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Multilevel Decomposition Approach to Integrated Aerodynamic/Dynamic/Structural Optimization of Helicopter Rotor Blades
| Content Provider | Semantic Scholar |
|---|---|
| Author | Joanne, L. Walsh Katherine, C. Young Jocelyn, I. Pritchard Howard, M. A. Wayne, R. Mantay |
| Copyright Year | 2003 |
| Abstract | This paper describes an integrated aerodynamic/dynamic/structural (IADS) optimization procedure for helicopter rotor blades. The procedure combines perfor-mance, dynamics, and structural analyses with a general purpose optimizer using multilevel decomposition tech-niques. At the upper level, the blade structure and response are represented in terms of global quantities (stiffnesses, mass, and average strains). At the lower level, the blade structure and response are represented in terms of local quantities (detailed dimensions and stresses). The upper level objective function is a linear combina-tion of performance and dynamic measures. Upper level design variables include pretwist, point of taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Upper level constraints consist of limits on power required in hover, forward flight, and maneuver; airfoil drag; minimum tip chord; trim; blade natural frequencies; autorotational inertia; blade weight; and average strains. The lower level sizes the internal blade structure at sev-eral radial locations along the blade. The lower level optimization assures that a structure can be sized to provide the stiffnesses required by the upper level and assures the structural integrity of the blade. The lower level design variables are the box beam wall thicknesses and several lumped areas that are analogous to longitudinal stringers in a wing box cross section. The lower level objective func-tion is a measure of the difference between the upper level stiffnesses and the stiffnesses computed from the wall thicknesses and lumped areas. Lower level constraints are on the Von Mises stress at the box corners for multiple load cases generated by several flight conditions, limits on wall thicknesses for thin wall theory, and other dimensional considerations. The IADS procedure provides an optimization tech-nique that is compatible with industrial design practices in which the aerodynamic and dynamic design is performed at a global level and the structural design is carried out at a detailed level with considerable dialogue and compromise among the aerodynamic, dynamic, and structural groups. The IADS procedure is demonstrated for several cases. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.cs.odu.edu/~mln/ltrs-pdfs/ahsasc.pdf |
| Alternate Webpage(s) | http://techreports.larc.nasa.gov/ltrs/PDF/ahsasc.pdf |
| Alternate Webpage(s) | https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940029394.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
