flexural analysis of carbon and e-glass reinforced … · properties of a hybrid composite not only...

$: FLEXURAL ANALYSIS OF CARBON AND E-GLASS REINFORCED … · properties of a hybrid composite not only depends on the volume fraction of each constituent, but it also depends on the$
FLEXURAL ANALYSIS OF CARBONAND E-GLASS REINFORCED

HYBRID COMPOSITES

1Eswara Kumar A, 2Ch. Yatish Chandra,3V. Sai Sumanth, 4V. Gopi Sai,

5K. Yaswanth1,2,3,4,5Koneru Lakshmaiah Education Foundation,

Vaddeswaram, Guntur [email protected]

June 14, 2018

Abstract

The fiber reinforced composites have been widely usedfor many applications such as carbon, glass fibers inaerospace applications and sport applications because oftheir higher strength to weight ratio. The properties of thecomposite materials will depend on its constituentmaterials. Flexural strength and flexural modulus werevery important in fields like sports, especially bad Mintonrackets. In the present work, carbon (AS 4/3501-6) andE-glass hybrid composite was fabricated as per ASTMD3801, ASTM D3774 and ASTM D1777. This hybridcomposite consists of five layers each layer havingthickness of 0.5mm. These five layers were stacked indifferent sequences. The sequences considered in thepresent study were [0/45/0/-45/90] and [45/90/0/90/-45].Flexural test was conducted as per standard ASTMD7264. Flexural strength, flexural modulus and flexuralstrain was calculated. It was observed that[0/45/0/-45/90] having high flexural strength, flexuralmodulus than [45/90/0/90/-45].

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International Journal of Pure and Applied MathematicsVolume 120 No. 6 2018, 7235-7247ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

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Keywords:Hybrid Composite, Carbon Epoxy, E-GlassEpoxy, Flexural Strength, Tangent Modulus

1 INTRODUCTION

Composite materials are tailored to get different better propertiesthan parent material. Hybrid composite is one such type ofcomposite tailored to get required properties. In macro level,hybrid composite consists of more than one lamina with differentmaterials. These laminas can be placed in different sequences.The properties of the material will also depend on the layupsequence. Flexural test is used to find the flexural strength andflexural modulus of the material. Three-point and four-point testsare two flexural testing methods. In a three-point bending test,specimen is placed horizontally over the two points by makingthem as a base or support and the force is applied at the top ofspecimen through single point then due to applied force specimenwill bent into shape of V. Where as in four-point bending testsupport to the specimen will be same as three-point bending test,here force is applied on specimen with two points instead of onepoint, then the specimen will have bent in the shape of U

K. K. Singh et al [1] fabricated the composite which contains 8layers of glass fiber epoxy, on which flexural tests were performedaccording to standard ASTM D790 and results are validated usingAnsys. The results state that the for unfilled glass fiber reinforcedpolymer, the flexural strength is found to be 227.74Mpa.Cusps/hackles have been observed on the fracture. Rajesh KumarPrusty et. Al. [2] Inter ply fiber hybridization improves themechanical properties of laminated fiber reinforced hybridcomposites. Glass epoxy and carbon epoxy hybrid compositesstates that carbon epoxy piles at tension side leads to increase instrength and flexural modulus. Results state that the flexuralproperties of a hybrid composite not only depends on the volumefraction of each constituent, but it also depends on the stackingsequence. Vinay h. b et al [3] Progressive failure process ofKevlar/carbon fiber with vinyl ester resin and Glass/carbon withvinyl ester resin hybrid laminated composite subjected to tensileload and flexural load and hardness tests is also performed on

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hybrid composites. Farid Bajuri et al [4] when silica nanoparticles are infused with epoxy resin, the results state that theflexural strength is decreased. 2vol% hydrophobic silicananoparticles decrease the flexural properties and compressiveproperties. Chensong Dong et al [5] Robustness for hybridcomposite T700Scarbon fiber and S-2 glass fiber is subjected toflexural loading. Flexural strengths of various stacking sequencesare computed using Classical laminate theory and regressionmodel and the concept of robustness is introduced to address boththe strength and robustness criteria.

2 TEST PROCEDURE

Carbon epoxy lamina of thickness 0.5mm and E-glass epoxy laminaof thickness 0.5mm were laid up alternatively to form sequence0/45/0/-45/90 and 45/90/0/90/-45 starting with carbon followedby E-glass. Test methods ASTM D3801, ASTM D3774 and ASTMD1777 are followed for Areal width, Width and dry fabric thicknessrespectively. Weight ratio of 60% was maintained throughout thecomposite. Laminate was prepared with vacuum molding process.

Figure 1: Specimen Dimensions

6 specimens were fabricated for each layup sequence andtested as per ASTM D7264. The dimensions of the specimenswere 48mm13mm2.5mm. Three-point bending/flexural test waschosen to find the properties. The span length of the specimen is40mm. 10% overhang was given on both sides. Stroke is appliedat a constant rate of 1mm/min. and results are plotted andcalculations are done theoretically.

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Figure 2: Specimen

Figure 3: Specimen Mounting

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3 RESULTS & DISCUSSIONS

Sequence 1: 0/45/0/-45/90, Sequence 2: 45/90/0/90/-45.Flexural Peak Stress: It is the maximum stress at which thespecimen breaks. It is also called as flexural strength. Fig 4 showsthe flexural strength/flexural peak stress of hybrid composite withdifferent sequence.

Figure 4: Flexural strength/Peak stress

From the Fig 4 it was observed that [0/45/0/-45/90] having highstrength than the second sequence. The sequence-1 has nearly 42%more than the sequence-2.

Stress strain diagram for sequence 0/45/0/-45/90 Stress straindiagram for the sequence 45/90/0/90/-45

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Figure 5: a, b: Stress -Strain Plot for Sequence -1 & Sequence-2

From the Fig 5a, nearly same type of stress- strain plot wasobserved for specimens considered. From the graphs it wasobserved that, a rise in the stress was observed after the suddenfall in the stress. It may be occurred due to the failure of theweaker lamina first in the hybrid composite. But for thesequence-2, the failure phenomenon is quite different. Eventhough, the material and weight fraction same for the bothsequences, there is huge difference in the properties. This may bedue to different layup sequence. In both sequences, layer 2 & 4 areE-glass composites. From the graphs, failure was occurred due toE-glass composite material. So it is inferred that among the bothsequences considered, the angle 45 played vital role.

Theoretical Calculations:

Maximum Flexural Stress for sequence 1 =(3 × P × L)

(2 × b× h2)

=(3 × 0.302 × (103 × 40)

(2 × 13.60 × 2.6202)= 194.09MPa

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Figure 6: Broken specimen


(2 × b× h2)

=(3 × 0.162 × (103 × 40)

(2 × 13.438 × 2.5622)= 111.1979MPa

Figure 7: Experimental and Theoretical comparison of flexural peakstress

Flexural Modulus: It is also called as bending stiffness. Higherflexural modulus represents high stiffer material. It is taken as slopeof the load vs Deflection curve as shown in the Fig 8.

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Figure 8: Flexural Modulus/ Tangent Modulus

From the Fig 8 it was observed that sequence-1 having moreflexural modulus than the sequence-2. Sequence-1 had nearly 55%more flexural modulus than sequence-2. The flexural modulus ofthe sequence-1 is 18.940 GPa.

From the figure 9a, b, the sequence-1 takes more load to givethe considerable deflection than sequence-2. One of the reason forthis type of the behavior is layup sequence. Another one may bethe weaker part lay-up angle.

Flexural Modulus for sequence 1 =(L3 ×m)

(4 × b× h3)= 18.767Gpa.

Flexural Modulus for sequence 2 =(L3 ×m)

(4 × b× h3)= 8.384Gpa.

Maximum Strain:From Fig 11, As the stress in sequence 1 is greater than stress

in sequence-2, we can observe that the strain in maximum strain insequence-2 is greater than sequence-1 at same proportion.

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Figure 9: a, b: Load vs Deflection curves of Sequence-1 & 2

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Figure 10: Theoretical and experimental comparison

Figure 11: Maximum Strain

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4 CALCULATION

When a beam is simply supported at two points and loaded at themidpoint, the maximum stress at the outer surface at the mid span.The Maximum stress can be calculated as:


(2 × b× h2)

Flexural Strength = Maximum Flexural Stress at peak appliedforce prior to failure, The maximum strain at the outer surface alsooccurs at mid span, and it is calculated as:

MaximumStrain =6 × δ × h

L2.

F lexuralModulus =L3 ×m

4 × b× h3.

5 CONCLUSIONS

From the above observations, it concluded that flexural strength,flexural modulus was high for [0/45/0/-45/90] than[-45/90/0/90/45]. In both sequences weaker composite lamina wasfailed first i.e. E-glass. The layup angle of weaker part plays vitalrole for flexural properties of the hybrid composite.

References

[1] S. K Chaudhary, K. K. Singh, R. Venugopal “Experimentaland numerical analysis of flexural test of unfilled glass fiberreinforced polymer composite laminate” Materials Today:Proceedings 5 (2018) 184-192.

[2] Rajesh Kumar Prusty, Dinesh Kumar Rathore, BhanuPratap Singh, Sarat Chandra Mohanty, Kishore KumarMahato, Bankim Chandra Ray, “Experimental optimization offlexural behavior through inter-ply fiber hybridization in FRPcomposite” Construction and Building materials 118 (2016)327-336.

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[3] Vinay H B, H K Govindaraju Prashanth, “Experimental studyon Mechanical Properties of polymer based hybrid Composite”Materials Today: Proceedings 4(10904-10912).

[4] Farid Bajuri, Norkhairunnisa Mazlan, Mohamad RidzwanIshak, and Junichiro Imatomi,“Flexural and CompressiveProperties of Hybrid Kenaf/Silica Nanoparticles in EpoxyComposite” Procedia Chemistry 19 (2016)955-960.

[5] Chensong Dong, Mehdi Kalantari, Ian J. Davies, “Robustnessfor unidirectional carbon/glass fiber reinforced hybrid epoxycomposites under flexural loading”, Composite Structures128(2015) 354-362.

[6] Bo Hu, Jingfeng Wang, “Experimental investigation andanalysis on flexural behavior of CFSTTC beams”, Thin WalledStructures, 116(2017)277-290

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flexural analysis of carbon and e-glass reinforced … · properties of a hybrid composite not only...

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