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  • 1.
    Belov, Ilia
    et al.
    Jönköping University, Sweden.
    Arwidson, Jonas
    Saab AB, Sweden.
    Poder, Ralf
    RISE - Research Institutes of Sweden.
    Johannesson, Pär
    RISE - Research Institutes of Sweden.
    Leisner, Peter
    RISE - Research Institutes of Sweden. Jönköping University, Sweden.
    Thermal fatigue prediction: consequences of cycle reduction and material property variation2016Inngår i: Electronic Environment, 2016, Vol. 1, s. 27-27Konferansepaper (Fagfellevurdert)
  • 2.
    Belov, Ilja
    et al.
    Jönköping University, Sweden.
    Arwidson, Jonas
    Saab AB, Sweden.
    Poder, Ralf
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Johannesson, Pär
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Leisner, Peter
    Jönköping University, Sweden.
    The effect of variations in temperature cycling profile and mechanical properties of solder on thermo-mechanical reliability of a lead-free BGA package2015Inngår i: 2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, 2015, s. 165-169, artikkel-id 7103102Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper investigates the effect of variations both in temperature cycling profile and in SAC305 solder Young's modulus in the PBGA256 package on the thermo-mechanical reliability. FE simulations quantify the effect of cycle reduction and counting techniques by introducing different temperature profiles having identical dwell- and period time characteristics. A difference of 30% in predicted accumulated creep strain energy density per cycle has been determined for the studied profiles. Under the provided modelling assumptions and simplifications, the maximum variation of the thermal fatigue life of SAC305 solder joints is within 30% as the result of experimentally determined Young's modulus variation in as-delivered packages.

  • 3.
    Jacobsson, Lars
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Flansbjer, Mathias
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Johannesson, Pär
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Lindqvist, Jan-Erik
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Brander, Linus
    RISE., SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Schouenborg, Björn
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    ONKALO POSE Experiment - Geological and Rock Mechanical Tests on Samples from a Heating Test at Olkiluoto2016Rapport (Annet vitenskapelig)
  • 4.
    Johannesson, Pär
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Podgórski, Krzysztof
    Lunds University, Sweden.
    Rychlik, Igor
    Chalmers University of Technology, Sweden.
    Laplace distribution models for road topography and roughness2017Inngår i: International Journal of Vehicle Performance, ISSN 17453194, Vol. 3, nr 3, s. 224-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gaussian models are frequently used for road elevations. However, these models are often only valid for short sections of the road. Here we present a comprehensive approach to describe various aspects of road surface/elevation by using extensions of Gaussian models arising from random gamma distributed variances. These random variances result in the Laplace distribution and thus we refer to the so defined models as Laplace models. The approach is shown to perform well in modelling road topography, road roughness and multi-valued responses of forces and bending moments containing transients. The different Laplace models are presented together with numerical examples and Matlab code for simulation.

  • 5.
    Johannesson, Pär
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Podgórski, Krzysztof
    Lund University, Sweden.
    Rychlik, Igor
    Chalmers University of Technology, Sweden.
    Modelling roughness of road profiles on parallel tracks using roughness indicators2016Inngår i: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 70, nr 2, s. 183-210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The vertical road input is the most important load for durability assessments of vehicles. We focus on stochastic modelling of the parallel road profiles with the aim to find a simple but still accurate model for such bivariate records. A model is proposed that is locally Gaussian with randomly gamma distributed variances leading to a generalised Laplace distribution of the road profile. This Laplace model is paired with the ISO spectrum and is specified by only three parameters. Two of them can be estimated directly from a sequence of roughness indicators, such as IRI or ISO roughness coefficients. The third parameter, needed to define the cross-spectrum between the left and right road profiles, is estimated from the sample correlation. Explicit approximations for the expected fatigue damage for the proposed Laplace-ISO model are developed. The usefulness of the methods is validated using measured road profiles.

  • 6.
    Johannesson, Pär
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Podgórski, Krzysztof
    Lund University, Sweden.
    Rychlik, Igor
    Chalmers University of Technology, Sweden.
    Shariati, Nima
    Lund University, Sweden.
    AR(1) time series with autoregressive gamma variance for road topography modeling2016Inngår i: Probabilistic Engineering Mechanics, ISSN 0266-8920, E-ISSN 1878-4275, Vol. 43, s. 106-116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A non-Gaussian time series with a generalized Laplace marginal distribution is used to model road topography. The model encompasses variability exhibited by a Gaussian AR(1) process with randomly varying variance that follows a particular autoregressive model that features the gamma distribution as its marginal. A simple estimation method to fit the correlation coefficient of each of two autoregressive components is proposed. The one for the Gaussian AR(1) component is obtained by fitting the frequency of zero crossing, while the autocorrelation coefficient for the gamma autoregressive process is fitted from the autocorrelation of the squared values of the model. The shape parameter of the gamma distribution is fitted using the explicitly given moments of a generalized Laplace distribution. Another general method of model fitting based on the correlation function of the signal is also presented and compared with the zero-crossing method. It is demonstrated that the model has the ability to accurately represent hilliness features of road topography providing a significant improvement over a purely Gaussian model.

  • 7.
    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.2014Inngår i: Proceedings of the 3rd International Commercial Vehicle Technology Symposium (CVT2014), 2014, , s. 99-108Konferansepaper (Fagfellevurdert)
  • 8.
    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 profiles2013Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 66, s. 464-473artikkel-id 464-473Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 9.
    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 indicators2012Rapport (Fagfellevurdert)
    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.

  • 10.
    Johannesson, Pär
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Rychlik, Igor
    Chalmers University of Technology.
    Modelling of road profiles using roughness indicators2012Rapport (Annet vitenskapelig)
    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.

  • 11.
    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 indicators2014Inngår i: International Journal of Vechicle Design, Vol. 66, nr 4, s. 317-346Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12.
    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 engineering2013Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 66, s. 12-25artikkel-id 12-25Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 13.
    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 Reliability2013Inngår i: Quality and Reliability Engineering International, Vol. 29, s. 17-32Artikkel, forskningsoversikt (Fagfellevurdert)
    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

  • 14.
    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 Engineering2013Rapport (Annet vitenskapelig)
  • 15.
    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 prediction2009Inngår i: Quality and Reliability Engineering International, ISSN 0748-8017, E-ISSN 1099-1638, Vol. 25, nr 2, s. 167-179Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 16.
    Maghsood, Roza
    et al.
    Chalmers University of Technology, Sweden.
    Johannesson, Pär
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Detection of steering events based on vehicle logging data using hidden Markov models2016Inngår i: International Journal of Vehicle Design, ISSN 0143-3369, E-ISSN 1741-5314, Vol. 70, nr 3, s. 278-295Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In vehicle design it is desirable to model the loads by describing load environment, customer usage and vehicle dynamics. In this study a method will be proposed for detection of steering events such as curves and manoeuvring using on-board logging signals available on trucks. The method is based on hidden Markov models (HMMs), which are probabilistic models that can be used to recognise patterns in time series data. In an HMM, 'hidden' refers to a Markov chain where the states are not observable. However, observations depending on the hidden Markov chain can be observed. The idea here is to consider the current driving event as the hidden state, while the on-board logging signals generate the observed sequence. Examples of curve detection are presented for both simulated and measured data on a truck. The classification results indicate that the method can recognise left and right turns with small misclassification errors.

  • 17.
    Maghsood, Roza
    et al.
    Chalmers University of Technology, Sweden.
    Johannesson, Pär
    RISE - Research Institutes of Sweden, Säkerhet och transport.
    Wallin, Jonas
    Lund University, Sweden.
    Detection of steering events using hidden Markov models with multivariate observations2016Inngår i: International Journal of Vehicle Systems Modelling and Testing, ISSN 1745-6436, E-ISSN 1745-6444, Vol. 11, nr 4, s. 313-329Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article we propose a method to identify steering events, such as curves and manoeuvres for vehicles. We use a hidden Markov model with multidimensional observations, to estimate the number of events. Three signals, lateral acceleration, steering angle speed and vehicle speed, are used as observations. We demonstrate that hidden Markov models with a combination of continuous and discrete distributions for observations can be used to detect steering events. Further, the expected number of events is estimated using the transition matrix of hidden states. The results from both measured and simulated data show that the method works well and accurately estimates the number of steering events.

  • 18.
    Maghsood, Roza
    et al.
    Chalmers University of Technology, Sweden.
    Rychlik, Igor
    Chalmers University of Technology, Sweden.
    Johannesson, Pär
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Load description and damage evaluation using vehicle independent driving events2015Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 101, s. 268-276s. 268-276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider the loads that are related to steering events, and focus on the events that cause high forces on steering components. The load is simplified by keeping the extreme force value for each driving event. We define a simplified stochastic model for the load by modeling the extreme value for each driving event by a random variable. We give formulas to compute the theoretical load spectrum and the expected fatigue damage caused by the driving events. Further, in a sensitivity study we investigate how much the expected damage depends on the variability of parameters of the proposed model.

  • 19.
    Pettersson, Pär
    et al.
    Chalmers University of Technology, Sweden.
    Berglund, Sixten
    Chalmers University of Technology, Sweden ; Volvo Global Truck Technology, Sweden.
    Jacobson, Bengt
    Chalmers University of Technology, Sweden.
    Fast, Lars
    RISE - Research Institutes of Sweden, Säkerhet och transport, Elektronik.
    Johannesson, Pär
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Santandrea, Fabio
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    A proposal for an operating cycle description format for road transport missions2018Inngår i: European Transport Research Review, ISSN 1867-0717, E-ISSN 1866-8887, Vol. 10, nr 2, artikkel-id 31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: This article presents a proposal for an operating cycle format for describing transport missions of road vehicles, for example a logging truck fetching its cargo. The primary application is in dynamic simulation models for evaluation of energy consumption and other costs of transportation. When applied to product development, the objective is an ensemble of components and functions optimised for specific tasks and environments. When applied to selection of vehicle configuration, the objective is a vehicle specification tailored for its task. Method: The proposal is presented and its four main parts: road, weather, traffic and mission, are thoroughly explained. Furthermore, we implement the proposal in an example of a dynamic forward simulation model. Results: The example model is used for two case studies: a synthetic example of a complex transport mission (a logging truck fetching its cargo) that shows some advanced format features, and an example from a real vehicle log file (cargo transport) that seeks to compare the resulting simulated speed profile to the measured one. Conclusion: The results show that the proposed format works in practice. It can represent complex transport missions and it can be used to reproduce the main features of a logged speed profile even when combined with simple driver and vehicle models.

  • 20.
    Pettersson, Pär
    et al.
    Chalmers University of Technology, Sweden.
    Jacobsson, Bengt
    Chalmers University of Technology, Sweden.
    Johannesson, Pär
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Berglund, Sixten
    Volvo, Sweden.
    Laine, Leo
    Volvo, Sweden.
    Influence of hill‐length on energy consumption for hybridized heavy transports in long‐haul transports2016Inngår i: 7th Commercial Vehicle Workshop, 2016Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Goods transports are big producers of CO2, i.e. consumers of energy. The conventional transport vehicles such as tractor-semitrailers can be replaced by long combination vehicles (LCVs). By doing so, fuel consumption will be reduced drastically, with up to 30%, mainly thanks to the reduced aerodynamic resistance per pay load mass and/or volume. Further reduction of CO2 improvements can be made by hybridization, if the road topography demands variable propulsion power due to up- and downhills. This gain is emphasized for heavier vehicles. So, hybridized LCVs are of special interest. When developing vehicles, or selecting vehicle for a certain transport, one needs to assume an operating cycle. To describe the operating cycle correctly is very important for this purpose. Traditionally, the magnitude of road grades is the only topography measure used to characterise the road. In this paper it is studied how an additional measure, hill length, influences these heavy hybridized LCVs. Together one can see these two measures as amplitude and wavelength. It is shown how energy saving varies for different types of roads (combinations of grade magnitude and hill-length) and different energy buffer sizes. Road topography is statistically generated for a good coverage of road types, but also examples of real roads are marked within these synthetic roads. The result can be combined with estimates of hybridization costs and conclusions can be drawn when it is beneficial to hybridize and with how large buffer. The main takeaways from the paper are that the potential energy savings for heavy LVCs due to hybridization are significant and that the hill-length is an important characteristic measure to include in operating cycle definitions.

  • 21.
    Pettersson, Pär
    et al.
    Chalmers University of Technology, Sweden.
    Johannesson, Pär
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Jacobson, Bengt
    Chalmers University of Technology, Sweden.
    Bruzelius, Fredrik
    Chalmers University of Technology, Sweden; VTI Swedish National Road and Transport Research Institute, Sweden.
    Fast, Lars
    RISE - Research Institutes of Sweden, Säkerhet och transport, Elektronik.
    Berglund, Sixten
    Chalmers University of Technology, Sweden; Volvo AB, Sweden.
    A statistical operating cycle description for prediction of road vehicles’ energy consumption2019Inngår i: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 73, s. 205-229Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose a novel statistical description of the physical properties of road transport operations by using stochastic models arranged in a hierarchical structure. The description includes speed signs, stops, speed bumps, curvature, topography, road roughness and ground type, with a road type introduced at the top of the hierarchy to group characteristics that are often connected. Methods are described how to generate data on a form (the operating cycle format) that can be used in dynamic simulations to estimate energy usage and CO2 emissions. To showcase the behaviour of the description, two examples are presented using a modular vehicle model for a heavy-duty truck: a sensitivity study on impacts from changes in the environment, and a comparison study on a real goods transport operation with respect to energy usage. It is found that the stop intensity and topography amplitude have the greatest impact in the sensitivity study (8.3% and 9.5% respectively), and the comparison study implies that the statistical description is capable of capturing properties of the road that are significant for vehicular energy usage. Moreover, it is discussed how the statistical description can be used in a vehicle design process, and how the mean CO2 emissions and its variation can be estimated for a vehicle specification.

  • 22.
    Sandström, Johan
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Johannesson, Pär
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Mikael, Sidenmark
    Ocean Harvesting Technologies AB, Sweden.
    Reliability analysis with VMEA of a rack and pinion mechanism in a wave energy gravity accumulator2018Rapport (Annet vitenskapelig)
    Abstract [en]

    The method Variation and Mode Effect Analysis (VMEA) is successfully implemented for the AGMA based gear design of the rack pinion mechanism. The rack and pinion is a feature in Ocean Harvesting Technologies (OHT) gravity accumulator device. The purpose of it is to make the electrical power output to the grid more uniform. This is a novel technology where previous experience in designing is absent. The VMEA method is there for useful for incorporating all known uncertainties to estimate the uncertainty and reliability of the technology. This allows for adequate safety factors to be set so the desired reliability can be achieved.

    The uncertainty and reliability analysis is performed for different OHT designs and methods where the reliability is calculated. This calculation can be used as basis for further analysis when more design details are determined and modifications are made, thus allowing for more optimized and reliable design to be made.

  • 23.
    Svensson, Thomas
    et al.
    TS Ingenjörsstatistik, Sweden.
    Hannes, Dave
    Inspecta Technology AB, Sweden.
    Johannesson, Pär
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Dahlberg, Magnus
    Inspecta Technology AB, Sweden.
    Anderson, Andreas
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SP – Sveriges Tekniska Forskningsinstitut / Hållfasthet (BMh).
    Three HCF models for strain fatigue life of welded pipes in austenitic stainless steel2015Inngår i: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 101, s. 476-484s. 476-484Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fatigue bending tests have been performed on welded pipes made from an austenitic stainless steel. Four types of loading were used: 1) constant amplitude, 2) a load expected at pressure vessel environment, 3) a Gaussian load, and 4) a specially constructed two-level block load. The twenty-eight test results are evaluated using three different models: 1) the classical Basquin equation neglecting the fatigue limit, 2) the ASME model with a fatigue limit, and 3) a model with continuously decreasing fatigue limit. No significant differences between the three models were found. Predictions based on constant amplitude results appear to be non-conservative.

  • 24.
    Williams Portal, Natalie
    et al.
    RISE., SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB, Betong & Berg. Chalmers University of Technology, Sweden.
    Flansbjer, Mathias
    RISE., SP – Sveriges Tekniska Forskningsinstitut. Chalmers University of Technology, Sweden.
    Johannesson, Pär
    RISE., SP – Sveriges Tekniska Forskningsinstitut.
    Malaga, Katarina
    RISE., SP – Sveriges Tekniska Forskningsinstitut, CBI Betonginstitutet AB.
    Lundgren, Karin
    Chalmers University of Technology, Sweden.
    Tensile behaviour of textile reinforcement under accelerated ageing conditions2016Inngår i: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 5, s. 57-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Textile reinforced concrete (TRC) has emerged as a promising alternative wherein corrosion is no longer an issue and much thinner and light-weight elements can be designed. Although TRC has been expansively researched, the formalization of experimental methods concerning durability arises when attempting to implement and design such innovative building materials. In this study, accelerated ageing tests paired with tensile tests were performed. The change in physico-mechanical properties of various commercially available textile reinforcements was documented and evaluated. The ability for the reinforcements to retain their tensile capacity was also quantified in the form of empirical degradation curves. It was observed that accelerated test parameters typically applied to fibre-reinforced polymer (FRP) bars and grids are generally too aggressive for the textile reinforcement products and alternative boundary conditions are necessary. The developed degradation curves were found to have an overall good correlation with the experimental findings.

  • 25.
    Johannesson, Pär ()
    RISE., SP – Sveriges Tekniska Forskningsinstitut, SP Bygg och Mekanik.
    Speckert, Michael ()
    Fraunhofer ITWM, Germany.
    Guide to Load Analysis for Durability in Vehicle Engineering2013Bok (Annet vitenskapelig)
    Abstract [en]

    The overall goal of vehicle design is to make a robust and reliable product that meets the demands of the customers and this book treats the topic of analysing and describing customer loads with respect to durability. Guide to Load Analysis for Durability in Vehicle Engineering supplies a variety of methods for load analysis and also explains their proper use in view of the vehicle design process. In Part I, Overview, there are two chapters presenting the scope of the book as well as providing an introduction to the subject. Part II, Methods for Load Analysis, describes useful methods and indicates how and when they should be used. Part III, Load Analysis in view of the Vehicle Design Process, offers strategies for the evaluation of customer loads, in particular characterization of customer populations, which leads to the derivation of design loads, and finally to the verification of systems and components.

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