Master’s degree thesis IP501909 MSc thesis, discipline oriented master Parametric Structural Analysis for a Platform Supply Vessel at Preliminary Design Phase – A Sensitivity Study via Design of Experiments 1103/Sthéfano Lande Andrade Number of pages including this page: 147 Aalesund, 03/06/2016 Mandatory statement Each student is responsible for complying with rules and regulations that relate to examinations and to academic work in general. The purpose of the mandatory statement is to make students aware of their responsibility and the consequences of cheating. Failure to complete the statement does not excuse students from their responsibility. Please complete the mandatory statement by placing a mark in each box for statements 1-6 below. 1. I/we herby declare that my/our paper/assignment is my/our own work, and that I/we have not used other sources or received other help than is mentioned in the paper/assignment. 2. I/we herby declare that this paper Mark each 1. 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I/we are aware of the NTNU’s rules and regulation for using sources. Publication agreement ECTS credits: 120 Supervisor: Henrique Murilo Gaspar / co-supervisor: Sören Ehlers Agreement on electronic publication of master thesis Author(s) have copyright to the thesis, including the exclusive right to publish the document (The Copyright Act §2). All theses fulfilling the requirements will be registered and published in Brage, with the approval of the author(s). Theses with a confidentiality agreement will not be published. I/we hereby give NTNU the right to, free of charge, make the thesis available for electronic publication: yes no Is there an agreement of confidentiality? yes no (A supplementary confidentiality agreement must be filled in and included in this document) - If yes: Can the thesis be online published when the period of confidentiality is expired? yes no This master’s thesis has been completed and approved as part of a master’s degree programme at NTNU Ålesund. The thesis is the student’s own independent work according to section 6 of Regulations concerning requirements for master's degrees of December 1st, 2005. Date: 03/06/2016 Master Thesis 2016 For STUD.TECHN. Sthéfano Lande Andrade Parametric Structural Analysis for a Platform Supply Vessel at Preliminary Design Phase – A Sensitivity Study via Design of Experiments The offshore market has been severely affected by the sudden drop in oil prices, affecting the support vessels industry. This challenged both shipyards and ship designers to find possible solutions that will raise their competitiveness, as structural optimization. The objective of the project is to create a method capable of performing a sensitivity analysis focusing on the structural optimization of Offshore Support Vessels from the PX family. The sensitivity analysis will be performed according to requirements defined by Ulstein. Master Thesis’ project plan:  Develop a structural Optimization Routine; o Optimization Model based on design of experiments; o Structural Analysis to be performed with FEM capable software (Ansys);  Apply routine to a simple case; o Loaded stiffened plate; o Different topology configurations;  Create Finite Element models of PSV; o Parametric Model; o Define a representative model (section vs entire vessel);  Run the routine on the model. Optimization results:  Propose effective solutions to minimize mass according to the requirements. iii Supervisor - Henrique Murilo Gaspar (NTNU) Co-Supervisor - Sören Ehlers (TUHH) Finish: 3rd June 2016 Supervisor Signature: Henrique Murilo Gaspar iv Abstract Parametric structural design analysis is a promising alternative to diminish the hull’s structural mass, resulting in a vessel with higher payload capacity as well as lower construction and maintenance costs. The challenge of investigating a large space of alternatives, e.g. testing topology and materials, is caused by the high amount of engineering time required to model, analyse and evaluate each of the possible configurations. The objective of this paper is to demonstrate the application of a structural sensitivity study for a parametrically model global structure of a platform supply vessel, focused on mass reduction during the preliminary design phase. The methodology starts with the CAD/FEM creation of a parametric model, representing the vessel’s middle sectional region. The focus on early design stages allows for simplifications in the structural model, gaining computational time when bypassing local details that would require finer mesh, which is not desirable for any kind of fast analyses procedures. Strength analyses are performed, following procedure of design of experiments methodology, which serves as a tool to understand mass efficiency based on the initially defined variables. The method gathers knowledge on impact of variables on various combined responses, and these are used to map the most efficient parameters and determine a viable solution space that better material usage in comparison to the original design. Keywords: Parametric Model; Structural Sensitivity Analysis; Response Surface Methodology. v Acknowledgements Primarily, I would like to thank my family, who always backed me up in my decisions. They encourage me to go beyond and to not doubt myself. Their continuous support and care has always been unparalleled. I also must thank my friends who were always present to help me in times of need and to commemorate accomplishments together. I must express my gratitude towards my supervisor, Henrique Gaspar. Beyond supervising, correcting and providing information for the thesis, he showed trust in my capabilities, helped me develop new skills, aided at moments of need and pushed me always do better. Sören Ehlers, my co-supervisor, provided a large amount of knowledge towards ship structural design and software based finite elements analysis, always with utmost patience. Moreover, during the initial stages of my thesis, Sören offered me the opportunity to study these topics directly at TUHH. I would like to thank Ulrikke Brandt and Ulstein, who provided technical knowledge about PSV’s structural design and helped me outline the boundaries of the case. Candidate Signature: Sthéfano Lande Andrade vi vii Table of Contents List of figures ........................................................................................................................ xi List of tables ........................................................................................................................ xiv Abbreviations ...................................................................................................................... xvi 1 Introduction ........................................................................................................................ 1 1.1 Project background ...................................................................................................... 1 1.2 Research Question ....................................................................................................... 2 1.3 Literature Review ........................................................................................................ 3 1.4 Thesis Scope ................................................................................................................ 4 2 Structural Design of Platform Supply Vessels at Early Design Stages ............................. 7 2.1 Conceptual Structural Design...................................................................................... 7 2.1.1 Global Loads ........................................................................................................ 8 2.1.2 Longitudinal Strength .......................................................................................... 9 2.1.3 Finite Elements applied to Ship’s Structural Design ......................................... 11 2.2 Platform Supply Vessel ............................................................................................. 14 2.3 Structural Optimization ............................................................................................. 15 2.3.1 Optimization of Shape ....................................................................................... 15 2.3.2 Optimization of Topology.................................................................................. 15 2.3.3 Optimization of Dimensioning .......................................................................... 16 3 Experimentation and Sensitivity Analysis ....................................................................... 17 3.1 Design of Experiments .............................................................................................. 18 3.2 Introduction to Response Surface Method ................................................................ 21 4 Methodology .................................................................................................................... 25 4.1 FE Model Creation Guidelines .................................................................................. 27 4.2 Design of Experiments applied to simulations .......................................................... 34 4.2.1 Central Composite Design ................................................................................. 35 4.2.2 D-Optimal Overdetermined. .............................................................................. 36 viii