GMMC - Ocean engineeringIgor Rychlik
Centre for Mathematical Sciences
Chalmers
GMMC - Ocean engineering – p. 1/12
The Group
Chalmers: Baxevani A., Åberg S., Mao W., Ringsberg J.,Rychlik I., Galtier T.
LTH Lund: Bengtsson A., Podgórski 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 50 100 150−60
−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, Probabilistic
Engineering 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 17th
ISOPE 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:
[ ] Åberg S., Rychlik I. (2007) Doppler-shiftapproximations of encountered wave statistics, Ocean
Engineering to appear.
[ ] Podgórski, 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 2007
meeting 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.
[ ] Bogsjö, 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
