Assessment of Fatigue Damage of Floating Fish Cages Due to Wave Induced Response

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Paul E. Thomassen ◽  
Bernt J. Leira
Keyword(s):  
Structural Analysis ◽  
Fatigue Damage ◽  
Design Procedure ◽  
Irregular Waves ◽  
Induced Response ◽  
Fish Farms ◽  
Analysis And Design ◽  
Drag Forces ◽  
Fatigue Design ◽  
Fish Cages

Floating fish cages provide the main production utilities for salmon farming. However, despite their pivotal role in production safety as well as in protection of the environment, there is still much room for improvement in relation to verified structural design procedures and computerized tools for structural analysis. To a large extent, they can be regarded as not being in accordance with the state-of-the-art of structural analysis and design for more traditional types of marine structures. In this paper, a study of fatigue design for floating fish farms is presented. This study is based on a structure that is being applied by the Norwegian fish farming industry today. The floater is made of steel cylinders that are configured as a square. The formulation for the wave loading is based on a combination of potential theory and horizontal drag forces on the floater. Horizontal and vertical drag forces on the netpen are also accounted for. A fatigue design procedure for floating fish farms in steel is suggested. The procedure is based on a time domain analysis of the structure in irregular waves. For each seastate, 1/2 h (real time) analysis is performed and the stress history for an assumed critical location is computed. Based on the stress histories, the fatigue damage is estimated by application of rain flow counting and a given SN curve. The scatter diagram for the seastates at a given location is generated from the associated wind speed distribution.

Assessment of Fatigue Damage of Floating Fish Cages Due to Wave Induced Response

2009 ◽  
Author(s):  
Paul E. Thomassen ◽  
Bernt J. Leira
Keyword(s):  
Structural Analysis ◽  
Fatigue Damage ◽  
Design Procedure ◽  
Irregular Waves ◽  
Induced Response ◽  
Fish Farms ◽  
Analysis And Design ◽  
Drag Forces ◽  
Fatigue Design ◽  
Fish Cages

Floating fish cages provide the main production utilities for salmon farming. However, despite their pivotal role in production safety as well as in protection of the environment, there is still much room for improvement in relation to verified structural design procedures and computerized tools for structural analysis. To a large extent they can be regarded as not being in accordance with the state-of-the-art of structural analysis and design for more traditional types of marine structures. In this paper a study of fatigue design for floating fish farms is presented. The study is based on a structure which is being applied by the Norwegian fish farming industry today. The floater is made of steel cylinders which are configured as a square. The formulation for the wave loading is based on a combination of potential theory and horizontal drag forces on the floater. Horizontal and vertical drag forces on the netpen are also accounted for. A fatigue design procedure for floating fish farms in steel is suggested. The procedure is based on a time domain analysis of the structure in irregular waves. For each seastate half an hour (real time) analysis is performed and the stress history for an assumed critical location is computed. Based on the stress histories, the fatigue damage is estimated by application of rain flow counting and a given SN curve. The scatter diagram for the seastates at a given location is generated from the associated wind speed distribution.

A Prototype Tool for Analysis and Design of Floating Fish Cages

2005 ◽  
Author(s):  
Paul E. Thomassen ◽  
Bernt J. Leira
Keyword(s):  
Structural Analysis ◽  
Object Oriented ◽  
Hydrodynamic Load ◽  
Fish Farms ◽  
Analysis And Design ◽  
Load Models ◽  
Current State ◽  
Production Safety ◽  
Fish Cages ◽  
Farming Industry

Floating fish cages are the main means of production in the multi billion euro salmon farming industry. Despite its pivotal role in production safety, protection of values, as well as in protection of the environment, neither verified structural design procedures nor computer tools for structural analysis and design have received much attention. To a large extent they can be regarded as not being in accordance with the current state-of-the-art of structural analysis and design of slender marine structures. A momentum to move towards a more scientific based design approach has been created by the requirements of the recently introduced Norwegian certification criteria and the accompanying design code NS 9415. A prototype for analysis and design of floating fish cages has been developed and is described herein. The tool is based on an object-oriented framework for general FE analysis. The framework has among other things been developed with ease of extensibility for the software developer in mind. The prototype is thus intended for iterative extension of the functionality. In the first development iteration, described here, the FE framework has been extended, with hydrodynamic load models and a user interface for analysis of floating fish farms. The development of the prototype shows that by building on an object oriented FE framework, specialized and focused applications for aquaculture can be developed with limited effort. As an example analysis — and a possible benchmark — a simplistic model of a steel frame is chosen. Comparison of results obtained with different load formulations indicated that the buoyancy load was more important than the hydrodynamic load.

Analysis and Design Procedure of a mm-Wave Class-E Power Amplifier

2021 ◽  
pp. 105036
Author(s):  
Habib Ghasemizadeh ◽  
Abdolreza Nabavi ◽  
Member IEEE ◽  
Mohsen Haghighat
Keyword(s):  
Power Amplifier ◽  
Design Procedure ◽  
Analysis And Design ◽  
Class E
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