Requirement for control performance has become severe in order to deal with the high performance aircraft, meanwhile, it is difficult to design the flight control systems precisely because of uncertainties such as nonlinearities involved in mathematical model. While adaptive control systems have been applied to the design of flight control system as more realistic applicative approaches, most of the existing methods are still inadequate for the consideration of these uncertainties. Recently, many researchers proposed some novel adaptive control systems with uncertainties. This paper presents a design approach of adaptive control system for the unknown system which has more general time-varying parameter uncertainties in the form of polynomial time function, then proposed method is applied to the flight control system for aircraft's longitudinal short-period motion. For demonstrating its effectiveness, some simulations are conducted using the hypothetic F-4C fighter.
Interlaminar delamination, which is formed in the composite plate by impact, fatigue etc. owing to its insuficient interlaminar toughness, is thought to cause not only the decrease of compressional strength but also the reduction of vibrational properties and undesirable phenomena. The effects of delamination size and location on vibrational properties of panels are investigated analytically. The vibrational equation is obtained based on Rayleigh-Ritz approximation technique with the use of global and local modes. The delamination opening is expressed with a fundamental mode. Geometric non-linearities owing to large deflection are considered at the delaminated portions. The responses to random excitations are solved numerically with the use of Newmark's β method. Phenomena expected at the delaminated portion, such as bouncing off and contact states, are simulated in an approximated manner. The results are discussed in probabilistic manner. Various interesting vibrational behaviors of delaminated panels are found. The nonlinear effects owing to the relative deflection of the delaminated portions play very important rolls in its vibration.
Dynamic forces on an aerofoil which changes pitch angle with constant speed in uniform air flow are measured. In our previous report, we could not measure these forces for high speed change of pitch angle because of resonance on the actuating and sensing systems. Pitching mechanism is improved: an actuator, which changes pitch angle speed, is exchanged from a pulse motor to a servomotor and a sensor is exchanged from an optical displacement meter to a load cell. Two dynamic characteristics are measured as follows: transient properties for quick increase of pitch angle and dynamic ones for triangular motion of an aerofoil (saw-toothwise change of pitch angle). We obtain the following results: For triangular pitching motion, clockwise hysteresis loops are formed in the lift and the drag curves. Then, the transition of those loops can be described. Maximum lift coefficient and dynamic stall angle of aerofoil tend to be saturated with increasing in the angular velocity of pitching motion.
Accurate estimation of thermal stress and strain level on rocket combustion chamber is important for increasing safety and reliability. In the National Aerospace Laboratory (NAL), two thermal fatigue failures have occurred with water-cooled combustion chambers. In this paper, the cause of failures and deformations of the chambers were investigated by inelastic analysis with the Finite Element Method (FEM). Analytical crack initiation life for low cycle fatigue agreed with observed result obtained by a scanning electron microscope (SEM). Analytical deformation with crack initiation model also agreed with observed one. The present analysis suggested that modifying cooling channel design would be able to increase crack initiation life. This study also showed that structural analysis with FEM would be effective method for estimation of thermal stress and strain level on rocket combustion chambers.