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Finite element analysis of dental implant prosthetics
(2018-01-01)
Aumnakmanee, Suchat
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Yodpiji, Nantakrit
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Jantong, Nattawut
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Jongprasithporn, Manutchanok
The paper presents the engineering analysis on stress characteristics of dental implant prosthetics. This research project focuses on a static simulation for dental implant using the three-dimensional finite element. Effects of four different Thread designs (Buttress Thread - US20140370459A1, Trapezoidal Thread - US20140212844A1, Reverse Buttress Thread - US20140816800A1 and a New Design) of dental implant prosthetics on stress are tested at four different areas (Abutment, Implant, Cortical Bone, and Cancellous Bone). Compressive forces, ranging from 60 to 200 N and Sheer force of 20 N with the force angle of 60°are applied to the dental implant models. Outcomes from this research project provide a better understanding of stress distribution characteristics that would be used for an improved design of dental implant Threads.
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Mitigations of flooding and soil erosions geo-disasters in Thailand and Laos due to climate change: From Mountains to Lowlands
(2017-06-01)
Bergado, D. T.
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Chaiyaput, S.
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Voottipruex, P.
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Hino, T.
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Chanmee, N.
In 2011, Thailand has suffered from devastating flooding due to climate change. During this time, 2 typhoons from the Pacific area went straight across Vietnam to Northern Laos and Northern Thailand instead of the usual path to Taiwan and Japan. Subsequently, huge flooding damaged many infrastructures and overtopped flood protection dikes of many industrial estates and educational institutions in the Central Plain of Thailand such as at Hi-Tech Industrial Estate, Bang Pain Industrial Estate. Navanakom Industrial Estate and Asian Institute of Technology, to name a few. The same phenomenon also occurred in neighboring Laos PDR which caused unusually heavy rains and widespread river flooding. Consequently, riverbank erosions accompanied by slope failures occurred at Xedon River in Pakse, Southern Laos due to saturation caused by high water levels accompanied by high velocity flow of the flooded river. To evaluate the stability of these mitigation structures, finite element and limit equilibrium methods were utilized. PLAXIS 2D software was used to analyze the slope protection schemes at low and high water levels incorporating the various supporting and reinforcing materials. Moreover, the PLAXIS 2D software was also utilized to predict the vertical deformations of improved flood control dikes with increased embankment height at different cases of flood water levels. In addition, the SLIDE software was used to predict the factor of safety by using limit equilibrium method for the various riverbank erosion protection structures. Furthermore. RESSA software was utilized to evaluate the slope stability of the erosion protection structures with geosynthetic reinforcements of Xedon riverbank in Pakse combined with gabions and mattresses. Laos PDR is mountainous with high elevations.
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A simplified model of a reinforced square hollow section T-joint for stress evaluation in bus superstructures
(2015-01-01)
Vichiensamuth, T.
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Pimsarn, M.
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Takahashi, K.
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Tantanawat, T.
This study aims to create a simplified model of a reinforced square hollow section (SHS) T-joint found in bus superstructures. The approach is to use a combination of one- and two-dimensional finite element models to represent a reference three-dimensional finite element model of the joint and determine stress correction factors as functions of the geometrical variables of the joint. This approach requires the stiffness of the simplified model to be equivalent to that of the reference model. By using a stiffness error function and a three-factor design of experiment (DOE), the best of four trial models, with minimum average stiffness error, was identified. The stress correction factors were then determined under static in-plane bending loads. A polynomial regression model was used to construct the relationship between the stress correction factors and the thickness-to-width ratios of the joint. The correlation coefficient of 0.9845 indicated a strong relationship and the t score confirmed its significance.
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Development of tolerance ring for cleanliness in assembly process
(2013-04-15)
Woraratsoontorn, Pattaraweerin
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Sooraksa, Pitikhate
In arm hookup assembly process, the tolerance ring is commonly used for coupling a bearing cartridge to an arm hookup. This process often encounter cleanliness problem which is caused by metal scratch between the arm hookup and the tolerance ring. The main purpose is development the tolerance ring using finite element 3D model and validation of experimental result. The result shows that the simulation result corresponds to the experimental result, the vulnerable point effect less movement of the tolerance ring. Moreover, the cleanliness problem in process was eliminated also. © (2013) Trans Tech Publications, Switzerland.
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Study swaging process for reduction swage effect in hard disk drive
(2013-04-15)
Bamrungwongtaree, Joompondej
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Mongkolwongrojn, Mongkol
In hard disk drive manufacturing common uses ball swaging. It is a process that used to assemble a boss tower and an arm aperture. The swage ball has a larger diameter than an inner diameter of the boss tower. Application a compression force to the inner surface of the boss tower to hold both components together with adequate holding force and without damaging the boss tower components result in HGA torque retention. Measurements of HSA KPIV after swaging obtained from deformation of base plate and arm pad together. Due to hard disk drive is dynamically developed by increasing in the areal density and reducing in size, thus the arm pad is thinned. This study focuses on reducing of the swage effect by control outer arm pad deformation to maintain HSA performance. HGA torque retention was considered to reduce gap to arm and to avoid HSA resonance while swaging quality was similar. The 3-D FE method was used for analysis. The analysis and experiment show that HGA torque retention and the arm aperture modified was almost linear. Furthermore, the reduction of arm deformation and gap to arm cause increasing in HSA performance. The arm aperture can be modified for manufacturability. © (2013) Trans Tech Publications, Switzerland.
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3D finite element analysis for varicose vein therapy by using microwave ablation
(2012-12-01)
Prasantamrongsiri, S.
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Phasukkit, P.
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Pintavirooj, C.
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Tungjitkusolmun, S.
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Sanpanich, A.
This paper presents three-dimensional finite element method for analyze a varicose vein microwave ablation. Varicose vein can contract by using heat from microwave ablation. Because of varicose vein patients have leg pain from long time standing, and do a lot of activities. Symptoms have influenced the daily life of patients. We study method for varicose vein therapy by using microwave ablation. Because of this method is easy to use for varicose vein therapy. In this research work, we propose simulation varicose vein that varicose vein is inserted with antenna into blood vessel. Simulation method delivers microwave to antenna inserted in varicose vein. For this reason, varicose vein is contract. Finite element analysis can apply in treatment planning and show temperature distribution and specific absorption rate (SAR) distribution for contract of varicose vein characteristic by using microwave therapy. And the doctor can be use the data for treat in future. ©2012 IEEE.
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A numerical treatment of air flow model in the area under the station platform of Thailand BTS sky train
(2010-12-01)
Pochai, Nopparat
Problem statement: The area under Phayathai station platform of sky train in Bangkok, Thailand, has a problem of air pollution control. Approach:The Bangkok Mass Transit System Company tries to set up the electric fans inside the area for air flow improvement. Results: The flow of the air is still not smooth and the air quality is still lower than standard. The assumption of the research that is the flow obstructs by the platform structures. Conclusion: In this research, a mathematical model can be simulating the causes of the flow obstacle. The numerical solution of the model is obtained by using a finite element technique. © 2010 Science Publications.
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The application of finite element to analyze the accuracy for radar system
(2008-12-01)
Smerpitak, Knt
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Boonsung, Nareerat
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Ukakimaparn, Prapart
Radar is one choice for level measurement in petrochemicals industry with high degree of accuracy. The radar provides a non-contact sensor that is virtually unaffected by change in process temperature, pressure or the gas vapor composition within a vessel. The measurement accuracy is unaffected by change in density, conductivity and dielectric constant of product being measure or by air movement above the product. These benefits have become more significant to the process industry since the advent of radar owing to low maintenance cost as there are no moving parts. This is the reason radar are so popular for industrial applications presently. However we found that some measurement value deviates from the actual level after the radar is in operation for few years. We have used Finite Element Technique to investigate for deviation, as our case study. © ICROS.
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Finite element analyses for a study of hepatic cancer tissue destruction using monopolar and bipolar radio-frequency ablation
(2005-11-28)
Tungjitkusolmun, S.
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Boontaram, A.
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Lertprasert, P.
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Krairiksh, M.
This paper presents three-dimensional finite element analyses of radio-frequency hepatic tumor ablation. The analyses performed in this paper are composed of two systems. In the first system, the simulation was of monopolar ablation (one needle), while the second system was the simulation of bipolar ablation (two needles). We performed a preliminary study of thermal and electrical distributions of both systems. Additional simulations of bipolar ablation were performed to investigate the effect of spacing distance between two needle electrodes (2 cm, 3 cm, 4 cm, and 5 cm). The ablation duration used in all cases was 10 min, and the controlled maximum temperature was set to 90°C. From the results, the electric field in monopolar ablation appeared to be distributed uniformly between the electrode and the ground surface, but the electric field in bipolar ablation was focused in the regions between the two electrodes. For bipolar ablation, when the distances between the electrodes were 2 cm and 3 cm, the lesion created was contiguous and covered the areas surrounding both electrodes. However, when the distances between the electrodes were 4 cm and 5 cm, the lesions created were not contiguous and shaped similar to performing two monopolar ablation operations.
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Guidelines for predicting lesion size at common endocardial locations during radio-frequency ablation
(2001-01-01)
Tungjitkusolmun, Supan
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Vorperian, Vicken R.
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Bhavaraju, Naresh
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Cao, Hong
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Tsai, Jang Zern
We used the finite element method to study the effect of radio-frequency (RF) catheter ablation on tissue heating and lesion formation at different intracardiac sites exposed to different regional blood velocities. We examined the effect of application of RF current in temperature- and power-controlled mode above and beneath the mitral valve annulus where the regional blood velocities are high and low respectively. We found that for temperature -controlled ablation, more power was delivered to maintain the preset tip temperature at sites of high local blood velocity than at sites of low local blood velocity. This induced more tissue heating and larger lesion volumes than ablations at low velocity regions. In contrast, for power-controlled ablation, tissue heating was less at sites of high compared with low local blood velocity for the same RF power setting. This resulted in smaller lesion volumes at sites of low local velocity. Our numerical analyzes showed that during temperature-controlled ablation at 60 °C, the lesion volumes at sites above and underneath the mitral valve were comparable when the duration of RF current application was 10 s. When the duration of RF application was extended to 60 s and 120 s, lesion volumes were 33.3% and 49.4% larger above the mitral valve than underneath the mitral valve. Also, with temperature-controlled ablation, tip temperature settings of 70 °C or greater were associated with a risk of tissue overheating during long ablations at high local blood velocity sites. In power-controlled ablation (20 W), the lesion volume formed underneath the mitral valve was 165.7% larger than the lesion volume above the mitral valve after 10 s of ablation. We summarized the guidelines for energy application at low and high flow regions.

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