Investigation Into the Effects of Process Parameters on Delamination-2

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International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976

6340(Print), ISSN 0976 6359(Online) Volume 4, Issue 3, May - June (2013) IAEME

136

INVESTIGATION INTO THE EFFECTS OF PROCESS PARAMETERS

ON DELAMINATION DURING DRILLING OF BD-CFRP COMPOSITE

USING TAGUCHI DESIGN OF EXPERIMENTS AND RESPONSE

SURFACE METHODOLOGY

Nagaraja*1, Mervin A Herbert

1, Divakara Shetty

2,

Raviraj Shetty2

and Murthy BRN2

*1(Corresponding Author: Department of Mechanical Engineering, National Institute of

Technology Karnataka, Srinivasa Nagar, Surathkal, Mangalore-575025, India)2(Department of Mechanical and Manufacturing Engineering, Manipal Institute of

Technology, Manipal University, Manipal-576 104, Karnataka, India)

ABSTRACT

Delamination is an inter-ply failure phenomenon induced by drilling and has been

recognized as a major damage encountered when drilling composite laminates. The damage

caused at the entry and exit of the drilled hole is characterized by delamination factor. In this

study, the effects of process parameters such as spindle speed, feed rate, drill diameter and

point angle on delamination during drilling of bidirectional carbon fiber reinforced polymer

(BD-CFRP) composite laminate have been investigated by using Taguchi design of

experiments (DOE). The results obtained are analyzed and validated using response surface

methodology (RSM) and analyses of variance (ANOVA). The study reveals that drill

diameter and spindle speed are the main contributing process parameters for the variation in

the drilling induced delamination of BD-CFRP composite laminate. It is evident from theinvestigation that feed rate and point angle are least sensitive to the drilling induced

delamination of BD-CFRP in high speed steel drills. The study shows that both experimental

and the predicted results of delamination factor are in good agreement.

Keywords: Drilling, delamination, feed rate, thrust force, torque, high speed steel,

bidirectional carbon fiber reinforced polymer composite.

INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING

AND TECHNOLOGY (IJMET)

ISSN 0976 6340 (Print)

ISSN 0976 6359 (Online)

Volume 4, Issue 3, May - June (2013), pp. 136-148

IAEME:www.iaeme.com/ijmet.aspJournal Impact Factor (2013): 5.7731 (Calculated by GISI)

www.jifactor.com

IJMET I A E M E


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1. INTRODUCTIONCarbon fiber-reinforced polymer (CFRP) composites are well recognized for their

superior mechanical properties such as low weight, high strength and stiffness, excellentfatigue and corrosion resistance and low thermal expansion [1]. CFRP composite laminates

find wide applications in aerospace industries, defense, ships, automobiles, machine tools,

sports equipments, transportation structures, power generation, and oil and gas industries [1,

2]. Composite materials are synergistic combination of two or more micro-constituents that

differ in physical form and chemical composition. The objective of having two or more

constituents is to get the benefit of superior properties of all the constituents without

compromising on weakness of either [3]. Although CFRP composites are produced to near-

net shape, machining is often needed to fulfill the requirements related to tolerances of

assembly needs. Among all machining processes, drilling is the most indispensable method

for fabrication of products with composite panels. The performance of these products is

mainly dependent on surface quality and dimensional accuracy of the drilled hole. The

quality of drilled hole is influenced by the cutting conditions, tool material and geometry[4].The material anisotropy resulting from fiber reinforcement considerably influences the

quality of the drilled hole. Hence, precise machining needs to be performed to ensure the

dimensional stability and interface quality [5].

The quality of the drilled hole is also influenced by the thrust force and torque

generated during drilling, which in turn is affected by the factors such as tool geometry,

speed, feed etc. Higher the value of thrust force and torque higher will be the structural

damage and tool wear. Therefore, many researchers have attempted to minimize the

generation of the thrust force and torque by designing different types of drilling tools [6]. The

drilling operation of CFRP composites has several undesirable effects such as fiber breakage,

de-bonding, pull-out, stress concentration, thermal damage, micro cracking, delamination etc.

[7, 8, 9]. Among the problems caused by drilling, delamination occurs mainly due to

localized bending in the zone situated at the point of attack of the drill. The delaminationdrastically reduces assembly tolerance and strength against fatigue, thus degrading the long-

term performance of composites [10, 11]. In practice, it has been found that the delamination

associated with push-out is more severe than that associated with peel-up [12]. Hence most of

the researchers paid attention to the push-out delamination. Several investigators have studied

analytically and experimentally the cases in which delamination in drilling have been

correlated to the thrust force during exit of the drill. The higher thrust force induces more

extensive delamination to the work piece [13].It was reported that the rejection of parts due to

delamination damage during the final assembly was as high as 60% in aircraft industries

[14].Chen proposed delamination factor to characterize the delamination in drilling of CFRP

composite [10].

It is observed that there is very little work that has been reported on the influence of

process parameters on delamination during drilling of BD-CFRP composite laminate withHSS drills, using Taguchis DOE, ANOVA and RSM. Hence, an attempt has been made in

this work for optimization of process parameters such as spindle speed, feed rate, drill

diameter and point angle on delamination in drilling of BD-CFRP composite through

integration of Taguchis design of experiments and RSM based mathematical model.


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2. MATERIALS AND METHODS

2.1. Preparation of Test Specimen

The BD-CFRP composite specimen of 200 mm 200 mm 4 mm was fabricated byhand lay-up followed by compression moulding technique at room temperature. The resin

content of the composite laminate is maintained around 50 weight % and post curing of the

composite laminate is carried out for about 8 hours at 80C. Bidirectional plain weave type

carbon fiber of arial density of 200 g.m-2

is used as reinforcement.

Figure 1 BD-CFRP composite specimen.

The resin used for the preparation of composite material is Bisphenol A based epoxy

resin L-12 and the hardener used is Amino K-6. The advantage of using BD-CFRP composite

laminate is that it has maximum stiffness and strength in all direction. The scanned image of

the test specimen is shown in Figure 1.

2.2. Experimental MethodA Matsuzawa micro-hardness testing machine (Model No MMT-X7A, Japan) is used

for measuring Vickers hardness of the BD-CFRP composite specimen. Tensile strength of the

specimen is measured as per ASTM: D 638, using a Universal Testing Machine (Lloyd

LR100 K, UK).

Figure 2 Experimental set up


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The three point bending technique is used for measuring the flexural properties of the

test specimen as per ASTM: D 790-10. The inter-laminar shear strength (ILSS) is

investigated according to ASTM: D 2344 (short beam shear test method) by Universal

Testing Machine (Instron 3366). The displacement method is used for measuring the densityof the composite specimen as per ASTM: D 792-08, using an electronic balance (Mettler

Toledo USA). The drilling experiments on BD-CFRP composite specimen are carried out

using CNC vertical (TRIAC VMC) machining centre as shown in figure 2.

The thrust force generated during drilling of BD-CFRP composite is measured by

9257BA KISTLER dynamometer. The mechanical properties of the BD-CFRP composite

laminate are given in Table 1.

Table 1 Mechanical Properties of BD-CFRP CompositeDensity

(g.cm-3

)

Vickers

hardness

Tensile

strength(MPa)

Youngs

modulus(GPa)

Elongation

(%)

Flexural

strength(MPa)

Flexural

modulus(MPa)

Inter-laminar

Shearstrength(MPa)

1.302 18.2 427.46 5.9 13.32 109.35 861.19130 20

Delamination factor (Fd) of the BD-CFRP composite laminate is estimated by using the

equation:

Fd = Dmax/Dnom (1)

where, Dmax is the maximum delaminated diameter and Dnom is the nominal diameter of the

drilled hole.

3. DESIGN OF EXPERIMENT

3.1. Taguchi Method

The traditional method of experimentation, i.e. varying one parameter at a time and

studying its effects is considered expensive and time consuming. Hence, the design of

experiments (DOE) technique has been selected which requires minimum number of

experiments to be conducted. Taguchis robust DOE is used to formulate the experimental

layout, analyze the effect of each cutting parameters and optimize the process parameters

which are least sensitive to the causes of variation.Taguchis approach to design of

experiments is easy to adopt and apply for users with limited knowledge of statistics; hence it

has gained a wide popularity in the engineering and scientific community [15].

Taguchi recommends analyzing the means and S/N ratio using conceptual approach

that involves graphing the effects and visually identifying the factors that appear to be

significant, without using ANOVA, thus making the analysis simple. The analysis is madeusing the popular software specially used for design of experiment applications known as

MINITAB 15. The S/N ratio characteristics can be divided into three categories:

Nominal is the best characteristic2

10logy

S y

N s=

(2)


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Smaller is the best characteristic ( )21

10logS

yN n

= (3)

Larger is the better characteristic2

1 1logS

N n y = (4)

Where,y the average of observed data, 2ys

is the variation of y, n is the number of

observations, andy is the observed data. For each type of the characteristics, with the above

S/N ratio transformation, the smaller the S/N ratio the better is the result when we consider

delamination factor, surface roughness, thrust force, torque and stress [16]. In this work, in

order to identify the best cutting parameters and to obtain minimum delamination, S/N ratio

characteristic andL27 orthogonal array are used. Table 2 indicates drilling test parameters and

levels.

Table 2 Level and Factors

Levels

(A)

Spindle Speed

(rpm)

(B)

Feed rate

(mm/min)

(C)

Point angle

(degree)

(D)

Drill diameter

(mm)

1 1200 10 90 4

2 1500 15 104 6

3 1800 20 118 8

3.2. Response Surface Methodology

Response surface methodology (RMS) is a collection of mathematical and statistical

techniques that are useful for modeling and analyzing problems in which a response ofinterest is influenced by several variables. The main goal of RSM is to optimize the response

that is influenced by various process parameters [17]. In this study, central composite design

is used to develop empirical relationships between the drilling parameters. Central composite

design is one of the important design methods used in RSM for establishing relationship

between the parameters and responses by using the smallest possible number of experiments

without losing accuracy. The number of experiments conducted in the present case is 30 and

the number of drilling parameter considered is 4.The second degree response surface

representing the delamination factor (Fd) can be expressed as follows:

Fd = 0 + 1(A)+2(B)+ 3(C)+ 4(D)+ 5(A2)+ 6(B

2)+ 7(C

2)+ 8(D

2)+

9(AB)+10(AC)+ 11(AD)+ 12(BC)+13(BD)+ 14(CD) (5)

From the observed data for delamination factor (Fd), the response function is given as

follows:

Fd= 0.156332 + 0.000558847A + 0.0125514B + 0.00446767C + 0.0737923D 2.02189E-

07A

2 1.47879E

-04B

2 2.39641E

-05C

2 0.00367424D

21.08333E

-06AB + 4.76190E

-07AC

9.16667E-06

AD 1.96429E-05

BC 4.37500E-04

BD + 6.25000E-05

CD (6)


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4. RESULTS AND DISCUSSION

Delamination in drilling is a highly undesirable problem and has been recognized as a

major defect encountered in drilling operation. Delamination not only reduces assemblytolerance, but also weakens the structural integrity of the composite materials. To have a

better surface finish of the drilled holes, it is necessary to control the influence of process

parameters such as spindle speed, tool feed rate, drill diameter and the point angle on

delamination during drilling in industry. In this study, the drilling experiments are conducted

at different cutting conditions using HSS drills and the results of delamination factor of BD-

CFRP composite laminate are shown in Table 3.

Table 3 Experimental and predicted results of delamination factor

Trial

No.

Spindle

speed(rpm)

Feed rate

(mm/min)

Point

angle(degree)

Drill

diameter(mm)

Experimental

Delamination

factor (Fd)

Predicted

Delamination

factor (Fd)

Error

(%)

1 1200 10 90 4 1.059 1.072 1.22

2 1200 10 90 6 1.132 1.127 0.44

3 1200 10 90 8 1.155 1.152 0.25

4 1200 15 104 4 1.102 1.097 0.45

5 1200 15 104 6 1.15 1.149 0.08

6 1200 15 104 8 1.168 1.172 0.34

7 1200 20 118 4 1.1 1.103 0.27

8 1200 20 118 6 1.156 1.152 0.34

9 1200 20 118 8 1.165 1.172 0.6

10 1500 10 104 4 1.074 1.083 0.83

11 1500 10 104 6 1.136 1.134 0.17

12 1500 10 104 8 1.149 1.155 0.52

13 1500 15 118 4 1.084 1.097 1.19

14 1500 15 118 6 1.147 1.146 0.08

15 1500 15 118 8 1.159 1.165 0.51

16 1500 20 90 4 1.107 1.104 0.27

17 1500 20 90 6 1.148 1.145 0.26

18 1500 20 90 8 1.152 1.156 0.34

19 1800 10 118 4 1.04 1.052 1.15

20 1800 10 118 6 1.104 1.099 0.45

21 1800 10 118 8 1.118 1.117 0.08

22 1800 15 90 4 1.065 1.058 0.65

23 1800 15 90 6 1.095 1.097 0.18

24 1800 15 90 8 1.115 1.107 0.71

25 1800 20 104 4 1.068 1.075 0.65

26 1800 20 104 6 1.11 1.111 0.09

27 1800 20 104 8 1.113 1.118 0.44

The main effect plots for Signal to Noise ratio (S/N) of delamination factor (smaller is

the better) is shown in figure 3.It is observed from the plots that the drill diameter and the

spindle speed are the most significant design parameters that influence the delamination as

the slope of these plots are large and variation of S/N ratio is also large. The feed rate and

point angle are the least contributing process parameters for push down delamination as the

slope gradient is smaller.


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Figure 3 Main effect plots for SN ratios of delamination factor

Figure 4 Delamination damage in drilling ofBD-CFRP composite laminate for drill diameter

of 6 mm, spindle speed of 1800 rpm, feed rate of 15 mm/min and point angle of 90

It is evident from the main effect plots of delamination factor (figure 3) that the

optimum parametric conditions for minimum push down delamination in drilling of BD-CFRP composite are obtained for drill diameter of 4 mm, feed rate of 10 mm/min, spindle

speed of 1800 rpm , and point angle of 90. Since the point angle does not have significant

influence on delamination, it can be set at the convenient value to get better surface

finish.The response table 4 for S/N ratio of delamination factor also indicates that drill

diameter is the dominant factor which influences the delamination in drilling of BD-CFRP

composite laminate followed by spindle speed. The figure 4 shows the image of drilling

induced delamination obtained by using HP high resolution scanner (4800dpi).


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Table 4 Responses for S/N ratio (smaller is the better) of delamination factor

LevelSpindle Speed

(rpm)

Feed rate

(mm/min)

Point angle

(degree)

Drill diameter

(mm)

1 -1.0718 -0.8810 -0.9353 -0.6480

2 -1.0465 -0.9845 -0.9720 -1.0669

3 -0.7619 -1.0147 -0.9729 -1.1654

Delta 0.3099 0.1336 0.0375 0.5174

Rank 2 3 4 1

Table 5 Analysis of variance for S/N ratios of delamination factor (Fd)

The analysis of variance (ANOVA) for S/N ratio of delamination factor is carried out

for a significance level of = 0.05, i.e. for a confidence level of 95%.The P values in the

ANOVA table 5 is the realized significance levels , associated with Fischers F test for each

source of variation. The sources with P values less than 0.05 are considered to have

statistically significant contribution to the performance measures. It can be seen from Table 5

that drill diameter has the highest contribution (P = 66.96%), followed by spindle speed (P =

26.27%). The interaction effects of process parameters on delamination factor during drilling

of BD-CFRP composite have no statistical and physical significance as shown in the

Table 5.The investigation reveals that ANOVA results of delamination are in good agreement

with the conceptual S/N ratio approach used for data analyses.

Source DF Seq SS Adj SS Adj MS F P P (%)

( A) Spindle

Speed(rpm)2 0.53293 0.53293 0.266467 80.05 0.000 26.270

(B) Feed

rate(mm/min)2 0.08843 0.08843 0.044214 13.28 0.006 4.358

(C) Point

angle(degree)2 0.00827 0.00827 0.004134 1.24 0.354 0.406

(D)Drill

diameter(mm)

2 1.35843 1.35843 0.679213 204.04 0.000 66.962

A*D 4 0.01410 0.01410 0.003526 1.06 0.451 0.347

B*D 4 0.05636 0.05636 0.014090 4.23 0.058 1.388

C*D 4 0.01075 0.01075 0.002688 0.81 0.563 0.265

Residual Error 6 0.01997 0.01997 0.003329

Total 26 2.08924 100


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The observed results of drilling induced delamination of BD-CFRP composite for

HSS drills, obtained from Taguchi DOE are validated and analyzed by using RMS model

(Eqn.6). It is evident from the Table 3 that the error between the experimental and the

predicted results of delamination factor is less than 2.5%, indicating that there is a goodagreement between the observed results of delamination factor and the predicted results of

delamination factor as per RSM model. The results obtained from Taguchi DOE can also be

verified by drawing a comparison plot as shown in figure 5. The figure indicates a very close

relationship between the experimental results and predicted results of delamination factor.

Figure 5 Comparison of experimental and predicted values of delamination factor.

The adequacy of RSM model has been tested through ANOVA method at 5%

significance level, i.e., for a level of confidence of 95% [17]. Result of ANOVA for the

response function delamination factor (Fd) is presented in Table 6. The sum of squares is

usually performed into contributions from regression model and residual error. Mean squareis the ratio of sum of squares to the degrees of freedom and F-ratio is the ratio of mean square

of regression model to the mean square of residual error. From the analysis of Table 5, it is

apparent that, the calculated value of F-ratio of the developed model (26.38) is greater than

the F-table value (F 0.05, 14, 15 =2.46) and hence the second degree response function model

developed is quiet adequate.

The delamination tendency of BD-CFRP composite laminate is analyzed by

generating 3D response surface plots and the corresponding contour plots. Figure 6 shows the

interaction effects of feed rate and the spindle speed on delamination factor with drill

diameter (8 mm) and point angle (118) are held constant.

Table 6 ANOVA for response function of the delamination factor (Fd)

Source DF Seq SS Adj MS F P

Regression 14 0.034670 0.002476 26.38 0.000

Residual Error 15 0.001314 0.000094

Total 29 0.035984


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(a) (b)

Figure 6 Interaction effects of feed rate and spindle speed on delamination factor for drill

diameter of 8 mm and point angle of118 (a) Response surface plot (b) Contour plot

It is observed from the response surface plot of figure 6(a) that the increase of feed

rate increases the drilling induced delamination due to the increase of thrust force in drilling

[18]. From the contour plot of figure 6(b), it is clear that with feed rate kept at low value,

minimum delamination can be achieved with higher spindle speed during drilling of BD-

CFRP composite laminate using HSS drills. This is due to the reason that the increase in

spindle speed increases the temperature produced in drilling of composites, which softens the

matrix material and shearing, intern the delamination is reduced. The result presented is

correlated with the result presented by Palanikumar et al [19].Figure 7(a & b) illustrates the interaction effect of feed rate and drill diameter on

delamination with spindle speed (1800 rpm) and point angle (118) are held constant. It is

evident from the figures that increase in drill diameter increases the delamination damage

during drilling of composite materials. The reason is that the increase of drill diameter

increases the contact area of the hole produced which increases the thrust force during

drilling of composites.The increase in thrust force leads to the increase of drilling induced

delamination [20, 21]. The results reveal that the increase in feed rate and drill diameter

increases the delamination factor and vice-versa. The influence of drill diameter and point

angle on delamination with feed rate (20 mm/min) and spindle speed (1800 rpm) are held

constant as illustrated in figure 8 (a & b).

It is noticed from the figure that the minimum delamination in drilling of BD-CFRP

composite is observed at lower drill diameter and minimum point angle. It is also noticedfrom the figure 8 that the delamination factor of BD-CFRP composite is least sensitive to the

variation in point angle.From the analyses of the figures, it is concluded that the maximum

spindle speed, minimum drill diameter, minimum feed rate and minimum point angle are

preferred to reduce the drilling induced delamination of BD-CFRP composite laminate.


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(a) (b)

Figure 7 Interaction effects of feed rate and drill diameter on delamination factor for spindle

speed of 1800 rpm and point angle 118 (a) Contour plot (b) Response surface plot

(a) (b)

Figure 8 Interaction effects of point angle and drill diameter on delamination factor for feed

rate of 20 mm/min and spindle speed of 1800 rpm (a) Contour plot (b) Response surface plot

5. CONCLUSIONS

Based on the experimental results, the following conclusions can be drawn in drillingof BD-CFRP composite laminate using HSS drills:

1. The model generated by means of the design software (MINITAB 15) package showsthe influence of the process parameters on delamination.

2. The results reveal that the drill diameter is the most influencing design parameter ondelamination followed by spindle speed.

3. The interaction plots reveal that the minimum delamination damage is obtained athigher spindle speed, lower drill diameter and lower feed rate.


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4. The investigation reveals that there is a perfect correlation between the experimentalresults of delamination factor and the predicted results of delamination factor as per

RMS.

5.

The results show that the drilling induced delamination is not influenced the variationin point angle.

6. The results of ANOVA for S/N ratio for delamination factor are in good agreementwith the responses obtained from S/N ratio of Taguchi analysis.

6. ACKNOWLEDGEMENTS

The authors are very grateful to the department of Mechanical Engineering, Manipal

Institute of Technology, Manipal University, Manipal for the support rendered for conducting

the drilling experiments.

7. REFERENCES

[1] Guu Y.H., Hocheng H, Tai N and Liu S.Y, Effect of electric discharge machining on

the characteristics of carbon fiber reinforced composites, Journal of Material Science 36,

2011, pp 2037-2043.

[2] Arul S, Vijayaraghavan L, Malhotra S.K, Krishnamurthy R, The effect of vibration

drilling on hole quality in polymeric composites, Int. J. Mach. Tools Manuf. 46, 2006, pp

252-259.

[3] Mohan N.S, Ramachandra A, Kulkarni S.M, Influence of process parameters on

cutting force and torque during drilling of glass-fiber polyester reinforced composites,

Compos. Structure, 71, 2005, pp 407-413.

[4] Murthy B. R. N, Lewlyn L. R Rodrigues, and Anjaiah Devineni, Process parameters

optimization in GFRP drilling through integration of Taguchi and response surface

methodology, Vol.1(6), 2012, pp 7-15.[5] Mohan N. S., Kulkarni S. M. and Ramachandra A, Optimization of process

parameters during drilling of Glass-Fiber-polyester reinforced composite using DOE and

ANOVA, IIUM Journal, 7, 2006, pp 13-21.

[6] Friedrich M. O.,Burant R. O, and Mc.Ginty M. J, Cutting tools/drills: part 5-point

styles and applications, Journal of Manufacturing, Engineering 83, 1979, pp 29-31.

[7] Mishra R, Malik J, Singh I, Devim J.P., Neural network approach for estimate the

residual tensile strength after drilling in uni-directional glass fiber reinforced plastic

laminates, Mater Des 31, 2010, pp 2790-2795.

[8] Wern C.W, Ramulu M, Shukla A, Investigation of stresses in the orthogonal cutting

of fiber-reinforced plastics, ExpMech, 1994, pp 33-41.

[9] Rao GVG, Mahajan P, Bhatnagar N, Micro-mechanical modeling of machining of

FRP composites cutting force analysis, Compos. Sci. Technol, 67, 2007, pp 573-579.[10] Chen W, Some experimental investigations in the drilling of carbon fiber-reinforced

plastics (CFRP) composite laminates, Int. J. Machine Tools Manuf. 37, 1997, pp 1097-1108.

[11] Won M.S, Dharan C. K. H, Drilling of aramid and carbon fiber polymer composites,

J. Manuf. Sci. Engg. ASME 124, 2002, pp 778-783.

[12] Khashaba U. A, Delamination in drilling GFRThermoset composites structure, 63,

2004, pp 313-327.


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148

[13] Hockeng H and Tsao C.C., Comprehensive analysis of delamination in drilling of

composite materials with various drill bits, J. Materials Processing Technology, 140, 2003,

pp 335-339.

[14] Wong T. L, Wu S.M, Croy G. M., An analysis of delamination in drilling compositematerials, Proceedings of 14th

SAMPE Technology Conference, Atlanta, GA, USA, 1982, pp

471-483.

[15] Montgomery, D.C, Design and Analysis of Experiments (John Wiley and Sons, New

York, 2005).

[16] Phadke M.S, Quality Engineering Using robust Design (Prentice Hall,

Englewood,Cliffs,NJ, 1989).

[17] Myers, R.H,Montgomery D.C, Response Surface Methodology, Process product

Optimization Using Designed Experiments (John Wiley and Sons, New York, 1995).

[18] Palanikumar K, Prakash S and Shanmugan K, Evaluation of delamination in drilling

GFRP composites, Mater Manuf. Process 8, 2008, 858-64.

[19] Palanikumar K, Latha B, Senthilkumar V and Paulo Davim, Analyses of drilling of

GFRP composites using grey relational analyses, 27, 2012, 297-305.[20] Rajamurugan T. V, Application of Acoustic Emission for the Evaluation of

Delamination in Drilling of GFRP Composites, Proc. of the International Conference: In

Smart Technologies for Materials, Communications, Controls, Computing and Energy,

Chennai, India, 2011.

[21] Palanikumar K, Experimental Investigation and Optimisation in Drilling of GFRP

Composites, Measurement 44, 2011, 2138-2148.

[22] Piyush P. Gohil, Vijaykumar Chaudhary and Kundan Patel, Significance of Drilling

Parameters on Delamination Factor in Gfrp: An Image Analysis Approach, International

Journal of Mechanical Engineering & Technology (IJMET), Volume 3, Issue 2, 2012,

pp. 200 - 209, ISSN Print: 0976 6340, ISSN Online: 0976 6359.

[23] P. Govinda Rao, Dr. C L V R S V Prasad, Dr.D.Sreeramulu, Dr.V. Chitti Babu and

M.Vykunta Rao, Determination of Residual Stresses of Welded Joints Prepared under theInfluence of Mechanical Vibrations by Hole Drilling Method and Compared by Finite

Element Analysis, International Journal of Mechanical Engineering & Technology (IJMET),

Volume 4, Issue 2, 2013, pp. 542 - 553, ISSN Print: 0976 6340, ISSN Online: 0976 6359.

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