term durability of urea formaldehyde glued joints (u

,RD-A149 053 LONG TERM DURABILITY OF UREA FORMALDEHYDE GLUED JOINTS 1/1REMOVED FROM VRMPI.. (U) AERONAUTICAL RESEARCH LABSMELBOURNE (AUSTRALIA) T VAN BLRRICUM ET AL. JUN 84

UNCLASSIFIED RRL-STRUC-TM-38i F/G 13/5 NLEilllllimlllu*uuuuuc~gguuuuuI.1

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NATIONAL BUREAU OF STANDARD)S-1963-A

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UNCLASSIFIED

DEPARTMENT OF DEFENCEDEFENCE SCIENCE AND TECHNOLOGY ORGANISATION

AERONAUTICAL RESEARCH LABORATORIESMELBOURNE, VICTORIA

In

4: LONG TERM DURABILITY OF UREA FORNALDEDGLUED JOINTS REOVED FROM VA14PIRE AIRCRAFT@

by

T. YW SLAZCUR akl C. A. WMCMWU

'~wj or o Public ftleam J A v ITH- UNITED STATi:S NATIONALTECHNIGAL INFORMAl ION SER VICEL AlJT O'0lSFO TO

LJ6., hPRODUCE AND SELL THIS REPOT

(c) m or AurZamsib 1664:::::.:

84 12 31 o 16CO"y No

AR-003-928

DEPARMENT OF DEFENCE

DEFENCE SCIENCE AND TECHNOLOGY ORGAN ISATION

AERONAUTICAL RESEARCH LABORATORIES

Structures Technical Memorandum 381 .

LONG TERM DURABILITY OF UREA FORMALDEHYDEGLUED JOINTS REMOVED FROM VAMPIRE AIRCRAFT.

by

T. VAN BLARkICtII and C. A. PATCHING

SUMMARY

Bonded wooden specimens were removed from twoVampire aircraft fuselages and held in store for 18 yearsunder ambient laboratory conditions to determine if glued-joint deterioration had occurred.

The examination did not reveal any significantdeterioration.

O CVIOHVEALTH OF AUSTRALIA 1984

P06AL ADDUISS: Director,* Aeronautical Research Laboratories, :j

P.O. box 4331, Nlbourne, Victoria, 3001, Australia

CONTENTS .

VS

Page No.

1. INTRODUCTION1

2. TEST SPECIMENS1

3.* TEST PROCEDURES 2

4. TEST RESULTS 2

5. DISCUSSION OF RESULTS 3

6. CONCLUSIONS 6

REFERENCES

TABLES

FIGURES

DISTRIBUTION

DOCUMENT! CONTROL DATA

ri -Al

1. INTRODUCTION

Two Vampire fusel geA7 an originally manufacturedin 1950 were used for the r.-.Vampire wing Fatigue Tests carried outbetween 1960 and 1965. rew&-4I

--The Vampre f"c Vampir fs a/" is of laminated wooden monocoque

construction Jut+&in spruce, improved wood and aircraft plywood,bonded with Urea Formaldehyde fetle -ement*>glue.

After completion of the wing fatigue tests a number of woodenspecimens were removed from these fuselages and stored under ambientlaboratory conditions until Sept6mbe1983. -. . . .I6 .. ...

At the time of specimen removal, the fuselages i46a-.---*79/ had been subjected to a total of 67,238 and 42,279 hours

actual flying and simulated life.

Careful inspection of the fuselages before removal of thespecimens revealed no indication of any defect indicating that designstrength requirements were not being met. 7 ,

This Technical Memorandumnescribes the condition of V5ee- .---'

-F a ldehyde; wooden joints from these specimens, broken open inSeptombeV 1983. At this time the glue bonds had reached a life of33 years. -- /- )

Examination of the condition of wooden joints from Vampireaircraft had been carried out by Hawker De Havilland Australia inMay 1964. (Ref. 2). The results of those tests indicated that nosignificant deterioration in bond strength had occurred in jointswith an age of 15 years. '.Alt

2. TEST SPECIMENS

Test specimens were removed from three areas of the aircraftfuselage as shown in Fig. 1

(a) Drag or OCO Joint Attachment Area identified as:

Specimens A79/467 and A79/915 Port 1, Starboard 1.

(b) Air Intake Lover Forward Area identified as:

Specimens A79/467 and A79/915 Port 2, Starboard 2.

(W) Rear of Air Intake Area identified as:

Specimens A79/467 and A79/915 Port 3, Starboard 3.

Figure 2 is a general view of the twelve specimens.

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3. TEST PROCEDUREI.

Part of each specimen was cut off and one or more of the

following types of joint broken open by inserting a thin bladed

chisel into the glue line:-

(a) Laminated Spruce to Improved Wood.

(b) Laminated Spruce to Plywood.

(c) Spruce to Plywood.

(d) Plywood to Plywood.

(e) Plywood to Improved Wood.

(f) Spruce to Improved Wood.

(g) Spruce to Spruce.

Where possible joints which had been damaged during removal of thespecimen from the aircraft were included in those selected for

examination.

Each bond was examined using a magnifying glass and to ascertainthe extent of wood failure as a percentage of the surface area of thejoint.

A 100% effective joint is defined as having 100% wood failureand no apparent glue failure.

In some instances it was necessary to employ a strong lightin order to detect the fine plywood fibres attached to the glue.

4. TEST RESULTS

Seven types of wooden joints bonded with Urea Formaldehyde 0glue were examined. Test results are given in Table 1. To enablea comparison of the different joints to be made the test resultshave been averaged as given in Table 2.

4.1 Joint Failure

"Wood failure" was the predominant mode of failure for alljoint types except in the case of Laminated Spruce to Improved Wood.The percentage wood failure refers to the percentage area of gluedsurface which is covered by wood fibres pulled from the matingtimber surface.

4.2 Performance of Individual Joint Types

4.2.*1 Laminated Spruce to Improved Wood

These joints had in most cases been damaged during removal of

the specimens from the aircraft. Fig. 3 illustrates a typical example.

EP;mn

Note the Spruce fibres adhering to glue on the Improved Wood. Theaverage amount of wood failure was 45% for 3 specimens.

4.2.2 Laminated Spruce to Plywood

A few examples of this type of joint had been damaged duringremoval of the specimens from the aircraft. The remainder were ingood condition and Figure 4 illustrates an example of a good LaminatedSpruce to Plywood joint. Note Spruce fibres adhering to glue. Theaverage of wood failure was 94% for 9 specimens.

4.2.3 Spruce to Plywood

A few examples of this joint had suffered some slightmechanical damage during removal of the specimens from the aircraft.The remainder were in good condition. Fig. 5 illustrates a Spruceto Plywood bond. Note the plywood fibres adhering to the glue on - .the Spruce. The three examples of this. joint all gave 100% woodfailure.

4.2.4 Plywood to Plywood

All examples of this joint were in good condition asillustrated in Fig. 6. Note plywood fibres adhering to glue. Theaverage of wood failure was 97% for 4 specimens.

4.2.5 Plywood to Improved Wood

Some examples of this joint had been slightly damaged duringremoval of the specimens from the aircraft. Fig. 7 illustrates oneexample with a thick glue line for over 40% of the joint area and nowood fibres detected on 30% of the joint area. The remainingundamaged bond area is covered in plywood fibres i.e. wood failure. -

The average of wood failure was 82% for 6 specimens.

4.2.6 Spruce to Improved Wood

All joints examined were in good condition. Fig. 8, illustrates 0an example of a good Spruce to Improved Wood joint with 100% Sprucefailure. The average of wood failure was 90% for 7 specimens.

4.2.7 Spruce to Spruce

All five joints examined were in good condition and exhibited100% wood failure. Fig. 9 illustrates a typical example.

5. DISCUSSION OF RESULTS

The test results indicated that the physical appearance of a bondline, for example apparent lack of glue does not correlate with itsmode of failure. Joints with a poor external appearance still gave

4 a high percentage of wood failure.

[41

Every joint tested required considerable effort to prizeit open with the chisel, indicating that the actual glue line wasproviding adhesion to both surfaces.

6. CNCLUSIONr -O.o')4

Rhe long term exposure (18 years) of these wooden specimensto an ambient laboratory environment had not led to any significant ---deterioration of the Urea Formaldehyde bonded joints, and that after33 years since manufacture the joints were still satisfactory.

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REFERENCES

1. BRUTON R.A. and PATCHING C.A. Fatigue Testing of VampireWings. Department of Defence, Aeronautical Research Laboratories.Structures Report 378. June 1979.

2. Estimated Life of th~e Vampire Trainer Fuselage WoodenStructure in Service. Hawker De Havilland Australia Pty Ltd. -

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TABLE 2 AVERAGED TEST RESULTS

TYPE OF BONDED JOINT AVERAGE %NUMBER OF . '

SPECIMENS

LAMINATED SPRUCE TO IMPROVED WOOD 45% 3

LAMINATED SPRUCE TO PLYWOOD 94% 9 Ak

SPRUCE TO PLYWOOD 100% 3

PLYWOOD TO PLYWOOD 97% 4

PLYWOOD TO IMPROVED WOOD 82% 6

SPRUCE TO IMPROVED WOOD 90% 7

SPRUCE TO SPRUCE 100% 5

A L

"C" Joint area

Rear of air intake area Air intake lower forward area

FIG. 1 SHOWING AREAS OF FUSELAGE FROM WHICH WOODEDSPECIMENS WERE REMOVED.

-. -- ,.. -. - - -' -.-. . ~ ..........-. ~ -. .

FIG.2 GEERA VIE OF ESTSPECNEN

(Scae: pecmen abes ae 11 mmX 6 mm

0 40ffnuiScale'______

FIG. 3 SPRUCE TO IMPROVED WOOD NOTE THICK GLUE LINE2

AND SPRUCE FIBRES ON IMPROVED WOOD (A79/915 PORT 3)

%'..

Scable ~m

FIG. 4 LAMINATED SPRUCE To PLYWOODNOTE HIGH- PERCENTAGE

WOOD FAILURE (A97/915 POT3

.-

PORT 31

Scale

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FIG. 6 TYPICAL PLYWOOD TO PLYWOOD JOINT FAILURE (A79/915 PORT 3)

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FIG. 7 AIRCRAFT PLYWOOD TO IMPROVED WOOD

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DISTRIBUTION

AUSTRALIA 0

Department of Defence

Central Office

Chief Defence Scientist )Deputy Chief Defence Scientist ) (1 copy)Superintendent, Science and Program Administration )Controller, External Relations, Projects sand

Analytical Studies )Defence Science Adviser (U.K.) (Doc Data sheet only)Counsellor, Defence Science (U.S.A.) (Doc Data sheet only) . .Defence Central LibraryDocument Exchange Centre, D.I.S.B. (18 copies)Joint Intelligence OrganisationLibrarian H Block, Victoria Barracks, MelbourneDirector General - Army Development (NSO) (4 copies)

Aeronautical Research Laboratories

DirectorLibraryDivisional File - StructuresAuthors: T. J. van Blaricum

C. A. Patching

Materials Research Laboratories

Director/Library

Defence Research Centre

Library

Navy Office

Navy Scientific AdviserSuperintendent, Aircraft Maintenance and Repair

Army Office

Army Scientific AdviserEngineering Development Establishment, Library

Air Force Office

Air Force Scientific AdviserAircraft Research and Development Unit .

Scientific Flight Group

LibraryTechnical Division LibraryNQ Support Comand [StMGO.WW Academy, Point Cook •3MF Laverton SENGO 21 Squadron

.%- ° ° -,'-

7-

DISTRIBUTION (CONT.D)

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Government Aircraft Factories

ManagerLibrary

Department of Aviation

LibraryFlying Operations and Airworthiness DivisionGliding Technical Liaison Officer, Essendon AirportAirworthiness Engineer, Victoria/Tasmania Region

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CSIRO, Materials Science Division, LibraryTrans-Australia Airlines, Library a-'

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Civil Engineer ing

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R.M.I.T. LibraryMr. N. Mileshkin, Department of Civil and

Aeronautical Engineeringu- '- '-'

DISTRIBUTION (CONT.D)

GERMANY

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SPARES (10 Copies

TOTAL (91 Copies) .

DOCUMENT CONTROL DATA

I bErmokhmr-1No2 Documen~t Dowe 3 Task NoAR-003-928 ARL-STRUC-TM-381 JUNE 1984 AUS 89/811

-o*5. SOCU'ITy 6. No Pollee

LONG TERM DURABILITY OF UREA FORMALDE - a, dorwntUNCLASSIFIED 12

HYDE JOINTS REMOVED FROM VAMPIRE b title C. astrt P40 FleAIRCRAFT. u u 2

Athorts) 9. 00-mgadova tns,..uctions

T. J. VAN BLARICUM andC. A. PATCHING

iO0 COrporMt Auvho& "i Ades II Author rty fa p'eti

Aeronautical Research Laboratories, ~ 3Fb~W D~* ~.P.O. Box 4331, MELBOURNE VIC 3001

12 becordlarV Dtw~wbon 1.1 M~as aoVwnio#,

Approved for Public Release

0'qw'" eiruwesi ou"Ki mawe 10"'..orl ~oow be referred Ar~ou0 ASOiS. Deeo t'fomwAtion srvton stench~.DW'Vrwn, of CD-vt. Cav4J Pak CANBERRtA ACT 2&0113 a The doeu-Writ uty tw AN40ONCEO rr =ftlog and eva~nn mWv.oi es v.b'e w.0

No Limitations .

13 b C..w'sn for ottw Pwo lot c ovn u; v be [ar" Lartsv "ed ,of/ ae tor 13 a14 Dewaems 16. COSATI Group

Urea formaldehyde resinWooden structuresBonded joints Vampire aircraft 11010Adhesive bonding Beetle glue 01030Laminating

Bonded wooden specimens were removed from~ two Vampireaircraft fuselages and held in storage for 18 years under ambientlaboratory environment to determine if glued joint deterioration hadoccurred.

The examination did not reveal any signficant deterioration.

PF 00

* This peap is to be uwd to record informstion which is required by the Estabfishment for its ow ue butwhich will mo be added to the DISTIS data baoe unless specifially requested.

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is 000ft swinm~ WO %WgrW 1. COW CodNM 20. Two of Romo Po gomC d

StructuresITechnical 26-5000Memorandum 381 ____________

21. CW~i.prpv Lnd

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2-85

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