealistic measured acceleration responses. For one of the measured responses, the risk for fatigue during service could be higher than the risk at the tests. The low frequency content of a test can be important as the measurements show higher low frequency content than in many of the standardized tests. But even the high frequency content of the test must be considered as batteries normally are equipped with a large number of small electrical devices with high critical frequencies. Only one of the standards requires a separate test of such devices.

  • 93. Larsson, Dan
    et al.
    Sjögren, Torsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Svensson, Ingvar L
    Modelling the plastic deformation behaviour of cast irons,2008In: International Foundry Research, Vol. 64, no 4, p. 08:16-Article in journal (Refereed)
  • 94.
    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.

  • 95.
    Lillbacka, Robert
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Mot ett virtuellt laboratorium för materialutveckling2008In: Bergsmannen, Vol. 192, no 5, p. 26-28Article in journal (Other (popular science, discussion, etc.))
  • 96.
    Lillbacka, Robert
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Ekh, Magnus
    Runesson, Kenneth
    A model framwork for anisotropic damage coupled to crystal (visco) plasticity2004In: International Journal of Plasticity, Vol. 20, no 12, p. 2143-2159Article in journal (Refereed)
  • 97.
    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)
  • 98.
    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)
  • 99.
    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)
  • 100.
    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.

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