MODELING CYLINDRICAL SHELL WITH INITIAL IMPERFECTIONS BY USING OPTICAL METHOD

1. MODELING CYLINDRICAL SHELL WITH INITIAL IMPERFECTIONS BY USING OPTICAL METHOD ○ M1 Hiroyoshi Kawabayashi Pro. Hiroshi Matsuda D1 Chao Cheng M2 Hayato Kouzuma Nagasaki university

2. CONTENTS 1.Background 2.Digital image correlation System 3.Experiment investigation 4.Test result 5.Analysis 6.Conclusions and discussions

3. BACKGROUND ・Branch of using shells etc… →Incresement of iron and steel resources →Economy and efficient →Thin-walled sturcures are widely used Axial load, bending load,torsion load and shear load. Buckling The stability of thin-walled structure is becoming an importance issue for reserachers

4. BACKGROUND Buckling of cylindrical shell Initial imperfection Important that consider geometric imperfection →Experiment and analysis Purpose Modeling cylindrical shell with initial imperfection →Easier Digital Image Correlation System(DIC) →High accuracy

5. N pixels N pixels Camera1 Specimen Camera2 Analysis system Consist of: 2 black and white digital cameras PC system Matching program (Vic-Snap) Y Z X DIGITAL IMAGE CORRELATION METHOD(DICM) Sketch of DICM Displacement Direction

6. C D O B A EXPERIMENT INVESTIGATION Specimen : Aluminium cylinder →Young’ modulus:70GPa →Poisson’s ratio:0.3

7. 1.Turn every 30 degrees by manufacture device METHOD OF EXPERIMENT Experiment scenery ・Measuring procedure Specimen 2.Measuring by DICM It is possible to measure geometric imperfection every 30 degree exactly. Manufacture device

8. dR(mm) 33.07 32.98 32.88 32.98 32.98 32.88 32.88 33.07 33.07 MAX:Outward displacement dR(mm) dR(mm) MIN:Inward displacement TEST RESULT ・Modeling procedure 1. Coordinate set 2. Two of the adjacent contours can be connected

9. 32.98 32.98 32.98 32.88 32.88 32.88 33.07 33.07 33.07 dR(mm) dR(mm) dR(mm) TEST RESULT connect ・Modeling procedure 1. Coordinate set 2. Two of the adjacent contours can be connected

10. ・Coordinate transformation equation

11. ・Total model in cylindrical shell

12. ・Total model in cylindrical shell ・Mesh model The software with named of “Rapid form” For FEM analysis

13. ・Boundary condition: Upper ・・・・・Displacement fixed:x,z Rotation fixed :x,y,z Lower ・・・・・Displacement fixed:x,y,z Rotation fixed :x,y,z ANALYSIS Analysis conditions ・Young’s modulus:70GPa ・Poisson’s ratio:0.3 ・Mesh model ・Strain load:Max is 0.5mm at a speed of 0.1mm/s ・Parameters of specimens

14. Analysis result ・With initial imperfection ・Without initial imperfection →Occupying from the boundaries uniformly →Diamond buckling The presented method is very useful for obtaining the real buckling mode in numerical simulation ・Experimental result

15. CONCLUSIONS AND DISCUSSIONS CONCLUSION ・By using DICM,mesh model of thin-walled cylindrical shell specimen with initial imperfection is achieved and can be easily employed in the numerical simulation. ・By the comparison of numerical simulation, it is clarified that the initial geometric imperfections have a great effects on the buckling behavior of thin- walled cylindrical shell structure. DISCCUSION ・In order to improve the analytical accuracy, all the manufacture devices employed in this study should be improved and well re-designed and further reseach is required.

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