Development of analytical solution for dynamic behavior of elastic flapping wing under inertial loading
Hadi
Zare
دانشجوی دکتری / دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف
author
Seyed Hossein
Pourtakdoust
عضو هیات علمی / دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف
author
Hasan
Haddadpour
عضو هیات علمی / دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف
author
Arian
Bighashdel
دانشجوی کارشناسی ارشد / دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف
author
text
article
2017
per
Structural dynamics (SD) behavior of an Elastic Flapping Wing (EFW) is analytically investigated for the first time. Due to importance of inertial forces and in order to seek analytical solution for EFW, they are the only forces considered in this study. The EFW governing equations are derived via a modal approach. A second order dynamic servo actuator is utilized to impose a sinusoidal motion on the EFW. The accelerated forcing effect of the servo on EFW is also analytically computed and augmented to the governing equations. The governing equations are next solved in a closed form. The EFW analytical solution allows for various analysis of its steady and transient response due to any changes in the forced motion and/or its structural parameters. Finally, as a case study, the EFW is modeled using elastic beam and shell elements in order to investigate its dynamic behavior while undergoing a prescribed sinusoidal motion. The proposed development paves the way for further analytical studies in the area of EFWs.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
7
17
http://www.astjournal.ir/article_30837_6782c7b61de6b873bd85db7384b5a85a.pdf
Evaluation of the effects of the intruder's behavioral change on the spatiotemporal coverage
Mohammad Ali
Ansari
همکار پژوهشی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالکاشتر
author
Seyyed Mohammad Mehdi
Dehghan
عضو هیات علمی / مجتمع دانشگاهی برق و الکترونیک، دانشگاه صنعتی مالک اشتر
author
text
article
2017
per
This paper investigates the correctness of the spatiotemporal coverage as a suitable criterion for performance evaluation of a border patrolling algorithm. This criterion, which determines the probability of the intruder observation, shows the coverage of different points of the border during a period of time. Spatiotemporal coverage depends on the effective velocity of the intruder which means the magnitude of the instantaneous velocity perpendicular to the border. In the previous research, the maximum of the average velocity of the intruder is used to calculate the spatiotemporal coverage. Computing this criterion in this manner can’t show the effect of the behavior change of the intruder on the spatiotemporal coverage and won't provide a correct evaluation of the border patrolling capability of the system. This paper tries to represent a better assessment of the coverage using probability density function for the intruder's uncertain behaviors in selecting different passage times and speeds. Simulation result shows that the calculation of the spatiotemporal coverage with this approach provides a better evaluation of aerial surveillance capability in comparison to the traditional methods of coverage evaluation.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
19
27
http://www.astjournal.ir/article_30838_b689d1dc32e030862b8705122470bfcb.pdf
Leader-follower formation control OF UAVs by PID-fuzzy
Ali
Ashrafi
دانشجوی کارشناسی ارشد / دانشکدة مهندسی هوافضا، دانشگاه صنعتی امیرکبیر
author
Mahdi
Mortazavi
عضو هیات علمی / دانشکدة مهندسی هوافضا، دانشگاه صنعتی امیرکبیر
author
Abdorreza
Askari
دانش آموختة دکترای / دانشکدة مهندسی هوافضا، دانشگاه صنعتی امیرکبیر
author
Amir
Gholami
دانشجوی دکترای / دانشکدة مهندسی هوافضا، دانشگاه صنعتی امیرکبیر
author
text
article
2017
per
This paper deals with the subject of leader- follower formation control of unmanned aerial vehicle (UAVs) by PID - fuzzy. This is done to increase the performance of follower in meeting the leader’s instructions on speed and altitude in group-flights as guidance parameters for better maintenance of flight orders and more rapid maneuvers between leader-follower arrangements. For this purpose, the formation method is considered to achieve the required aim for maintaining three parameters of speed, altitude and heading angle according to leader-made changes and relative changes between the leader and follower. The simulation results are taken for 6 degrees of nonlinear freedom for a two-seat group of unmanned aerial vehicle by a body coordinate system. The considered control is for unmanned aerial vehicle with nonlinear inverse dynamic control. According to the results, the improving of the follower speed performance following the leader is observed in appropriate velocity and altitude parameters.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
29
40
http://www.astjournal.ir/article_30839_070e0c6cedfa329f9f1697a547ad860a.pdf
Stress intensity factor calculation in orthotropic functionally graded layers using element-free Galerkin method
Mahmoud
Shariati
عضو هیات علمی / دانشکدة مهندسی مکانیک، دانشگاه فردوسی مشهد
author
Mohammad Bagher
Nazari
عضو هیات علمی/ دانشکدة مهندسی مکانیک، دانشگاه صنعتی شاهرود
author
Masoud
Mahdizadeh Rokhi
عضو هیات علمی / گروه مهندسی رباتیک، دانشگاه صنعتی شاهرود
author
text
article
2017
per
Production methods of functionally graded materials cause anisotropic behavior. In this paper, the element-free Galerkin method is used to study of fracture behavior of orthotropic functionally graded materials. In this method, numerical calculation of the main and auxiliary strain fields is simply done while, in finite element and extended finite element methods, it is associated with difficulties. In addition to in this paper, a path-independent integral is presented to compute the fracture parameters in heterogeneous materials which has a unique form for mechanical and thermal loading. This new form of interaction integral includes terms with the certain physical interpretation. Also, the presented form of interaction integral has fixed term for interaction of linear fields on elastic field and it is systematically extensible. In this paper, the stress intensity factors in orthotropic functionally graded materials are obtained by using this interaction integral formula. The element-free Galerkin method is implemented to discrete the governing equations. The effect of materials characteristics on the stress intensity factors is studied in several examples. The obtained results are in good agreement with reported ones in existence papers.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
41
54
http://www.astjournal.ir/article_30840_bba33f2b6faebbfed1f7e8b76cf08ee4.pdf
Investigation of arc model adhesive joint strength in the cap of a composite tank
Mahnaz
Zakeri
عضو هیات علمی / آزمایشگاه تحقیقاتی سازه های پیشرفته، دانشکدة مهندسی هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Vahid
Dindarlou
کارشناس ارشد / دانشکدة مهندسی هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
text
article
2017
per
One of the causes of failure of adhesive joints is the stress singularity that often occurs at the free edge of the bond end. Geometric model change at the joint end can be used to reduce the stress concentration at this location. In this study, a new design called "arc adhesive model" is suggested for adhesively bonded joint of the cap of a rotational composite tank; and is compared with two conventional geometrical models including baseline model, and concave end model. Regarding to importance of transverse shear stress and normal peeling stress in examination of bonding strength, the stresses at the free end of bond are investigated using numerical analysis for all three models. Also, effect of tank rotation frequency on the stress components is investigated. Results show that the arc adhesive model can cause a significant decrease in transverse shear stress and peeling stress in adhesive joint of the cap.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
55
63
http://www.astjournal.ir/article_30841_eba3adbfe5302800ee6b100b1f501499.pdf
Investigating the nonlinear free vibrations of Nanocomposite beam based on multiscale modeling
Majid
Jamal-Omidi
عضو هیات علمی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
Mahdi
ShayanMehr
دانشجوی دکتری / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
Saeed
Shokrollahi
عضو هیات علمی / مجتمع دانشگاهی هوافضا، دانشگاه صنعتی مالک اشتر
author
text
article
2017
per
The main aim of this paper is to investigate the nonlinear free transverse vibration of representative volume element (RVE) of nanocomposites based on multiscale method, in order to predict the vibration behavior of nanocomposite beam at macro scale. To reach this object, first, mechanical properties of volume element containing carbon nanotube (CNT) is determined. In this regard, various RVEs with different length ratios are considered, where each of them represents a kind of distribution in the nanocomposite environment. Then with finite element modeling and analytical solutions, in linear domain, modal analysis of CNTs and RVEs are investigated. The results indicate that the higher ratio of nanotubes, which represents the uniform distribution of the nanotubes in the resin, has a higher natural frequency. Also, the results of analytical solution have shown good agreement with the FE modeling. In order to further validate the results of modal analysis is performed on CNT and compared with previous studies. Then, the vibration equations of volume element based on the Von-Kármán theory are obtained and nonlinear free vibration behavior of RVEs are investigated in different boundary conditions. The nonlinear frequency of volume element as a function of vibration amplitude showed that the boundary conditions and dispersion state of CNTs have a great effect on the rate of the system nonlinear behavior. Results indicate that in clamp-pinned condition the nonlinear frequency rate is approximately 20% more than clamp-clamp condition and also the values of frequency increase by improving the dispersion state of system.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
65
75
http://www.astjournal.ir/article_30842_98cb454fb8236d770971550938266b6f.pdf
An experimental investigation in effects of side slip on static aerodynamics specifications and longitudinal dynamics measurements of a delta wing airplane model
Arsalan
Ghajar
دانشجوی دکتری / پژوهشگاه هوافضا
author
Seyed Arash
Seyed Shams Taleghani
عضو هیات علمی / پژوهشگاه هوافضا
author
Mohammad Reza
Soltani
عضو هیات علمی / دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف
author
Mehran
Masdari
Tehran university
author
text
article
2017
per
In this study, the effects of side slip has investigated on a delta wing airplane model aerodynamics specifications and also an experimental method for airplane dynamics stability derivatives determination is presented. Measured data obtained from force oscillation tests are time historical of aerodynamic forces and moments. Using this data in-phase and out-of-phase of aerodynamic coefficient will be determined. In this investigation results of static and dynamic tests of a model at high angle of attack maneuver in National Low Speed Wind Tunnel (NLSWT) at Reynolds number about 1.75 millions are presented. Increasing of side slip angle results that maximum lift coefficient, slop of lift curve and longitudinal stability will be decreased. At small mean angle of attack there is no variation in in-phase and out-of-phase of normal force coefficient at larger mean angle of attack these variation is significant. Also In-phase and out-of-phase of pitching moment coefficient is strongly depend on angle of attack.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
77
92
http://www.astjournal.ir/article_30843_92b01f0d253581b76562ad592ccd6f77.pdf
Reduced order model of inverse shape design and flow field analysis using combined form of geometrical and flow modes based on proper orthogonal decomposition
Mohammad Kazem
Moayyedi
عضو هیات علمی / آزمایشگاه پژوهشی توربولانس و دینامیک سیالات محاسباتی، گروه مهندسی مکانیک، دانشگاه قـم
author
Morteza
Marvi
پژوهشگر / آزمایشگاه پژوهشی توربولانس و دینامیک سیالات محاسباتی، دانشگاه قـم
author
text
article
2017
per
This paper presents a method for inviscid airfoil analysis and design optimization that uses reduced order models based on proper orthogonal decomposition. The aim of this research is about development of reduced order approach which can perform optimum design of aerodynamic surfaces based on solution of Euler equations. This model is reduced cost of computations compared with CFD simulation approach. Aerodynamic data is obtained from an inviscid flow simulation code using different airfoil geometries. The outcome model is based on combination of Proper Orthogonal Decomposition (POD) method with solution of least squares problem to obtain the pressure distribution or any desired criteria. For reconstruction of this model, snapshot of airfoil surface pressure distribution has been used. In one of the sections of this paper presents the airfoil inverse design model for a case which is out of snapshots ensemble’s vector space. The obtained results from reduced order model are compared with direct CFD simulation and show good accuracy of the proposed approach.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
93
103
http://www.astjournal.ir/article_30844_11b72ff159bc724558af8142f76723ce.pdf
The impact of the changes in the generalized fluid dynamics equation on the two dimensional shear-free turbulent mixing layer
Hossein
Ettehadi
دانشجوی دکتری / دانشکدة مهندسی هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Mani
Fathali
عضو هیات علمی / دانشکدة مهندسی هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Masoud
Mirzaei
عضو هیات علمی / دانشکدة مهندسی هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
text
article
2017
per
The impact of the different alpha on the dynamics of a shear-free turbulent mixing layer is investigated. To this end, two-dimensional incompressible generalized equation is numerically solved using pseudo-spectral method. Is a positive number that it shows relation between stream function and vorticity in furrier space. (This study so called alpha turbulence). Dynamics of the turbulent interaction is examined through relevant statistical parameters such as skewness and kurtosis of the velocity components. It has been observed that decreasing the alpha, increases the intermittency and anisotropic level of interaction. The family includes two physically realizable members. It is shown that the enstrophy cascade is spectrally local for , but becomes dominated by nonlocal interactions for . Numerical simulations indicate that the spectral slopes are systematically steeper than those predicted by the local scaling argument. Furthermore, it is found that the physical space structure for the local transfer is dominated by the small scale vortical structure, while it for the non-local transfer is done by the smooth and thin striped structures caused by the random straining motions.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
105
115
http://www.astjournal.ir/article_30845_1ba9246efa44120325f9e775c972685c.pdf
Multi-objective 3d optimization of film cooling configurations in a high pressure vane based on genetic algorithm -artificial neural network
Mohammad Hossein
Shahdad
دانشجوی دکتری / مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر
author
Mahmoud
Adami
عضو هیات علمی / مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر
author
Ali Reza
Mostofizadeh
عضو هیات علمی / مجتمع دانشگاهی مکانیک و هوافضا، دانشگاه صنعتی مالک اشتر
author
text
article
2017
per
In this paper, the optimum parameters of a row of cylindrical film cooling holes has been investigated using a multi-objective evolutionary approach so as to achieve a compromise between film cooling effectiveness and coolant massflow rate which are in opposite directions and compete with each other. For this purpose, chordwise position of film holes, as well as diameter and injection angles were chosen as design parameters. Thirty samples were generated as database through CFD runs and artificial neural network (ANN) method was used to construct the surrogate model to approximate the optimization targets as functions of design parameters and genetic algorithm (GA) was used as optimizer. Design iterations were repeated 6 times and optimum configuration resulted in objective function values was found.
Aerospace Knowledge and Technology Journal
Malek ashtar University of Technology
2322-1070
6
v.
شماره 3 (ویژه نامه)
no.
2017
117
128
http://www.astjournal.ir/article_30846_891bc63ffb508f8b43c4a87ae2195476.pdf