• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.96-111
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• 1995

A bellows is a component installed in the automobile exhaust system to reduce the impact from an engine. It's stiffness has a great influence on the natural frequency of the system. Therefore, it must be designed to keep the specified stiffness that requires in the system. This study present the finite element analysis of U-typed bellows using a curved conical frustum element and the shape optimal design with specified stiffness. The finite element analysis is verified by comparing with the experimental results. In the shape optimal design, the weight is considered as the cost function. The specified stiffness from the system design is transformed to equality constraints. The formulation has inequality constraints imposed on the fatigue limit, the natural frequencies, the buckling load and the manufacturing conditions. A procedure for shape optimization adopts a thickness, a corrugation radius, and a length of annular plate as optimal design variables. The external loading conditions include the axial and lateral loads with a boundary condition fixed at an end of the bellows. The recursive quadratic programming algorithm is selected to solve the problem. The result are compared with the existing bellows, and the characteristics of the bellows is investigated through the optimal design process. The optimized shape of the bellows are expected to give quite a good guideline to the practical design.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.123-129
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• 2006

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 desirable that the fatigue life 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 bellows using the finite element analysis. The design factors, mountain height, length, thickness, and the number of convolutions are considered and the proper values are chosen for the simulation. The results shaw that as the number of convolutions reduces, the volume decreases while the stress increases. However, as the number of convolutions increases, 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 mass and stress are decreasing at a certain lower value region. Also, we investigated shape optimization with considering maximum stress distribution tendency.

• 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.