asr lab karthik

8/13/2019 ASR Lab Karthik

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SCHOOL OF MECHANICAL ENGINEERING

DEPARTMENT OF AERONAUTICAL ENGINEERING

Lab Manual of Semester -

U!AEA"# $ A%r&raft Stru&tures Re'a%r Lab

Prepared by

J.Karthik

Assistant. Professor.

Department of Aeronautical Engineering


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EL TECH Dr( RR ) Dr(SR TECHNICAL UNIERSIT*

DEPARTMENT OF AERONAUTICAL ENGINEERING

OBJECTIVE

To give training on riveting, patchwork, welding and carpentry

LIST OF EXPERIMENTS

1. Aircraft wood gluing2. Study of welded patch repair by TIG, MIG and !ASMA A"#.$. %elded patch repair by MIG&. welded patch repair by TIG'. (abric atch repair

). "iveted patch repair*.+. "epair of copo*ite*.-. "epair of *andwich panel*.. Sheet etal foring.1/. #ontrol cable in*pection and repair.


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E+'( No, -

A%r&raft .oo/ 0lu%n0-s%n0le s&arf 1o%nt

A%m(

To study the aircraft wood gluing-single scarf oint

!n this day and age of composite and modern aluminum aircraft it would seem that wood

airplanes would be a thing of the past. "orking with wood is more enoyable than other

mediums# and also can be less to$ic. "ood aircraft are strong# safe# and easy to build. !f

properly protected# the wood will last a lifetime and longer. "ood aircraft can be built lighter# as

fast# and as safe as other more modern types of construction. %onstructing an aircraft from wood

re&uires only basic hand tools and a few power tools. 'uilding a wood aircraft is a series of small

obs. (luing gussets takes only about an hour of time.

Def%n%t%on, S&arf 2o%nt(A scarf oint is a lap-style oint where both pieces of wood to be oined

are tapered at the same angle then laid on top of one another. The final thickness is the same as

the thickness of the plywood itself.

S'e&%f%&at%ons!t is recommended that a taper of )*+) to ),+) be used for this type of oint to insure ade&uate

surface area for gluing the oint. The ratio is )* times to ), times the thickness of the plywood.

or this application# we are using mm /0)1234 for the hull sides and rub rails# and ),mm /0)1,34

for the bottom. ! prefer to use a ),+) scarf. or )123 plywood# the ratio of taper to thickness will

be ),5*.,63 7 83. This means that the plywood pieces will be lapped by 83 when glued up. This

also means that you technically lose 83 from a sheet of plywood. Two 9: sheets with a ),+) scarf

will result in an o;erall length of )6:-


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The oint is formed by cutting opposing tapered ends on each member which are then fitted

together. "hen working with wood# this gi;es better long grain to long grain gluing surface#

which yields a stronger oint than would be achie;ed with a simple butt oint. The tapers are

generally cut at an angle between )+9 to )+)*. The ends of a plain scarf are feathered to a fine

point which aids in the obscuring of the oint in the finished work# while in other forms of scarf

the ends are fre&uently cut to a blunt 3nib3 which engages a matching shoulder in the mating

piece.

"here scarfed oints are used in the restoration of ;intage aircraft most de;eloped countries will

only issue an airworthiness certificate if all such oints ha;e used an angle no less than )+9.

ig.). 'efore oining ig.,. After oining

Result,

Thus the study of aircraft wood gluing-single scarf oint has completed.
http://www.ask.com/wiki/Wood?qsrc=3044http://www.ask.com/wiki/Long_grain?qsrc=3044http://www.craftsmanspace.com/images/stories/Scarf%20Joint/Scarf%20Joint/scarf_joint.gifhttp://www.craftsmanspace.com/images/stories/Scarf%20Joint/Scarf%20Joint/scarf_joint_e.gifhttp://www.ask.com/wiki/Long_grain?qsrc=3044http://www.ask.com/wiki/Wood?qsrc=3044


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A%r&raft .oo/ 0lu%n0-/ouble s&arf 1o%nt

A%m(

To study the aircraft wood gluing-double scarf oint

A s&arf 1o%ntis a method of oining two members end to end in woodworkingor metalworking.

The scarf oint is used when the material being oined is not a;ailable in the length re&uired. !t is

an alternati;e to other oints such as the butt ointand the splice ointand is often fa;ored o;er

these inoinerybecause it yields a barely ;isible glue line.

The scarf oint in wood

!n woodworking# there are two distinctly different categories of scarf# based on whether the oint

has interlocking faces or not. A plain scarf is simply two flat planes meeting on an angle relati;e

to the a$is of the stock being oined# and depends entirely on adhesi;e and1or mechanical

fastening /screws# bolts# etc.4 for all strength. =ooked# keyed# and nibbed scarfs are some of the

many e$ample of interlocking scarfs# offering ;arying degrees of tensile and compressi;e

strength# though most still depend on mechanical fastening to keep the oint closed.

The plain scarf is not preferred when strength is re&uired# so it is often used in decorati;e

situations# such as the application of trim or moulding. The use of modern high-strength

adhesi;es can greatly increase the structural performance of a plain scarf.

The keyed hook scarf is common in ship and boat-building# as well as timber framing and

wooden bridge construction. !n large timbers such as these the scarf is ;irtually always secured

with through bolts# and is fre&uently reinforced e$ternally with iron or steel fishplates# and1or

strapping.

A scarf oint may also be used to fi$ problems caused when a board is cut too short for the

application. The board can be cut in half with a tapered cut yielding a scarf oint. "hen the oint is

glued together# the tapers are slid against each other so that the two sections are no longer in line

with each other. This has the effect of making the board longer. >nce the glue has set# the boardcan be planed down to an e;en thickness# resulting in a longer but thinner board.
http://www.ask.com/wiki/Woodworking?qsrc=3044http://www.ask.com/wiki/Metalworking?qsrc=3044http://www.ask.com/wiki/Butt_joint?qsrc=3044http://www.ask.com/wiki/Splice_joint?qsrc=3044http://www.ask.com/wiki/Joinery?qsrc=3044http://www.ask.com/wiki/Ship?qsrc=3044http://www.ask.com/wiki/Boat_building?qsrc=3044http://www.ask.com/wiki/Woodworking?qsrc=3044http://www.ask.com/wiki/Metalworking?qsrc=3044http://www.ask.com/wiki/Butt_joint?qsrc=3044http://www.ask.com/wiki/Splice_joint?qsrc=3044http://www.ask.com/wiki/Joinery?qsrc=3044http://www.ask.com/wiki/Ship?qsrc=3044http://www.ask.com/wiki/Boat_building?qsrc=3044


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DOETAILED SCARF 2OINT


TA3LED SCARF 2OINT


TA3LED SCARF 2OINT 4ITH STRAPS

ig.8. 'efore oining ig.2. After oining

Result,

Thus the study of aircraft wood gluing-double scarf oint has completed.
http://www.craftsmanspace.com/images/stories/Scarf%20Joint/Tabled%20Joint%20with%20Straps/tabled_joint_with_straps.gifhttp://www.craftsmanspace.com/images/stories/Scarf%20Joint/Tabled%20Joint%20with%20Straps/tabled_joint_with_straps_e.gifhttp://www.craftsmanspace.com/images/stories/Scarf%20Joint/Tabled%20Scarf%20joint/tabled_scarf_joint.gifhttp://www.craftsmanspace.com/images/stories/Scarf%20Joint/Tabled%20Scarf%20joint/tabled_scarf_joint_e.gifhttp://www.craftsmanspace.com/images/stories/Scarf%20Joint/Dovetailed%20Scarf%20Joint/dovetailed_scarf_joint.gifhttp://www.craftsmanspace.com/images/stories/Scarf%20Joint/Dovetailed%20Scarf%20Joint/dovetailed_scarf_joint_e.gif


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E+'( No, - "

Study on MIG, TIG & PLASMA weldin o! "i#$#"!t$o%onent'

A%m(

To study the MIG, TIG 0 !ASMA welding of aircraft coponent*.

Tun0sten Inert Gas 4el/%n0

(as tungsten arc welding /(TA"4# also known as tungsten inert gas /T!(4 welding# is an arc

weldingprocess that uses a non consumable tungstenelectrodeto produce the weld. The weld

area is protected from atmospheric contamination by a shielding gas/usually aninert gassuch as

argon4# and a filler metalis normally used# though some welds# known as autogenous welds# do

not re&uire it. A constant-current welding power supplyproduces energy which is conducted

across the arc through a column of highly ioni?ed gas and metal ;apors known as aplasma.

T!( is most commonly used to weld thin sections of stainless steeland non-ferrous metals such

as aluminum# magnesium# and copperalloys. The process grants the operator greater control o;er

the weld than competing procedures such as shielded metal arc welding and gas metal arc

welding# allowing for stronger# higher &uality welds. =owe;er# T!( is comparati;ely more

comple$ and difficult to master# and furthermore# it is significantly slower than most other

welding techni&ues. A related process# plasma arc welding# uses a slightly different welding

torch to create a more focused welding arc and as a result is often automated

@anual gas tungsten arc welding is often considered the most difficult of all the welding

processes commonly used in industry. 'ecause the welder must maintain a short arc length# great

care and skill are re&uired to pre;ent contact between the electrode and the work piece. imilar

to torch welding# T!( normally re&uires two hands# since most applications re&uire that thewelder manually feed a filler metal into the weld area with one hand while manipulating the

welding torch in the other. =owe;er# some welds combining thin materials /known as

autogenous or fusion welds4 can be accomplished without filler metalB most notably edge#

corner# and buttoints.
http://en.wikipedia.org/wiki/Arc_weldinghttp://en.wikipedia.org/wiki/Arc_weldinghttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Shielding_gashttp://en.wikipedia.org/wiki/Inert_gashttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Filler_metalhttp://en.wikipedia.org/wiki/Current_sourcehttp://en.wikipedia.org/wiki/Welding_power_supplyhttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Stainless_steelhttp://en.wikipedia.org/wiki/Aluminumhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Shielded_metal_arc_weldinghttp://en.wikipedia.org/wiki/Gas_metal_arc_weldinghttp://en.wikipedia.org/wiki/Gas_metal_arc_weldinghttp://en.wikipedia.org/wiki/Plasma_arc_weldinghttp://en.wikipedia.org/wiki/Welding_jointshttp://en.wikipedia.org/wiki/Arc_weldinghttp://en.wikipedia.org/wiki/Arc_weldinghttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Shielding_gashttp://en.wikipedia.org/wiki/Inert_gashttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Filler_metalhttp://en.wikipedia.org/wiki/Current_sourcehttp://en.wikipedia.org/wiki/Welding_power_supplyhttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Stainless_steelhttp://en.wikipedia.org/wiki/Aluminumhttp://en.wikipedia.org/wiki/Magnesiumhttp://en.wikipedia.org/wiki/Copperhttp://en.wikipedia.org/wiki/Shielded_metal_arc_weldinghttp://en.wikipedia.org/wiki/Gas_metal_arc_weldinghttp://en.wikipedia.org/wiki/Gas_metal_arc_weldinghttp://en.wikipedia.org/wiki/Plasma_arc_weldinghttp://en.wikipedia.org/wiki/Welding_joints


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To strike the welding arc# a high fre&uency generator pro;ides a sparkB this spark is a conducti;e

path for the welding current through the shielding gas and allows the arc to be initiated while the

electrode and the work piece are separated# typically about ).6C8 mm /*.*C*.), in4 apart. This

high ;oltage# high fre&uency burst can be damaging to some ;ehicle electrical systems and

electronics# because induced ;oltages on ;ehicle wiring can also cause small conducti;e sparks

in the ;ehicle wiring or within semiconductor packaging. ehicle ), power may conduct

across these ioni?ed paths# dri;en by the high-current ), ;ehicle battery. These currents can be

sufficiently destructi;e as to disable the ;ehicleB thus the warning to disconnect the ;ehicle

battery power from both ), and ground before using welding e&uipment on ;ehicles.

Pro&e/ure

>nce the arc is struck# the welder mo;es the torch in a small circle to create a welding pool# the

si?e of which depends on the si?e of the electrode and the amount of current. "hile maintaining

a constant separation between the electrode and the workpiece# the operator then mo;es the torch

back slightly and tilts it backward about )*C)6 degrees from ;ertical. iller metal is added

manually to the front end of the weld pool as it is needed.

"elders often de;elop a techni&ue of rapidly alternating between mo;ing the torch forward /to

ad;ance the weld pool4 and adding filler metal. The filler rod is withdrawn from the weld pool

each time the electrode ad;ances# but it is ne;er remo;ed from the gas shield to pre;ent

o$idation of its surface and contamination of the weld. iller rods composed of metals with low

melting temperature# such as aluminum# re&uire that the operator maintain some distance from

the arc while staying inside the gas shield. !f held too close to the arc# the filler rod can melt

before it makes contact with the weld puddle. As the weld nears completion# the arc current is

often gradually reduced to allow the weld crater to solidify and pre;ent the formation of crater

cracks at the end of the weld.

O'erat%on mo/es

T!( can use a positi;e direct current# negati;e direct current or an alternating current# depending

on the power supply set up. A negati;e direct current from the electrode causes a stream of

electrons to collide with the surface# generating large amounts of heat at the weld region. This

creates a deep# narrow weld. !n the opposite process where the electrode is connected to the

positi;e power supply terminal# positi;ely charged ions flow from the part being welded to the

tip of the electrode instead# so the heating action of the electrons is mostly on the electrode. This


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mode also helps to remo;e o$ide layers from the surface of the region to be welded# which is

good for metals such as aluminum or magnesium. A shallow# wide weld is produced from this

mode# with minimum heat input. Alternating current gi;es a combination of negati;e and

positi;e modes# gi;ing a cleaning effect and imparts a lot of heat as well.

A''l%&at%ons

"hile the aerospace industry is one of the primary users of gas tungsten arc welding# the process

is used in a number of other areas. @any industries use T!( for welding thin workpieces#

especially nonferrous metals. !t is used e$tensi;ely in the manufacture of space ;ehicles# and is

also fre&uently employed to weld small-diameter# thin-wall tubing such as those used in the

bicycle industry. !n addition# T!( is often used to make root or first pass welds for piping of

;arious si?es. !n maintenance and repair work# the process is commonly used to repair tools and

dies# especially components made of aluminum and magnesium.F))G'ecause the weld metal is not

transferred directly across the electric arc like most open arc welding processes# a ;ast

assortment of welding filler metal is a;ailable to the welding engineer. !n fact# no other welding

process permits the welding of so many alloys in so many product configurations. iller metal

alloys# such as elemental aluminum and chromium# can be lost through the electric arc from

;olatili?ation. This loss does not occur with the T!( process. 'ecause the resulting welds ha;e

the same chemical integrity as the original base metal or match the base metals more closely#

T!( welds are highly resistant to corrosion and cracking o;er long time periods# T!( is the

welding procedure of choice for critical welding operations like sealing spent nuclear fuel

canisters before burial.F

igure ). chematic diagram of T!( welding process
http://en.wikipedia.org/wiki/TIG#cite_note-10http://en.wikipedia.org/wiki/Spent_nuclear_fuelhttp://en.wikipedia.org/wiki/TIG#cite_note-11http://en.wikipedia.org/wiki/TIG#cite_note-11http://en.wikipedia.org/wiki/File:GTAW_setup.pnghttp://en.wikipedia.org/wiki/TIG#cite_note-10http://en.wikipedia.org/wiki/Spent_nuclear_fuelhttp://en.wikipedia.org/wiki/TIG#cite_note-11


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The electrode used in T!( is made of tungsten or a tungsten alloy# because tungsten has the

highest melting temperature among pure metals# at 8#2,, H% /#)


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4el/%n0 0un an/ .%re fee/ un%t

The typical @!( welding gun has a number of key partsIa control switch# a contact tip# a power

cable# a gas no??le# an electrode conduit and liner# and a gas hose. The control switch# or trigger#

when pressed by the operator# initiates the wire feed# electric power# and the shielding gas flow#

causing an electric arc to be struck. The contact tip# normally made of copper and sometimes

chemically treated to reduce spatter# is connected to the welding power source through the power

cable and transmits the electrical energy to the electrode while directing it to the weld area. !t

must be firmly secured and properly si?ed# since it must allow the passage of the electrode while

maintaining an electrical contact. 'efore arri;ing at the contact tip# the wire is protected and

guided by the electrode conduit and liner# which help pre;ent buckling and maintain an

uninterrupted wire feed. The gas no??le is used to e;enly direct the shielding gas into the

welding ?oneIif the flow is inconsistent# it may not pro;ide ade&uate protection of the weld

area. Larger no??les pro;ide greater shielding gas flow# which is useful for high current welding

operations# in which the si?e of the molten weld pool is increased. The gas is supplied to the

no??le through a gas hose# which is connected to the tanks of shielding gas. ometimes# a water

hose is also built into the welding gun# cooling the gun in high heat operations.F9G

The wire feed unit supplies the electrode to the work# dri;ing it through the conduit and on to the

contact tip. @ost models pro;ide the wire at a constant feed rate# but more ad;anced machines

can ;ary the feed rate in response to the arc length and ;oltage. ome wire feeders can reach feed

Ele&tro/e

Electrode selection is based primarily on the composition of the metal being welded# the process

;ariation being used# oint design and the material surface conditions. Electrode selection greatly

influences the mechanical properties of the weld and is a key factor of weld &uality. !n general

the finished weld metal should ha;e mechanical properties similar to those of the base material

with no defects such as discontinuities# entrained contaminants or porosity within the weld. To

achie;e these goals a wide ;ariety of electrodes e$ist. All commercially a;ailable electrodes

contain deo$idi?ing metals such as silicon# manganese# titanium and aluminum in small

percentages to help pre;ent o$ygen porosity. ome contain denitriding metals such as titanium

and ?irconium to a;oid nitrogen porosity.F)2G Depending on the process ;ariation and base

material being welded the diameters of the electrodes used in @!( typically range from *. to

,.2 mm /*.*,9C*.*


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generally up to ).)2 mm /*.*26 in4F)6G are associated with the short-circuiting metal transfer

process# while the most common spray-transfer process mode electrodes are usually at least

*.< mm /*.*86 in4.

@!( %ircuit diagram. /)4 "elding torch# /,4 "ork piece# /84 Power source# /24 "ire feed unit#/64 Electrode source# /4 hielding gas supply.

Plasma arc welding /PA"4 is an arc weldingprocess similar to gas tungsten arc welding /T!(4.

The electric arc is formed between an electrode /which is usually but not always made of

sintered tungsten4 and the work piece. The key difference from T!( is that in PA"# by

positioning the electrode within the body of the torch# the plasma arc can be separated from the

shielding gas en;elope. The plasmais then forced through a fine-bore copper no??le which

constricts the arc and the plasma e$its the orifice at high ;elocities /approaching the speed ofsound4 and a temperature approaching ,*#*** H%. Plasma arc welding is an ad;ancement o;er

the T!( process. This process uses a non-consumable tungsten electrode and an arc constricted

through a fine-bore copper no??le. PA" can be used to oin all metals that are weldable with

T!( /i.e.# most commercial metals and alloys4. e;eral basic PA" process ;ariations are

possible by ;arying the current# plasma gas flow rate# and the orifice diameter# including+

@icro-plasma /M )6 Amperes4

@elt-in mode /)6C2** Amperes4

Keyhole mode /N)** Amperes4

Plasma arc welding has a greater energy concentration as compared to T!(.

A deep# narrow penetration is achie;able# with a ma$imum depth of ), to )9 mm /*.2 to

*.) in4 depending on the material.F)G
http://en.wikipedia.org/wiki/Metal_Inert_Gas#cite_note-14http://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Gas_tungsten_arc_weldinghttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Sinterhttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Shielding_gashttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Plasma_arc_welding#cite_note-0http://en.wikipedia.org/wiki/File:GMAW_Circuit.pnghttp://en.wikipedia.org/wiki/Metal_Inert_Gas#cite_note-14http://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Gas_tungsten_arc_weldinghttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Sinterhttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Shielding_gashttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Plasma_arc_welding#cite_note-0


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(reater arc stability allows a much longer arc length /stand-off4# and much greater

tolerance to arc length changes.

PA" re&uires relati;ely e$pensi;e and comple$ e&uipment as compared to T!(B proper

torch maintenance is critical

"elding procedures tend to be more comple$ and less tolerant to ;ariations in fit-up# etc.

>perator skill re&uired is slightly greater than for T!(.

>rifice replacement is necessary.

Gases

At least two separate /and possibly three4 flows of gas are used in PA"+

Plasma gas C flows through the orifice and becomes ioni?ed

hielding gas C flows through the outer no??le and shields the molten weld from the

atmosphere

'ack-purge and trailing gas C re&uired for certain materials and applications.

These gases can all be same# or of differing composition.

5e6 'ro&ess 7ar%ables

%urrent Type and Polarity

D%EO from a %% source is standard

A% s&uare-wa;e is common on aluminum and magnesium

"elding current and pulsing - %urrent can ;ary from *.6 A to ),** AB %urrent can be

constant or pulsed at fre&uencies up to ,* k=?

(as flow rate /This critical ;ariable must be carefully controlled based upon the current#

orifice diameter and shape# gas mi$ture# and the base material and thickness.4

Result,

Thus the study of the MIG, TIG 0 !ASMA welding of aircraft coponent*has

completed.


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E+'( No, - 8

(elded 'inle & dou)le V*+oint'Ai%

To study the %elded *ingle 0 double 3oint*

"elding oints are formed by weldingtwo or more workpieces# made of metals or plastics#

according to a particular geometry. The most common types are butt and lap ointsB there are

;arious lesser used welding oints including flange and corner oints.

3utt 1o%nt 0eometr%es

There are many types of butt welds# but all fall within one of these categories+ single welded butt

oints# double welded butt oint# and open or closed butt oints. A single welded butt oint is the

name for a oint that has only been welded from one side. A double welded butt oint is created

when the weld has been welded from both sides. "ith double welding# the depths of each weld

can ;ary slightly. A closed weld is a type of oint in which the two pieces that will be oined are

touching during the welding process. An open weld is the oint type where the two pieces ha;e a

small gap in between them during welding.

-2o%nts

ingle--Joint butt welds are similar to a be;el oint# but instead of only one side ha;ing the

be;eled edge# both sides of the weld oint are be;eled. !n thick metals# and when welding can be

performed from both sides of the work piece# a double--oint is used. "hen welding thicker

metals# a double--oint re&uires less filler material because there are two narrower -oints

compared to a wider single--oint. Also the double--oint helps compensate for warping

forces. "ith a single--oint# stress tends to warp the piece in one direction when the -oint is

filled# but with a double--oint# there are welds on both sides of the material# ha;ing opposing

stresses# straightening the material.

Plate Edge Preparation

!n common welding practices# the welding surface needs to be prepared to ensure the strongest

weld possible. Preparation is needed for all forms of welding and all types of oints. (enerally#
http://en.wikipedia.org/wiki/Weldinghttp://en.wikipedia.org/wiki/Welding


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butt welds re&uire ;ery little preparation# but some is still needed for the best results. Plate edges

can be prepared for butt oints in ;arious ways# but the fi;e most common techni&ues are

o$yacetylene cutting /o$y-fuel welding and cutting4# machining# chipping# grinding# and air

carbon-arc cuttingor gouging. Each techni&ue has uni&ue ad;antages to their use.

or steel materials# o$yacetylene cutting is the most common form of preparation. This

techni&ue is ad;antageous because of its speed# low cost# and adaptability. @achining is the most

effecti;e for reproducibility and mass production of parts. Preparation of J or oints is common

prepared by machining due to the need for high accuracy. The chipping method is used to

prepare parts that were produced by casting. The use of grinding to prepare pieces is reser;ed for

small sections that cannot be prepared by other methods. Air carbon arc welding is common in

industries that work with stainless steels# cast iron# or ordinary carbon steel

igure.). "elding sections

Result,

Thus the study of the he %elded *ingle 0 double 3oint* has completed.
http://en.wikipedia.org/wiki/Oxy-fuel_welding_and_cuttinghttp://en.wikipedia.org/wiki/Air_carbon-arc_cuttinghttp://en.wikipedia.org/wiki/Air_carbon-arc_cuttinghttp://en.wikipedia.org/wiki/File:Butt_Weld_Geometry.GIFhttp://en.wikipedia.org/wiki/Oxy-fuel_welding_and_cuttinghttp://en.wikipedia.org/wiki/Air_carbon-arc_cuttinghttp://en.wikipedia.org/wiki/Air_carbon-arc_cutting


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E+'( No, - !

Fabr%& 'at&9 re'a%r.

AIM: Making repair to the fabric covered surface in a manner that will returnoriginal strength and tautness

THEORY:Introduction: Fabric covering of aircraft has been in use for many years because ofits low cost, ease of installation, ease of repair, light weight strength anddurability. Aircraft covering fabrics are made of cotton, polyester fiber,glass fiber.

NOMENCLATURE OF FABRICS:BIAS:

A cut, fold or seam made diagonally across the ward and fill fibres of apiece of cloth.

BLEACHING: Achemical process used to whiten textile materials.CALENDARING: A process of ironing fabric by threading it wetFILL: The fibers are a piece of fabric of fabric that are woven into the warpfibre. These fibres run perpendicular to the length of fabrics.SELVAGE: The bond edge of a length of fabric. The selvage is where the till fibresturn around and go back through the warp fibres.

TYPES OF FABRICS: .!rganic fabrics

". #norganic fabricsORGANIC FABRICS: !rganic fabrics are those made from plant materialse!"#$e: merceri$ed cotton clothINORANIC FABRICS: #norganic fibres is one that re%uires chemical processing to create thefiber.e!"#$e:polyesters, fiber glass


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TOOLS AND E%UIPMENTS FOR COVERING:HARNESS TOOL: This tool is udeful for making small holes in fabrics.MAGNETIC TAC& HAMMER: This is most useful for picking up and holding tacks that are too small

to be held in the fingers.POC&ET &NIFE: This knife is useful for cutting textile materials .NEEDLES: &eedles are re%uired for rib lacing and hand seving.BENT'HANDLE TRIMMER(S SHEAR(S: This is re%uired for cutting fabrics, tapes etc...STEEL MEASURING TAPE:

This is necessary for measuring wings, fuselages and length of fabrics.SE)ING THIMBLE:

This is useful for pushing a needle through thick seams where extra

pressure is necessary.EASEL:

This may be useful to support the airfoil in a vertical position while thefabric covering is being rib lased.TRESTLES:

This is needed to support wing panels in hori$antal.FABRIC SEAMS:

These are used to 'oin piece of fabric together and to attach fabric tothe aircraft structure.TYPES OF SEAMS:. (lain overlap

". Folded fell). French fell*. Modified trench fell

COVERING METHODS:. +nvelope". lanket

+nvelope method involves making or buying a sleeve that can slideover the prepare structure.

lanket method covering involves the use of fabrics as it comes off theroll. it is cut to si$e and folded over the structure to be covered.

REPAIR OF FABRIC COVERING:TEAR IN FABRIC:Tears in a fabric covering can usually be re%uired by sewing and

doping on a fabric patch. The ob'ective is restore the original strength andfinish to the repaired area.

-ewing the tear using a base ball stitch. ock has been done every / to0 inches.METHOD OF SE)ING A V'TYPE TEAR:


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SE)N IN PATCH:The damage does not exceed 1 inch in any direction , a sewn2in patch

can be used.The first step is to trim out the damge in a rectangular shape.

the dope is then removed for atleast )./ cm from edge of fabric.

A patch of material of the same type as being repaired is then cut tobe sewn into the opening.Tack stichers are used to hold the patch in position. The patch is then

sewed in using a base ball stich.DOPED ON A PANEL REPAIR:

3hen the damage to an alc fabric surface is greater than 1 inches.Apanel should be doped on.DOPE:

4ope is defined as collidial solution of a cellulose acetate butyrate orcellulose nitrate, have been developed that serve the function of dope forsealing, tautening and protecting airplane fabric covering.

SA)N IN PANEL REPAIR:#f a panel repair cannot give the proper tautness by using the doped

on panel repair, a sawn repair, a sawn in panel repair can be performed..

Result,

Thus the study of the fabric patch repair has completed.


19/31

E+'( No, - :

Ri-eted "t$. #e"i#'.

Ai%/

To study the riveted patch repair*.

The many ad;antages of the material properties afforded by today:s ad;anced composite

materials ha;e brought about their wide use in the manufacture of many of today:s aerospace

;ehicles. Particularly in military aircraft# the beha;iour of damaged composites and subse&uentrepairs are of great interest.

The current repair techni&ues for the repair of battle damaged composite panels# based onsimplicity# speed# and reliability of the repair# re&uire that an aluminium patch be fastened with

bolts: o;er the damaged section of the composite panel. The purpose of repair is not to fully

restore the original properties of the panel. !t is# instead intended to match the properties closelyenough that the aircraft can be returned to ser;ice in a timely manner or# if damaged beyond the

repair abilities of the unit# allow the aircraft to safely fly to a more capable repair facility.

nderstanding of how these repairs might affect the natural fre&uencies of the panel is essential.The natural fre&uency is the fre&uency that a lightly damped structure can ;ibrate at a

continually increasing amplitude. To a;oid a failure of the section under otherwise normal

operating condition# the effect of the repair on the natural fre&uency should be ascertained.

The core material is nome$ honey comb. =owe;er# this core alone is not strong enough 9 layers

of carbon# fiber# Ke;lar# and glass material are bounded to increase stiffness. inally# the panel is

pi;oted with polyurethane point for the resistance.

These skins although incredibly strong# still get damaged from baggage holders# debris on run

way whether this happens the plane are taken to composite repair facility. Damage is repaired asfast as possible.

Although difficult to see in photo# abo;e the gauge is centered in concentric circle drawn by

repair personnel with appro$imately 9 inch radius. The skin with in the circle will be carefullycut and remo;ed from honey comb core.

After top layer of fiber material is remo;ed# the damages of honey comb care and surroundingsarea is then remo;ed.

A new honey comb core section is cut to appropriate si?e and potted to plane using aerospaceadhesi;e.


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Three layers of fabric are then laminated o;er new honey comb# the second layer is slightly

beyond. irst and outside layer e$tends to edge of remo;ed skit. 'y laminating new fibrereinforcement material beyond distance of remo;ed honey comb an inefficient lap oint is

created# thus pre;enting further damage to structure.

The final surface is then slightly sanded to remo;e e$cess resin# the prepped and primed for

polyurethane and aircraft is ready to continue ser;ice.

Result,

Thus# the repair of fabric patch is studied.


21/31

E+'( No, - ;

Tube ben/%n0 an/ flar%n0

Ai%/

To study the tube bending and flaring.

Tubes are usually used as flow lines for gases and fluids in the food processing# medical#

hydraulic# and pneumatic or process industries. Tubes are cylindrical# hollow items used in tube

bending# the si?e of which is indicated by an outside diameter usually in inches. Pipes can be

used for transporting fluids and solids in many types of industries. Pipes are more rigid than

tubes# with their si?e indicated by the inside diameter usually in inches. ome tubes can be found

in s&uare# rectangular# round and o;al shapes. Tubes that can be bent are made from carbon steel#

stainless steel# aluminum# brass# copper# poly;inyl choride /P%4# titanium# superalloys# nickel

alloys and plastics.

Tube ben/%n0

ome specifications that are re&uired for tube bending# includes the wall thickness# the outside

diameter referred to as the >.D.# the inside diameter referred to as the !.D. and the radius of the

bend. The degree of bend /D>'4# the length or position of the bend and the plane or orientation

are also needed to complete the tube bending process.

The cost of tooling for tube bending can be reduced by using a bend radii that is considered a

standard si?e and readily a;ailable at the tube bending company you chose. Also opting to use

the same radius for se;eral bends will reduce set-up costs for tube bending.

Tube bending includes flaring# beading or swaging# also referred to as end forming# are processes

used to interconnect tubes or eliminate the need for connectors. Tube beading is used in the

bending process to amplify the efficiency of a connection and to lessen ;ibrations in e$haust

systems or fuel systems. waging reduces or increases the end diameter by using a compressi;e

force to reshape the tube. The medical# automoti;e# aerospace# and commercial industries utili?e


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swaging in the tube bending process. Tube flaring increases the efficiency of li&uid or air tight

connections in the automoti;e# aircraft# cooling# hydraulic or heating industries.

The hand tube bender shown in figure consists of four parts - handle# radius block /mandrel4#

clip#and slide bar. The radius block is marked in degrees of bend ranging from * to )9*. The

slide bar has a mark which is lined up with the ?ero mark on the radius block. The tube is

inserted in the tool# and after lining up the marks# the slide bar is mo;ed around until the mark on

the slide bar reaches the desired degrees of bend on the radius block. ollow the procedure

indicated in figure.

This type of bender is furnished in 81)@# )123# 61)3# 8193# and )1,3 si?es. or larger si?es of

tubing similar mandrel-type benders are used. The only difference is that these larger benders are

geared for greater mechanical ad;antage.

Tube flar%n0

Tube flaring is a method of forming the end of a tube into a funnel shape so that it can be held by

a threaded fitting. A partially threaded flare nut is slipped o;er the tube# the end of the tube is

flared# the flare is seated with the inside of the flare against the end of a fitting which has threads

on the outside# and then the flare nut is screwed onto the fitting# pushing the outside of the flare

against the seating surface of the fitting.

The tube-flaring tool shown in figure is one type which is commonly used to flare copper tubing.

To flare the end of tubing# first check to see that it has been cut off s&uarely and has the burrs

remo;ed from both inside and outside. emember to slip the flare nut on the tube before you

make the flare. Then# as shown in figure# open the flaring tool at the die which corresponds to the

si?e of the tubing being flared. !nsert the end of the tubing to protrude slightly abo;e the top face

of the die blocks. The amount by which the tubing e$tends abo;e the blocks determines the

finished diameter of the flare. The flare must be large enough so that it will seat properly against

the fitting# but small enough so that the threads of the flare nut will slide o;er it. Qou determine

the correct si?e by trial-and-error. Then# close the die block and secure the tool with the wing

nut. se the handle of the yoke to tighten the wing nut. Then place the yoke o;er the end of the

tubing# and tighten the handle to force the cone into the end of the tubing. The completed flare

should be slightly ;isible abo;e the face of the die blocks.


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igure ). Tube bending


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igure ,. laring metallic tubing

Result,

Thus# the study of the tube bending and flaring has performed.


25/31

E+'( No, -

asr lab karthik

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