THERMALLY-INDUCED TWIST IN COMPOSITE TUBES AND THEIR APPLICATIONS TO HELICOPTER ROTOR BLADES WITH CONTROLLABLE TWIST


TUTUNCU N., WINCKLER S.

JOURNAL OF THE AMERICAN HELICOPTER SOCIETY, cilt.39, ss.41-49, 1994 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 39 Konu: 1
  • Basım Tarihi: 1994
  • Doi Numarası: 10.4050/jahs.39.41
  • Dergi Adı: JOURNAL OF THE AMERICAN HELICOPTER SOCIETY
  • Sayfa Sayıları: ss.41-49

Özet

Controlled thermally induced twist of a composite rotor blade modeled as a single-cell cross section shell is investigated. Using the anisotropic thermal expansion properties of composite materials, considerable twist can be induced thermally. The twist rate of a non-circular thin-walled cross section is obtained using the thermal shear strain calculated using Classical Laminated Plate Theory. The results show that a significant amount of thermal twist can be induced within a temperature change of 100-degrees-F. In addition, scaling the wall thickness does not affect the magnitude of thermal strains; hence, the composite shell can be made as stiff as desired without compromising the required thermal twist. Effects of hygrothermal degradation on thermal shear is discussed. By using hybrids with vast differences in thermal expansion coefficients, even in fiber-dominated mode, which is the least affected by hygrothermal environment, substantial thermal twist is obtained. Maximizing the thermal twist rate, which involved both material and geometric parameters, is discussed, and a thermal shear optimization parameter is suggested. Finally, an example application to rotor blades is presented.