• Journal of Ocean Engineering and Technology
• /
• v.2 no.1
• /
• pp.170-175
• /
• 1988

A study on the dynamic vibration absorber with coil spring and oil damper was carried out both theoretically and experimentally. A main mass is attached to a foundation using coil spring and oil damper. A harmonic motion was applied to the foundation. The effects of the dynamic vibration sbsorber are theoretically summarized in graphs, and tested on a vibratory model for the isolation of actual mechanical vibration. As a result, the first resonance amplitude ratio increased and the second resonance amplitude ratio decreased as the absorber spring constant increased. When the absorber mass increase, the first resonance amplitude ratio is decreased and the second resonace amplitude ratio is increased.

• The korean journal of orthodontics
• /
• v.26 no.4
• /
• pp.341-348
• /
• 1996

The efficiency of maxillary canine retraction by means of sliding mechanics along an 0.016 continuous labial arch and an 0.009 inch in diameter with a lumen of 0.030 inch NiTi closed coil spring was compared with that using the same NiTi closed coil spring and Molar Anchoring Spring(MAS) which was designed by author. MAS was made of .017" X .025" TMA wire and was given 60 degree tip-back bend on the wire close to the molar tube. This study was designed to investigate molar and canine root control during retraction into an extraction site with continuous arch wire system. Two techniques were tested with a continuous arch model embedded in a photoelastic resin. A photoelastic model was employed to visualize the effects of forces applied to canine and molar by two retraction mechanics. With the aid of polarized light, stresses were viewed as colored fringes. The photoelastic overview of the upper right quadrant showed that stress concentrations were observed in its photoelastic model. The obtained results were as follows. 1. Higher concentration of compression can be seen clearly at the distal curvature of the canine and mesial curvature of the molar and premolar when NiTi closed coil spring was applied only, which means severe anchorage loss of the molar and uncontrolled tipping of the canine. 2. The least level compression was presented at the mesial root area of the molar and premolar, and mesial root area of the canine when NiTi closed coil spring and MAS were used simultaneously. Especially mesial alveolar crest region of the canine was shown moderate level of compression that means MAS can be used as a appliance for anchorage control and prevention of canine extrusion and uncontrolled tipping during canine retraction.

• Journal of Technologic Dentistry
• /
• v.16 no.1
• /
• pp.5-11
• /
• 1994

On purpose of relative comparison of between air-vent attached pattern and non attached one, casting tests were accomplished by castability analysis unrig wax screen mesh pattern. Experimental specimens are divided Into 4groups. 1) Air-vent attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 2) Air-vent attached pattern with low casting pressure(coil spring type centrifugal casting machine 1.5turn). 3) Air vent non attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 4) Air-vent non attached pattern with low casting pressure(coil spring type centrifrgal casting machine 1.5turn). The main results are as follows : 1) The condition of high casting pressure no.1, no.3 were showed perfect castability. 2) The condition of low-casting pressure, there is a wide difference between no.2, no.4 group. Castability of no.2 group preferable to no.4 group(p<0.001). 3) Low casting pressure and complex shape cause the low-castability. So it is recommanded that use of air-vent in case of complex shaped wax pattern with low easting pressure.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.2
• /
• pp.138-150
• /
• 2000

This study is concerned with computerized multi-level substructuring methods and stress analysis of coil springs. The purpose of substructuring methods is to reduce computing time and capacity of computer memory by multiple level reduction of the degrees of freedom in large size problems which are modeled by three dimensional continuum finite elements. In this paper, a super element has been developed for stress analysis of coil springs. The spring super element developed has been examined with tension and torsion simulation of cylindrical bars for demonstrating its validity. The result shows that the super element enhances the computing efficiency while it does not affect the accuracy of the results and it is ready for application to the coil spring analysis.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2001.11a
• /
• pp.21-27
• /
• 2001

Springs are widely utilized in machine element. To find out stiffness of frustum-shaped coil spring, the space beam theory using the finite element method is adopted in this paper In three dimensional space, a space frame element is a straight bar of uniform cross section which is capable of resisting axial forces, bending moments about two principal axes in the plane of its cross section and twisting moment about its centroidal axis. The corresponding displacement degrees of freedom are twelve. To find out load vector of coil spring subjected to distributed compression, principle of virtual work is adapted The displacements of nodal points due to small increment of force are calculated by the finite element method and the calculated nodal displacements are added to coordinates of nodal points. The new stiffness matrix of the system using the new coordinates of nodal points is adopted to calculate the another increments of nodal displacements, that is, the step by step method is used in this paper. The results of the finite element method are fairly well agreed with those of various experiments. Using MATLAB program developed in this paper, spring constants and stresses can be predicted by input of few factors.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.25 no.4
• /
• pp.347-354
• /
• 2012

The recovery force and displacement occur due to the phase transformation from the martensite phase to the austenite phase induced by the mechanical loading or thermal loading. These recovery force and displacement depend on an initial geometrical configuration of SMAs and loading conditions. Although the SMAs generally generates large recovery forces, the sufficient recovery displacement cannot be expected without a proper design strategy. The functionality of SMAs is limited due to the unbalance between the large recovery force and the small recovery displacement. This study suggests the double coil SMA spring in order to amplifying the recovery displacement induced by the phase transformation. By predicting the recovery displacement of doble coil SMA springs and one coil SMA springs induced by thermal loading, we show that the double coil SMA spring not only mitigate the unbalance of performance but also have a large recovery displacement for its recovery force than one coil SMA spring.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.3 no.4
• /
• pp.394-397
• /
• 2014

This paper deals with the comparison and dynamic behavior of a moving-coil linear oscillatory actuator (MCLOA) with/without a mechanical spring. On the basis of a dynamic simulation model, the dynamic characteristics such as a current and a stroke of the MCLOA without the spring are predicted for various values of frequency. And then, dynamic test results are given to confirm the dynamic simulations. Finally, this paper describes the influence of the spring on the dynamic behavior of the MCLOA from the dynamic experiments of the MCLOA with/without the spring.

• 연구논문집
• /
• s.34
• /
• pp.87-99
• /
• 2004

A spring tension control device is used as a very important part of an twister system. The friction force of tensioner must keep same friction force during winding in package. For satisfy this function, many device used common compression coil spring. In this paper, by using the case-building technique which was based on simple theory that unknown design variables are induced by given input design variables by the designer, design automation algorithm about rectangular section compression springs with elastic characteristic is developed. Four design equation are justified in using of analysis of torsion of straight bar of rectangular section and geometrical condition of coil spring. Four design equation and nine design variables are computed by case-building technique.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.1
• /
• pp.31-36
• /
• 2014

This paper shows the feasibility of using carbon-fiber-reinforced polymer (CFRP) composite materials for manufacturing automotive coil springs. For achieving weight reduction by replacing steel with composite materials, it is essential to optimize the material parameters and design variables of the coil spring. First, the shear modulus of a CFRP beam model, which has $45^{\circ}$ ply angles for maximum torsional stiffness, was calculated and compared with the test results. The diameter of the composite spring was predicted to be 17.5 mm for ensuring a spring rate equal to that when using steel material. Finally, a finite element model of the composite coil spring with $45^{\circ}$ ply angles and 17.5 mm wire diameter was constructed and analyzed for obtaining the static spring rate, which was then compared with experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.3
• /
• pp.275-280
• /
• 2016

In this study, a release test bed is designed to evaluate the dynamic behaviors of a coil spring. From the release tests, the dynamic behaviors of a coil spring are analyzed. A lumped parameter spring model was established for numerical simulation of a spring. The design variables of a coil spring are optimized by using the design of experiments approach. Two-level factorial designs are used for the design optimization, and the primary effects of the design variables are analyzed. Based on the results of the interaction analysis and design sensitivity analysis, the level of the design variables is rearranged. Finally, the mixed-level factorial design is used for the optimum design process. According to the optimum design of the opening spring, the dynamic performance of the spring-operated mechanism increases by 2.90.