4.

4 RESULTS FOR OPTIMIZATION:

Taguchi Design
Design Summary

Table:4.10 summary of design

Taguchi Array L9(3^3)

Factors: 3
Runs: 9

Regression Analysis: Yield Strength(experimental) versus ... e diameter

The following terms cannot be estimated and were removed:
Porosity*Nozzle diameter, Angle*Nozzle diameter

Regression Equation

Yield = 514.3 - 1600 Porosity - 1.100 Angle - 557 Nozzle diameter

Strength(experimental) + 1567 Porosity*Porosity - 0.00593 Angle*Angle
+ 733 Nozzle diameter*Nozzle diameter
+ 3.444 Porosity*Angle

Taguchi Analysis: Yield Strength(experimental) versus ... zzle diameter

Response Table for Means

Table:4.11 Response table for means
Nozzle
Level Porosity Angle diameter
1 24.00 16.00 28.67
2 15.33 29.33 14.00
3 38.00 32.00 34.67
Delta 22.67 16.00 20.67
Rank 1 3 2

46
 These are the results for the optimization technique done to the results obtained from
the tests like UTM. So, from these the optimized scaffold could be for the scaffold sample-04
with the following independent parameters porosity-40%, angle of filament-[30,90], nozzle
diameter-0.5mm.
Later these results were plotted as per the means effect plot
Main Effects Plot for Means

Fig.5 Effect on means of parameters

From the above optimization technique of taguchi it was evident that if the
combination of the independent parameters are taken in the above order that is of porosity of
60%, angles of 60°, 90° and nozzle diameter of 0.5mm then the scaffold has the highest
compressive strength of the all combinations.
Conversely, if the combinations of 40% porosity, strut angles of 0°,90° and of nozzle
diameter of 0.3mm then the scaffold has the least compressive strength of all the scaffolds.
Similarly, if porosity of 50%, angles of 30° ,90° and nozzle diameter of 0.4mm it has
the optimized compressive strength of all the scaffolds.
Now experimentally, the scaffold-04 with porosity of 40%, angles of struts as 30° , 90°
and nozzle diameter of 0.5mm is the optimized one with required compressive strength of
the trabecular bone.

47
 CHAPTER 5
CONCLUSION

In this study, bone scaffolds were fabricated from polycaprolactone material, which is
a bioactive material, from the pneumatic extrusion or micro-syringe extrusion process, thereby
applying the concept of design of experiments to decide the combination of the independent
parameters to be experimented to arrive at a meaningful results at low cost and less iterations.
Later these scaffolds for scrutinized for mechanical property of compressive strength under
UTM tests. The results were in the form of stress-strain graphs for the scaffold material and
yield strengths of these scaffolds were compared with compressive strength of the trabecular
bone regions of the body. This was an optimization study involving the comparision of the
compressive strengths of the bone scaffolds and the trabecular bone regions. From this study
the scaffold sample-4 with porosity of 40%, angles of struts as 30° , 90° and nozzle diameter
of 0.5mm was proved to be the most optimized scaffold for the trabecular bone regions for
bone tissue engineering applications.

48
 CHAPTER 6
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