Prediction of Mechanical Properties in Rotational Moulding …
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Fig. 3 Polynomial regression prediction curve for a tensile strength versus oven residence time,
b impact strength versus oven residence time, c flexure strength versus oven residence time
For tensile strength versus oven residence time, degree five polynomial was
obtained,
T (t) = 0.0001t
5
− 0.0254t
4
+ 1.7892t
3
− 62.288t
2
+ 1073.1t − 7302.7
For impact strength versus oven residence time, degree five polynomial was
obtained,
I (t) = 0.000005t
5
− 0.0008t
4
+ 0.0505t
3
− 1.4305t
2
+ 18.176t − 73.628
For flexure versus oven residence time, degree four polynomial was obtained,
F(t) = −0.0008t
4
+ 0.1242t
3
− 6.9535t
2
+ 172.13t − 1570.8
From these hypothesis polynomials, values of various mechanical properties were
obtained for different oven residence timings (every interval of 30 s) (Table 2).
This technique shows clear advantage over manually obtaining mechanical
properties of roto moulded product for different oven residence timings.
And by acquiring the data that has larger range of input values that is oven residence time to the corresponding output values that are mechanical properties, a larger
range of predictions can be obtained.