• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.637-640
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• 2005

The mechanical properties of bellows, such as the extensibility and the strength can be changed depending on the shape. For the shipbuilding material, it is favorable that the fatigue lift is long due to the elastic property and the reduction of thermal stress in piping system. Nowadays, the domestic production and design of bellows are based on the E.J.M.A Code. Therefore, the design standard is in need because of much errors and lack of detailed analysis. In this study, it is attempted to find out the optimal shape of U-type ship's bellows that is applied to design of experiment using the finite element method. The effective factors, mountain height, length, thickness, and number of mountains and the length of joint are considered and the proper values are chosen for the simulation. The number of mountains are increased, the volume increases above the standard volume and the stress obviously increases. In addition, the effect of the thickness of bellows on the stress is very large. Both of the volume and stress are decreasing at a certain lower value region.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.10
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• pp.52-58
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• 2020

Bellows are corrugated mechanical elements used to absorb displacements or vibrations caused by temperature changes, pressure, earthquakes, waves, etc., which are welded to flanges or directly connected to pipes. Expansion joint bellows must not only be designed to sufficiently withstand the internal pressure of the pipes but also accommodate axial, transverse, and rotational deformations to minimize the transfer of forces to the sensitive components of the system. Bellows have various types of corrugations, but U-type bellows are most commonly used in general piping systems. In this study, the behavior of U-shaped one-, two-, and three-ply bellows with the same inner diameter under pressure and forced displacement was analyzed using the finite element method. The results were compared with the design formula in the Expansion Joint Manufacturers Association (EJMA)'s code. Manufacturer data were used for the applied pressure and force displacement. The behavioral characteristics of the three cases were compared via structural analysis because the stress levels will be different for each model, even if they have the same inner diameter. Since the analytical model has an axisymmetric shape but displacement occurs in the transverse direction, the finite element model was composed of 1/2 of the whole model, and ANSYS Workbench 17.2 was employed for the analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.1-6
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• 2009

The temperature of exhaust gas was raised by increasing of engine movement on developing engine. Thermal of high temperature and pressure reverse in bellows, because of increasing of engine movement and the thermal performance of converter in combustion. As a result, thermal loss is increased and thermal efficiency is decreased rapidly in bellows, it can occur to damage in mechanical structure. In this study, it was necessary to analyze back pressure performance and thermal characteristic on driving condition in exhaust system. It was adapted braid type bellows and straight type exhaust pipe. It was compared with curve type exhaust pipe for lay-out on considering to design of exhaust system. It was necessary to improve thermal characteristic and back pressure performance so that expansion cavity pipe(ECP) was installed between bellows and catalyst convert. Not only decreasing back pressure was solved but also thermal characteristic problems in exhaust pipe because of increasing capacity. According to this study, the basis of data is presented when new exhaust system is designed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.615-618
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• 2005

All over the world, many kinds of micro-actuators were already developed for various applications. The actuators are using various principles such as electromagnetic, piezoelectric and thermopneumatic etc. The most of the micro-actuators have been made using 2D based MEMS technology. In these actuators, it is difficult to drive 3-dimensional motion. This characteristic gives the limit of actuator application. However, micro-stereolithography technology has made it possible to fabricate freeform three-dimensional microstructures. In this technology, 2-dimensional micro-shape layer is cumulated on the other layers. This layer-by-layer process is the main principle to fabricate 3-dimensioal micro-structures. In this research, a micro-bellows actuator that is vertically moving was developed using the micro-stereolithography technology. When pressure was applied into the bellows, a non-contact actuating motion is generated. For actuation experiment, syringe pump and laser interferometer were used for applying pressure and measuring the displacement. Several hundreds micro-scale actuation was observed. And, to demonstrate the feasibility of proposed actuation principle, in this research, a micro-gripper was developed using half-bellows structure.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.21-32
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• 1994

The Problem of mechanical vibration is investigated for an automotive exhaust system. The vibrational reduction effect is systematically evaluated according to the attachment of the exhaust system. Moreover, the optimal attachment position of bellows is determined from the viewpoint of vibration isolation. The structure is analysed by the finite element technique where the geometry, the mass, the stiffness and the damping properties of the exhaust pipe are modeled. The validity of the developed model is verified by comparing with the experimental results. An optimization is carried out by the quadratic approximation algorithm. The reaction transferred to an automobile body by the hanger is considered ad the objective function. It is shown that the exhaust system which has the bellows at the optimal position is more effective for the vibrational characteristics than the others. It is also proved that this analytical method is quite useful in the design stage of the exhaust system.

• Aerospace Engineering and Technology
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• v.11 no.1
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• pp.91-97
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• 2012

The structural analyses and experimental results for the bellows of a gas-generator liquid oxygen shut-off valve were presented. The bellows experiences axial compression and external high pressure loadings at cryogenic temperatures. The analyses were performed using EJMA (Expansion Joint Manufacturing Association) standard and the commercial FE (finite element) analysis program, Abaqus v6.9, at room and cryogenic temperatures. The spring modulus, the induced stress and the expected fatigue life of the bellows were compared respectively. The effects by the contact and the material plasticity on the FE analysis results were also analyzed. Also, FE analyses related to a burst test were presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.776-779
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• 2002

A bellows diaphragm design program for mechanical seal was developed in this study. This program was written in AutoLISP on the AutoCAD system with a personal computer. Basic design concept used in this program is composition of a convolution that is tangent to two lines and five circles from given design parameters(initial radius, inner and outer diameter, thickness, pitch, etc.). The effects of altering some design parameters on stress distribution of bellows were estimated using commercial FEM code, NISAII. As a result, the bellows diaphragm for mechanical seal was successfully designed by the program. The FEM result shows that stress is dependent on straight line length and bellows diameter with same span.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.1
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• pp.39-46
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• 2024

As the development of hydrogen vehicles has accelerated in recent years, it is necessary to develop a storage tank for hydrogen fueling stations capable of high-pressure charging, and for this purpose, a new system with a compressor-embedded refueling tank is required. In this study, the parametric study of shape design based on strength performance evaluation was carried out to find the optimal shape design of bellows, the core component of compressor-embedded refueling tank for a newly developed hydrogen refueling station capable of high-pressure charging above 1,000 bar. The design factors for parametric study were contour shape and radius of bellows, and the performance factors were the maximum stress and the gap distance in the contact direction. In the shape design of the compressor bellows for hydrogen refueling station considered in this study, it was found that adjusting the contour radius is an appropriate design method to improve the compression performance and structural safety.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.75-82
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• 2024

In this study, design parameter exploration based on finite element analysis was performed to find the optimal shape of bellows, the key component of compressor-embedded refueling tank for a newly developed hydrogen refueling station capable of high-pressure charging above 900 bar. In the design parametric study, the design variables took into account the bellows shapes such as contour radius and span spacing, and the response factors were set to the maximum stress and the gap in the contact direction. In the shape design of the compressor bellows for hydrogen refueling station considered in this study, it was found that adjusting the contour span is an appropriate design method to improve the compression performance and structural safety. From the selection of optimal design, the maximum stress was reduced to 49% compared to the initial design without exceeding the material yield stress.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.659-663
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• 1997

In this paper, a simplified vibration analysis model for bellows was presented to avoid excessive effort required for shell model. To reduce degree of freedom, bellows was modelled using one dimensional beam element. The equivalent mass and stiffness matrices were obtained based upon Guyan reduction process. The results were compared with the confirmed results, which were in good agreement.