Passive approach of controlling twist in composite tilt-rotor blades

John B. Kosmatka; Renee C. Lake

doi:10.1117/12.239076

1 May 1996 Passive approach of controlling twist in composite tilt-rotor blades

John B. Kosmatka, Renee C. Lake

Proceedings Volume 2717, Smart Structures and Materials 1996: Smart Structures and Integrated Systems; (1996) https://doi.org/10.1117/12.239076
Event: 1996 Symposium on Smart Structures and Materials, 1996, San Diego, CA, United States

Abstract

This paper examines the static and dynamic behavior of initially twisted composite spars for tilt-rotor applications, as well as documenting the fabrication of five pairs of initially twisted advanced composite single-cell spars. Spars having five different material stacking sequences were fabricated for a given geometric and pretwist definition so as to determine the maximum and minimum spar untwist for a given unit load (stiffness approach) and a given maximum load (strength approach). Analytical static stiffness and strength results are presented using a detailed shell-type finite element model, along with a two-dimensional elasticity approach to show how the maximum elastic beam untwist varies as a function of the composite spar geometric parameters and material ply orientation. Experimentally measured free-free and cantilevered natural frequencies and damping levels of the spars are presented along with a correlation to a highly refined shell-type finite element model. These vibration results reveal that both ply angle orientation and initial twist significantly alter the spar natural frequencies, where the effects are largest in the higher bending and torsion modes. Damping level changes were clearly observed with ply orientation changes (i.e. increases in extension-torsion coupling produced bending mode damping increases and torsion mode damping decreases).

Citation Download Citation

John B. Kosmatka and Renee C. Lake "Passive approach of controlling twist in composite tilt-rotor blades", Proc. SPIE 2717, Smart Structures and Materials 1996: Smart Structures and Integrated Systems, (1 May 1996); https://doi.org/10.1117/12.239076

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available