FEA AND EXPERIMENTAL

QUASI-STATIC CRUSHING OF

ALUMINIUM HONEYCOMB

STRUCTURE

Guide:

MUJEEB PASHA

Presenting by:• MANJUNATH . M. C• MUDKA VISHAL• RAKESH. R• T. P. KUSHALAPPA

CONTENTS

• OBJECTIVES AND SCOPES

• INTRODUCTION

• OUT OF PLANE CONFIGURATION

• DEFORMATION ZONES

• EXPERIMENTAL PROCEDURE

• SOFTWARES USED

• STEPS INVOLVED IN MODELING AND ANALYSIS

• RESULTS AND DISCUSSION

• CONCLUSION

OBJECTIVES OF THE

STUDY

•To evaluate the energy absorbed

Experimental

Finite Element Analysis

•Comparison of the results.

SCOPE OF THE STUDY

• To evaluate the energy absorbed by the

aluminium honeycomb in out-of-plane

configuration.

• To evaluate the specific energy absorbed by

the aluminium honeycomb in out-of-plane

configuration.

INTRODUCTION• Aluminium honeycomb is a structure made of

hexagonal foil cells.

• It derives it’s name from its close resemblance to a

bee honeycomb.

• Materials with high strength and low density are used

core material.

• Honeycomb is a typical cellular structure which has

been extensively used as energy absorbers to resist

external loads.

HONEYCOMB TERMINOLOGY

DIMENSIONS

• Length = 75mm

• Width = 75mm

• Thickness = 50mm

• Cell size = 6.3mm

• Material used = Aluminium 3003 alloy

SPECIFICATIONS OF

ALUMINIUM HONEYCOMB

MATERIAL SPECIFICATIONS

Aluminium-Honeycomb

Shape : Hexagonal

Material : 3003-Aluminium alloy

Foil thickness : 0.068 mm

Core density : 85-100 kg/m3

Cell size : 6.3 mm

Material Composition (%)

Aluminium Balance

Copper 0.05 - 0.2

Iron 0.7 max

Manganese 1 - 1.5

Silicon 0.6 max

Zinc 0.1 max

COMPOSITION OF ALUMINIUM 3003 ALLOY

Pro’s of Honeycomb structures

• Considerable rigidity in shear.

• High crushing stress.

• Almost constant crushing force.

• Low weight.

• Relative insensitivity to local loss of stability.

• Minimization of the amount of material used.

OUT OF PLANE COMPRESSION

•Out-of-plane direction refers to the direction along the

cell axis, parallel to the thickness of the honeycomb.

•Honeycombs are much stiffer and stronger when loaded

along the cell axis.

•The initial linear-elastic deformation involves, significant

axial deformations of the cell walls.

DEFORMATION ZONES

Zone 1

• Stiff and elastic zone.

• Deformation is symmetric about their axes.

• Deformation is uniform throughout the length of the

specimen.

• Crushing of cells occurred at top end at an average

load of 12 kN.

Zone 2:

• This represents the progressive folding collapse.

• Characterized by the fluctuations of little amplitude.

• Amplitude of the fluctuations is higher initially.

• Deformation front was continued for 80% of the

specimen volume.

Zone 3:

• This is the solid phase compression of a perforated

plate.

• The load increased very rapidly indicating the

densification of the specimen.

EXPERIMENTAL PROCEDURE

• The specimen was placed in between the flat platens

of the Universal Testing Machine.

• Uni-axial compressive loading was applied at a

deformation rate of 1mm/min.

• The energy absorbing capacity of aluminium

honeycomb was calculated from the Load-

Displacement curve.

COMPARISONS OF LOAD-

DISPLACEMENT CURVES

• HC13-2 :433.331 J

• HC13-3 :472.411 J

• HC13-4 :452.214 J

• HC13-6 :453.638 J

Energy absorbed by each specimen was found to be

approximately same.

Average energy absorbed was 452.261 J.

SOFTWARES USED

HYPER MESH

• Altair Hyper mesh is a high-performance finite

element pre- and post-processor for major finite

element solvers.

Benefits

• High speed, High Quality Meshing.

• Increases End-User Modelling Efficiency.

• Reduces training time and cost through elimination of

Redundant Tools.

• Closes the loop between CAD and FEA.

LS-DYNA

• It is a general-purpose finite element program

capable of simulating complex real world

problems.

• It is used by the automobile, aerospace,

construction, military, manufacturing, and

bioengineering industries.

Uses of LS-DYNA

• Automotive crash (deformation of chassis).

• Explosions (underwater Naval mine).

• Manufacturing (sheet metal stamping).

STEPS INVOLVED IN HONEYCOMB

MODELING AND ANALYSIS

1. A unit cell of specified dimensions was created in “Catia-V5”.

2. This regular hexagon shaped unit cell was then

duplicated along x and y axis to get the quarter part of

the final model.

3. The Catia model was converted from ‘.CATPart’ to

‘.igs’ format.

4. This file was imported to ‘Hypermesh’ software.

5. The mid-surface of the entire quarter part was

extracted.

6. By using ‘Reflect’ command, quarter part was duplicated to

get the model of dimensions 75x75x50.

7. The model was meshed with mesh density of 2.5 using quad

elements.

8. The requisite conditions of the model were specified

through the Property, Material and Component

collectors.

9. The Impactor and Base were modeled with requiredproperties by following same procedure.

10. The Quasi-static velocity was imparted to the impactorusing ‘load collectors’ and ‘XY plots’.

11. The impactor was constrained in all directions except

along axis of the cell and base was constrained in all

directions.

12. The Automatic General type of contact was given at

the model-impactor interface and model-base interface.

13. In control cards the termination time was given as 40ms,

SECFORCE as 0.1ms and NODOUT as 0.1ms.

14. This file was exported as ‘.dyn’ format.

15. This dyna file was imported in Ls-Dyna and wasanalysed and executed.

BOUNDARY CONDITIONS

INCORPORATED IN FE MODEL

• Contact condition used:• Contact_Automatic_General

• Boundary Conditions:• The specimen was rested on a rigid surface (base

plate).

• Base plate was fixed in all directions.

• The impactor plate was constrained to move only in Z-direction.

• The velocity input of 1000 mm/sec was given throughthe command - Load collector.

RESULTS AND DISCUSSIONS

Specimen

Code

Deformation

Rate

(mm/min)

Thickness

(mm)

Mass

x10-3(kg)

Energy Absorbed

(J)

Experiment FEA

HC13-2 3 50 22.640 433.331 429.514

HC13-3 3 50 23.234 472.411 468.521

HC13-4 1 50 23.867 452.214 451.235

HC13-6 1 50 23.249 453.638 452.981

Mean load (kN) Energy absorbed (J)

Simulation 11 439.187

Experimental 12 452.261

APPLICATIONS OF HONEYCOMB

• In automobiles.

• As energy absorbers.

• Landing Gear Doors of aircrafts.

• Solar panels.

• In engine rotor blades of aircrafts.

CONCLUSIONS

• Honeycomb cores used as energy absorbers must beplaced in out-of-plane configuration, so thatmaximum energy can be absorbed.

• The specific energy absorption capacity and meancrushing loads obtained during investigation can beused as data in designing the energy absorbers forvarious engineering applications like impact energyabsorbers, crash pads.

• From the experiment, it can be concluded that withslow deformation rate the energy absorptionincreases.

THANK YOU