Abstract
This paper investigates the integrated control of an air-breathing hypersonic vehicle considering the safety of propulsion system under acceleration. First, the vehicle/engine coupling model that contains a controloriented vehicle model and a quasi-one-dimensional dual-mode scramjet model is established. Next, the coupling process of the integrated control system is introduced in detail. Based on the coupling model, the integrated control framework is studied and an integrated control system including acceleration command generator, vehicle attitude control loop and engine multivariable control loop is discussed. Then, the effectiveness and superiority of the integrated control system are verified through the comparison of normal case and limiting case of an air-breathing hypersonic scramjet coupling model. Finally, the main results show that under normal acceleration case and limiting acceleration case, the integrated control system can track the altitude and speed of the vehicle extremely well and adjust the angle deflection of elevator to offset the thrust moment to maintain the attitude stability of the vehicle, while assigning the two-stage fuel equivalent ratio to meet the thrust performance and safety margin of the engine. Meanwhile, the high-acceleration requirement of the air-breathing hypersonic vehicle makes the propulsion system operating closer to the extreme dangerous conditions. The above contents demonstrate that considering the propulsion system safety will make integrated control system more real and meaningful.
Address
Chengkun Lv, Juntao Chang: Harbin Institute of Technology, Harbin, 150001, PR China
Lei Dai: Shenyang Airplane Design and Research Institution, Shenyang, 110013, PR China
Abstract
The present study proposes a theoretical and numerical investigation on the dynamic response behaviour of a functional graded (FG) ceramic-metal tapered rotor shaft system, by the differential quadrature finite elements method (DQFEM) to identify the natural frequencies for modelling and analysis of the structure with suitable validations. The purpose of this paper is to explore the influence of heat gradients on the natural frequency of rotation of FG shafts via three-dimensional solid elements, as well as a theoretical examination using the Timoshenko beam mode, which took into account the gyroscopic effect and rotational inertia. The functionally graded material's
distribution is described by two distribution laws: the power law and the exponential law. To simulate varied thermal conditions, radial temperature distributions are obtained using the nonlinear temperature distribution (NLTD) and exponential temperature distribution (ETD) approaches. This work deals with the results of the effect on the fundamental frequencies of different material's laws gradation and temperature gradients distributions. Attempts are conducted to identify adequate explanations for the behaviours based on material characteristics. The effect of taper angle and material distribution on the dynamic behaviour of the FG conical rotor system is discussed.
Key Words
DQFEM; exponential temperature distribution; functionally graded material; non-linear temperature distribution; rotor dynamics; tapered shaft
Address
Fethi Hadjoui: IS2M Laboratory, Faculty of Technology, University of Tlemcen, Algeria
Ahmed Saimi: IS2M Laboratory, Faculty of Technology, University of Tlemcen, Algeria; National Higher School of Hydraulic, Blida, Algeria
Ismail Bensaid: IS2M Laboratory, Faculty of Technology, University of Tlemcen, Algeria
Abdelhamid Hadjoui: IS2M Laboratory, Faculty of Technology, University of Tlemcen, Algeria
Abstract
In this paper, the effect of deepness on in-plane free vibration behavior of a curved functionally graded (FG) nanobeam based on nonlocal elasticity theory has been investigated. Differential equations and boundary conditions have been developed based on Hamilton's principle. In order to figure out the size effect, nonlocal theory has been adopted. Properties of material vary in radial direction. By using Navier solution technique, the amount of natural frequencies has been obtained. Also, to take into account the deepness effect on vibrations, thickness to radius ratio has been considered. Differences percentage between results of cases in which deepness effect is included and excluded are obtained and influences of power-law exponent, nonlocal parameter and arc angle on these differences percentage are studied. Results show that arc angle and power law exponent parameters have the most influences on the amount of the differences percentage due to deepness effect. It has been observed that the inclusion of geometrical deep term and material distribution results in an increase in sensitivity of dimensionless natural frequency about variation of aforementioned parameters and a change in variation range of natural frequency. Finally, several numerical results of deep and shallow curved functionally graded nanobeams with different geometry dimensions are presented, which may serve as benchmark solutions for the future research in this field.
Key Words
analytical solution; deep and shallow curved beam; deepness effect; free vibration; functionally graded nanobeam; nano structure
Address
S.A.H. Hosseini: Buein Zahra Technical University, Buein Zahra, Qazvin, Iran
O. Rahmani: Smart Structures and New Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan, Iran
V. Refaeinejad: Smart Structures and New Advanced Materials Laboratory, Department of Mechanical Engineering, University of Zanjan, Zanjan, Iran
H. Golmohammadi: Buein Zahra Technical University, Buein Zahra, Qazvin, Iran
M. Montazeripour:
Abstract
Linear array imaging sensors are widely used in remote sensing satellites. The final products of an imaging sensor can only be used when they are geometrically, radiometrically, and spectrally calibrated. Therefore, at the first stages of sensor design, a detailed calibration procedure must be carefully planned based on the accuracy requirements. In this paper, focusing on inherent optical distortion, a step-by-step procedure for laboratory geometric calibration of a typical push-broom satellite imaging sensor is simulated. The basis of this work is the simulation of a laboratory procedure in which a linear imager mounted on a rotary table captures images of a pin-hole pattern at different angles. By these images and their corresponding pinhole approximation, the correction function is extracted and applied to the raw images to give the corrected ones. The simulation results illustrate that using this approach, the nonlinear effects of distortion can be minimized and therefore the accuracy of the geometric position of this method on the image screen can be improved to better than the order of sub-pixel. On the other hand, the analyses can be used to proper laboratory facility selection based on the imaging sensor specifications and the accuracy.
Key Words
geometrical calibration; high resolution payload; laboratory calibration; optical distortion; remote sensing satellite
Address
Reza Sh. Hafshejani and Javad Haghshenas: Department of Remote Sensing Payloads, Satellite System Research Institute, Iranian Space Research Center, Tehran, Iran
Abstract
In this work, the static behavior of FGM macro and nano-plates under thermomechanical loading. Equilibrium equations are determined by using virtual work principle and local and non-local theory. The novelty of the current model is using a new displacement field with four variables and a warping function considering the effect of shear. Through this analysis, the considered sandwich FGM macro and nanoplates are a homogeneous core and PFGM faces, homogeneous faces and an E-FGM core and finally P-FGM faces and an E-FGM core. The analytical solution is obtained by using Navier method. The model is verified with previous published works by other models and very close results are obtained within maximum 1% deviation. The numerical results are performed to present
the influence of the various parameters such as, geometric ratios, material index as well as the scale parameters are
investigated. The present model can be applicable for sandwich FG plates used in nuclear, aero-space, marine, civil and mechanical applications.
Key Words
functionally graded material; local and nonlocal theory; nanoplate structure; new plate displacement field; sandwich structure; static analysis
Address
Soumia Benguediab: Department of Civil Engineering and Hydraulic, Faculty of Technology, University of Saida, Algeria
Tayeb Kebir: Department of Technical Sciences Center University Salhi Ahmed, Naâma 45000, Algeria
Fatima Zohra Kettaf: Department of Mechanical Engineering, University of Sciences and Technology Mohamed Boudiaf Oran, Algeria
Ahmed Amine Daikh: Department of Technical Sciences Center University Salhi Ahmed, Naâma 45000, Algeria; Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie, Université Mustapha Stambouli, Mascara 29000, Algeria
Abdelouahed Tounsi: Laboratory of Materials and Hydrology, Faculty of Technology, University of Sidi Bel Abbes, Algeria
Mohamed Benguediab: Laboratory of Materials and Reactive Systems, Faculty of Technology, University of Sidi Bel Abbes, Algeria
Mohamed A. Eltaher: Faculty of Engineering, Mechanical Design and Production Dept, Zagazig University, Zagazig, Egypt; Faculty of Engineering, Mechanical Engineering Department, King Abdulaziz University, Jeddah, P.O. Box80204, Saudi Arabia
