Composite Structures Lab Manuel
Transcript of Composite Structures Lab Manuel
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SATHYABAMA UNIVERSITY
CHENNAI 600 119
DEPARTMENTOF AERONAUTICAL
ENGINEERING
SAEX 4011 COMPOSITE STRUCTURES LAB MANUAL
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CO NTENTS
LIST OF EXPERIMENTS
1. Fabrication of glass epoxy laminates using hand layup
process.
2. Fabrication of Carbon polyster laminate using compression
moulding
3. Fabrication of glass fiber filament wound pipes using
filament winding machine
4. Calculation of material properties of bi directional composite
laminate
5. Determination of material properties of cross ply laminate
6. Determination of shear modulus of composite laminate
7. Fabrication of sandwich beam
8. Determination inter laminar shear strength of a composite
laminate
9. Failure analysis of composite laminate using matlab
10.Determination of material properties using plate theory
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1.FABRICATION OF CLASSEPOXY LAMINATES USING HAND LAYUP PROCESS
AIM :
i) To fabricate Fiber reinforced laminated (FRP) composites using hand layup process
ii) To determine the void fraction of the laminate
iii) To determine the density of the laminate
iv) To determine the fiber volume fraction
APPARATUS AND MATERIALS REQUIRED:
Scale, Roller, weighing balance, Glass fabric, epoxy resin and accesories
PROCEDURE :
1. Thoroughly clean the aluminum plate using acetone or a detergent. Then apply mold-release agent to thetop surface of the aluminum plate twice.
2. Lay one sheet of Teflon film and the peel-ply nonstick nylon cloth on the aluminum plate. The Teflon film
is used to release the lay-up from the aluminum plate, and the peel-ply is used to achieve the required surface
finish on the laminate. Note: There should be no wrinkles or raised regions in the peel ply, and its dimensions
should be identical to those of the laminate.
3. Cut the given glass oven fabric cloth into required size(1feetx1feet).No of ply is based on the required
thickness. Weigh the fabric using weighing balance.
4. Now measure the epoxy LY556 resin whose weight is equivalent to 100% of the fiber weight. Add
hardener(HY 956) of weight 10% weight of the resin and stir well.
5.Using painting brush apply this epoxy hardener mix over the Teflon sheets.6.Lay one layer fiber cloth over the plate then again apply the resin over the fiber cloth. This process is
repeated until the desired thickness is achieved. Excess resins are removed using roller.
7. Laminates are left to cure under standard atmospheric conditions for about 24 hours.
8. Fiber /resin volume fraction can be determined using digestion test.
9. Density of the laminate can be determined using buoyancy test.10.Void fraction
OBSERVATION :
C . S dimensions of the specimen =
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TABULATION :
Sl .No Load in N Cross sectional area of
the specimen
( mm2)
Compressive strength
N / mm2
CALCULATION:
Ultimate compressive load
Compressive strength of the given specimen =
C. S area of the specimen
RESULT :
The compressive strength of the given specimen =
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2.DEFLECTION TEST
AIM :
To determine the Youngsmodulus of the given material and verify Maxwells
law of reciprocal deflection .
APPARATUS :
1. Knife edge supports
2. Deflectometer
3. Set of weights with hanger.
4. Scale5. Vernier caliper .
PRINCIPLE :
According to Maxwells law of reciprocal deflection in a simply supported beam
AB = BA
where AB Deflection of the beam measured at A due to the load at B
BA Delection of the beam measured at B due to the load at A
PROCEDURE :
1. Measure the dimensions of the beam.
2. Place the given beam on knife edge supports with equal overhangs on either side
of the beam .
3. Place the deflectometer at a distance xfrom the support.
4. Place the weight hanger at a distance of a from the support. Note the initial
reading of the deflectometer.
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5. Now increase the load gradually and take the corresponding deflectometer
readings.
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6. Now decrease the load in the same intervals and note the deflectometer
readings.
7. Draw a graph Load vs Deflection .
OBSERVATION :
x < a & x < b
C . S . dimensions of the beam =
Span ( l ) =
Distance ( x ) =
Distance ( a ) =
Distance ( b ) =
TABULATION :
S.No Load
Deflectometer reading Young
modul
in
N/mm
x < a x < b
gm N Loading Unloading Mean Loading Unloading Mean
1.
2.
3.
4.
5.
6.
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CALCULATION:
x < a
w b x
= ( l2 b2 x2 )
6 E I l
x < b
w a x
= ( l2 a2 x2 )
6 E I l
RESULT :
Youngs modulus of the given material (E) =
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3. COMPRESSION TEST ON OPEN COILED HELICAL SPRING
AIM :
To conduct a compression test on the given helical spring and hence determine
the following, a) Shear modulus b) Stiffness of the spring c) Proof load d) Strain
energy stored at proof load
APPARATUS :
1. Spring testing machine
2. Vernier caliper
3. Scale
MACHINE DESCRIPTION :
The machine mainly consists of loading mechanism, load measuring system,
indicating mechanism, recorder and electrical controls.
Loading mechanism :
The base is connected to torque plate by two columns forming the main structureof the machine .The measuring system is assembled on top plate and is covered by top
cover. The side panel fixed to the right column consists of indicating and recording
mechanisms
Load measuring sytems (Pendulum dynamometer):
The load measuring system is supported on the top plate and is covered by the
top cover. The upper grip head is fixed to the central member .A spring steel strip with
one end fixed to the pendulum shaft runs around the shaft and its end is fixed to the
central member.
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Indicating mechanism:
The rack pusher fixed to the pendulum lower pushes the rack which slides over
the rack guide pulleys .The lower movement of the rack rotates the pinion .The pinion is
fixed on a pointer shaft running in ball bearing. A dummy pointer which moves forward
with the main pointer is provided for maximum load reading .
PROCEDURE :
1. Measure the mean coil diameter and the diameter of wire of the spring .Also note
the number of free coils in the spring.
2. Place the spring in position in between the platforms for compression spring.
3. Adjust the indicator of the load dial, to read 0.4. Apply compressive load by increasing at suitable intervals and note the
corresponding deflections.
5. Draw graph load vs deflection .
OBSERVATION :
Mean coil diameter ( D )=
Wire diameter (d )=
No. of turns ( n ) =
Free height of the spring (H) =
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TABULATION :
S.No
Load
(N )
Deflection (mm ) Stiffness
N/mm
Proof
Load
( N)
Shear
stress
N/mm2
Rigidity
modulus
N/mm2
Stra
ene
Nm
Loading Unloading Mean
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
CALCULATION:
64 R3
n w
Rigidity modulus ( G ) = x
d4
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w
Stiffness of the spring ( K ) =
Proof load (wp ) = K (H n d)
16 wpR
Shear stress (p ) = =
d3
(p )2 d2
Strain energy stored ( Uwp ) = x x Dn
4 G 4
RESULT :
Rigidity modulus =
Stiffness of the spring =
Proof load =
Strain energy stored at proof load =
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4. TENSION TEST ON CLOSED COILED HELICAL SPRING
AIM :
To conduct a tension test on the given helical spring and hence determine the
following a) Shear modulus b) Stiffness of the spring.
APPARATUS :
1. Spring testing machine2. Vernier caliper3. Scale
MACHINE DESCRIPTION :
The machine mainly consists of loading mechanism, load measuring system,
indicating mechanism, recorder and electrical controls.
Loading mechanism:
The base is connected to torque plate by two columns forming the main structure
of the machine. The measuring system is assembled on top plate and is covered by topcover. The side panel fixed to the right column consists of indicating and recording
mechanisms
Load measuring systems (Pendulum dynamometer ):
The load measuring system is supported on the top plate and is covered by the
top cover.The upper grip head is fixed to the central member .A spring steel strip with
one end fixed to the pendulum shaft runs around the shaft and its end is fixed to the
central member.
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Indicating mechanism :
The rack pusher fixed to the pendulum lower pushes the rack which slides over
the rack guide pulleys .The lower movement of the rack rotates the pinion .The pinion isfixed on a pointer shaft running in ball bearing. A dummy pointer which moves forward
with the main pointer is provided for maximum load reading .
PROCEDURE :
1. Measure the mean coil diameter and the diameter of wire of the spring .Also
note the number of free coils in the spring .
2. Place the spring in position by attaching it to hooks for tension spring .
3. Adjust the indicator of the load dial ,to read 0 .4. Apply tensile load by increasing at suitable intervals and note the corresponding
deflections .
5. Draw graph load vs deflection.
OBSERVATION :
Mean coil diameter (D) =
Wire diameter (d ) =
No. of free coils ( n ) =
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TABULATION :
S.No
Load
(N )
Deflection (mm ) Stiffness
N/mm
Shearstress
N/mm2
Rigiditymodulus
N/mm2
Strainenergy
NmmLoading Unloading Mean
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
CALCULATION:
64 R3
n w
Rigidity modulus ( G ) = x
d4
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w
Stiffness of the spring ( K ) =
16 w R
Shear stress ( ) =
d3
( )2 d2
Strain energy stored ( Uwp ) = x x Dn
4 G 4
RESULT :
Rigidity modulus =
Stiffness of the spring =
Proof load =
Strain energy stored at proof load =
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5. TORSION TEST ON MILD STEEL ROUND BAR
AIM:
To conduct a torsion test on the given mild steel wire and hence determine the
modulus of rigidity .
APPARATUS :
1. Torsion testing machine
2. Vernier caliper.
3. Scale
MACHINE DESCRIPTION:
The machine consists of two units namely, loading unit and the measuring
control panel. It consists of robust base fitted with control panel. The gear box assembly
is guided on the base. A driving chuck and angle measuring pulley is mounted on a lever
spindle assembly is connected to a pendulum dynamometer. The autographic recorder
is fitted on the control panel .The recorder will show the relation between torque and
twist angle
PROCEDURE :
1. Measure the diameter of the specimen in both perpendicular directions and take
the average .
2. Fix the specimen between the driving chuck and the driven chuck.
3. Set the angle measuring dial at 0o
position.
4. Now apply torque to the specimen.
5. Note the torque readings by changing the angle of twist.
6. Draw the graph torque Vs angle of twist.
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OBSERVATIONS :
Length of the specimen ( l ) =
Diameter of the specimen ( d ) =
TABULATION :
Sl . No Angle of twist () Torque ( T ) Rigidity modulus (G )
N/mm2
degree radians kg f cm Nmm
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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CALCULATIONS
d3
Polar M.I. (J) =
32
T L
Rigidity modulus (G ) = x
J
RESULT:
Modulus of rigidity of the given material is =
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6. IZOD IMPACT TEST
AIM :
To determine the impact strength of the given specimen.
APPARATUS REQUIRED:
1. Izod impact testing machine
2. Scale
.
MACHINE DESCRIPTION :
The pendulum impact testing machine consists of the single piece frame, the
pendulum, the specimen support and the measuring equipment. The pendulum is fastenedto the pendulum shaft. The range within which the pendulum is swinging is partially
protected by the guard. There is a dial attached concentrically with the pendulum shaft.
The scale is designed such that the impact energy absorbed in breaking the specimen canbe read directly.
Angle of drop of pendulum = 900
Striking velocity of pendulum = m / sec
PROCEDURE :
1. Firmly secure the proper striker to the bottom of the hammer with the help of
damping piece.2. Firmly secure the latching tube for Izod test to the barring housing at the side of
the columns. The steel wire coming from the latch is carried through the latching
tube and is fastened to the interior of the release lever.3. For determining the frictional loss in the machine, adjust the reading pointer along
with pointer carrier to 300 J reading on the dial when the pendulum is swinging
free.4. Note the reading on the scale against the pointer, which gives initial error if any.
5. Now lift the pendulum again to its starting position.
6. Fix the specimen for Izod test to the support.
7. Release the pendulum as before. The hammer strikes the specimen.
8. Note the reading against the pointer. This gives the energy absorbed by the
specimen.
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OBSERVATION:
Length of the specimen =
Effective crosssectionalarea =
Energy absorbed by the specimen =
TABULATION:
Sl .No Effective crosssectional
area ( mm2 )
Energy absorbed by the
specimen ( J )
Impact strength
(J / mm2)
CALCULATION:
Energy absorbed by the specimen
Impact strength =
Effective crosssectional area
RESULT:
Impact strength of the given specimen =
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7. TENSION TEST ON MILD STEEL BAR
AIM:
To study the behaviour of a mild steel specimen under tension when tested todestruction and also to determine the following.
a) Youngs modulus b) Yield stress c) Ultimate stress d) Breaking stress
e) Percentage elongation in length f) Percentage reduction in area.
APPARATUS REQUIRED :
1. Universal testing machine
2. Extensometer
3. Vernier caliper
4. Scale
DESCRIPTION OF MACHINE :
The machine consists of two units namely
1. The loading unit
2. The control unit.
The loading unit consists of a robust base. The main hydraulic cylinder is to be
fitted in the centre of the base and the piston slides in the cylinder. It consists of a lower
table, which is connected to the main piston through a ball and ball seal joint and two
cross heads. The lower table and the upper cross head assembly moves up and down
with the main piston.
The main units in the control panel are
1. The oil tank which contains the hydraulic oil.
2. The pump which assures a continuous high pressure non pulsating of current
for the smooth application of load on the specimen.
3. Two valves one at the right hand side and the other at the left side are used to
control the oil flow in the hydraulic system and Dynamometer is a unit which
measures and indicates the load. It is a pendulum dynamometer consisting of a
cylinder in which the piston reciprocates.
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4. The displacement of the piston causes the pendulum to deflect and this
deflection represents the measurement of the load on the specimen.
THEORY:
Within the elastic limit for ductile materials, stress bears a constant ratio with
the applied stress. When the test sample is tested by varying the stress in UTM at the
time of yield, the point steps for a moment. This will be followed by the scaling off from
the surface of the specimen. Further increase in load will be the ultimate load and this
will be shown by the dummy indicator on the load scale and the breaking load will be
shown by the active indicator needle when the specimen fails.
PROCEDURE :
Initial adjustment: Before the testing, adjust the pendulum weight
according to the capacity of the test. Adjust the corresponding range on the dial with
the range adjusting knob.
1. Measure the diameter of the specimen in two directions perpendicular to each
other atleast at three places on the bar and take the average .
2. Mark the gauge length on the bar.
3. Select the appropriate measuring range by placing proper weights on the
Pendulum of the U . T . M.
4. Fix one end of the mild steel bar in the clamping jaws of the U. T. M
5. Now adjust the lower head to the required distance and grip the other end of
the mild steel bar in the clamping jaws in it.
6. Clamp the extensometer.
7. Apply the load gradually by opening the right control valve and note the
corresponding extensometer reading.
8. At a particular stage there will be a pause in the increase of load. The load at that
point is noted as yield point load.
9. After the pointer reaches the maximum, there will be a sudden drop in the load
and this is recorded as ultimate load.
10. A neck is formed at the center of the specimen and continue the loading with a
dummy pointer accompanying the load pointer until the mild steel bar breaks.Note the breaking load at the time of fracture.
1. Now close the right control valve. Remove the specimen from the machine.
2. Measure the final length and the diameter of the mild steel bar.
3. Calculate the stress and strain for each reading and plot a graph. Slope of the line
gives the Modulus of Elasticity.
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OBSERVATION:
Diameter of the specimen (D) =
Gauge length of the specimen (L) =
Neck diameter after fracture(D1) =
Final gauge length after fracture (L1) =
Yield load =
Ultimate load =
Breaking load =
TABULATION :
Sl. No Load Extensometer reading
mm
Strain Stress
N/mm2
Youngs
Modulus
N/mm2
Kgf N Dial I Dial II Mean
1.
2.
3.
4.
5.
6.
7.
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CALCULATION:
Initial crosssectional area (A) =
Final crosssectional area (A1)
% reduction in area
=
= Initial area Final area
X100
Initial area
Final length Initial length
% Elongation in length = x 100
Initial length
Yield load
Yield stress =
Initial crosssectional area
Ultimate load
Ultimate stress =
Initial crosssectional area
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Breaking load
Nominal Breaking stress =
Original area of cross section
Breaking load
Actual Breaking stress =
Final area of cross section
Axial stress
Youngs modulus =
Axial strain
RESULT :
1. Young s modulus =
2. Yield stress =
3. Ultimate stress =
4. Nominal breaking stress =
5. Actual Breaking stress =
6. % reduction in area =
7. % elongation in length =
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8. Determination inter laminar shear strength of a composite laminate
AIM :
To determine the Inter laminar shear strength of the given laminated composite
material .
GENERAL :
The most common test for measuring shear delamination is the short beam
shear test shown below, where a small specimen (
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the same procedure for further specimens.
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TABULATION :
RESULT :
The Rockwell hardness number for
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9. BRINELL HARDNESS TEST
AIM :
To determine the Brinell hardness number for the given specimens.
APPARATUS :
1. Brinell hardness testing machine.
2. Microscope.
DESCRIPTION OF MACHINE :
The machine consists of a Jframe, main lever, hanger, elevating screw, loading
unloading mechanism and damper system. The load is applied on the specimen through
ball holder, it is effected through a lever mechanism.
The main lever carries three male vees, one for hanger, second for spindle shaft
and third for pivot vee. The elevating screw can be moved up and down by rotating the
hand wheel. The five detachable weights, each equivalent to 500 kg and to be made use
of for application of desired load in addition to the bottom weight equivalent to 500 kg.
The operating lever is provided for loading and unloading.
PROCEDURE :
1. Polish the surface of the specimen.
2. Place the specimen on the worktable.
3. Keep the operating lever in horizontal position.
4. Turn the hand wheelin clockwise direction so that the specimen touches the
ball indentor.
5. Lift the operating lever from horizontal position upwards slightly after which
it rotates automatically.
6. Wait till the lever becomes standstill.
7. Bring the lever back to horizontal position.
8. Turn back the hand wheel and remove the specimen from the machine. Carry
on the same procedure for further specimens.
9. Measure the diameter of impression by Brinell Microscope.10. Find the Brinell hardness number using the formula
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FORMULA:
P
Brinell Hardness Number =
D / 2 [ D (D2 d2 ) ]
Where P loadin Kgf
D Dia. of indenter in mm
d Dia. of indentation in mm
For Steel , P = 30 D2
For Brass , P = 10 D2
For Aluminium, P = 5 D2
OBSERVATIONS :
Diameter of indentor , D =
Diameter of indentation, d =
TABULATION :
Sl . No Specimen Diameter ofindentor D
(mm)
Load
kgf
Diameter of impression(mm)
Brinellhardness
numberTrial
1
Trial
2
Trial
3
Mean
RESULT :
Brinell hardness number for the given specimens =
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10.DOUBLE SHEAR TEST
Aim:
To find the double shear test of the given specimen.
Apparatus required:
1. UTM
2. shear test attachment
3. vernier calipers
formula:
double shear strength : shear load / 2 X area of C.S.
machine details:
name of the machine : universal testing machine
model : UTK 40
type : vertical
range available : 4, 10, 20 & 40 tones.
Load application : hydraulic
Load measurement : pendulum type dynamometer
Details about the attachment:
1. it is having the parts of die set & die set holder.
2. the dies are different diameter.
3. it is made of high carbon steel & the steel holder is made of mild steel with
hardened surface.
Procedure:
1. initial adjustment: before testing, adjust the pendulum weight according to the
capacity of test. Adjust corresponding range on the dial with adjusting knob.
2. measure the specimen diameter of the rod using the vernier caliper.
3. then using the mean diameter, the area cross section of the specimen is
calculated.
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4. the specimen is fixed on the die set exactly then it is placed in between and the
bottom table of the UTM.
5. the machine is operated and the load is given to the specimen.
6. when the specimen breaks, the black pointer will return to zero. We have to take
the value the red point reaches.
7. take the readings in kgf, convert to Newton and apply it in the formula.
Tabulation:
S. No. Load N C.S area of the
specimen mm2
Double shear
strength N/mm2
Observation:
Diameter of specimen (d) :
Load when specimen breaks:
Crosssectional area ( A): d2
/ 4 =
Calculation:
Result:
Thus the shear strength of the given specimen was found.