TOOLED THICK COMPOSITES by ARVEN H. SAUNDERS III ...

For any timestep the resin pressure is used to calculate the resin flow velocity from
Darcy’s Law, and the resin flow volume rate based on the current cross-sectional area. At the
beginning of the next timestep, the new resin volume is calculated by subtracting the resin flow
volume rate * delta time from the previous volume. The last resin pressure level is not
maintained or used for the next timestep when Pappl is monotonically increasing. Each timestep
is then treated discretely with respect to resin pressure: the new Pappl value is applied to the split
of resin pressure vs. ESS based on Vf. New resin pressure value is not added to the previous
one. However, when a constant Pappl (mode 2) or a constant Z position (mode 3) is used, a resin
bleed mechanism utilizing the pressure film approach is used.
Hubert used an independent laminate sample to achieve full consolidation achieving a
final strain point of 0.184 and serve as a reference for calibration of the compaction curve
datapoints. The flat laminate model prediction was close to this, achieving strain of 0.202. The
following 2 figures illustrate the validation of the flat laminate model in relation to Hubert’s work
with fiber bed compaction curves. Figure 3.5 displays the total pressure required to produce a
Pressure k Pa
50.00
45.00
40.00
35.00
30.00
25.00
20.00
15.00
10.00
5.00
0.00
Pressure kPa Resin Pressure kPa
Total Pressure Required Lam Top Surface Height m
0 50 100 150 200
time secs
Figure 3.5. Flat Laminate Model Constant Displacement Rate and Position Hold.
34
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Height m