선박 및 해양구조물의 공법 설계 검증을 위한 다물체 동역학 기반의 통합 시뮬레이션 방법

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 조선해양공학과, 2018. 8. 노명일.It is the most important to verify the safety of the production design before the real operation. However, the verification which depends on the experience of the production engineer or the rule and regulation cannot be clearly proven or results in overestimation. Therefore, the verification based on dynamic analysis is widely adopted. However, it is impossible for existing programs to support some mechanical equipment such as the equalizer and SPMT (Self-Propelled Modular Transporter). Therefore, this study analyzes the requirements that are essential to simulate the lifting and erection operation in ships and offshore structures and proposes the integrated simulation framework based on multibody dynamics. The proposed framework is composed of five layers such as simulation core layer for solving the equations of motion, interface layer for data communication, simulation components layer including constraints, forces and collision, equipment layer, and service layer. This study develops a dedicated and differentiated program for dynamic analysis in ships and offshore structures, named SyMAP (SyDLabs Multibody Analysis Program). The proposed simulation framework integrates several modules based on various theoretical backgrounds. First of all, the equations of motion are based on multibody dynamics. Among the several formulations, we adopt the DELE (Discrete Euler-Lagrange Equation) to achieve the robustness during numerical integration. Furthermore, we formulate the equations of motion of the 1D frame element and 2D shell element based on ANCF (Absolute Nodal Coordinate Formulation). Kinematic constraints including joints and constraint-based wire rope between the rigid bodies, and between the rigid and flexible bodies are also derived. Especially, an equalizer which distributes the tension of wire ropes between the load and equipment equally is modeled based on the real mechanism by using the constraint-based wire rope. Meanwhile, we also deal with special issues in collision detection and response. Because the shape exports from the ship CAD system contains unenclosed meshes, we propose the position difference method which checks an intersection using the line segment made by the two vertices or the trigonal prism consisting of the two triangular meshes at time t0 and t1. Furthermore, BVH (Bounding Volume Hierarchy) and exclusion boxes were adopted to increase the performance. For collision response, non-interpenetration constraint method between a vertex and a plane is derived. This method is applicable when two bodies collide at the multiple points, and it does not compulsively violate the kinematic constraint because the collision force was also solved together when the equations of motion were solved numerically. Moreover, the collision force could be determined automatically, reflecting material properties such as restitution and softness. This study proposes the modeling of the mechanical parts of the SPMT taking into consideration the axle compensation mechanism to maintain the level of the platform when the SPMT drives over an uneven roadway by lifting up and down the wheel. As external forces, hydrodynamic force, wind force, current force, and mooring force are also explained. For the verification, comparison of the benchmarking tests of multibody systems and the examples of commercial multibody software DAFUL is conducted. The analytic solutions and the simulation results are compared in case of the flexible multibody dynamics. To verify the characteristics of the motion due to the hydrodynamic forces, the motion of the floating barge is compared with RAO given by WADAM, OrcaFlex, and SIMA. For the validation, the simulation results are compared with the data collected in the real operations. Finally, we provide four representative applications such as block lifting using equalizers, LPG tank erection considering a collision, thin plate block lifting considering deformation, and block offloading using SPMT, which have not been solved before. We conclude that the problems issued in ships and offshore structures are solved by the proposed or adopted methods. We convince that the developed program based on the proposed integrated simulation framework is able to cover all of the operations in ships and offshore structures.Nomenclature 1 1. Introduction 2 1.1. Research necessities 2 1.2. Requirements for new design verification software 6 1.2.1. Block lifting by the gantry and floating cranes 6 1.2.2. Block lifting considering deformation 9 1.2.3. Collision detection and response 10 1.2.4. Block offloading by SPMTs 11 1.2.5. Summary of requirements 15 1.3. Related work 16 1.3.1. Related work for simulation framework 16 1.3.2. Related work for dynamic analysis including flexible bodies 17 1.3.1. Related work for collision detection and response 18 1.3.2. Related work for the equalizer 19 1.3.3. Related work for block offloading 22 1.4. Configuration of integrated simulation framework 24 1.4.1. Simulation core layer 24 1.4.2. Interface layer 28 1.4.3. Simulation component layer 28 1.4.4. Equipment layer 28 1.4.5. Service layer 29 1.4.6. Library diagram and relations 29 1.4.7. New production design verification program 31 1.5. Research objective and work scope 32 2. Theoretical backgrounds 33 2.1. Multibody dynamics for rigid bodies 33 2.1.1. Discretization of the Euler-Lagrange equation 33 2.1.2. Discrete Euler-Lagrange equation with constraints 38 2.1.3. Discrete Euler-Lagrange equation with constraints and non-conservative forces 42 2.1.4. Regularization 44 2.1.5. Stabilization 47 2.1.6. Final form of the Discrete Euler-Lagrange equation 48 2.1.7. Physical meanings of the parameters in DELE 50 2.2. Multibody dynamics for deformable bodies (1D frame element) 52 2.2.1. Overview of flexible multibody dynamics 52 2.2.2. Kinematic description of frame element 54 2.2.3. Strain energy 61 (1) Axial strain energy 61 (2) Bending strain energy 65 (3) Torsional strain energy 66 (4) Summary of strain energy 68 2.2.4. Equations of motion for 1D frame element 68 (1) Euler-Lagrange equation revisit 68 (2) Kinetic energy of frame element 69 (3) Strain energy of frame element 71 (4) External forces 76 (5) Summary of equations of motion for 1D frame element 81 2.2.5. Discrete Euler-Lagrange equation including Flexible body 82 2.3. Multibody dynamics for deformable bodies (2D shell element) 86 2.3.1. Kinematic description of shell element 86 2.3.2. Strain energy for shell element 90 2.3.3. Strain energy for membrane element 94 2.3.4. Equations of motion for 2D shell element 95 (1) Kinetic energy of shell element 95 (2) Longitudinal and shear strain energy of shell element 97 (3) Bending and twisting strain energy of shell element 104 (4) External forces 105 (5) Summary of equations of motion for 2D shell element 110 2.4. Kinematic constraints between rigid bodies 111 2.4.1. Ball joint 111 2.4.2. Universal joint 113 2.4.3. Hinge joint 114 2.4.4. Slider joint 116 2.4.5. Fixed joint 117 2.4.6. Slider-hinge joint 119 2.4.7. Wire rope constraint 119 2.5. Kinematic constraints between rigid and flexible bodies 123 2.5.1. Joints on 1D frame element 123 (1) Ball joint between rigid and 1D flexible bodies 123 (2) Fixed joint between rigid and 1D flexible bodies 125 2.5.2. Joints on 2D shell element 127 (1) Ball joint between rigid and 2D flexible bodies 127 (2) Fixed joint between rigid and 2D flexible bodies 129 2.6. Collision detection and response 132 2.6.1. Collision detection 132 (1) Position difference method 134 (2) Space partitioning 141 (3) Exclusion box 143 2.6.2. Collision response 144 (1) Classification of collision response 145 (2) Non-interpenetration constraint method 146 (3) Consideration of material properties 151 2.6.3. Dynamic analysis including collision detection and response 153 2.6.4. Case studies of collision detection and response 154 (1) Collision for multibody system 154 (2) Performance tests of collision detection 158 (3) Collision between complex shapes 163 (4) Collision according to material properties 165 (5) Comparison with open source program 167 2.6.5. Consideration of impulse and impulsive force 168 2.7. Modeling of Equalizer 173 2.7.1. Real mechanism of the equalizer 173 2.7.2. Modeling of pulleys and the equalizer 174 2.7.3. Case studies 176 (1) Pulleys 176 (2) Equalizer 178 2.8. Modeling of Self-propelled modular transporter (SPMT) 184 2.8.1. Modeling of SPMT and axle compensation mechanism 184 2.8.2. Replication of ballasting and de-ballasting for the floaters 187 2.8.3. Case studies of SPMT 189 (1) Pass through small bump 189 (2) Pass through inclined bump 192 2.9. External forces 196 2.9.1. Hydrodynamic force 196 2.9.2. Buoyant force 198 2.9.3. Wind force 199 2.9.4. Current force 201 2.9.5. Catenary mooring 202 2.9.6. Wire rope tension 203 3. Verification and validation 204 3.1. Verification of multibody dynamics for rigid bodies 204 3.1.1. Multibody benchmarking tests 204 (1) A01. Simple pendulum 204 (2) A02. N-four-bar mechanism 205 (3) A03. Andrews mechanism 207 (4) A04. Bricards mechanism 210 3.1.2. Verification by commercial software 213 (1) Three links connected by hinge joints (Open loop system) 214 (2) Three links connected by hinge joints (Closed loop) 216 3.2. Verification of multibody dynamics for deformable bodies 219 3.2.1. Verification of 1D frame element 219 3.2.2. Verification of 2D shell element 224 3.3. Verification of hydrodynamic force 228 3.3.1. Barge motion by a regular wave (I) 228 3.3.2. Barge motion by a regular wave (II) 230 3.3.3. Barge motion connected by 4 springs 232 3.4. Verification of catenary mooring 238 3.5. Validation by real operation (1) Module erection 239 3.5.1. Modeling 239 3.5.2. Scenario 243 3.5.3. Comparison of the posture by images 245 3.5.4. Comparison of tensions 247 3.6. Validation by real operation (2) LQ erection 250 3.6.1. Modeling 250 3.6.2. Operation sequence 252 3.6.3. Comparison of tensions 253 4. Applications 255 4.1. Block lifting using equalizers 255 4.1.1. Load lifting simulation using a gantry crane 255 4.1.2. Load lifting simulation using a floating crane 259 4.2. LPG tank erection considering collision 264 4.3. Thin plate block lifting considering deformation 270 4.3.1. Thin plate block turn-over by a gantry crane 270 4.3.2. Thin plate block lifting by a floating crane 273 4.4. Block offloading using SPMTs 276 5. Conclusion and future work 289 5.1. Summary 289 5.2. Contributions (Originality) 291 5.2.1. Theoretical contributions 291 5.2.2. Contributions for applications 291 5.2.3. Other contributions 292 5.3. Future works 292 Reference 293 국문 초록 298Docto

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