2 - Dependability of Offshore Wind Turbines - Arangio

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ASCE Earth & Space 2010 OWT Symposium …

ASCE Earth & Space 2010 OWT Symposium

http://content.asce.org/files/pdf/EarthSpace2010Prelim-FINAL.pdf

http://ascelibrary.org/doi/book/10.1061/9780784410967

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  • 1. DEPENDABILITY OF OFFSHOREDEPENDABILITY OF OFFSHORE WIND TURBINESWIND TURBINES Franco Bontempi, Marcello Ciampoli, Stefania Arangio University of RomeUniversity of Rome ““La SapienzaLa Sapienza”” Department ofDepartment of Structural and Geotechnical EngineeringStructural and Geotechnical Engineering Honolulu, March 17th 2010
  • 2. OUTLINEOUTLINE Conclusions ConclusionsConclusionsConclusionsConclusions System approach for structural engineering applications IntroductionIntroductionIntroductionIntroduction The concept of dependability PartIPartIPartIPartIPartIIPartIIPartIIPartII Application to an offshore wind turbine support structure Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 3. Definition of structure Stefania Arangio - Structural integrity monitoring of long span bridges using adaptive models “device for channeling loads that results from the use and/or presence of the building to the ground” STRUCTURE This definition does not consider some important aspects: INTERACTION AMONG DIFFERENT STRUCTURAL PARTS INTERACTION BETWEEN THE WHOLE STRUCTURES AND THE DESIGN ENVIRONMENT Interactions are characterized by nonlinearities and uncertainties COMPLEXITY
  • 4. Structure vs. Structural System STRUCTURE SYSTEM APPROACH STRUCTURAL SYSTEM “a set of interrelated components working towards a common purpose” INTERACTION AMONG DIFFERENT STRUCTURAL PARTS INTERACTION BETWEEN THE WHOLE STRUCTURES AND THE DESIGN ENVIRONMENT Interactions are characterized by nonlinearities and uncertainties COMPLEXITY Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 5. NASA System complexity Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines IntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 6. Structure vs. Structural System Stefania Arangio - Structural integrity monitoring of long span bridges using adaptive models STRUCTURAL DECOMPOSITION Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines SYSTEM APPROACH STRUCTURAL SYSTEM INTERACTION AMONG DIFFERENT STRUCTURAL PARTS INTERACTION BETWEEN THE WHOLE STRUCTURES AND THE DESIGN ENVIRONMENT Interactions are characterized by nonlinearities and uncertainties COMPLEXITY
  • 7. Structural decomposition Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines IntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 8. OWT Structural decomposition SCALE DETAIL LEVEL FINITE ELEM. SYSTEM LEVEL MACRO LEVEL MESO-LEVEL MICRO-LEVEL Wind farm Single turbine Single turbine Individual components Idealized model components Approximate shape of the components Detailed shape of the components Detailed shape of the connections BLOCK elements BEAM elements SHELL and SOLID elements SHELL and SOLID elements
  • 9. OUTLINEOUTLINE Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines System approach for structural engineering applications IntroductionIntroductionIntroductionIntroduction The concept of dependability PartIPartIPartIPartIPartIIPartIIPartIIPartII Application to an offshore wind turbine support structure
  • 10. How is possible to define (and measure ) the quality of complex structural systems as the OWT farms? We need a concept able to take properly into account the different aspects related to conceptual and structural design, construction and maintenance during the whole lifetime. DEPENDABILITY It is a global concept that describes the aspects assumed as relevant with regards to the quality performance and its influencing factors (Bentley,1993) In rigorous terms, the dependability of a system reflects the user’s degree of trust in that system, i.e. the user’s confidence that the system will operate as expected and will not “fail” in normal use (Sommerville, 2000): the system shall give the expected performance during the whole lifetime Dependability (1) Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 11. Dependability (2) DEPENDABILITY OF STRUCTURAL SYSTEMS MEANS THREATS ATTRIBUTES Objective measure of the dependability Things that can undermine the dependability Ways to improve the dependability Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines IntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 12. Availability Integrity Safety Reliability Maintainability Security High level/ Active performance Low level/ Passive performance Attributes of the dependability ATTRIBUTES Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 13. ReliabilityReliability: the system capacity of failure-free operation over a specified time in a given environment for a given performance (can be expressed quantitatively by a probability … ) AvailabilityAvailability: the system capacity (or readiness) at a point in time of being operational and able to perform as required (can be expressed quantitatively by a probability … ) MaintainabilityMaintainability: the system attribute concerned with the ease of repairing the system after a failure has been discovered or improving the system to include new features Active performance Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines IntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 14. IntegrityIntegrity: absence of alterations of structural response (related to the completeness and consistency of the structural configuration) SafetySafety: is a property of the system that reflects its ability to operate, normally or abnormally, without danger of causing human injury or death and without damage to the system’s environment (safety-related prescriptions usually exclude undesirable situations, rather than specify required performances) SecuritySecurity: The system property that reflects the system’s ability to protect itself from accidental or deliberate external attack (robustnessrobustness) Passive performance Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines IntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 15. Reliability and safety are related but distinct o In general, reliability (and availability) is necessary but not sufficient condition for system safety o Reliability is concerned with conformance to a given specification for a given performance o Safety is concerned with ensuring system cannot cause damage irrespective of whether or not it conforms to its specification ReliabilityReliability SafetySafety SecuritySecurity It is an essential pre-requisite for availability, reliability and safety. Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines IntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 16. Failure Fault Error Permanent interruption of the system ability to perform a required function under assigned operating conditions THREATS The system is in an incorrect state: it may or may not cause failure Defect that represents a potential cause of error, active or dormant Fault managing Fault detection Fault diagnosis MEANS Fault tolerant design Inverse problems
  • 17. ATTRIBUTES THREATS MEANS RELIABILITY FAILURE ERROR FAULT FAULT TOLERANT DESIGN FAULT DETECTION FAULT DIAGNOSIS FAULT MANAGING DEPENDABILITY of STRUCTURAL SYSTEMS AVAILABILITY SAFETY MAINTAINABILITY permanent interruption of a system ability to perform a required function under specified operating conditions the system is in an incorrect state: it may or may not cause failure it is a defect and represents a potential cause of error, active or dormant INTEGRITY ways to increase the dependability of a system An understanding of the things that can affect the dependability of a system A way to assess the dependability of a system the trustworthiness of a system which allows reliance to be justifiably placed on the service it delivers SECURITY High level / active performance Low level / passive performance ATTRIBUTES THREATS MEANSMEANS RELIABILITYRELIABILITY FAILURE ERROR FAULT FAULT TOLERANT DESIGN FAULT TOLERANT DESIGN FAULT DETECTIONFAULT DETECTION FAULT DIAGNOSISFAULT DIAGNOSIS FAULT MANAGINGFAULT MANAGING DEPENDABILITY of STRUCTURAL SYSTEMS AVAILABILITY SAFETY MAINTAINABILITY permanent interruption of a system ability to perform a required function under specified operating conditions the system is in an incorrect state: it may or may not cause failure it is a defect and represents a potential cause of error, active or dormant INTEGRITY ways to increase the dependability of a system An understanding of the things that can affect the dependability of a system A way to assess the dependability of a system the trustworthiness of a system which allows reliance to be justifiably placed on the service it delivers SECURITY High level / active performance Low level / passive performance Dependability Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 18. Analysis and design of complex structural systems Stefania Arangio - Structural integrity monitoring of long span bridges using adaptive models STRUCTURAL SYSTEM INTERACTION AMONG DIFFERENT STRUCTURAL PARTS INTERACTION BETWEEN THE WHOLE STRUCTURE AND THE DESIGN ENVIRONMENT Interactions are characterized by strong character, nonlinearity and uncertainty COMPLEXITY DECOMPOSITION STRATEGY SYSTEM APPROACH QUALITY ON THE WHOLE FOR THE STRUCTURAL SYSTEM: DEPENDABILITY ATTRIBUTES THREATS MEANS STRUCTURAL INTEGRITY PERFORMANCE BASED DESIGN IntroductionIntroductionPartIPartIPartIIPartII ConclusionConclusion ss
  • 19. OUTLINEOUTLINE Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines 1/31 System approach for structural engineering applications IntroductionIntroductionIntroductionIntroduction The concept of dependability PartIPartIPartIPartIPartIIPartIIPartIIPartII Application to an offshore wind turbine support structure
  • 20. Progressive loss of structural integrity 105m 35m • Water level: 35 m • Heigth of the structure above water level: 105 m • Pile length under sea bed • Steel 355 •Turbine 5/6 MW For wind farms with a lot of structures it is interesting to investigate the ability of the system to sustain further levels of demand after the ULS up to extreme loading conditions Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines IntroductionIntroductionPartIPartIPartIIPartIIConclusionsConclusions
  • 21. Description of the analysis (1) The survivability of the system is investigated allowing large damage developing inside the structural system: the spread of the plasticity is allowed until the last configuration of equilibrium is reached Non linear analysis: -Material plasticity -Large displacements Integer structure (ULS) Loss of structural integrity λ = 1.00 λ = 1.44
  • 22. Increase of damage from the reference baseline ULS configuration to the last equilibrium configuration λ = 1.44λ = 1.00 λ = 1.32λ = 1.10 Description of the analysis (2) Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines
  • 23. Measuring the loss of integrity 1st freq 2nd freq 3rd freq A quantitative measure can be obtained considering the modal behavior Load multiplier Frequencies
  • 24. OUTLINEOUTLINE Bontempi F., Ciampoli M., Arangio S. – Dependability of offshore wind turbines System approach for structural engineering applications IntroductionIntroductionIntroductionIntroduction The concept of dependability PartIPartIPartIPartIPartIIPartIIPartIIPartII Application to an offshore wind turbine support structure
  • 25. Conclusions Offshore wind turbines (OWT) are complex structural systems Their complexity is related to: - nonlinearities - uncertainties - interaction between the parts - interaction between the whole structure and the environmental design University of Rome “La Sapienza” A global concept is needed to the define the quality of the OWT in a comprehensive way DEPENDABILITY
  • 26. Conclusions (2) The concept of dependability has been applied to OWT support structures to investigate the survivability of the system in presence of extreme actions University of Rome “La Sapienza” λ = 1.44λ = 1.00 The increasing of damage from the reference ULS configuration has been considered by means of the load multiplier and considering the modal behavior of the structure