2017-10-24T13:06:00Z
http://jacm.scu.ac.ir/?_action=export&rf=summon&issue=1411
Journal of Applied and Computational Mechanics
JACM
2015
1
4
Local and Global Approaches to Fracture Mechanics Using Isogeometric Analysis Method
Abdolghafoor
Khademalrasoul
Reza
Naderi
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.
Fracture mechanics
Isogeometric analysis method
Knot insertion
NURBS
T-spline
2015
12
01
168
180
http://jacm.scu.ac.ir/article_11237_6e78c51216bf17ef960003a0c08445e3.pdf
Journal of Applied and Computational Mechanics
JACM
2015
1
4
Vibration analysis of a rotating closed section composite Timoshenko beam by using differential transform method
Saeed
Talebi
Hamed
Uosofvand
Alireza
Ariaei
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.
Rotating beam
Composite
Natural frequency
Mode shape
DTM
2015
12
01
181
186
http://jacm.scu.ac.ir/article_11256_03281b99be3d5ae2b2cb443990f44fe6.pdf
Journal of Applied and Computational Mechanics
JACM
2015
1
4
Dynamical Behavior of a Rigid Body with One Fixed Point (Gyroscope). Basic Concepts and Results. Open Problems: a Review
Svetoslav
Nikolov
Nataliya
Nedkova
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.
Gyroscopic systems
theory of dynamical systems
dynamical behavior
2015
12
01
187
206
http://jacm.scu.ac.ir/article_11949_d960168e6836b18dcb446814e81f298c.pdf
Journal of Applied and Computational Mechanics
JACM
2015
1
4
Buckling Analysis of Cantilever Nanoactuators Immersed in an Electrolyte: A Close Form Solution Using Duan-Rach Modified Adomian Decomposition Method
Mohammad
Ghalambaz
Mehdi
Ghalambaz
Mohammad
Edalatifar
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.
Nanoactuator
Duan and Rach ADM
Analytic Solution
Electrolyte
2015
12
01
207
219
http://jacm.scu.ac.ir/article_12024_46bf28975511f8c180458d56cdffc012.pdf
Journal of Applied and Computational Mechanics
JACM
2015
1
4
Analytical Solution of Linear, Quadratic and Cubic Model of PTT Fluid
Naeem
Faraz
Hou
Lei
Yasir
Khan
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.
Phan-Thein-Tanner (PTT) model
homotopy perturbation method
Nonlinear
2015
12
01
220
228
http://jacm.scu.ac.ir/article_12047_812e9e73d9bd80ef37b22977eaa26b04.pdf
Journal of Applied and Computational Mechanics
JACM
2015
1
4
Pull-in behavior of a bio-mass sensor based on an electrostatically actuated cantilevered CNT with consideration of rippling effect
Nazanin
Farjam
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.
Bio-mass sensor
Rippling Deformation
CNT
Pull-in instability
2016
06
10
229
239
http://jacm.scu.ac.ir/article_12006_9adc81349880a9abe9be76b9d8b6b934.pdf