DOE coupled MLP-ANN for optimization of thrust force and torque during drilling of CCFRP composite laminates

Figures & data

Figure 1. Workpiece specimen (a) Image of coconut coir fiber (b) Image of CCFRP composite laminates (c) Microstructure of CCFRP composite laminates.

Table 1. Mechanical properties coir fiber (Hasan et al., 2021).

Fiber	Density (g/cm^3)	Length (mm)	Failure strain (%)	Tensile strength (MPa)	Stiffness/ Young’s modulus (GA)	Specific tensile strength (MPa/gcm^3)	Specific Young’s modulus (GA/gcm^3)
Coir	1.2	20–50	15–30	131–220	4–6	110–180	3.3–5

Table 2. Properties of epoxy resin and hardener (Hasan et al., 2021).

Epoxy resin LY-556	Hardener HY-951
Visual aspect – Clear, pale yellow liquid Viscosity at 250 °C – 10000-12000 MPa Density at 250 C – 1.15-1.20 gm/cm^3 Flash point – 1950 °C	Density = 0.95 gm/cm^3 Melting point = 120 °C (lit.) Boiling point = 266-267 °C (lit.) Water solubility = Soluble Flash point = 143.33 °C

Table 3. Drilling test parameters and levels.

Levels	(A) Spindle Speed (rpm)	(B) Feed Rate (mm/min)	(C) Point Angle (degree)	(D) Fiber Length (mm)	(E) Fiber Volume (%)	(F) Fiber Diameter (microns)
1	1000	15	90	4	30	4
2	1500	20	104	5	40	7
3	2000	25	118	6	50	10

Figure 2. Schematics of MLP Artificial Neural Network.

Figure 3. Main Effect Plot for Thrust force (N) against (a) Spindle Speed (RPM), (b) Feed Rate (mm/min), (c) Point Angle (Degrees), (d) Fiber Length (mm), (e) Fiber Volume (%), (f) Fiber Diameter (microns).

Figure 4. Main Effect Plot for Torque (N-m) against (a) Spindle Speed (RPM), (b) Feed Rate (mm/min), (c) Point Angle (Degrees), (d) Fiber Length (mm), (e) Fiber Volume (%), (f) Fiber Diameter (microns).

Table 4. Experimental values of Thrust Force (N) and Torque (N-m).

Sl. No	Spindle speed (rpm)	Feed rate (mm/min)	Point angle (degree)	Fiber length (mm)	Fiber volume (%)	Fiber diameter (microns)	Thrust force (N)	Torque (N-m)
1	1000	15	90	4	30	4	28.12	1.56
2	1000	15	90	4	40	7	29.11	1.78
3	1000	15	90	4	50	10	30.13	1.88
4	1000	20	104	5	30	4	28.99	1.99
5	1000	20	104	5	40	7	29.14	2.05
6	1000	20	104	5	50	10	31.23	2.12
7	1000	25	118	6	30	4	29.12	1.77
8	1000	25	118	6	40	7	30.11	1.9
9	1000	25	118	6	50	10	31.03	2
10	1500	15	104	6	30	7	24.65	1.01
11	1500	15	104	6	40	10	25.89	1.1
12	1500	15	104	6	50	4	26.45	1.11
13	1500	20	118	4	30	7	25.23	1.08
14	1500	20	118	4	40	10	27.94	1.11
15	1500	20	118	4	50	4	28.1	1.13
16	1500	25	0	5	30	7	25.9	1.11
17	1500	25	90	5	40	10	26.78	1.18
18	1500	25	90	5	50	4	27.99	1.21
19	2000	15	118	5	30	10	22.12	0.76
20	2000	15	118	5	40	4	23.43	0.81
21	2000	15	118	5	50	7	24.65	0.86
22	2000	20	90	6	30	10	22.98	0.8
23	2000	20	90	6	40	4	23.41	0.89
24	2000	20	90	6	50	7	24.54	0.91
25	2000	25	104	4	30	10	25.34	0.86
26	2000	25	104	4	40	4	26.87	0.9
27	2000	25	104	4	50	7	26.99	0.94

Figure 5. Images of drilled hole under different spindle speeds (a) 1000 rpm (b) 1500 rpm (c) 2000 rpm.

Figure 6. SEM images of drilled hole under different spindle speeds. (a) 1000 rpm (b) 1500rpm (c) 2000rpm.

Figure 7. Images of chips formed under different spindle speed (a) 1000 rpm (b) 1500 rpm (c) 2000 rpm.

Table 5. Analysis of variance for SN ratios for Thrust force (N).

Source	DF	SeqSS	AdjMS	F	P	P %
A	2	13.018	6.509	331.2	0.000	75.37
B	2	1.5290	0.764	38.91	0.000	8.99
C	2	0.2934	0.146	7.47	0.024	1.65
D	2	0.7212	0.360	18.35	0.003	4.06
E	2	2.0672	1.033	52.61	0.000	8.94
F	2	0.0361	0.018	0.92	0.449	0.56
B*E	4	0.0200	0.005	0.25	0.897	0.05
B*F	4	0.1369	0.034	1.74	0.259	0.38
Residual Error	6	0.1179	0.019
Total	26	17.939

Table 6. Analysis of variance for SN ratios for Torque (N-m).

Source	DF	SeqSS	AdjMS	F	P	P %
A	2	219.44	109.72	4165.4	0.000	95.88
B	2	3.682	1.841	69.89	0.000	1.62
C	2	1.045	0.522	19.84	0.002	0.44
D	2	0.588	0.294	11.15	0.010	0.28
E	2	3.828	1.914	72.67	0.000	1.65
F	2	0.081	0.041	1.54	0.288	0.05
B*E	4	0.202	0.051	1.92	0.227	0.04
B*F	4	0.213	0.053	2.02	0.210	0.04
Residual Error	6	0.158	0.026
Total	26	229.23

Figure 8. Thrust force (a) contour plot and (b) surface plot in spindle speed- fiber volume% plane at constant feed rate, point angle, fiber length and fiber diameter.

Figure 9. Torque (a) contour plot and (b) surface plot in spindle speed- fiber volume% plane at constant feed rate, point angle, fiber length and fiber diameter.

Figure 10. Thrust force signals for (a) Fiber volume of 50% (b) Fiber volume of 40% and (c) Fiber volume of 30% CCFRP composite.

Figure 11. Torque signals for (a) Fiber volume of 50% (b) Fiber volume of 40% and (c) Fiber volume of 30% CCFRP composite.

Table 7. Analysis of variance for Thrust force (N).

Source	DF	Seq SS	Adj MS	F	p
Regression	27	200.594	7.42942	4.19	0.000
Residual Error	25	44.308	1.77232
Pure Error	8	0.000	0.00000
Total	52	244.902

Table 8. Analysis of variance for Torque (N-m).

Source	DF	Seq SS	Adj MS	F	p
Regression	27	7.28632	0.269864	11.23	0.000
Residual Error	25	0.60080	0.024032
Pure Error	8	0.00000	0.000000
Total	52	7.88712

Figure 12. Plot for composite desirability factor [Thrust force (N)].

Figure 13. Plot for composite desirability factor [Torque (N-m)].

Figure 14. Validation of MLP-ANN Thrust Force prediction using TDOE and RSM results.

Figure 15. Validation of MLP-ANN Torque prediction using TDOE and RSM results.

Table 9. Validation of MLP-ANN prediction results using experimental data.

Sl. No	Experimental thrust force	ANN predicted thrust force	Error %	Experimental torque	ANN predicted torque	Error %
1	28.12	29.14	3.627	1.56	1.51	3.2
2	29.11	29.24	0.446	1.78	1.7	4.4
3	30.13	29.88	0.8	1.88	1.82	3.19
4	28.99	29.56	1.966	1.99	2.05	3.015
5	29.14	30.02	3.019	2.05	2.01	1.95
6	31.23	31.15	0.25	2.12	2.26	6.603
7	29.12	30.22	3.777	1.77	1.66	6.21
8	30.11	30.56	1.494	1.9	1.82	4.21
9	31.03	31.11	0.257	2	2.06	3
10	24.65	25.02	1.501	1.01	0.89	11.88
11	25.89	25.81	0.3	1.1	0.93	15.45
12	26.45	25.99	1.73	1.11	1.02	8.1
13	25.23	26.19	3.804	1.08	1.19	10.18
14	27.94	28.22	1.002	1.11	1.04	6.3
15	28.1	28.34	0.854	1.13	1.02	9.78
16	25.9	25.46	1.69	1.11	1.18	6.306
17	26.78	26.12	2.46	1.18	1.14	3.336
18	27.99	28.36	1.321	1.21	1.12	7.4
19	22.12	22.55	1.943	0.76	0.82	7.8
20	23.43	23.91	2.048	0.81	0.74	8.6
21	24.65	24.01	2.59	0.86	0.76	11.6
22	22.98	23.55	2.480	0.8	0.77	3.75
23	23.41	23.91	2.135	0.89	0.83	6.74
24	24.54	24.11	1.75	0.91	0.85	6.59
25	25.34	26.06	2.841	0.86	0.88	2.325
26	26.87	26.99	0.446	0.9	0.82	8.88
27	26.99	27.23	0.889	0.94	0.88	6.38
Total Error %			1.7566			6.5622

Hasan, K. M. F., Horváth, P. G., Bak, M., & Alpár, T. (2021). A state-of-the-art review on coir fiber-reinforced biocomposites. RSC Advances, 11(18), 10548–10571. https://doi.org/10.1039/D1RA00231G

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Hasan, K. M. F., Horváth, P. G., Kóczán, Z., & Alpár, T. (2021). Thermo-mechanical properties of pretreated coir fiber and fibrous chips reinforced multilayered composites. Scientific Reports, 11(1), 3618. https://doi.org/10.1038/s41598-021-83140-0

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