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

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maximum future cure rate value is determined <strong>by</strong> the cure kinetics model and this is used as a proportional feedback to the temperature rate. Figure 4.5 indicates how the cure rate was used to slow down the heat up rate during the ramp from 90 to 177°C. Rather than following a constant rate for the second ramp the tool temperature rate was altered based on the predicted cure rate. Using the constraint of
Temperature (C) 200 180 160 140 120 100 80 60 40 20 S2/8552 Flexbeam Model 0 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680 1800 1920 2040 2160 2280 2400 2520 Time (min) Figure 4.6. Acceptable S2/8552 Flexbeam Temperature Cycle. 57 ToolTemp MinLamT MaxLamT MaxTDelta constraints, the next temperature setpoint is reduced, and so on for each next minute. This is equivalent to having many more individual temperature stages using the Rai model. The groundrules that were specified for temperature optimization served as basic rules or constraints applied to the self-directed control approach to find a reasonable optimum cure process. Thus the constraints act as rules that guide the “controller” at each timestep, effectively paring down the optimum domain space <strong>by</strong> eliminating from consideration those values that would violate the constraints. While not guaranteed to be the global (which is improbable) optimum, it is assured to be a local optimum cure process. For the 3501-6 flexbeam laminate, a similar course of action was followed, in order to arrive at an acceptable temperature cycle, subject to the same constraints of maximum temperature and maximum temperature difference within the laminate. These results are presented in Figure 4.7. Note that the total process time to complete the 177°C dwell is 35 hours, less than the S2/8552 flexbeam laminate.
Page 1 and 2:
PROCESS MODELING SYSTEM FOR PRESS C
Page 3 and 4:
ACKNOWLEDGEMENTS This dissertation
Page 5 and 6:
TABLE OF CONTENTS ACKNOWLEDGEMENTS
Page 7 and 8:
4. RESULTS ........................
Page 9 and 10:
4.7 Acceptable IM7/3501-6 Flexbeam
Page 11 and 12:
CHAPTER 1 INTRODUCTION 1.1 Backgrou
Page 13 and 14:
Inspection and evaluation technique
Page 15 and 16: Figure 1.3. Fiber/Layer Waviness in
Page 17 and 18: CHAPTER 2 REVIEW OF RELATED RESEARC
Page 19 and 20: greatly lag in temperature. As a re
Page 21 and 22: Physics-based models are often used
Page 23 and 24: equation above can be solved by wri
Page 25 and 26: keep the cure on track. Examples of
Page 27 and 28: (Chen, 2002). However, because they
Page 29 and 30: during cure and consolidation. In a
Page 31 and 32: initially in the cure process but w
Page 33 and 34: Figure 3.1. Generic Flexbeam with T
Page 35 and 36: Permeability describes the resistan
Page 37 and 38: patterns velocity and timing during
Page 39 and 40: S ii 2 f r = 4k ii ( 1− V where r
Page 41 and 42: proportion of the applied pressure
Page 43 and 44: At any timestep in the simulation,
Page 45 and 46: constant displacement ramp followed
Page 47 and 48: 6 5 4 3 2 1 0 Figure 3.8. Model Con
Page 49 and 50: decrease for CVs that were previous
Page 51 and 52: total resin volume rate for the lam
Page 53 and 54: series electrical circuits—a left
Page 55 and 56: hold these values, with R(k) being
Page 57 and 58: • Resin pressure causes resin flo
Page 59 and 60: where α is cure, An is the pre-exp
Page 61 and 62: temperature conditions. The princip
Page 63 and 64: cycle. The ability to optimize temp
Page 65: Temperature (C) 200 180 160 140 120
Page 69 and 70: useful; as pointed out by Cirisciol
Page 71 and 72: Flexbeam (z) Height and Tool Lid Po
Page 73 and 74: 55 minutes into the S2/8552 cycle,
Page 75 and 76: Resin Pressure (Pa) 1.2E+06 1.0E+06
Page 77 and 78: -7.138E-12 -7.138E-12 -6.517E-12 -5
Page 79 and 80: keeping the level below a certain t
Page 81 and 82: feedback to set the temperature cur
Page 83 and 84: (Chen, 2002) Chen, Y., "Modeling of
Page 85 and 86: (Mitra, 2009) Mitra, K., Majumder,
Page 87 and 88: (Walia, 2006) Walia, R., Shan, H.,
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