TAILIEUCHUNG - Encyclopedia of Smart Materials (Vols 1 and 2) - M. Schwartz (2002) WW Part 2

Tham khảo tài liệu 'encyclopedia of smart materials (vols 1 and 2) - m. schwartz (2002) ww part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | nao me OIHUIICOU 11 111 11 0 Iieignu anu mc laiguou m a spanwise direction. This means that the structure needs the largest cross sections of its skins on the upper and lower surfaces. Therefore to deform a wing in bending actively would be difficult but not impossible. However the bending deformation of an unswept wing has no impact on the aerodynamic characteristics or loading conditions. Only swept wings are sensitive in this respect. Swept forward bending increases the local aerodynamic angle of attack in the streamwise direction as indicated in Fig. 4. This increases the bending moment and causes structural divergence at a flight speed called the divergence speed which depends on the bending stiffness and geometric properties of the wing. The same effect reduces the bending moment on a swept-back wing under load which acts as a passive load alleviation system. But to control these deformations actively by internal forces would mean stretching and compressing the skins in the spanwise direction a rather difficult task. The aerodynamic drag forces that act in the streamwise direction are smaller than the lift forces by a factor of 10. At the same time the shape of the airfoil creates a high static moment of resistance in this direction. For these reasons the loads in this direction need no special attention in the structural design. An active deformation would be both very difficult and meaningless. Torsional loads on a wing can be very high depending on the chordwise center of pressure locations and on additional forces from deflected control surfaces. A center of pressure in front of the fictive elastic axis through the wing cross sections causes torsional divergence at a certain flight speed and a center of pressure too far behind the elastic axis twists the wing against the desired angle control effectiveness. This active control by could theoretically be achieved by active m skins or by an internal torque device fixed a and attached to the wing

TỪ KHÓA LIÊN QUAN
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.