Multi-objective/loading optimization for rotating composite flexbeams

With the evolution of advanced composites, the feasibility of designing bearingless rotor systems for high speed, demanding maneuver envelopes, and high aircraft gross weights has become a reality. These systems eliminate the need for hinges and heavily loaded bearings by incorporating a composite flexbeam structure which accommodates flapping, lead-lag, and feathering motions by bending and twisting while reacting full blade centrifugal force. The flight characteristics of a bearingless rotor system are largely dependent on hub design, and the principal element in this type of system is the composite flexbeam. As in any hub design, trade off studies must be performed in order to optimize performance, dynamics (stability), handling qualities, and stresses. However, since the flexbeam structure is the primary component which will determine the balance of these characteristics, its design and fabrication are not straightforward. It was concluded that: pitchcase and snubber damper representations are required in the flexbeam model for proper sizing resulting from dynamic requirements; optimization is necessary for flexbeam design, since it reduces the design iteration time and results in an improved design; and inclusion of multiple flight conditions and their corresponding fatigue allowables is necessary for the optimization procedure

Paper Session II-A - Space Commerce - Market Driven Opportunities for Future Space Commercialization

As we head into the 21st century, there has been a significant, on-going paradigm shift occuring in the space industry. The once secretive and often adversarial Cold-War relationships that have turned into Post Cold-War cooperation and partnerships have paved the way for market driven opportunities in Space Commerce. The space industry is slowly shifting away from governmental domination, fueled by Cold-War politics and national security fears, to one of open commercial markets most notably in the areas of launch services as well as telecommunications and navigation satellites. In addition, futuristic commercialization opportunities are possible in remote sensing, microgravity research, vacuum based material processing, space derived energy, and space tourism. This paper will focus on current hardware development programs, the commercial trends and future outlook in each of these areas. Private companies are exploiting these various markets by relying less on the government and more on competitive business models supported by market demand or partnerships to share cost, technology and risk