Numerical and Experimental Investigations on the Structural Behavior of Glass Windows in Ships

Transcription

1 Institut für Konstruktion und Festigkeit von Schiffen Numerical and Experimental Investigations on the Structural Behavior of Glass Windows in Ships B. Gerlach, W. Fricke, M. Guiard Glass Workshop

2 Contents 1. Overview on completed/current glass projects 2. Quasi-static ultimate load of windows 3. Dynamic ultimate load of windows 4. In-plane shear stiffness of walls with windows 5. Conclusions 6. Outlook 2

3 1. Overview on glass projects Structural Behavior of Large Ship Windows Objectives: Ultimate load of windows subjected to quasi-static lateral pressure Effect of windows on the shear stiffness of ship walls Simplified approach to consider additional shear stiffness in FE overall ship models Project Monitoring Group: 3

4 1. Overview on glass projects Ultimate strength of window structures in areas relevant for damage stability and safety ( ) Part of Maritime Safety Aspects Regarding Installation and Maintenance of Offshore Wind Turbines Funded by Research and Science Foundation Hamburg Objectives: Load Carrying Behavior of windows under dynamic loading Numerical Calculations Drop Tests 4

5 Contents 1. Overview on completed/current glass projects 2. Quasi-static ultimate load of windows 3. Dynamic ultimate load of windows 4. In-plane shear stiffness of walls with windows 5. Conclusions 6. Outlook 5

6 2. Quasi-static ultimate load Test set-up for quasi-static ultimate load test 6

7 2. Quasi-static ultimate load Test models and load area stiffened steel plate, ca mm x 2800 mm with laminated safety glass (LSG) windows load area 1500 mm x 1200 mm 1600 mm x 1900 mm 1900 mm x 1600 mm Model 1 to 3: LSG 12/12mm 2x clamped, 1x bonded Model 4: LSG 10/12 mm, bonded Model 5: LSG 10/12 mm, bonded 7

8 2. Quasi-static ultimate load Test model 1 (design pressure p D =20kPa) Drawing of test model Section A-A (clamped connection) 8

9 2. Quasi-static ultimate load Result of ultimate load test with model 1 Glass pane slipped out of clamped connection (p u =120 kpa) Top view on retaining frame just before (left) and after slip-out (right) 9

10 2. Quasi-static ultimate load Finite element (FE) simulation of the test Section view on clamped connection with no load (left) and animation up to a pressure p U =120 kpa (right) 10

11 2. Quasi-static ultimate load Deflection of the glass pane ca. 35mm within glass pane Measured (with markers) and calculated deflection 11

12 2. Quasi-static ultimate load Maximum stress on tensioned glass surface Breaking stress range of safety glass: ca N/mm² according to glass tests Measured (with markers) and calculated maximum stress 12

13 2. Quasi-static ultimate load Summary of quasi-static ultimate load tests model size connection p D (kpa) p U (kpa) p U /p D failure mechanism x 1200 clamped slip-out x 1200 clamped slip-out x 1200 bonded defect in glass x 1600 bonded slip-out x 1900 bonded breaking stress Model 4 Bonded connection 13

14 Contents 1. Overview on completed/current glass projects 2. Quasi-static ultimate load of windows 3. Dynamic ultimate load of windows 4. In-plane shear stiffness of walls with windows 5. Conclusions 6. Outlook 14

15 3. Dynamic ultimate load Test set-up for dynamic ultimate load test Rubber bag filled with water Advantage of drop tests controlled conditions Table: Test parameter of drop tests test height (m) mass (kg) speed (m/s) glass intact/ broken intact intact intact broken Test wall (p D = 80 kpa) with bonded window 900 mm x 900 mm on four load cells 15

16 3. Dynamic ultimate load Simulation of drop tests in LS-DYNA with FEM and Smoothed Particle Hydrodynamics (SPH) Water modeled with Smoothed Particles steel structure (shell elements), bonding and glass (solid elements) Hydroelastic effects are fully included! 16

17 3. Dynamic ultimate load Simulation with adjusted shape and impact position Shape and position adjusted according to photos The influence of the rubber bag turned out to be marginal Photos (left) and corresponding LS-DYNA simulation (right) 17

18 3. Dynamic ultimate load Comparison of measured tensile stresses in the middle of the pane with simulation results (test 2, glass intact) Reasonable calculation results. Stresses near lower bound of breaking range of safety glass. 18

19 3. Dynamic ultimate load Last drop test with 1000 liters of water from 20 m height Test model after impact Video of impact 19

20 Contents 1. Overview on completed/current glass projects 2. Quasi-static ultimate load of windows 3. Dynamic ultimate load of windows 4. In-plane shear stiffness of walls with windows 5. Conclusions 6. Outlook 20

21 4. In-plane shear stiffness Large window openings cause decrease in shear stiffness Window corners (at superstructure ends) are highly stressed Complicated/ expensive reinforcements of corners State of the art: window panes are not considered But bonded or clamped window panes increase shear stiffness/may reduce stresses Source: Schröter T. (1975): Methode zur Ermittlung der Mittragewirkung von Aufbauten und Deckshäusern an der Längsfestigkeit und zum Spannungsnachweis von Fensterecken. In: Seewirtschaft 7:

22 4. In-plane shear stiffness Test set-up for shear tests 22

23 4. In-plane shear stiffness Measured shear stiffness Q H /u without c and with window pane c W Q H u Q H Model 1-3 Model 4 Model 5 c 115 kn/mm c W 120 kn/mm + 4% c 38 kn/mm c W 45 kn/mm + 18 % c 0,68 kn/mm c W 6,7 kn/mm % 23

24 4. In-plane shear stiffness Modeling variant 1 Shear stiffness with window needed for determination of t 2, E 2, G 2 Shear stiffness calculated nummerically or analitically 24

25 4. In-plane shear stiffness Analysis of stresses in radii with ship model and submodel Detailed submodel Detailed submodel boundary conditions = nodal displacements -19% Stress reduction -25% Ship model -20% Source: Vural Havuc, diploma thesis in

26 4. In-plane shear stiffness Modeling variant 2 Shear stiffness with window needed for determination of t 2, E 2, G 2 Shear stiffness calculated nummerically or analitically 26

27 4. In-plane shear stiffness Overall model of "Costa Victoria" Modeling variant 2 would be suitable for this mesh size Source: Germanischer Lloyd (1995): Schiffstechnische Beratung. In: Fachlicher Teil des Geschäftsberichtes 1995, Hamburg: Germanischer Lloyd 27

28 5. Conclusions Ultimate load Small overlaps of glass and frame lead to early slip-out of glass panes Increase of overlap recommended (e.g. in ISO ) Calculation results (FEM) in good agreement with measurements (quasistatic) Calculation results (FEM/SPH) reasonable/ sensitive to water shape Numerical simulations can be employed to check/improve window designs Shear stiffness Clamped and bonded glass panes contribute to the stiffness which can affect stress in window corners (e.g. 25 % reduction) FE models of windows require a very fine mesh, thus a simplified model is necessary for overall ship models For simplified model the shear stiffness of a characteristic section has to be calculated analytically or numerically Stresses can be analysed in a submodel 28

29 6. Outlook Incorporation of bonded window strips in strength calculations (expected start: ) Objectives: Parameter Identification of several adhesives Evaluation of window effect in overall FE ship models Concept to consider additional shear stiffness due to windows in strength calculation (e.g. in fatigue design) Large scale ultimate shear load tests Project Monitoring Group: (many Partners of the completed Project) Additional Partners: 29

30 Institut für Konstruktion und Festigkeit von Schiffen Thank you for your attention! Glass Workshop