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New Perspectives on Analysis and Design of High-Speed Craft with Respect to Slamming
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.ORCID iD: 0000-0002-2093-3073
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

High-speed craft are in high demand in the maritime industry, for example, in maintenance operations for offshore structures, for search and rescue, for patrolling operations, or as leisure craft to deliver speed and excitement. Design and operation of high-speed craft are often governed by the hydrodynamic phenomena of slamming, which occur when the craft impact the wave surface. Slamming loads affect the high-speed craft system; the crew, the structure and various sub-systems and limit the operation. To meet the ever-increasing demands on safety, economy and reduced environmental impact, there is a need to develop more efficient high-speed craft. This progression is however limited by the prevailing semi-empirical design methods for high-speed planing craft structures. These methods provide only a basic description of the involved physics, and their validity has been questioned.

This thesis contributes to improving the conditions for designing efficient highspeed craft by focusing on two key topics: evaluation and development of the prevailing design methods for high-speed craft structures, and development towards structural design based on first principles modeling of the slamming process. In particular a methodological framework that enables detailed studies of the slamming phenomena using numerical simulations and experimental measurements is synthesized and evaluated. The methodological framework involves modeling of the wave environment, the craft hydromechanics and structural mechanics, and statistical characterization of the response processes. The framework forms the foundation for an extensive evaluation and development of the prevailing semi-empirical design methods for high-speed planing craft. Through the work presented in this thesis the framework is also shown to be a viable approach in the introduction of simulation-based design methods based on first principles modeling of the involved physics. Summarizing, the presented methods and results provide important steppingstones towards designing more efficient high-speed planing craft.

Place, publisher, year, edition, pages
Stockholm: Kungliga tekniska högskolan, 2016. , 35 p.
Series
TRITA-AVE, ISSN 1651-7660 ; 2016:20
Keyword [en]
Slamming, high-speed craft, finite-element analysis, design methods, experimental analysis, numerical simulations, design loads, statistical analysis
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
URN: urn:nbn:se:kth:diva-190861ISBN: 978-91-7595-976-4OAI: oai:DiVA.org:kth-190861DiVA: diva2:958409
Public defence
2016-09-29, F3, Lindstedtsvägen 26, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

QC 20160907

Available from: 2016-09-07 Created: 2016-08-17 Last updated: 2016-09-07Bibliographically approved
List of papers
1. On Structural Design of High-Speed Planing Craft with Respect to Slamming
Open this publication in new window or tab >>On Structural Design of High-Speed Planing Craft with Respect to Slamming
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2012 (English)In: 8th International Conference on High-Speed Marine Vehicles, 2012Conference paper (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-118806 (URN)
Conference
8th International Conference on High-Speed Marine Vehicles, Mülheim an der Ruhr, Germany, 26-28 September, 2012
Note

QC 20130228

Available from: 2013-02-28 Created: 2013-02-28 Last updated: 2016-09-07Bibliographically approved
2. Proposal of a New Standard for Wave Realizations in Time-Domain Simulations
Open this publication in new window or tab >>Proposal of a New Standard for Wave Realizations in Time-Domain Simulations
(English)Manuscript (preprint) (Other academic)
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
Identifiers
urn:nbn:se:kth:diva-189253 (URN)
External cooperation:
Note

QC 20160907

Available from: 2016-06-30 Created: 2016-06-30 Last updated: 2016-09-07Bibliographically approved
3. Experimental Evaluation of Slamming Pressure Models Used in Structural Design of High-Speed Craft
Open this publication in new window or tab >>Experimental Evaluation of Slamming Pressure Models Used in Structural Design of High-Speed Craft
2014 (English)In: International Shipbuilding Progress, ISSN 0020-868X, E-ISSN 1566-2829, Vol. 61, no 1-2, 17-39 p.Article in journal (Refereed) Published
Abstract [en]

In this paper a methodology that enables detailed studies of the momentary slamming pressure distribution and the related structural loads is presented. The methodology involves pressure measurements, spatial and temporal pressure distribution reconstruction, and finite element analysis. Using a set of model experiments with a high-speed planing craft towed in irregular waves, the methodology is applied to evaluate different slamming pressure models regarding their ability to accurately represent the structure loads. The slamming equivalent uniform pressure model used in the prevailing semi-empirical design methods, and non-uniform time-dependent pressure models used in a method for direct calculation, are considered. It is concluded that for smaller structure members, typically found in densely spaced metal structures, the uniform pressure model performs well with respect to accurately representing the structure loads. However, for larger members found in modern sandwich structures, the underestimation of structure loads is significant, especially with respect to the shear forces. The non-uniform pressure modeling technique is concluded to be promising regarding its ability to accurately represent the structure loads, regardless of structure member size. The presented methodology is concluded to be a useful tool in further research regarding the evaluation and development of methods for high-speed craft structural design.

Keyword
Local slamming, structural loads, high-speed craft, experiments, finite element modeling
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-118808 (URN)10.3233/ISP-130104 (DOI)2-s2.0-84898473968 (ScopusID)
Note

QC 20150624

Available from: 2013-02-28 Created: 2013-02-28 Last updated: 2016-09-07Bibliographically approved
4. On high-speed craft acceleration statistics
Open this publication in new window or tab >>On high-speed craft acceleration statistics
2016 (English)In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 114, 115-133 p.Article in journal (Refereed) Published
Abstract [en]

Design and operation of high-speed planing craft is ruled by the hydrodynamic impact loads and the related craft responses occurring at violent wave encounters. Simulation, measurement and characterization of these loads and responses is however far from trivial. Hereby the general knowledge about these processes is actually rather limited and it is common to rely on simple semi-empirical formulas when designing and analyzing high-speed craft. This paper presents a unique set of impact acceleration data for a high-speed craft in waves, generated based on non-linear strip simulations. Methods and measures for statistical characterization of the acceleration process are established and evaluated, and by application of these methods on the simulation data a number of issues are clarified, for example: slamming time scales and selection of appropriate sampling rates and filtering levels; identification of peak values in acceleration signals; statistical distributions and convergence; and the relation between the statistical peak fraction averages that are commonly used as design parameters and the actual extreme values. The established methods and generated results form a valuable basis for setting up and analyzing high-speed craft experiments and simulations, and for validating and updating the prevailing semi-empirical methods.

Keyword
Slamming, High-speed craft statistics, Acceleration, Experiments, Simulations
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:kth:diva-185379 (URN)10.1016/j.oceaneng.2016.01.004 (DOI)000372382000011 ()2-s2.0-84957010524 (ScopusID)
Note

QC 20160418

Available from: 2016-04-18 Created: 2016-04-18 Last updated: 2016-09-07Bibliographically approved
5. Allen and Jones revisited
Open this publication in new window or tab >>Allen and Jones revisited
2014 (English)In: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 89, 119-133 p.Article in journal (Refereed) Published
Abstract [en]

In this paper the prevailing semi-empirical design method, used to predict design slamming pressures for high-speed craft and which is implemented in the scantling rules of the classification societies, is reconstructed and evaluated using numerical and experimental methodologies. It is shown that the present formulations are relevant in terms of the predicted pressures, but that there is room for improvements, particularly in relationship to modern high-speed craft structures. The design method is therefore modified in relationship to these observations using the numerical methodology, and it is concluded that these modifications result in significant improvements regarding the predicted design pressures. Finally a discussion on the analysis methodology; the formulation of lifetime design loads; and the structural loads developed due to the simplified design pressure model is presented.

Keyword
Local slamming, High-speed craft, Structural design, Experiments, Finite-element modeling
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-156124 (URN)10.1016/j.oceaneng.2014.07.005 (DOI)000343690000011 ()2-s2.0-84906718892 (ScopusID)
Note

QC 20141217

Available from: 2014-12-17 Created: 2014-11-21 Last updated: 2016-09-07Bibliographically approved

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