علي طالب عبدالزهرة الفلوجي

This paper deals with the behavior of state variables in the high-performance jet fighter at stall-spin phenomenon. A stall-spin phenomenon represented by set of equations of motion is solved in order to illustrate the nonlinear dynamic behavior for jet fighter. Statistical research has presents that an enough minus slope of lift could restrict the motion of cycle oscillations. The observed acts relay on operation produced by the decrease in lift coefficient rising which indicates the limit of period behavior. A computational model designed for a high-performance F-16 jet fighter solves and shows the outcomes. The impacts of important variables like ∆

Flutter is aero-elasticity phenomenon concerning the analysis of the relationship among aerodynamic and elastic forces, aerodynamic forces (static-aeroelasticity). Inertia, elastic and aerodynamic forces (dynamic-aeroelasticity). Elastic forces and laws of control (aero-servo-elasticity). Modern airplane designs can be very versatile and this versatility of the airframe allows aero-elastic analysis an essential part of airplane construction and Procedures for validation. Torsional and wing flutter are the two major aero-elastic phenomena considering in airplane architecture. Hopf bifurcation is a instability case that happens when the torsional stiffness of the system is counteracted by static aerodynamic impact. Flutter is a fluctuating motion due to instability in aero-elastic influences defined by a continuous fluctuation of the system resulting from the interaction among the inertial, elastic and aerodynamic forces operating on the entire body. This article provides a better understanding for flutter phenomena and aero-elasticity issues that seek to offer readers an understanding of the topic.

During this paper, characterizing of tensile behavior of dry jute yarn and inseminated jute yarn is planned. The results from dry yarn tensile take a look as showed the presence of four zones on the load-displacement curve and people of inseminated yarn tensile tests showed the presence of only 1 linear zone. Average Young’s modulus, average doggedness, and average breaking stress of inseminated yarn square measure superior to those of dry yarn whereas average breaking strain of inseminated yarn are less than that of dry yarn. Morphologies of tested yarns wherever mentioned elucidating harm mechanisms.

This research studied a practical effect of adding a group of concentrations of natural material scales to polymeric materials to form new compounds with good properties that differ from the original polymeric materials. Where he studied the effect of adding the nuclei of dates, olives and buckthorn to polyester and its effect on hardness and mechanical tension. In this work, samples were manufactured by adding 5%,10% and 15% of the concentration of natural materials to one liter of polyester with a amount of 0.6 from the hardener at room temperature. Through this practical study, we noticed an improvement in the hardness properties of the samples added to them natural substances for all concentrations from the original samples without adding with ratio 86%, 71% and 32% to the samples of olive and buckthorn and date palm seeds respectively, from the original samples, but a slight decrease in the tensile test by 24% For the original sample

The objective of control of the suspension system is to improve the ride comfort and road holding ability under different road conditions. The main contribution in this paper is to present a method, to design a robust control strategy in an active suspension system for one-quarter car model. The methodology for calculation the control gains by making a PID as a function of mass and velocity vehicle. The robust PID controller is tested at different road profiles (bumps). Good results for robust PID controller against passive system, the average reduction in peak overshoot for all road types that taken were %87. The performance of robust and unrobust PID controller in active suspension was compared. Finally, it means that robust PID controller is the best for active suspension system.

Based on Lyapunov exponent criterion, the aircraft lateral-directional stability during critical flight cases is presented. A periodic motion or limit cycle oscillation isdisplayed. A candidate mechanism for the wing rock limit cycle is the inertia coupling between an unstable lateral-directional (Dutch roll) mode with stable longitudinal (short period) mode. The coupling mechanism is provided by the nonlinear interaction of motion related terms in the complete set equations of motion. To analyze the state variables of the system, the complete set of nonlinear equations of motion at different high angles of attack are solved. A novel analysis including the variation of roll angle as a function of angle of attack is proposed. Furthermore the variation of Lyapunov exponent parameter as function of time is introduced. The numerical result indicated that the system became lightly damped at high angle of attack with increasing the amplitude of aircraft state variables limit cycle. A good agreement between the numerical result and published work is obtained for the onset of limit cycle oscillation, almost at( = 20° − 23°).