Chalmers University of TechnologyDepartment of Mathematical SciencesGöteborg, Sweden

Safety of maritime operations - loads and responses.

Igor Rychlik

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Outline of presentation

• Introduction

• Marine research in Chalmers

• Environmental loads1. Modelling significant wave height2. Wave loads (Gaussian & non-Gaussian) WAFO

http://www.maths.lth.se/matstat/wafo/ 3. Responses (Linear & non-Linear)4. Risk for capsizing

• Ongoing projects

Marine research in Chalmers (SMT) Group of Jonas Ringsberg

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Mathematical Sciences cooperate within I & IV.

Researches on environmental models

• Models of Sea state variability

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tttp cos)cos( )(XE(t) 210t

= 2/365.2 ; Xt(p) = ln(Hs(p)); p=(p1,p2), position; t – time.

Model for the mean value of Hs

Model for the covariance function of X(p,t) and encountered Hs; z(t)=X(p(t),t). Application: Estimates of 100-year Hs

Simulation of encountered Hs:

04/19/23

04/19/23

5

80oW 60oW 40oW 20oW 0o

12oN

24oN

36oN

48oN

60oN

The whole measurement positions for all the voyages

Wave loads and responses

• Fatigue and extreme responses• Wave loads (Gaussian & Second order model)• Structural responses linear, quadratic filters Gaussian and non-Gaussian input• Goal: Estimation of design values (extreme)

and fatigue life• Uncertainty analysis

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Ongoing projects (1)

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No.1: fatigue routing and extreme estimation

• Investigate crossing of quadratic responses with Laplace Moving Average excitation

• Thomas Galtier, joint PhD student Chalmers and UBS Vannes. IFREMER

Ongoing projects (2)

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• Investigation of fatigue in ship details and estimation of extreme responses

• Non-Gaussian stress models (spectrum, skewness, kurtosis)

• Structural analysis and stochastic models gives parametric function of operation conditions

Ongoing projects (3)

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Ongoing projects (4)

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• Chasing uncertainties Uncertainties in material related parametersChaos expansion for parameters in models (wave loads

and responses)Variability of load condition

• For North Atlantic DNV uses 3 parameter Weibul model• The DNV model gives about 50% smaller expected damage per sea state

then observed. Another methods are needed. We use more detailed model for Hs variability, presented before.

Thank you!

http://www.chalmers.se/math/EN/research/research-groups3561/spatio-temporal

Email: Rychlik@chalmers.se