Manufacturing and characterization of adaptive structures with fluidic flexible matrix composite tubes

Open Access
Vashisth, Aniruddh
Graduate Program:
Engineering Science and Mechanics
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 14, 2014
Committee Members:
  • Charles E Bakis, Thesis Advisor
  • Christopher Rahn, Thesis Advisor
  • Francesco Costanzo, Thesis Advisor
  • FMC
  • F2MC
  • adaptive
  • structure
  • tubes
  • morphing
  • steerable stiffness
  • polyurethane
  • bilayer
  • multilayer
Adaptive structures are structures that have the ability to change shape, stiffness and provide damping and actuation force. Such structures with tunable properties could be of great advantage in aviation, construction industry etc. It has always been a challenge to miniaturize adaptive structures. Fluidic flexible matrix composite (F2MC) tubes are fiber reinforced elastomeric tubes filled with fluid that can change shape or exert external force upon pressurization and change axial stiffness based on valve control of fluid flow into and out of the tubes. F2MC tubes have been embedded in elastomeric potting materials to create plate-like structures with similar properties as the tubes. However, little investigation has been done on miniaturization of F2MC tubes, to-date. The objective of the current investigation is to manufacture, test, and model composites made with millimeter sized F2MC tubes. F2MC tubes were evaluated individually and embedded in elastomeric matrix materials. The performance of F2MC tubes arranged unidirectionally in mono-layer laminates was roughly consistent with a simple rule-of-mixtures expression for the effective properties of unidirectionally reinforced composites. Bilayer laminates containing two layers of longitudinally oriented F2MC tubes with different fiber angles were capable of bending with pressurization, as predicted by a shear-deformable beam model developed in the investigation. A six-layer laminate with F2MC tubes arranged in a [0/60/-60]s stacking sequence was shown to be capable of providing independently adjustable stiffness in three directions. To the author’s knowledge, this is the first time F2MC tubes with valve actuation have been used to make composites with steerable anisotropic stiffness. The steerable stiffness of the six-layer laminate could be modelled using a semi-empirical rule-of-mixtures approach.