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| 2. |
- Begovic, Ermina, et al.
(författare)
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Experimental modelling of local structure responses for high-speed planing craft in waves
- 2020
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Ingår i: Ocean Engineering. - : Elsevier Ltd. - 0029-8018 .- 1873-5258. ; 216
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Tidskriftsartikel (refereegranskat)abstract
- The modelling of planing craft dynamics in waves and related fluid-structure interaction is a hard challenge due to the highly nonlinear, transient and stochastic nature of the whole process. This paper explores the prospectives of detailed experimental modelling of the local structure responses for high-speed planing craft in waves. A novel experimental setup is presented where a well-defined model structure is integrated into the hull bottom of a typical planing craft model. The model is instrumented for measuring strains in the model structure, related slamming pressures, craft rigid body motions and accelerations. The experimental setup is thoroughly described and motivated and crucial aspects of the setup are verified through testing in idealized static loading conditions and by modal analysis. The capabilities of the experimental setup are demonstrated through systematic experiments in regular waves. The most indicative results are presented and discussed in relation to corresponding results from time-domain simulations The presented experimental modelling approach is concluded to enable uniquely detailed studies of the complete slamming related fluid-structure interaction process and provides a good tool for further research and development towards establishment of first principles-based methods for hydrodynamic and structure design of high-speed planing craft.
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| 3. |
- Razola, Mikael, 1984-
(författare)
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New Perspectives on Analysis and Design of High-Speed Craft with Respect to Slamming
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 4. |
- Razola, Mikael, 1984-
(författare)
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On Structural Design of High-Speed Craft
- 2013
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development in structural design and construction of high-speed craft has been extensive during the last decades. Environmental and economical issues have increased the need to develop more optimized structures, using new material concepts, to reduce weight and increase performance efficiency. However, both lack of, and limitations in design methodology, makes this a difficult task.In this thesis a methodological framework which enables detailed studies of the slamming loads and associated responses for high-speed planing craft in irregular waves is established. The slamming loads can either be formulated based on numerical simulations, or on experimental measurements and pressure distribution reconstruction. Structure responses are derived in the time-domain using finite element analysis. Statistical methods are used to determine design loads and lifetime extreme responses.The framework is applied to perform phenomenological studies of the slamming loading conditions for high-speed craft, and used to highlight and quantify the limitations in the prevailing semi-empirical method for design load determination with respect to slamming. A number of clarifications regarding the original derivation and the applicability of the prevailing semi-empirical method are presented. Finally, several potential improvements to the method are presented and the associated implications discussed.The long-term goal of the research project is to establish a method for direct calculation of loads and response for high-speed planing craft, which can enable design of truly efficient craft structures. The methodology and the results presented in this thesis are concluded to be important stepping-stones towards this goal.
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| 5. |
- Rosén, Anders, et al.
(författare)
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High-speed craft dynamics in waves: challenges and opportunities related to the current safety philosophy
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper considers the assessment of vertical accelerations of high speed planing craft in waves as the principal element for the risk management approach, i.e. formulation and application of operational limitations and operational guidance. Semi-empirical methods used by classification societies for vertical acceleration assessment are scrutinized. Insights from model experiments performed at the University of Naples “Federico II” (UNINA) and simulations performed at the Royal Institute of Technology (KTH) are presented. Deficiencies of the prevailing semi-empirical methods, and challenges and opportunities with a combined experimental-numerical approach, are discussed in perspective of the IMO high-speed craft safety philosophy.
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| 6. |
- Rosén, Anders, et al.
(författare)
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Numerical modelling of structure responses for high-speed planing craft in waves
- 2020
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Ingår i: Ocean Engineering. - : Elsevier. - 0029-8018 .- 1873-5258. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents an approach for time-domain simulation of structure responses, along with hydromechanic and structure inertia loads and motions responses, for high-speed planing craft in waves. Hydromechanic loads and motion responses are calculated with a non-linear time-domain strip method. A pressure shape function is introduced which enables formulation of detailed slamming pressure distributions sequences from the section forces in the strip method simulations. Structure responses are calculated quasi-dynamically by applying the momentary distributed pressure loads on a global finite element representation of the hull structure with use of inertia relief. From the time series output extreme responses are determined by means of short-term statistics. Promising results are demonstrated in applications on a high-speed planing craft, where extreme values of simulated structure responses are compared with responses to uniform design pressures from classification rules and measured responses from full-scale trials. The approach is concluded to be a useful tool for further research which has potential to form the basis for establishment of a computationally efficient simulation-based design methodology. A corresponding experimental modelling approach is presented in a parallel paper.
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