Finite Elements Method (FEM)
Farshid Ahmadi; Rohollah Mohammadi
Abstract
Abstract The first step of implanting teeth is to drill a hole in the jaw bone. Excessive temperature produced during drilling is one of the destructive factors for bony tissue. If the temperature generation during surgical drilling exceeds the critical temperature, it could lead to osteonecrosis. This ...
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Abstract The first step of implanting teeth is to drill a hole in the jaw bone. Excessive temperature produced during drilling is one of the destructive factors for bony tissue. If the temperature generation during surgical drilling exceeds the critical temperature, it could lead to osteonecrosis. This research intends to study drilling parameters such as drilling speed, feed rate, cooling condition and tool geometry by FEM method in order to achieve the most appropriate drilling conditions. Three dimensional modeling of lower jaw bone from the CT scan images was made by Mimics 10.01 software. In order to place the drill bit on the mandibular model, two teeth were removed from the final part of model by CATIA V5R20 software. DEFORM-3D (Version 10.2) was used for mandibular cortical bone drilling simulation. For this purpose, drill bits with different geometrical parameter including point angles of 90, 70, and 118 degrees and helix angles of 20, 23, and 30 degrees were designed in the software. The simulations were carried out using different feed rates (60, 90, 120 and 200 mm/min) and rotational speeds (200, 400, 800, and 1200 rev/min). The simulation results showed that the most appropriate conditions for the lowest temperature was as follows: 70 degrees for drill bit point angle, 23 degrees for helix angle, 200 mm/min for feed rate, and 200 rev/min for rotational speed. Also, by using coolant the maximum temperature reduced by approximately 12 degrees. The results also suggest that the rotational speed of 200 rev/min and feed rate of 200 mm/min have the largest thrust force in drilling area. The finite element results were validated by available experimental data.
Finite Elements Method (FEM)
Zuliang Lu*
Abstract
In this paper, a positive definite semi-discrete mixed finite element method was presented for two-dimensional parabolic equations. In the new positive definite systems, the gradient equation and flux equations were separated from their scalar unknown equations. Also, the existence and uniqueness ...
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In this paper, a positive definite semi-discrete mixed finite element method was presented for two-dimensional parabolic equations. In the new positive definite systems, the gradient equation and flux equations were separated from their scalar unknown equations. Also, the existence and uniqueness of the semi-discrete mixed finite element solutions were proven. Error estimates were also obtained for the semi-discrete schemes.Finally, a numerical example was presented to show theoretical results.
