PSI - Issue 13

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C P Okeke et al. / Procedia Structural Integrity 13 (2018) 1460–1469 C P Okeke et al / Structural Integrity Procedia 00 (2018) 000–000

1467

6,04

0,73 Relative Error (m 2 /s 4 ) ‐1,5 0,5 2,5 4,5 6,5

4,51

4,31

2,58 1,73

2,29

1,06

0,62

Secant

Stiffness

Initial Tensile Stiffness PC‐ABS

Initial Tensile Stiffness PPT40

Initial Tensile Stiffness PMMA

Nonlinear

Hyperelastic

Figure 5: Mean square error of acceleration

It appears that the materials with lower strength had higher mean square error of acceleration for the hyperelastic material model. PMMA material which was the strongest of the three materials had the smallest mean square error followed by PC-ABS and then PPT40 material which had the largest error. The materials with lower strength exhibited stronger nonlinearity and larger errors. 6.2. Statistical analysis of response of the Mooney-Rivlin stiffness based damping matrix Figs 6-8 show the response statistics of numerically simulated responses based on the Mooney-Rivlin model damping matrix which was compared with that measured using shaker tests. The experimental curve fell within the numerically obtained upper and lower bound response curves for all the three materials. The time histories were divided into two for clarity, (a) represents the first half of the curve and (b) represents the second half. It is worth noting that the result of the experiment was based on only one specimen.

(b)

(a)

Max Min Mean Exp

500

250

-250 a (m/s²)

-500

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Time (s)

Figure 6: Dynamic response acceleration- PC-ABS - (a) 0 to 0.2sec, (b) 0.2 to 0.4sec

Max Min Mean Exp

(a)

(b)

Max Min Mean Exp

200

100

-100 a (m/s²)

-200

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Time (s)

Figure 7: Dynamic response acceleration- PMMA - (a) 0 to 0.2sec, (b) 0.2 to 0.4sec

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