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Thermoelastic stability of closed cylindrical shell in supersonic gas flow

G.Y. Baghdasaryan, M.A. Mikilyan, I.A. Vardanyan, P. Marzocca

Accepted Manuscript , doi: 10.1016/j.taml.2019.05.001

[Abstract] (22) [FullText HTML] (8) [PDF 2449KB] (4)

Abstract:
In this paper the problem of linear stability of a closed cylindrical shell under the action of both non-uniform temperature field and supersonic gas flow is considered. The stability conditions for the unperturbed state of the aerothermoelastic system are obtained. It is shown that, by the combined action of the temperature field and the ambient supersonic flow, the process of linear stability can be controlled and the temperature field affects significantly the critical flutter speed.

Crashworthiness assessment of thin-walled double bottom tanker: A variety of ship grounding incidents

Aditya Rio Prabowo, Sukmaji Indro Cahyono, Jung Min Sohn

Accepted Manuscript , doi: 10.1016/j.taml.2019.05.002

[Abstract] (26) [FullText HTML] (7) [PDF 3085KB] (3)

Abstract:
This study addresses the issue of ship accidental grounding as an impact phenomenon, with the assumption that an interaction of its structure with the oceanic seabed (obstruction), idealized as rock topology, is capable of initiating a so-called hard ground scenario. This occurrence variation was considered by performing two main instances, encompassing raking and stranding, often experienced by oil/chemical tankers as thin-walled structures. In addition, a failure criterion was implemented on the structural geometry, in order to define its ultimate limit and possible damage, during interaction with the obstructions. Subsequently, the analysis results were compiled to assess structural crashworthiness as well as progressive failure of the double bottom part of the tanker, where energy criterion indicated the raking to be more destructive. Meanwhile, detailed observation of the failure sequence indicated the stranding to have successfully breached the inner bottom shell.

Thermoelastic waves in helical strands with Maxwell-Cattaneo heat conduction

Dansong Zhang, Martin Ostoja-Starzewski

Accepted Manuscript , doi: 10.1016/j.taml.2019.05.003

[Abstract] (4) [FullText HTML] (2) [PDF 2631KB] (2)

Abstract:
Harmonic thermoelastic waves in helical strands with Maxwell-Cattaneo heat conduction are investigated analytically and numerically. The corresponding dispersion relation is a sixth-order algebraic equation, governed by six non-dimensional parameters: two thermoelastic coupling constants, one chirality parameter, the ratio between extensional and torsional moduli, the Fourier number, and the dimensionless thermal relaxation. The behavior of the solutions is discussed from two perspectives with an asymptotic-numerical approach: (i) the effect of thermal relaxation on the elastic wave celerities, and (ii) the effect of thermoelastic coupling on the thermal wave celerities. With small wavenumbers, the adiabatic solution for Fourier helical strands is recovered. However, with large wavenumbers, the solutions behave differently depending on the thermal relaxation and chirality. Due to thermoelastic coupling, the thermal wave celerity deviates from the classical result of the speed of second sound.

On time independent Schrödinger equations in quantum mechanics by the homotopy analysis method

Jyotirmoy Rana, Shijun Liao

Accepted Manuscript

[Abstract] (0) [FullText HTML] (0) [PDF 2551KB] (0)

Abstract:
A general analytic approach, namely the homotopy analysis method (HAM), is applied to solve the time independent Schrödinger equations. Unlike perturbation method, the HAM-based approach does not depend on any small physical parameters, corresponding to small disturbances. Especially, it provides a convenient way to gain the convergent series solution of quantum mechanics. This study illustrates the advantages of this HAM-based approach over the traditional perturbative approach, and its general validity for the Schrödinger equations. Note that perturbation methods are widely used in quantum mechanics, but perturbation results are hardly convergent. This study suggests that the HAM might provide us a new, powerful alternative to gain convergent series solution for some complicated problems in quantum mechanics, including many-body problems, which can be directly compared with the experiment data to improve the accuracy of the experimental findings and/or physical theories.

3D thermally induced analysis of annular plates of functionally graded materials

Yun-Fang Yang, Ding Chen, Bo Yang

Accepted Manuscript

[Abstract] (0) [FullText HTML] (0) [PDF 2903KB] (0)

Abstract:
Within the framework of three-dimensional elasticity theory, this paper investigates the thermal response of functionally graded annular plates in which the material can be transversely isotropic and vary along the thickness direction in an arbitrary manner. The generalized Mian and Spencer method is utilized to obtain the analytical solutions of annular plates under a through-thickness steady temperature field. The present analytical solutions are validated through comparisons against those available in open literature. A parametric study is conducted to examine the effects of gradient distribution, different temperature fields, different diameter ratio and boundary conditions on the deformation and stress fields of the plate. The results show that these factors can have obvious effects on the thermo-elastic behavior of functionally gradient materials (FGM) annular plates.

Sensitivity analysis of the vane length and passage width for a radial type swirler employed in a triple swirler configuration

Foad Vashahi, Shahnaz Rezaei, Reza Alidoost Dafsari, Jeekeun Lee

Accepted Manuscript , doi: 10.1016/j.taml.2019.05.004

[Abstract] (2) [FullText HTML] (2) [PDF 1515KB] (1)

Abstract:
The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field. In the meantime, the number of unknown parameters increases with the number of concentrically mounted swirlers. The available literature is nonetheless limited, and designers are obligated to increase the number of initial assumptions. In this article, Three kinds of triple swirlers are employed and simulations are performed to determine the effect of each parameter on the swirler performance. Based on the correlation provided, over-lengthening the radial vane length could result in significant changes in the flow field from the jet-like pattern to a wide swirl-jet angle due to the Coanda effect. Passage width should also have the potential to alter the swirl-jet angle and velocity field at the exit of the swirler.

Stochastic transient analysis of thermal stresses in solids by explicit time-domain method

Houzuo Guo, Cheng Su, Jianhua Xian

Accepted Manuscript , doi: 10.1016/j.taml.2019.05.007

[Abstract] (3) [FullText HTML] (3) [PDF 2590KB] (1)

Abstract:
Stochastic heat conduction and thermal stress analysis of structures has received considerable attention in recent years. The propagation of uncertain thermal environments will lead to stochastic variations in temperature fields and thermal stresses. Therefore, it is reasonable to consider the variability of thermal environments while conducting thermal analysis. However, for ambient thermal excitations, only stationary random processes have been investigated thus far. In this study, the highly efficient explicit time-domain method (ETDM) is proposed for the analysis of non-stationary stochastic transient heat conduction and thermal stress problems. The explicit time-domain expressions of thermal responses are first constructed for a thermoelastic body. Then the statistical moments of thermal displacements and stresses can be directly obtained based on the explicit expressions of thermal responses. A numerical example involving non-stationary stochastic internal heat generation rate is investigated. The accuracy and efficiency of the proposed method are validated by comparison with the Monte-Carlo simulation.

Iterative technique for circular thin plates on Gibson elastic foundation using modified Vlasov model

Feng Yue, Ziyan Wu, Haifeng Yang, Mengying Li

Accepted Manuscript , doi: 10.1016/j.taml.2019.04.007

[Abstract] (39) [FullText HTML] (16) [PDF 2785KB] (8)

Abstract:
In this paper, to investigate the influence of soil inhomogeneity on the bending of circular thin plates on elastic foundations, the static problem of circular thin plates on Gibson elastic foundation is solved using an iterative method based on the modified Vlasov model. On the basis of the principle of minimum potential energy, the governing differential equations and boundary conditions for circular thin plates on modified Vlasov foundation considering the characteristics of Gibson soil are derived. The equations for the attenuation parameter in bending problem are also obtained, and the issue of unknown parameters being difficult to determine is solved using the iterative method. Numerical examples are analyzed and the results are in good agreement with those form other literatures. It proves that the method is practical and accurate. The inhomogeneity of modified Vlasov foundations has some influence on the deformation and internal force behavior of circular thin plates. The effects of various parameters on the bending of circular plates and characteristic parameters of the foundation are discussed. The modified model further enriches and develops the elastic foundations. Relevant conclusions that are meaningful to engineering practice are drawn.

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Letter

Analysis on nasal airway by using scale-adaptive simulation combined with standard $ k-\omega $ model and 3D printing modeling physical experiment

Jiemin Zhan, Yangyang Xi, Kay Lin, Weiguang Yu, Wenqing Hu

2019, 9(4): 215 -219. doi: 10.1016/j.taml.2019.04.001

[Abstract] (171) [FullText HTML] (59) [PDF 2585KB] (16)

Abstract:
The physiological structure of the upper respiratory tract is complex and varies with each individual, and the circulating air has turbulent performance. In this paper, based on computed tomography (CT) medical images published online and the three-dimensional (3D) printing technology, a 3D model of the human upper respiratory tract was reconstructed and an experimental device of the upper respiratory tract was made. We implemented the respiratory experiment and measured the flow rate, and a scale-adaptive k–

\begin{document}$ \omega $\end{document}

model is applied for numerical simulation, the results are in good agreement. The flow field during respiratory was analyzed by coronal velocity cross section, vortex line and particle tracks. We found that the relatively strong shear effect happens at the areas of nasal valve and nasopharynx. In the middle and upper nasal tract, vortex line separation occurs and there is significant passage effect. The results indicate that SAS method is effective in studying upper respiratory airflow.

Numerical analysis of a simplest fractional-order hyperchaotic system

Dong Peng, Kehui Sun, Shaobo He, Limin Zhang, Abdulaziz O. A. Alamodi

2019, 9(4): 220 -228. doi: 10.1016/j.taml.2019.03.006

[Abstract] (112) [FullText HTML] (68) [PDF 3251KB] (7)

Abstract:
In this paper, a simplest fractional-order hyperchaotic (SFOH) system is obtained when the fractional calculus is applied to the piecewise-linear hyperchaotic system, which possesses seven terms without any quadratic or higher-order polynomials. The numerical solution of the SFOH system is investigated based on the Adomian decomposition method (ADM). The methods of segmentation and replacement function are proposed to solve this system and analyze the dynamics. Dynamics of this system are demonstrated by means of phase portraits, bifurcation diagrams, Lyapunov exponent spectrum (LEs) and Poincaré section. The results show that the system has a wide chaotic range with order change, and large Lyapunov exponent when the order is very small, which indicates that the system has a good application prospect. Besides, the parameter a is a partial amplitude controller for the SFOH system. Finally, the system is successfully implemented by digital signal processor (DSP). It lays a foundation for the application of the SFOH system.

Pendulum systems for harvesting vibration energy from railroad tracks and sleepers during the passage of a high-speed train: A feasibility evaluation

Franco E. Dotti, Mauricio D. Sosa

2019, 9(4): 229 -235. doi: 10.1016/j.taml.2019.03.005

[Abstract] (99) [FullText HTML] (48) [PDF 3294KB] (4)

Abstract:
We evaluate the feasibility of recovering energy from the vibrations of track and sleepers, during passage of a high-speed train, by means of a pendulum harvester. A simple mathematical model of the parametric pendulum is employed to obtain numerical predictions, while measured data of vibration tests during the passage of a Thalys high-speed train are considered as input forcing. Since a sustained rotation is the most energetic motion of a pendulum, the possibility of achieving such state is evaluated, taking into account the influence of initial conditions, damping and other factors. Numerical simulations show that rotating pendulum harvesters with sufficiently low viscous damping could be able to generate a usable average power on the order of 5–6 W per unit. Considering a modular arrangement of devices, such energy is enough to feed variety of rail-side equipment, as wireless sensors or warning light systems. However, a suitable choice of initial conditions could be a difficult task, leading to the need of a control action.

Thermal explosion and irreversibility of hydromagnetic reactive couple stress fluid with viscous dissipation and Navier slips

S.O. Salawu, M.S. Dada, O.J. Fenuga

2019, 9(4): 246 -253. doi: 10.1016/j.taml.2019.04.003

[Abstract] (81) [FullText HTML] (35) [PDF 3027KB] (2)

Abstract:
The study examines the thermal explosion branched-chain and entropy generation as a result of irreversibility of hydromagnetic reactive couple stress liquid with viscous heating and Navier slips. The reactive fluid flow is enhanced by heat dependent pre-exponential factor and axial pressure gradient in a porous wall. The flow equations for the non-Newtonian couple stress fluid model and heat transfer are solved by employing a semi-analytical collocation weighted residual method (CWRM). The efficiency and validity of the obtained results was verified with the existing results. The results reveal that at low hysteresis magnetic and viscous dissipation the irreversibility process is minimized and thermodynamic equilibrium is improved. The results from this study can assist in understanding the relationship between thermal and thermal explosions branched-chain.

Direct method for a Cauchy problem with application to a Tokamak

Mohsen Tadi

2019, 9(4): 254 -259. doi: 10.1016/j.taml.2019.04.002

[Abstract] (95) [FullText HTML] (39) [PDF 2810KB] (7)

Abstract:
This note is concerned with a new direct (non-iterative) method for the solution of an elliptic inverse problem. This method is based on the application of the Green's second identity which leads to a moment problem for the unknown boundary condition. Tikhonov regularization is used to obtain a stable and close approximation of the missing boundary condition without any need for iterations. Four examples are used to study the applicability of the method with the presence of noise.

Comparative numerical study on the child head injury under different child safety seat angles

Reza Razaghi, Hasan Biglari, Mojtaba Hasani, Alireza Karimi

2019, 9(4): 260 -263. doi: 10.1016/j.taml.2019.04.005

[Abstract] (124) [FullText HTML] (51) [PDF 2544KB] (5)

Abstract:
It has been shown that annually around 1250 children younger than 15 years old die in traffic accident. The number of children who also injured as a consequence of car accidents is noticeably higher. According to the ECE-R44 regulation the safety of children in the cars, the use of a child safety seat (CSS) is highly recommended. Using a CSS would dramatically diminish the injuries of traffic accidents. However, the posture, especially the angle, of a child when seating on a seat may also affect the amount of injury occurs during the accident. It has been revealed that during the accident only few children remained seated in the standard position, and most of them whether slouched or slanted and turned their head to the side-support of the CSS. Extreme positions, such as leaning forward, escaping from the harness or holding feet were also observed. This study aimed to perform a finite element (FE) study to figure out what angle of seating would result in the least amount of injury to the child head in a typical car crash under the speed of 47 km/h. To do that, a 1.5 years old child dummy (a dummy representing the anthropometry of a 1.5 years old child) has been accommodated on a seat under the angles of 15°, 30°, and 45°. The results revealed. The resulted displacements in the head after the accident were also calculated at X, Y, and Z directions. The results in this regard indicated a higher displacement at X direction whereas the lowest one was seen at Y direction. The results have implications not only for understanding the amount of injury to the child head after the accident under different seating angles, but also for giving an insight to the CSS industries and families to choose the right seating posture for the child in the car to reduce the severity of injury.

Article

On the Weissenberg effect of turbulence

Yu-Ning Huang, Wei-Dong Su, Cun-Biao Lee

2019, 9(4): 236 -245. doi: 10.1016/j.taml.2019.03.004

[Abstract] (86) [FullText HTML] (32) [PDF 2579KB] (13)

Abstract:
Within the framework of the Navier–Stokes equations, the Weissenberg effect of turbulence is investigated. We begin with our investigation on the elastic effect of homogeneous turbulent shear flow. First, in the sense of Truesdell (Physics of Fluids, 1964) on the natural time of materials, we derive the natural time of turbulence, and use it together with the natural viscosity of turbulence derived in the article of Huang et al. (Journal of Turbulence, 2003) to define the natural Weissenberg number of turbulence as a measure of the elastic effect of homogeneous turbulence. Second, we define a primary Weissenberg number of turbulence, which in laminar flow reduces to the Weissenberg number widely applied in rheology to characterize the elasticity of visco-elastic fluids. Our analysis based on the experimental results of Tavoularis and Karnik (Journal of Fluid Mechanics, 1989) indicates that the larger is the Weissenberg number of turbulence, the more elastic becomes the turbulent flow concerned. Furthermore, we put forth a general Weissenberg number of turbulence, which includes the primary Weissenberg number of turbulence as a special case, to measure the overall elastic effects of turbulence. Besides, it is shown that the general Weissenberg number can also be used to characterize the elastic effects of non-Newtonian fluids in laminar flow.

Analytical modeling for rapid design of bistable buckled beams

Wenzhong Yan, Yunchen Yu, Ankur Mehta

2019, 9(4): 264 -272. doi: 10.1016/j.taml.2019.04.006

[Abstract] (47) [FullText HTML] (10) [PDF 3000KB] (2)

Abstract:
Double-clamped bistable buckled beams demonstrate great versatility in various fields such as robotics, energy harvesting, and microelectromechanical system (MEMS). However, their design often requires time-consuming and expensive computations. In this work, we present a method to easily and rapidly design bistable buckled beams subjected to a transverse point force. Based on the Euler–Bernoulli beam theory, we establish a theoretical model of bistable buckled beams to characterize their snapthrough properties. This model is verified against the results from a finite element analysis (FEA) model, with maximum discrepancy less than 7%. By analyzing and simplifying our theoretical model, we derive explicit analytical expressions for critical behavioral values on the force-displacement curve of the beam. These behavioral values include critical force, critical displacement, and travel, which are generally sufficient for characterizing the snap-through properties of a bistable buckled beam. Based on these analytical formulas, we investigate the influence of a bistable buckled beam's key design parameters, including its actuation position and precompression, on its critical behavioral values, with our results validated by FEA simulations. Our analytical method enables fast and computationally inexpensive design of bistable buckled beams and can guide the design of complicated systems that incorporate bistable mechanisms.