1. WARSAW UNIVERSITY OF TECHNOLOGY
Politechnika Warszawska
FACULTY OF POWER AND AERONAUTICAL
ENGINEERING
Wydział Mechaniczny Energetyki i Lotnictwa
DIVISION: Strength of Materials and Structures
Zakład: Wytrzymałości Materiałów i Konstrukcji
Anticlastic Behaviour Analysis of Sandwich Honeycomb Core
(Hexagonal)
Badanie Antyklastycznej Deformacji Rdzenia Przekładkowego o Strukturze Plastra Miodu
(Sześciokąta)
Supervisor/Promotor: Dr. Inz. Adam DackoMaster Diploma Thesis Presentation
Presented By: SUMIT SINGH
Student Index Number: 265593
M.Sc. Aerospace Engineering

2. Presentation Plan
 Introduction
 Thesis Objectives
 Honeycomb Core Modelling
 MPC (Constrained Equations) – RBE 3 Application
 Loads and Boundary Conditions
 Material Properties and Manufacturer Data for Honeycomb Core
 Analysis and Results
 Conclusion
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3. Introduction
 Application of Sandwich Honeycomb Core
 Hollow Hexagonal Cells
 High Strength to Weight Ratio
 Increased Bending Stiffness
 Anticlastic/Saddle Behaviour
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4. Thesis Objectives
 Anticlastic Behaviour Analysis of a Rectangular Block of Honeycomb Core.
 Global Apparent Poison’s Ratios Comparison of Four Different Cell Sized
Square Block of Honeycomb Core While Bent Out of Plane.
 Out of Plane Bending Comparison of Two thin Plates (Made of Isotropic and
Orthotropic Material Respectively) and Honeycomb Core.
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5. Honeycomb Core Modelling
 Single Hexagonal Cell Creation and Translation  Creation of Elements on Curve and Extrusion
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6. MPC – RBE 3 Application
 RBE 3 is an interpolation element which defines a linear relationship
between nodal DOFs.
 RBE 3 Comprises one Dependent Node and many Independent Nodes.
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7. MPC – RBE 3 Application
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8. Loads and Boundary Conditions
 Moments
 Displacements
Input Data Descriptions (N.mm)
Force (F1,F2,F3) < >
Moment (M1,M2,M3) <0, ±200, 0>
Input Data Descriptions (mm)
Translations (T1,T2,T3) <0, 0, 0>
Rotations (R1,R2,R3) <0, 0, 0>
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9. Loads and Boundary Conditions
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10. Material Properties and Manufacturer Data
for Honeycomb core
 Material Properties
 Manufactures Data for Honeycomb Core
Material E11 (MPa) G11 (MPa) µ
Aluminium 68000 25564 0.33
Sample Code
Aluminium
Cell Size (mm) Core Thickness (mm) Cell Wall Thickness (mm) Material Density (ton/mm3)
AL002540 3.2 20 0.025 0.072E-9
AL002640 4.8 20 0.038 0.070E-9
AL002840 6.4 20 0.038 0.054E-9
AL002940 13 20 0.1 0.062E-9
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11. Cell Wall Thickness for Honeycomb core
 Assumed Cell Wall Thickness for Numerical Experiments
Cell Size (mm) Cell Wall Thickness 1 (mm) Cell Wall Thickness 2 (mm)
3.2 0.05 0.1
4.8 0.05 0.1
6.4 0.05 0.1
13 0.05 0.1
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12. Cell Size Comparison of honeycomb cores
 Four Different Cell Sized Honeycomb Core
13 mm Cell Size
4.8 mm Cell Size 3.2 mm Cell Size
6.4 mm Cell Size
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13. Analysis and Results
 3.2 mm Cell Size
0.025 mm Cell Wall Thickness
0.05 mm Cell Wall Thickness
0.1 mm Cell Wall Thickness
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14. Analysis and Results
 4.8 mm Cell Size
0.038 mm Cell Wall Thickness
0.05 mm Cell Wall Thickness
0.1 mm Cell Wall Thickness
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15. Analysis and Results
 6.4 mm Cell Size
0.038 mm Cell Wall Thickness
0.05 mm Cell Wall Thickness
0.1 mm Cell Wall Thickness
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16. Analysis and Results
 13 mm Cell Size
0.05 mm Cell Wall Thickness
0.1 mm Cell Wall Thickness
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17. Global Apparent Poison’s Ratios
Comparison
0
2
4
6
8
10
12
14
0 0.2 0.4 0.6 0.8 1 1.2 1.4
CellSize
Global Apparent Poison's Ratio
Cell Size vs. Global Apparent Poison's Ratio
Global Apparent Poison's ratio obtained from manufacturer data cell wall thickness
Global Apparent Poison's ratio obtained from 0.05mm cell wall thickness
Global Apparent Poison's ratio obtained from 0.1mm cell wall thickness
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18. Out of Plane Bending of Honeycomb
Core with Skin
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19. Material Properties of thin plates
 Isotropic Material
 Orthotropic Material
Material E11 (MPa) G11 (MPa) µ
Aluminium 68000 25564 0.33
Material E11 (MPa) E22 (MPa) G11 (MPa) µ
S2-Glass Epoxy 52000 11700 7600 0.28
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20. Comparison of Out of Plane Bending between
Thin Plates and Honeycomb Core
Isotropic Orthotropic
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21. Comparison of Global Apparent Poison’s
Ratio of Thin Plates and Honeycomb Core
Thin Square Plate Orthotropic
Material, 1.58
Honeycomb Core Isotropic
Material, -0.99
Honeycomb Core Orthotropic
Material, -0.93
Thin Square Plate Isotropic
Material, 0.0413
-1.5
-1
-0.5
0
0.5
1
1.5
2
GlobalApparentPoison'sRatio
Global apparent Poison's Ratio vs. change in materials of
thin plate and honeycomb core
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22. Conclusion
 Relation between Hexagon Cell Size and Global Apparent Poison’s ratio is
not predictable.
 Increase in Hexagon Cell Wall Thickness reduces Global Apparent Poison’s
Ratio.
 Application of Skin on Honeycomb Core Destroys the Anticlastic Behaviour.
 Change in Material Doesn’t affect Anticlastic Bending.
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