Title page for ETD etd-03282006-101109

Type of Document Master's Thesis
Author Sarles, Stephen Andrew
Author's Email Address sarles@vt.edu
URN etd-03282006-101109
Title Active Rigidization of Carbon Fiber Reinforced Composites via Internal Resistive Heating
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Leo, Donald Committee Chair
Goulbourne, Nakhiah C. Committee Member
Inman, Daniel J. Committee Member
  • resistive heating
  • rigidizable materials
  • temperature control
  • composites
Date of Defense 2006-02-20
Availability unrestricted
The use of inflatable, rigidizable structures in solar arrays and other space structures has the potential to drastically reduce the weight, volume, and cost of placing payloads into orbit. Inflatable components consist of ultra-lightweight, flexible materials that enable compact packaging prior to launch. These structures are then transformed from their initially flexible state to one that offers permanent shape-holding and structural integrity through a tailored rigidization process. Inflatable spacecraft must be impervious to the environmental conditions in space--such as ionizing radiation, UV and particle radiation, atomic oxygen, and impacts from space debris and meteoroids. They must also exhibit stable operation over a useful storage and mission life. Methods for causing rigidization in inflatable spacecraft include both passive and active techniques. Passive techniques rely on an uncontrolled, unprovoked reaction between the rigidizable materials in the structure and the surrounding space environment. The benefits of a passive system are offset by their inherent lack of control, which can lead to long curing times and weak spots due to uneven curing.

This work presents internal resistive heating as an alternative approach for inducing matrix consolidation and curing of thermoset-coated carbon fiber tows. The ability to dictate this physical transformation through temperature-controlled resistive heating highlights the responsive nature of thermoset polymer composites and demonstrates the advantages of active rigidization. Feedback temperature control is implemented so as to provide a reliable, robust heating method for prescribing material-specific curing profiles. Resistive heating curing schedules developed from previous thermal analysis on two resins, U-Nyte Set 201A and 201B, are prescribed for samples of carbon fiber tow coated with each resin. The rigidization success of each curing profile is then evaluated with respect to both the increase in mechanical stiffness and the cure completion. These experiments indicate that rigidizing the coated fiber tow results in a composite material that is 20 times stronger in bending than prior to curing. The stiffening process requires roughly 1W-hr of energy with 5W peak power over the course of a 24-minute curing schedule. Curing temperature, curing time, and heating rate are also individually varied to determine their effect on rigidization as well as develop methods for reducing curing time and energy. The rigidization of an inflatable structure culminates this work and demonstrates the ability to achieve real strengthening through temperature-controlled internal resistive heating.

  Filename       Size       Approximate Download Time (Hours:Minutes:Seconds) 
 28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access 
  01_titlepage.pdf 39.63 Kb 00:00:11 00:00:05 00:00:04 00:00:02 < 00:00:01
  02_abstract.pdf 46.53 Kb 00:00:12 00:00:06 00:00:05 00:00:02 < 00:00:01
  03_dedication.pdf 31.78 Kb 00:00:08 00:00:04 00:00:03 00:00:01 < 00:00:01
  04_acknowledgments.pdf 42.06 Kb 00:00:11 00:00:06 00:00:05 00:00:02 < 00:00:01
  05_tableofcontents.pdf 57.64 Kb 00:00:16 00:00:08 00:00:07 00:00:03 < 00:00:01
  06_listoftables.pdf 40.58 Kb 00:00:11 00:00:05 00:00:05 00:00:02 < 00:00:01
  07_listoffigures.pdf 80.98 Kb 00:00:22 00:00:11 00:00:10 00:00:05 < 00:00:01
  08_chapter_1.pdf 4.55 Mb 00:21:04 00:10:50 00:09:28 00:04:44 00:00:24
  09_chapter_2.pdf 2.26 Mb 00:10:28 00:05:23 00:04:42 00:02:21 00:00:12
  10_chapter_3.pdf 1.36 Mb 00:06:17 00:03:13 00:02:49 00:01:24 00:00:07
  11_chapter_4.pdf 775.44 Kb 00:03:35 00:01:50 00:01:36 00:00:48 00:00:04
  12_chapter_5.pdf 85.48 Kb 00:00:23 00:00:12 00:00:10 00:00:05 < 00:00:01
  13_bibliography.pdf 76.45 Kb 00:00:21 00:00:10 00:00:09 00:00:04 < 00:00:01
  14_vita.pdf 51.44 Kb 00:00:14 00:00:07 00:00:06 00:00:03 < 00:00:01

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