Obtain the knowledge needed for understanding, calculation and the analysis of the problems related to collision and grounding of ships. In particular, introduction to nonlinear finite element method analysis.

Student responsibilities:

Grading and evaluation of student work over the course of instruction and at a final exam:

Methods of monitoring quality that ensure acquisition of exit competences:

Upon successful completion of the course, students will be able to (learning outcomes):

Lectures

1. Introduction to collision and grounding (C&G). Treatment of C&G, accident statistics, collision scenarios. Overview and history of C&G.

2. Theoretical background for collision and grounding. Definition of inner mechanics (IM), external dynamics (ED) and coupling of both.

3. Parameters affecting the collision and grounding event. Influence of ship velocity, striking angle, ship mass etc. on the collision consequences. A short review on experimental testing is given. IM and ED experiments, large- and model-scale ship collision experiments.

4. Coupled and/or uncoupled IM and ED, simple calculation examples of IM and ED.

5. General IM principles, different deformation mechanisms. Geometrical and material nonlinearities. Brief introduction to theory of large deformations.

6. IM: failure mechanics, theoretical background of applicable failure criteria: equivalent plastic strain, thru thickness strain, RTCL.

7. Short FE introduction, general treatment of large deformations, explicit methods, nonlinear solution methods and material models. Modeling principles, shell element technology, hourglassing, discretization, contact definition.

8. Failure criteria implementation, control options, time-step control. Evaluation of true stress-strains from engineering designs. Evaluation of failure initiation and crack propagation.

9. Modeling of collision in LS-Dyna (geometry definition, material definition, meshing, contact definition, finalizing the input deck, calculation and post-processing).

10. Analysis of ED including the principles of C&G, conservation of momentum, equilibrium of energy and force are given. The kinematics and dynamics of C&G, the motions during C&G and hydromechanics" effects.

11. Calculation models to analyze C&G. Simplified closed-form models, time-domain simulation models. Illustrative example of the (in)elastic collision of two objects including hydrodynamic effects.

12. Design for crashworthiness: general background, main design principles, modified structural and general arrangement, implementation to ship.

13. Optimization for crashworthiness, simplified approaches for structural resistance. The concept for rational increase of safety. Risk analysis.

14. Practical examples, topology definition. Presentation of crashworthy designs, optimization and design selection procedure.

15. ALE method in C&G analysis. Overview of the work done. Practical examples and comparison with the experimental results.

Exercises

1. Introduction to first C&G analysis and Minorsky calculations.

2. Analysis of IM and ED parameters in C&G calculations.

3. Overview of the measuring techniques in C&G analysis. Measured values and the analysis of data.

4. Interactive analysis of simple C&G calculations by varying the parameters. The analysis of results.

5. Examples of problems related to geometry and material nonlinearity.

6. Practical examples of using different failure criteria in C&G calculations. The comparison of results, differences and conclusions.

7. Example of simple non-linear FEM calculation (test specimen) in LS-Dyna. Material models. Illustration of hourglassing problem, boundary conditions, load, sensitivity analysis.

8. Analysis control, control of the time step, setting up the analysis parameters, failure analysis and analysis of the structural collapse.

9. Introduction to material models, complex geometry modeling, buoyancy modeling (springs).

10. Calculation and analysis of collision in realistic example (ship side structure). Energy calculation, force-displacement curve.

11. Modeling of added mass and influence of the hydrodynamic forces on the results. Illustrative example. Discussion over results.

12. Comparative analysis of the side structure collision for various designs. Sandwich technology. Laser welding.

13. Example of the C&G risk analysis.

14. Analysis of un-optimized and optimized structures. Comparison of deformations and energy absorption.

15. Example of sloshing calculation during ship collision. Analysis of the calculation parameters.

Compulsory literature:

Recommended literature: