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Comparative Study of Evaluations of Bearing Capacity Using Conventional Method and Finite Element Method
(2024-01-01)
Manandhar, Suman
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Karmacharya, Sunny
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Vootripruex, Panich
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Chaiyaput, Salisa
Kathmandu Clay, also called the black clay, found near the sub-surface of the valley sediments, incorporating with its low strength and high compressibility. In this research, the vertical bearing capacity of strip footing on Kathmandu Clay was analyzed using Mohr–Coulomb soil model both in drained and undrained conditions through finite elements. The analyses were focused on the failure patterns of the footing for both drained and undrained conditions. The failure analyses showed a varying degree of effects of the friction angle of the soil both in drained and undrained conditions. The results were further compared with Vesic’s and Prandtl’s methods of evaluating bearing capacities. Hence, obtained results of simulated failure plane and the conventional one preceded by Prandtl show a good agreement between each other and validated the results.
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Structural Responses of a Tunnel Lining Due to an Adjacent Loaded Pile
(2023-06-01)
Lueprasert, Prateep
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Jongpradist, Pornkasem
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Jongpradist, Pattaramon
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Schweiger, Helmut F.
The work reported in this article numerically investigates the structural forces in a tunnel lining after applying an adjacent loaded pile for varying pile tip positions considering the tunnel and soil stratum. Analysis reveals that the structural responses are strongly associated with the distorted elliptical shape of the deformed tunnel, which depends on the relative position of the pile tip with respect to the tunnel crown. The change in bending moment in the tunnel lining is of greater concern than the change in the axial force of the tunnel lining. Although the maximum change in structural forces can be up to 115% of the initial value, assessment in terms of maximum change in the structural forces is unsuitable. This is because the maximum change does not occur at the location that has large initial forces. The total combined bending moment and axial force in the lining at the tunnel spring line and in the tunnel invert zone are recommended for cases where the pile tip level is at the tunnel spring line and cases with the deepest possible pile tip elevation, respectively, for the assessment.
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A dual coil induction heating machine for jewelry factories developed by electromagnetic analysis
(2023-06-01)
Pattanapichai, Sorathorn
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Jansaengsuk, Thodsaphon
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Thongsri, Jatuporn
An induction heating machine (IHM) generates magnetic flux density (B) and high temperature for combining precious metals as products in a jewelry factory. Since factories require new generation IHMs for increased productivity and cost savings, a dual coil IHM development approach is presented here to replace conventional, single-coil IHM using electromagnetic analysis (EMA). First, the experiments and the EMA investigated B generated by a conventional one using the factory operating condition. Both agreed, confirming the methodology and reliability of the EMA, which was analyzed to determine B<inf>p</inf>. The B<inf>p</inf> represents a B property for the new dual coil IHM to be expected to generate a comparable signal to the single coil. Then, in development, two novel designs of dual coil IHM (series and parallel) were investigated based on current flow circuits. For these designs, B<inf>p</inf> was investigated using the EMA. As expected, the EMA results showed that both coils generated a different B<inf>p</inf>, which was unfortunately incompatible with the conventional IHM and thus was inappropriate in actual use. However, the series dual coil showed better applicability since it generated B higher than the parallel coil under the same operating conditions. Next, the EMA was applied to determine the B<inf>p</inf> of the series dual coil by varying the applied current (I), frequency (f), number of coil turns (N), and distance between coils (d). Finally, the EMA results revealed two options of the series dual coil with the optimum I, f, N, and d generating B<inf>p</inf> comparable to the conventional IHM, as intended, achieving the factory's need with two times the productivity.
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The Flow in Periciliary Layer in Human Lungs with Navier-Stokes-Brinkman Equations
(2021-11-10)
Oangwatcharaparkan, Nattapol
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Wuttanachamsri, Kanognudge
In the human respiratory tract, air breathed in is often contaminated with strange particles such as dust and chemical spray, which may cause people respiratory diseases. However, the human body has an innate immune system that helps to trap the debris by secreting mucus to catch the foreign particles, which are removed from the body by the movement of tiny hairs lining on the surface of the epithelial cells in the immune system. The layer containing the tiny hairs or cilia is called Periciliary Layer (PCL). In this research, we find the velocity of the fluid in the PCL moved by a ciliary beating by using the Navier-Stokes-Brinkman equations. We apply the Galerkin finite element method to determine numerical solutions. For the steady linear case of the equation, the numerical result is in good agreement with an exact solution. Including the time derivative and nonlinear terms, we show that the velocity of the liquid is affected by the velocity of the solid, which follows the physical meaning of the fluid flow. The result can be applied as a bottom boundary condition of the mucous layer to be able to find the velocity of mucus in the human lungs.
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Fem-pgd based technique for column shape optimization against buckling
(2021-10-01)
Prasertsri, Tosporn
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Sartbumrung, Supin
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Suewongprayoon, Suneenut
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Sinsamutpadung, Natdanai
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Rungamornrat, Jaroon
This paper presents a simple numerical procedure based upon the projected gradient descent (PGD) and finite element method (FEM) for the shape optimization of laterally restrained columns to attain the maximum elastic buckling load under the specified volumetric constraint. The analysis of the buckling load is achieved via the formulation based on Euler-Bernoulli beam theory, the discretization by the standard finite element technique, and the determination of the least eigenvalue and the corresponding eigenvector via the power method with Rayleigh quotient. In the optimization, the profile of the cross-sectional area of the column is represented by piecewise polynomial interpolation functions. The gradient information and the projection operator required in PGD iterations are obtained explicitly in a closed form. A selected set of results is reported to demonstrate not only the good convergence behavior and accuracy of numerical solutions, but also the capability of the proposed technique to attain the optimal shape of columns for various scenarios.
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Optimal antenna slot design for hepatocellular carcinoma microwave ablation using multi-objective fuzzy decision making
(2020-10-01)
Nantivatana, Petch
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Phasukkit, Pattarapong
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Tungjitkusolmun, Supan
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Chayakulkheeree, Keerati
This paper presents the optimal antenna slot position and sizing (OASPS), for microwave (MW) hepatocellular carcinoma (HCC) treatment, using multi-objective fuzzy decision making (MOFDM). In the optimal design problem formulation, the multi-objective for, (1) achievement for a near-spherical zone for ablation defined by axial ratio (AR), (2) the minimum reflection coefficient (S11), and (3) maximum volume of destroying (VD), are desired. The finite element method (FEM) is used for MW distribution simulation for coordination analysis with the proposed MOFDM based OASPS. The investigation on the design results shown that the temperature distribution of the proposed MOFDM for OASPS is in the more controllable shape comparing to the existing design, due to the sharp beam of temperature distribution to the target at the front side of slot with the less temperature distribution at the rare side of slot. The results also show that the proposed MOFDM for OASPS for OASPS design is easier to manage with the less effect to the rare side of the slot. Moreover, the proposed MOFDM for OASPS resulted in the temperature distribution shape closer to round shape than the existing design. The MOFDM for OASPS is tested on designing of the antenna build up from the coaxial cable. The coaxial cable used is Semi-rigid 141 (RG402 M17/130-RG402 Copper Jacket) including Inner conductor, Dielectric, and Outer conductor. In the simulation, the slot distance from conductor end (Lts), representing the slot position, is varied as 2.3mm, 3.3mm, 4.3mm, 5.3mm, 6.3mm, 7.3mm, and 8.3mm. Meanwhile, the slot size (Wd), is varied as 1mm, 2mm, 3mm, 4mm, 5mm, and 6mm. The input power (Pi) used is 50 W with the duration of 300 seconds. The comparison of obtained by different L<inf>ts</inf> and W<inf>d</inf>, is investigated. The simulation results show that the proposed MOFDM based OASPS can efficiently and effectively provide the near-spherical zone of ablation result with simultaneously trade-off between S11 minimization and VD maximization.
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Silver thin film and water dielectric SPR sensor experimental and simulation characteristics
(2019-01-01)
Leelawattananon, Tanaporn
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Chittayasothorn, Suphamit
This research project is the study of the Surface Plasmon Resonance (SPR) at the interface between silver thin film and the water dielectric layer. The purpose is to find the suitable thickness of the silver thin film layer which produces SPR and is suitable for SPR sensor applications. Both physical experiments and simulations are conducted using the Kretschmann Configuration. In the physical experiments, BK7 prisms are coated with silver thin films with the thickness of 60Â nm, 80Â nm, and 100Â nm. The light source is p-polarized He-Ne Laser with the wavelength of 632.8Â nm. Hawkeye laser detectors are used to detect the laser light intensity of reflected light for each desired angle. In the simulations, results of SPR signals are analyzed using the finite element method. The simulated results are found to agree with the results from the physical experiments.
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Numerical investigation of tunnel deformation due to adjacent loaded pile and pile-soil-tunnel interaction
(2017-11-01)
Lueprasert, Prateep
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Jongpradist, Pornkasem
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Jongpradist, Pattaramon
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Suwansawat, Suchatvee
An adjacent construction with a pile foundation in dense urban areas can contribute to possible damage to or an operational safety concern for existing tunnels. To establish a preventive measure in the design stage, a proper assessment method for the impacts of an adjacent pile under loading on a tunnel and an understanding of pile-soil-tunnel interaction are essential. This article recommends an assessment method for tunnel deformation, defined by the maximum extension and maximum contraction of the tunnel diameter and their associated axes with respect to the horizontal and vertical directions, respectively. The method could appropriately trace the changes to the tunnel diameter and the global distortion of the tunnel lining. Using a series of three-dimensional elasto-plastic numerical analyses conducted to investigate the influences of an adjacent loaded pile on an existing tunnel for varying pile tip positions with respect to the tunnel and soil stratum, the proposed method can effectively capture the response of the deformed tunnel as a distorted ellipse shape. Investigation of the analysis results from this assessment method in conjunction with those of the supplementary analyses of pile load reasonably reveal the pile-soil-tunnel interaction mechanism behind the tunnel deformation behaviour due to an adjacent loaded pile.
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Development of a new part of casing cap for the parking brake cable using finite element analysis
(2017-04-01)
Buthgate, Siwawong
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Saenthon, Anakkapon
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Kaitwanidvilai, Somyot
The brake system is an important safety system in every vehicle. This system is utilized for controlling of the vehicle movement. This paper proposes a new design and development of casing cap for the parking brake cable by applying the finite element technique to analyzing and evaluating the feasibility of the material and the design of the product. The study and analysis of influential factors affecting the parts of casing cap by JASO standard F903-75 control cable for automobiles are described. The results show that the plastic PA GF15 can be used to replace the conventional material that is steel casing cap, and will then be able to reduce the overall cost material by 2.5%. In addition, the results of the analysis illustrate that all features of the new product are complied with JASO F903-75, the control cable standard for vehicles.
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3D FEM validation of ultra-small inner spiral ribbed copper tube using the tube sinking method
(2015-12-01)
Tangsri, Tanit
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Norasethasopon, Somchai
This research related to the development of ultra-small inner spiral ribbed copper tubes (ISRCTs) which have high quality and efficiency in transferring heat. The deformation behaviour of the ISRCT was studied. Three-dimensional finite element models were constructed for the various process parameters: the change of the cross-section profiles of the ribbed contours and the spiral angle of the ribbed area of the ISRCT, for twelve multi-pass drawings through the die using the tube sinking method. The effect of the ribbed spiral angle and the ribbed cross-sectional profile was also studied. Modelling and simulation techniques were performed using commercial Abaqus software to learn whether the surface profiles of the ISRCT increased or reduced with tube sinking using the finite element method (FEM). Results of the multi-pass drawing analysis were summarised and compared to the experimental findings. The FEM simulation approach was used to analyse the changes of ten parameters: von Mises stress, wall thickness, ribbed base width, ribbed tip width, ribbed base gap, ribbed tip gap, ribbed height, ribbed pitch, axial displacement and ribbed spiral angle. This procedure can be used to improve product quality and to study the effect of the various parameters. The results will be very valuable for researchers and well engineers for future design of ultra-small ISRCT to improve the quality and efficiency of heat transfer.

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