PEELING OF COMPOSITE SANDWICH

STRUCTURE(C.S.S )

GROUP PRESENTER AND SUPERVISOR

SUPERVISOR :

DR ZAHURIN BINTI HALIM

PRESENTER :

1) NURUL NAJWA AHMAD 0822450

2) SITI NORAINI KAWAEED 0724126

3) MOHD BUKHARI YAHYA 0827361

DEFINITIONS

PEELING : A piece or strip, as of skin or vegetable rind, that has been peeled off.

COMPOSITE : Made up of distinct components; compound.

CONTINUE.. SANDWICH : A laminar construction, consisting of

thin facings bonded to a relatively thick lightweight core,resulting in a rigid and lightweight panel. In this standard, bonded means “joined by welding, brazing or adhesive. ”

STRUCTURE : 1. Something made up of a number of parts that are

held or put together in a particular way 2. The arrangement or formation of the tissues,

organs, or other parts of an organism.

PROBLEM STATEMENT Weak joints between an outer metal

sheet and the core of sandwich assemblies.

Fracture toughness of the facesheet bond.

Crack defects

INTRODUCTION A composite sandwich structures: 1) special class of composite materials 2) fabricated by attaching two thin but stiff skins

to a lightweight but thick core.

WHAT IS CORE? A lightweight natural, synthetic, or

fabricated material bonded between the facings of

sandwich construction in order to separate the facings. to support them against buckling under

stress.

REVIEW Review of the current state of research related

to the topic : THE FLEXURAL BEHAVIOR OF COMPOSITE SANDWICH STRUCTURE[MOHD HAKIMI BIN OMAR,2008]COMPOSITE SANDWICH STRUCTURE WITH GRID STIFFENED CORE[VENKATA DINESH MUTHYALA,2005]A TEST TECHNIQUE FOR ASSESSING CORE-SKIN ADHESION IN COMPOSITE STRUCTURES

Types of composite sandwich structure

SANDWICH PANEL

foam

HONEY COMB SANDWICH

SANDWICH PANEL

PROCEDURE TEST Problems on the sandwich structure has been

identified from the problem statement: One of them is poor bonding face problem In order to solve that problem, Climbing drum

peel test is used in this case.

PEELING OF C. S. S.

CONTINUE..

PEELING TEST

Climbing drum peel fixture for ASTM D1781

This test method covers the determination of the peel resistance of a sandwich structure and its core

CONTINUE..

-AdvantagesEvaluate strength of skin-core

-DisadvantagesDifficult if the sandwich skin’s is too thin or too thick

APPLICATION

Railway floors, doors, interiors, fairing panels Boat hulls and interior panels and furniture Racing car chassis and body panels Specialist flight cases Helicopter blades Aircraft engine structures Aircraft doors and hatches Aircraft floor panels Racing car structures and aerofoils Energy absorbers

SHIP AND AUTOMOTIVE

DISCUSSION

HOW TO PREVENT PEELING

Apply good original fiber, matrix and resin.

Use suitable core. Honeycomb is one of

good core for composite sandwich structure.

Get the best strength of the weight ratios.

HOW TO REPAIR THE PEELED SECTION.

Cosmetic repair>In this case inspection has determined that the damage has not affected the structural integrity of the component. A cosmetic repair is carried out to protect and decorate the surface. This will not involve the use of reinforcing materials.

STRUCTURAL REPAIR

If the damage has weakened the structure through fibre fracture, delamination or disbonding the repair will involve replacement of the damaged fibre reinforcement, and core in sandwich structures to restore the original mechanical properties.

Since a bonded-on repair constitutes a discontinuity of the original plies, and therefore a stress raiser, structural repair schemes normally require extra plies to be provided in the repair area.

If the damaged area is very small it can be questionable whether a structural repair is required but more preferable to a cosmetic repair

PATCH REPAIR

In this case the thickness of the original laminate is made up with filler plies and the repair materials are bonded to the surface of the laminate.

Advantages> Quick and simple to do>Requires minimum preparation

Disadvantages>A repaired laminate is thicker and heavier than the original>Very careful surface preparation is needed for good adhesion

Conclusion

CONCLUSION Peeling is one of the

major problem in the c.s.s.

It can be prevent by applying good fiber, matrix and resin.

It can be tested using Climbing drum peel fixture

REFERENCES www.sandwichpanels.org/articles/article_whatisasandwich.html

http://jcm.sagepub.com/content/38/10/805.abstract

http://www.com-ten.com/climbing-drum-peel-fixture-astm-d1781.html

The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company

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