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

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LIST OF TABLES Table Page 3.1 Material Property Constants.................................................................................................. 49 3.2 Cure Kinetics and Viscosity Model Parameters.. .................................................................. 49 x
CHAPTER 1 INTRODUCTION 1.1 Background The employment of composite materials continues to increase, especially for high performance aerospace products. Thick laminates are a class of laminates that are employed for critical applications, such as rotorcraft components (for example, blade spars, flex beams, and yokes) that carry power to the rotor blades. These components are flight-critical, tasked with carrying heavy static and vibratory loads. Because of their stringent dimensional tolerances required, they are most often press cured in closed-cavity tooling. While their design is driven to meet the loads associated with form, fit, and function, manufacturing such components has often proven to be a challenge. Some background on the nature of the fabrication and cure process steps will be presented next. Figure 1.1 summarizes the sequence of major process Raw materials Sampling Kitting Decision Layup Tooling Feedback- cured ply thickness, etc. 1 Cure Figure 1.1. Composite Part Fabrication Overview. Inspect Cured parts steps for fabrication of thick composite laminates. The primary raw materials are preimpregnated composite (prepreg), comprised of (uncured) resin with multiple reinforcing fibers. The most commonly used resin is epoxy, and typical resin content of prepreg is in the range of 33% <strong>by</strong> weight. The balance of the weight is contributed <strong>by</strong> high modulus fibers, used
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: 4.7 Acceptable IM7/3501-6 Flexbeam
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
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cycle. The ability to optimize temp
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Temperature (C) 200 180 160 140 120
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Temperature (C) 200 180 160 140 120
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useful; as pointed out by Cirisciol
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Flexbeam (z) Height and Tool Lid Po
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55 minutes into the S2/8552 cycle,
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Resin Pressure (Pa) 1.2E+06 1.0E+06
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-7.138E-12 -7.138E-12 -6.517E-12 -5
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keeping the level below a certain t
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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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TOOLED THICK COMPOSITES by ARVEN H. SAUNDERS III ...

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