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  • GMMC - Ocean engineeringIgor Rychlik

    rychlik@math.chalmers.se

    Centre for Mathematical Sciences

    Chalmers

    GMMC - Ocean engineering p. 1/12

  • The Group

    Chalmers: Baxevani A., berg S., Mao W., Ringsberg J.,Rychlik I., Galtier T.

    LTH Lund: Bengtsson A., Podgrski K., Wegener J.

    Oslo: Brodtkorb P-A.

    Bretagn: Ailliot P., Mombet V., Provosto M., Olagnon M.

    UNC US: - Leadbetter M.R.

    GMMC - Ocean engineering p. 2/12

  • Motivation for research:

    Due to globablisation, increase of energy costs, possibleclimate change, vessels, offshore structures, are (will be)exposed to different loads than were design against.Hence one needs to monitor/describe actual loads actingon vessels, estimate probability for fatigue failure anddesign inspections intervals.

    General concern for risks associated with maritimeoperations calls for better mathematical methods todescribe time-space variability of environment and moredetailed modeling of responses of structures to the loads.

    GMMC - Ocean engineering p. 3/12

  • Spatio-temporal models:

    Models used for analysis of satellite, wind and pressurevelocity data. Possible applications in estimation

    of long term risks for fatigue damage,

    frequency of dangerous sea conditions meetingoffshore structures - 100 years waves, storms.

    or planning of ship routs that minimize the expectedfatigue damage and fuel consumption.

    GMMC - Ocean engineering p. 4/12

  • Median Hs in Feb., Aug., std. of ln(Hs), 100 years Hs

    150 100 50 0 50 100 15060

    40

    20

    0

    20

    40

    60

    100 years significant wave heights in m5 10 15 20 25

    GMMC - Ocean engineering p. 5/12

  • Papers 2007:

    [ ] Baxevani, A., Rychlik, I. (2007) Fatigue Life Predictionfor a Vessel Sailing the North Atlantic Route, ProbabilisticEngineering Mechanics, 22, pp. 159-169.

    [ ] Baxevani, A. Borget, C. and Rychlik, I. (2007) SpatialModels for the Variability of the Significant WaveHeight on the World Oceans. Proceedings of the 17thISOPE conference

    [ ] Baxevani A., Caires S. and Rychlik I. (2007)Spatio-temporal statistical modelling of significantwave heigth, Environmetrics to appear.

    GMMC - Ocean engineering p. 6/12

  • Wave distributions under stationary conditions:

    Distributions of geometrical wave characteristics:wavelength, wave height, steepness, velocity.

    Probability of meeting dangerous waves - risk forcapsizing,

    Length and energy in a wave group.

    Frequency, shape and life time of extreme waves.

    GMMC - Ocean engineering p. 7/12

  • Papers 2007:

    [ ] berg S., Rychlik I. (2007) Doppler-shiftapproximations of encountered wave statistics, OceanEngineering to appear.

    [ ] Podgrski, K., and Rychlik, I. (2007) EnvelopeCrossing Distributions for Gaussian Fields, underrevision for Probabilistic Engineering Mechanics.

    [ ] Rychlik I. and Leadbetter M.R. (2007) Estimatingcapsize risk for a vessel in a following sea. ISI 2007meeting in Lisbon pp. 1-4

    GMMC - Ocean engineering p. 8/12

  • Responses to environmental loads

    Evaluation of risks for fatigue damage and/or extremeresponses of vessels offshore structures to combinedwave - wind loads.

    Non-linear systems with Gaussian inputs.

    Non Gaussian loads.

    Superposition of loads - transients.

    GMMC - Ocean engineering p. 9/12

  • Transients

    0 50 100 150 200 250 300 350 400

    x [m]

    Z0(x)

    + Z11(x) + Z

    12(x) + Z

    13(x)

    = Z(x)

    0 10 20 30 40 50 60 70 800

    10

    20

    g(x)

    [1/

    m] theoretical intensity

    observed intensity

    0 10 20 30 40 50 60 70 800

    0.5

    1

    x [m]

    g(x)

    [1/

    m] theoretical intensity

    mean of 1000 obs.

    GMMC - Ocean engineering p. 10/12

  • Papers 2007:

    [ ] Bengtsson A., K., and Rychlik, I. (2007) Uncertaintyin fatigue life prediction of structures subject toGaussian loads, submitted.

    [ ] Bogsj, K., and Rychlik, I. (2007) Vehicle fatiguedamage caused by road irregularities, submitted.

    [ ] Gupta S., Rychlik I. (2007) Rain-flow Fatigue Damagedue to Nonlinear Combination of Vector GaussianLoads, Probabilistic Engineering Mechanics 22 pp. 231-249.

    GMMC - Ocean engineering p. 11/12

  • Other problems:

    Ergodicity and its lack.

    How long should one measure for reliable damageestimation?

    Random models of material strength (FCC, SP group).

    WAFO program package system that are used forfatigue analysis and wave modeling (Oslo,FCC,LTH).

    GMMC - Ocean engineering p. 12/12

    small The Groupsmall Motivation for research:small Spatio-temporal models:{small Median $H_s$ in Feb., Aug., std. of $ln (H_s)$,100 years $H_s$}{small Papers 2007:}{small Wave distributions under stationary conditions:}{small Papers 2007:}{small Responses to environmental loads}{small Transients}{small Papers 2007:}{small Other problems:}

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