• Journal of Dental Rehabilitation and Applied Science
• /
• v.18 no.4
• /
• pp.277-288
• /
• 2002

Seven finite element models were constructed in mandible having single screw-type implant fixture connected to the premolar superstructure, in order to evaluate how the length, diameter and platform shape of a screw-type fixture influence the stress in the supporting tissue around fixtures. Each finite element model was varied in terms of length, diameter, and platform shape of the fixture. In each model, 250N of vertical load was placed on the central pit of an occlusal plane and 250N of oblique load placed on the buccal cusp. The stress distribution in the supporting tissue and the other components was analysed using 2-dimensional finite element analysis and the maximum von Mises stress in each reference area was compared. Under lateral loading, the stress was larger at the abutment/fixture interface, and in the crestal bone, compared to the stress pattern under vertical loading. The amount of stress at the superstructure was similar regardless of the length, diameter and platform shape of a fixture. Around the longer fixture, the stress was decreased at the bone crest and subjacent cancellous bone and increased in the cancellous bone area apical to the fixture. Around the wider fixture, the stress was decreased at the abutment/fixture interface, and the bone crest and increased in the cancellous bone area apical to the fixture. Around the fixture having wider platform, less stress was produced at the abutment/fixture interface and the upper part of the cortical bone, compared to the fixture having standard platform. In conclusion, the stress distribution of the supporting tissue was affected by length, diameter, and platform shape of a fixture, and the fixture which was larger in diameter and length could reduce the stress in the supporting tissues at the bone-fixture interface and bone crest area.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.21 no.2
• /
• pp.153-167
• /
• 2005

The purpose of this study was to compare the v-shape thread with the square shape thread of fixture in the view of stress distribution pattern using finite element stress analysis. The finite element model was designed with the parallel placement of two standard fixtures(4.0 mm diameter ${\times}$ 11.5 mm length) on the region of mandibular 1st and 2nd molars. Three dimensional finite element model was created with the components of the implant and surrounding bone. This study simulated loads of 200 N at the central fossa in a axial direction (load A), 200 N at the buccal offset load that is 2 mm apart from central fossa in a axial direction (load B), 200 N at the buccal offset load that was 4 mm apart from central fossa in a axial direction (load C). These forces of load A',B',C' were applied to a $15^{\circ}$ inward oblique direction at that same site with 200 N. Von Mises stress values were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study : 1. The highest stress concentration occurred at the cervical region of the implant fixture. 2. Von Mises stress value of off-site region was higher than that of central fossa region. 3. Square shape thread type showed more even stress distribution in the vertical and oblique force than V-shape thread type. 4. Stress distribution was the most effective in the case of buccal offset load (2, 4 mm distance from central fossa) in the square shape thread type. 5. V-shape thread type revealed higher von Mises stress value than square shape thread type in all environmental condition. The results from numerical analyses concluded that square shape thread type had the lower destructive stress and more stress distribution between the fixture and bone interface than V-shape thread type. Therefore, square shape thread type was regarded as optimal thread configuration in biomechanical concepts.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.142-145
• /
• 2004

More complex geometric shapes, including freeform surfaces, are adopted for the design of products to emphasize styling or aesthetics. Modeling of these products is extremely difficult, and often impossible. Reverse engineering is an emerging technology that can resolve this problem by generating CAD models from the physical mockups or prototype models. The laser scanner if often used to acquire the surface information of the part, but is limited in its measuring direction, which if fixed only along the z-axis. A Designed fixture of new shape to supplement these problems in this paper. The new fixture using several joints and an tooling ball holder is designed considering the convenience of the part set-up and the accuracy of the registration. The location of the tooling balls can be arranged to avoid the occlusion of the part and to minimize the registration error. The new fixture is apply to an object part having freeform surfaces to verify the effectiveness of the proposed design.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.10a
• /
• pp.95-98
• /
• 2005

Shafts having asymmetry or odd number of symmetry in the cross-section can not be simply manufactured by conventional incremental radial forging. In order to manufacture such shafts, the new concept of incremental forging with one punch and a flexible fixture is developed by suggesting a flexible fixture, instead of two opposed punches used in radial forging, so that the flexible fixture only supports the workpiece while the punch is moving during forming. A new flexible fixture is designed using the steel shots and vacuum technology. An equilateral triangular cross-section is selected as the sample shape to be manufactured by the proposed manufacturing method. The desired triangular cross-sectional shaft is manufactured with the errors of $3.0\%$.

• The Journal of Korean Academy of Prosthodontics
• /
• v.42 no.2
• /
• pp.226-237
• /
• 2004

Purpose: Four finite element models were constructed in the mandible having a single implant fixture connected to the first premolar-shaped superstructure, in order to evaluate how the shape of the fixture and the implant-abutment connection would influence the stress level of the supporting tissues fixtures, and prosthethic components. Material and methods : The superstructures were constructed using UCLA type abutment, ADA type III gold alloy was used to fabricate a crown and then connected to the fixture with an abutment screw. The models BRA, END , FRI, ITI were constructed from the mandible implanted with Branemark, Endopore, Frialit-2, I.T.I. systems respectively. In each model, 150 N of vertical load was placed on the central pit of an occlusal plane and 150 N of $40^{\circ}$ oblique load was placed on the buccal cusp. The displacement and stress distribution in the supporting tissues and the other components were analysed using a 2-dimensional finite element analysis . The maximum stress in each reference area was compared. Results : 1. Under $40^{\circ}$ oblique loading, the maximum stress was larger in the implant, superstructure and supporting tissue, compared to the stress pattern under vertical loading. 2. In the implant, prosthesis and supporting tissue, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 3. In the superstructure and implant/abutment interface, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 4. In the implant fixture, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 5 The stress was more evenly distributed in the bone/implant interface through the FRI of trapezoidal step design. Especially Under $40^{\circ}$ oblique loading, The maximum stress was smallest in the bone/implant interface. 6. In the implant and superstructure and supporting tissue, the maximum stress occured at the crown loading point through the ITI. Conclusion: The stress distribution of the supporting tissue was affected by shape of a fixture and implant-abutment connection. The magnitude of maximum stress was reduced with the internal connection type (FRI) and the morse taper type (ITI) in the implant, prosthesis and supporting tissue. Trapezoidal step design of FRI showed evenly distributed the stress at the bone/implant interface.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.23 no.5
• /
• pp.465-470
• /
• 2014

Thin and wide airfoils are difficult to be machined precisely because they are deformed during and after machining processes. This paper presents the results of the airfoil deformation measured by three-dimensional (3D) scanning equipment. It also discusses the influences of fixture and the machining process on the distortion of the thin airfoil. The simple fixture bended the thin airfoil to a U-shape at the first process, and the vacuum fixture decreased the distortion of the machined airfoil at the second process. The long and thin airfoil supported by two points was buckled during the machining at its two end-regions at the third process. Results from this study suggest that use of vacuum fixture decreases the machining distortion of thin and wide airfoils.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.17 no.4 s.121
• /
• pp.350-355
• /
• 2007

Accelerometer mounting fixtures were prepared with the different materials(Ti and SUS). The dynamic characteristics of the mounting fixture were analyzed by finite element method(FEM), and the mode shape of each order and the displacement response for modelling the mounting fixture were analyzed by ANSYS, then resonant frequencies of the mounting fixtures with Ti and SUS were 22.700 and 23.390 kHz, respectively. The dynamic characteristics of the mounting fixture with the different positions were obtained by using laser interferometer. The response of the accelerometer was nearly a constant from 40 Hz to 500 Hz, but the change of the acceleration was increased with an increase of the frequency above 500 Hz.

• The Journal of Korean Academy of Prosthodontics
• /
• v.40 no.4
• /
• pp.374-385
• /
• 2002

A total of 605 implant fixture prosthesis delivered by 3 clinics and 2 laboratories were examined in this study, The object of this study was to determine the proper length of screw head. The depth of access hole were measured and compared to the type of fixture, abutment, gold screw and prosthesis. The results were as follows : 1 The average number of fixtures per patient were 2.97. 2. The number of fixture installed in the upper posterior area are 327(55.56 %), the upper posterior area 171 (28.25%). 3. The depth of access hole is 4.23 mm in shallow area, and 5.46 mm in deep area and the differences were 1.23 mm. 4. The average depth of the aceess hole of the UCLA abutment were 5.02 mm. 5. The number of 4-5 mm access hole depth were 60(22.39%) in abutment screw level and the number of 4-5 mm depth in fixture level were 101 (29.19%). 6. In the shape of screw head, hexed type were 576(95.21%), slotted type were 29(4.79%).

• Proceedings of the KIEE Conference
• /
• 2003.10a
• /
• pp.53-56
• /
• 2003

Photometric analysis is essential process to make design for 300W Electrodeless flood lighting fixture. But lighting source's unusual shape makes it difficult to fix in and so we supposed two kinds of installation method to solve this matter. One is to place lamp base down and second is to put lamp base side like normal HID lamps. In result, former photometric analysis came to reach a target for similar asymmetric photometric data meanwhile we can not escape work to design complicated reflector. Second analysis reached conclusion that it is more simplified reflector than former. On its lighting fixture's design, the former reflector is new and attractive breaking fixed idea but the latter is only staying in the range of existing HID lighting design.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.1
• /
• pp.51-56
• /
• 2015

This paper presents an investigation of abnormal wear of a contact jig between a nail and a nail fixture in electric resistance welding. To perform an analysis on the abnormal wear phenomenon, several methods are provided. Based on the theory of electric resistance welding, are analyzed. Using microscopic analysis, surface craters are observed. In the measurement of the electric current flow in the nail fixture, the current flow distribution is measured. From several analyses, the cause of abnormal wear in the contact jig is measured using the electric discharge of high current density at the inflow point of the electric supply to the nail fixture. An alternative shape for normal wear is proposed.