2. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
Testing of metals is not a difficult task, being aided by the strain hardening isotropic homogeneous nature
of the material [3]. At its simplest, a piece of stock material can be pulled in a testing machine and fail in its mid
length: locally reducing the cross-section of the test piece can ensure that failure occurs away from the grips. It is
important to understand that, where composite materials are concerned, there are two separate and possibly distinct
aims when carrying out a materials test. The first is to establish fundamental material properties for subsequent use
with structural analysis and design techniques [4]. The second aim is to determine the properties, or investigate the
behavior, of an existing material. This is likely to involve testing material with fibers lying at a number of angles to
the principal loading direction [5]. Natural polymer hybrid composites have become popular due to their ability to
modify the mechanical properties by incorporating the different reinforcements. From literature survey it is clear that
incorporation of natural and synthetic reinforcements, they have positive effect on mechanical properties.
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2. EXPERIMENTAL DETAILS
Fig 1: Hand Lay-up Method
Carbon and jute fiber woven mate is used as a reinforcing material in epoxy composite. K-10 is used as
hardener. Dry hand lay-up technique was employed to fabricate the composites. The release film was placed on the
lower surface of the mould coated with anti adhesive gent. Carbon fiber woven mat is placed on it, on which a
mixture of matrix system (consists of matrix material of epoxy resin plus hardener k-10 was used) is coated with
help of a brush. The stacking procedure was followed: placing of the carbon fiber woven mat one at the bottom
followed by jute and at the top again the carbon fiber thus forming a natural – polymer hybrid composite by coating
with the mixture prepared well on it and covering film was again used to complete the stack. To ensure approximate
thickness of the sample, a spacer was used. At the last again release film coated with anti adhesive agent was kept
and on it another large granite stone was again placed over it to apply enough load on it was also coated with anti
adhesive agent in order to aid the ease of separation on curing. Enough load was ensured and then it was allowed to
cure for a day at room temperature. Test samples according to ASTM D-638 (ASTM STANDARDS) were prepared
from the cured sheet using cut-off machine.
2.1 Tensile Testing
Fig 2: Computerized Universal Testing Machine
Computerized Universal testing machine which uses modern software for material test and analysis is used.
A sophisticated data gathering algorithm might be expected to adjust the rate of data collection in conjunction with
varying rates of change in load or strain, and so on. Most testing machine software is intended to be used in routine
testing and permits automatic calculation of information such as elastic modulus, and statistical analysis of the
results. Stress and strain data are to be taken by the computer software called Nexygen Plus Material test and
analysis, from a printed graph. The Composite materials are usually gripped using some form of ‘friction grip’,
where the load is transferred to the specimen through gripping faces which are roughened with serrations or a cross-cut
pattern. A fine-scale roughening is recommended for use with composites in order to spread the gripping force
over the largest possible area and to minimize damage to the specimen. Parallel clamping grips, positively closed by
manual or hydraulic means, allow the operator to control the gripping force on the specimen. Ideally, this should be
no more than is necessary to grip the material under test until maximum load is reached. The lack of any yielding
3. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
mechanism in composites means that even small misalignments, and the resultant bending, may result in large local
stresses, so that accuracy of alignment is important if reliable results are to be obtained. The strain measurement
technique is normally done by the use of extensometer. To avoid damaging the extensometer it should be removed,
or released from the specimen, prior to failure, as the sudden, almost explosive, release of the large amount of elastic
energy stored by composites specimens can easily wreck even the most robust extensometer. After measurement and
inspection, the specimen can be mounted in the grips. The centre line of the specimen should be aligned with the axis
of the testing machine so as to eliminate Bending and asymmetric loading. An extensometer is being used, this
should be attached to the centre of the specimen and the initial gauge length measured. A small preload may be
applied to the specimen before the extensometer is attached. Adequate guards should be placed round the specimen,
or test machine, if there is any possibility of an explosive failure. Start the machine, slowly the specimen is
uniformly loaded. The loading is done on the specimen until it breaks and finally the computer will record the
necessary data. Automatically the stress– strain graph is generated which includes all the features likely to be found
in a loading curve, including evidence of changes in stiffness, progressive failure and so on.
Fig 3: Specimens before and after failure
Table 1: Tensile properties of 0° orientation
53
Sl. No Maxi. Load
in N
Stress at
Maxi. Load
in MPa
Young’s Modulus
in MPa
1
3896.69 87.68 7086.49
Table 2: Tensile properties of 30° orientation
Sl. No Maxi. Load
in N
Stress at
Maxi. Load
in MPa
Young’s Modulus
in MPa
1
3179.57 71.55 6585.02
Table 3: Tensile properties of 45° orientation
Sl. No Maxi. Load
in N
Stress at
Maxi. Load
in MPa
Young’s Modulus
in MPa
1
3626.02 81.59 5753.83
4. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
54
3. RESULTS AND DISCUSSION
The tensile strength of carbon and jute fiber reinforced with epoxy composite is found to be 87.68 MPa for
0° orientation. The variation of the tensile strength of the hybrid composite is not much influenced by varying the
fiber orientation. Fig 4, 5 & 6. Shows the stress Vs strain plot obtained under tensile loading for carbon and jute fiber
reinforced – epoxy composite with 0°, 30° & 45° orientations. For 0° orientation, it exhibited better result, then the
remaining. The composite with orientations of 30° and 45° showed the decreased tensile strength. It was observed
that the lowest values of tensile strength were seen with 30° and 45° orientation in carbon and jute fibers reinforced
– epoxy composite shown in Fig 5 and 6 respectively. From the tables 1, 2 & 3 for different orientation with carbon
and jute fiber – epoxy composite, therefore for 0° orientation young’s modulus for composite showed optimal value.
Fig 4: Stress Vs Strain for 0° orientation Fig 5: Stress Vs Strain for 30° orientation
Fig 6: Stress Vs Strain for 45° orientation
Fig 7: Comparison of Ultimate Tensile Stress
From the fig 7, it indicates the comparative result of ultimate tensile stress of the developed hybrid
composite. For 0° orientation, the ultimate tensile stress high when compared with 30° and 45° orientations.
5. Proceedings of the 2nd International Conference on Current Trends in Engineering and Management ICCTEM -2014
17 – 19, July 2014, Mysore, Karnataka, India
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4. FEA ANALYSIS
Finite Elemental analysis is carried out to investigate the various parameter of Natural – polymer hybrid
composite material. For the tested specimen of 0° orientation, the von misses’ stresses developed in the natural
polymer hybrid composite is analyzed, its values indicate 99.79 MPa as a matching value with the results obtained
from the tested once as shown in the fig 8.
Fig 8: Contour plot of Von-mises stress for 00orientation
5. CONCLUSIONS
The Natural – polymer hybrid composite consists of carbon and jute fiber reinforced with epoxy composite
have been experimentally evaluated and studied for varying orientation and the same is analyzed using Ansys
software and the following conclusions were drawn:
• The hybrid composite consisting of carbon – jute fiber reinforced with epoxy composite for 0° orientation
showed a better tensile strength and can withstand the strength of 87.68 MPa.
• Generally composite materials, particularly if they contain a large proportion of 0° fibers, have substantially
linear stress–strain characteristics but it is not uncommon for the curve to show Nonlinearities at the start of
the test.
• Tensile test results of hybrid composite with 0° orientation showed a better tensile strength, compared to 30°
and 45°.
• It can be seen that there is only a marginal decrease in maximum stress when compared with 30° & 45°
orientation.
• Finally the natural – polymer hybrid composite with 0° orientation resulted in optimal.
• By the data obtained from the result of analysis, which is carried out by ansys software. For 0° orientation the
stresses developed is 99.79 MPa, which is 12.11% is more the experimental result. This shows that the values
are closing to each other and resulted in optimality.
6. REFERENCES
[1] ASTM D3039M,”Standard test method for tensile properties of polymer matrix composite materials”,
American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428,
USA,Vol 15.03, 1997.
[2] S T Burr, P G Ifju and D H Morris, “A method for determining critical strain gage size in anisotropic
materials with large repeating unit cells”, Experimental Techniques, September/October, 25–27, 1995.
[3] Xinran Xiao, “Dynamic tensile testing of plastic materials”, General Motors Corporation, MC 480-106- 710,
30500 Mound Road, Warren, MI 4800-055, USA Received 1 August 2007; accepted 15 September 2007.
[4] L J Hart-Smith, “Generation of higher composite material allowable using improved test coupons”,
36th International SAMPE Symposium, 1991.
[5] Takeda, N.; Wan, L. “In High Strain Rate Effects on Polymer, Metal and Ceramic Matrix Composites and
Other Advanced Materials”, ASME Vol. 48, pp. 109–113.1995.
[6] ASTM Hand Book for testing of advanced composite materials.
[7] Prashanth Banakar1, H.K. Shivananda “Preparation and Characterization of the Carbon Fiber Reinforced
Epoxy Resin Composites” ISSN: 2278-1684 Volume 1, Issue 2, PP 15-18, May-June 2012.