Non-linear simulation of controller for longitudinal control augmentation system of F-16 using numerical approach

The non-linear simulation of controller for automatic flight control system is an essential part of the complete control design process. After using the linear approach in the design and simulation of the controller (control laws), it is important to simulate the controller on the non-linear real aircraft model. This simulation allows us to evaluate its functional performance during the real-time flight on the computer. The results of that process are used to determine whether the designed controller meets the design requirement and objective or not. The paper deals with application of numerical method fourth-order Runge–Kutta to simulate the function of the longitudinal-CAS controller that is embedded into the non-linear, six degree of freedom model of fighter F-16. A computer program is made to implement the numerical approach and to illustrate the result of that simulation on the computer

Evaluation of properties and FEM Model of the Friction welded mild Steel-Al6061-Alumina

Evaluation of mechanical and interfacial properties of friction welded alumina-mild steel rods with the use of Al6061 sheet are presented in this work. SEM, EDX analysis, hardness and bending strength tests were conducted. The bonds were attained through interfacial interlocking and intermetalllic phase formation with average bending strengths in the range of 40 to 200 MPa and insignificant hardness change in the parent alumina and mild steel. A preliminary simulation was made to predict the deformation, stress, strain and temperature distribution during the joining operation using a fully coupled thermo-mechanical FE model. The aluminum alloy metal being rubbed was simulated using a phenomenological Johnson-Cook viscoplasticity material model, which suited for materials subjected to large strains, high strain rates and high temperatures. The highest stress, strain and deformation are found to be within the heat affected zone of the weld close to the periphery rubbing surface region and correspond to the highest temperature profiles observed