eng
Shahid Chamran University of Ahvaz
Journal of Applied and Computational Mechanics
2383-4536
2383-4536
2015-12-01
1
4
168
180
10.22055/jacm.2015.11237
11237
مقاله پژوهشی
Local and Global Approaches to Fracture Mechanics Using Isogeometric Analysis Method
Abdolghafoor Khademalrasoul
ag.khadem@yahoo.com
1
Reza Naderi
rz_naderi@yahoo.com
2
Ph.D. Student of Civil Engineering, Shahrood University of technology, Iran.
Department of Civil Engineering. Shahroud University of technology.
The present research investigates the implementations of different computational geometry technologies in isogeometric analysis framework for computational fracture mechanics. NURBS and T-splines are two different computational geometry technologies which are studied in this work. Among the features of B-spline basis functions, the possibility of enhancing a B-spline basis with discontinuities by means of knot insertion makes isogeometric analysis method a suitable candidate for modeling discrete cracks. Also, the repetition of two different control points between two patches can create a discontinuity in and demonstrates a singularity in the stiffness matrix. In the case of a pre-defined interface, non-uniform rational B-splines are used to obtain an efficient discretization. T-splines constitute a type of computational geometry technology with the possibility of local refinement and with no topologically rectangular arrangement of control points. Therefore, T-splines can decrease superfluous control points which do not have any major effects on the geometry. Various numerical simulations demonstrate the suitability of the isogeometric approach in fracture mechanics.
http://jacm.scu.ac.ir/article_11237_6e78c51216bf17ef960003a0c08445e3.pdf
Fracture mechanics
Isogeometric analysis method
Knot insertion
NURBS
T-spline
eng
Shahid Chamran University of Ahvaz
Journal of Applied and Computational Mechanics
2383-4536
2383-4536
2015-12-01
1
4
181
186
10.22055/jacm.2015.11256
11256
مقاله پژوهشی
Vibration analysis of a rotating closed section composite Timoshenko beam by using differential transform method
Saeed Talebi
saeed.talebi68@gmail.com
1
Hamed Uosofvand
mr.uosofvand@gmail.com
2
Alireza Ariaei
ariaei@eng.ui.ac.ir
3
Department of Mechanical Engineering, University of Isfahan
department of mechanical engineering, university of kashan, Kashan, Iran
Department of Mechanical Engineering, Faculty of Engineering, University of Isfahan, isfahan, iran
This study introduces the Differential Transform Method (DTM) in the analysis of the free vibration response of a rotating closed section composite, Timoshenko beam, which features material coupling between flapwise bending and torsional vibrations due to ply orientation. The governing differential equations of motion are derived using Hamilton’s principle and solved by applying DTM. The natural frequencies are calculated and the effects of the bending-torsion coupling, the slenderness ratio and several other parameters on the natural frequencies are investigated using the computer package, Mathematica. Wherever possible, comparisons are made with the studies in open literature.
http://jacm.scu.ac.ir/article_11256_03281b99be3d5ae2b2cb443990f44fe6.pdf
Rotating beam
Composite
Natural frequency
Mode shape
DTM
eng
Shahid Chamran University of Ahvaz
Journal of Applied and Computational Mechanics
2383-4536
2383-4536
2015-12-01
1
4
187
206
10.22055/jacm.2015.11949
11949
مقاله پژوهشی
Dynamical Behavior of a Rigid Body with One Fixed Point (Gyroscope). Basic Concepts and Results. Open Problems: a Review
Svetoslav Nikolov
s.nikolov@imbm.bas.bg
1
Nataliya Nedkova
nataliya_nedkova@abv.bg
2
Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. BonchevStr., Bl. 4, Bulgaria
University of Transport, G. Milev Str., 158, 1574 Sofia, Bulgaria
The study of the dynamic behavior of a rigid body with one fixed point (gyroscope) has a long history. A number of famous mathematicians and mechanical engineers have devoted enormous time and effort to clarify the role of dynamic effects on its movement (behavior) – stable, periodic, quasi-periodic or chaotic. The main objectives of this review are: 1) to outline the characteristic features of the theory of dynamical systems and 2) to reveal the specific properties of the motion of a rigid body with one fixed point (gyroscope).This article consists of six sections. The first section addresses the main concepts of the theory of dynamical systems. Section two presents the main theoretical results (obtained so far) concerning the dynamic behavior of a solid with one fixed point (gyroscope). Section three examines the problem of gyroscopic stabilization. Section four deals with the non-linear (chaotic) dynamics of the gyroscope. Section five is a brief analysis of the gyroscope applications in engineering. The final section provides conclusions and generalizations on why the theory of dynamical systems should be used in the study of the movement of gyroscopic systems.
http://jacm.scu.ac.ir/article_11949_d960168e6836b18dcb446814e81f298c.pdf
Gyroscopic systems
theory of dynamical systems
dynamical behavior
eng
Shahid Chamran University of Ahvaz
Journal of Applied and Computational Mechanics
2383-4536
2383-4536
2015-12-01
1
4
207
219
10.22055/jacm.2015.12024
12024
مقاله پژوهشی
Buckling Analysis of Cantilever Nanoactuators Immersed in an Electrolyte: A Close Form Solution Using Duan-Rach Modified Adomian Decomposition Method
Mohammad Ghalambaz
m.ghalambaz@gmail.com
1
Mehdi Ghalambaz
ghalambaz.mehdi@gmail.com
2
Mohammad Edalatifar
m.edalatifar@gmail.com
3
Department of Mechanical Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran.
Department of Mechanical Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran.
Department of Electrical Engineering, Dezful Branch, Islamic Azad University, Dezful, Iran.
A new modified Adomian Decomposition Method (ADM) was utilized to obtain an analytical solution for the buckling of the nanocantilever actuators immersed in liquid electrolytes. The nanoactuators in electrolytes are subject to different nonlinear forces including ionic concentration, van der Waals, external voltage and electrochemical forces. The Duan–Rach modified Adomian decomposition method was used to obtain a full explicate solution for the buckling of nanoactuators free of any undetermined coefficients. The results were compared with those of Wazwas ADM and of a finite element method available in the literature and excellent agreement was found between them.
http://jacm.scu.ac.ir/article_12024_46bf28975511f8c180458d56cdffc012.pdf
Nanoactuator
Duan and Rach ADM
Analytic Solution
Electrolyte
eng
Shahid Chamran University of Ahvaz
Journal of Applied and Computational Mechanics
2383-4536
2383-4536
2015-12-01
1
4
220
228
10.22055/jacm.2015.12047
12047
مقاله پژوهشی
Analytical Solution of Linear, Quadratic and Cubic Model of PTT Fluid
Naeem Faraz
nfaraz_math@yahoo.com
1
Hou Lei
houlei@staff.shu.edu.cn
2
Yasir Khan
yasirmath@yahoo.com
3
Shanghai University, Shanghai China
Shanghai University, Shanghai China
Hafr al Batin Saudia Arabia
An attempt is made for the first time to solve the quadratic and cubic model of magneto hydrodynamic Poiseuille flow of Phan-Thein-Tanner (PTT). A series solution of magneto hydrodynamic (MHD) flow is developed by using homotopy perturbation method (HPM). The results are presented graphically and the effects of non-dimensional parameters on the flow field are analyzed. The results reveal many interesting behaviors that warrant further study on the equations related to non-Newtonian fluid phenomena.
http://jacm.scu.ac.ir/article_12047_812e9e73d9bd80ef37b22977eaa26b04.pdf
Phan-Thein-Tanner (PTT) model
Homotopy perturbation method
Nonlinear
eng
Shahid Chamran University of Ahvaz
Journal of Applied and Computational Mechanics
2383-4536
2383-4536
2016-06-10
1
4
229
239
10.22055/jacm.2016.12006
12006
مقاله پژوهشی
Pull-in behavior of a bio-mass sensor based on an electrostatically actuated cantilevered CNT with consideration of rippling effect
Nazanin Farjam
nazanin.farjam@gmail.com
1
Shahid Chamran University of Ahvaz
This paper examines the pull-in behavior of a bio-mass sensor with a cantilevered CNT actuated electrostatically by considering rippling deformation. Although this phenomenon can remarkably change the behavior of CNT, its effect on the performance of a CNT-based mass sensor has not been investigated thus far. This investigation is based on modified Euler-Bernoulli beam theory and rippling effect is entered into the equations related to the cantilevered CNT-bases sensor. The impact of other properties like different masses, mechanical damping and intermolecular force is studied in this paper, as well. The results reveal that rippling deformation decreases the pull-in voltage and tip deflection of CNT but enhances the pull-in time. Results related to the impact of other mentioned properties are presented, too. The results are compared with other pull-in sensor equations in the literature and “molecular dynamics”, in both of which an excellent agreement is seen, to verify the soundness of this study.
http://jacm.scu.ac.ir/article_12006_9adc81349880a9abe9be76b9d8b6b934.pdf
Bio-mass sensor
Rippling Deformation
CNT
Pull-in instability