The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
A. Novokhatski - One of the best experts on this subject based on the ideXlab platform.
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Simulation of HOM leakage in the PEP-II Bellows
Proceedings of the IEEE Particle Accelerator Conference, 2005Co-Authors: C.k. Ng, N. Folwell, J. Langten, L. Q. Lee, A. NovokhatskiAbstract:An important factor that limits the PEP-II from operating at high currents is higher-order-mode (HOM) heating of the Bellows. One source of HOM heating is the formation of trapped modes at the Bellows as a result of geometry variation in the vacuum chamber, for example, the masking near the central vertex chamber. Another source comes from HOMs generated upstream that leak through the gaps between the Bellows fingers. Modeling the fine details of the Bellows and the surrounding geometry requires the resolution and accuracy only possible with a large number of mesh points on an unstructured grid. We use the parallel finite element eigensolver Omega3P for trapped mode calculations and the S-matrix solver S3P for transmission analysis. The damping of the HOMs by the use of absorbers inside the Bellows will be investigated.
A. A. Shipkov - One of the best experts on this subject based on the ideXlab platform.
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Bellows Expansion Joints of the Main Heating Network Pipelines: Problems and Damage Prevention
Thermal Engineering, 2019Co-Authors: G. V. Tomarov, A. A. ShipkovAbstract:The problems of Bellows expansion joints conditioned by their design features and the quality of the heat carrier are considered. It is testified that typical damage of Bellows expansion joints are deformations, changes in geometric characteristics, and through defects of structural elements. Prevention and timely detection of damaged Bellows expansion joints is an important task of the heating system’s operation. Examples of damage to Bellows expansion joint elements are presented, including those with corrosive destruction of pearlitic steel corrugated inner layers and outer high-alloyed steel corrugations. Some survey results are presented and factors are analyzed that may affect the damageability of Bellows expansion joints of the main heating network pipelines at PAO MOEK^1. The causes and dominant damage mechanism of Bellows expansion joints, caused by the formation of crevice defect with penetration of the heat carrier into the inner space of the pearlitic steel corrugated layers, have been established. Practice has shown that most of the damage is detected in pressure testing and is associated with mechanical deformations of the Bellows without depressurization and without unsealing and loss of the heat carrier. Four main corrosion and damage stages of heating system Bellows expansion joints are identified. It is proposed, depending on the initial and operating conditions, to consider possible scenarios of a two-stage mechanism of destruction of Bellows expansion joints, including the development of a crevice defect up to the through leakage of heat carrier into the Bellows interlayer space and corrosion damage to the inner corrugated Bellows surface. Recommendations to prevent damage to Bellows expansion joints of heating systems are provided.
D S Weaver - One of the best experts on this subject based on the ideXlab platform.
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transverse natural frequencies and flow induced vibrations of double Bellows expansion joints
Journal of Fluids and Structures, 1999Co-Authors: V F Jakubauskas, D S WeaverAbstract:This paper considers the transverse vibrations of fluid-filled double-Bellows expansion joints. The Bellows are modelled as a Timoshenko beam, and the fluid added mass includes rotary inertia and Bellows convolution distortion effects. The natural frequencies are given in terms of a Rayleigh quotient, and both lateral and rocking modes of the pipe connecting the Bellows units are considered. The theoretical predictions for the first six modes are compared with experiments in still air and water and the agreement is found to be very good. The flow-induced vibrations of the double Bellows are then studied with the Bellows downstream of a straight section of pipe and a 90° elbow. Strouhal numbers are computed for each of the flow-excited mode resonances. The Bellows natural frequencies are not affected by the flowing fluid but the presence of an immediate upstream elbow substantially reduces the flow velocity required to excite resonance.
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Axial Vibrations of Fluid-Filled Bellows Expansion Joints
Journal of Pressure Vessel Technology, 1996Co-Authors: V F Jakubauskas, D S WeaverAbstract:This paper presents the results of a project undertaken to study the axisymmetric natural vibrations and fluid-added mass of fluid-filled Bellows expansion joints. The Bellows were modeled using axisymmetric shell finite elements, while the fluid region was discretized using axisymmetric triangular elements. The in-vacuo Bellows modes were used as boundary conditions on the potential flow model for the fluid and the added mass determined for each Bellows mode. This added mass was then used to determine the in-fluid Bellows natural frequencies. Experiments were conducted to verify the theoretical model and agreement was found to be very good. The results were also compared with the frequency predictions of previously developed relatively simple theoretical models.
James F. Wilson - One of the best experts on this subject based on the ideXlab platform.
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Mechanics of fluid-activated, clustered satellite Bellows
International Journal of Solids and Structures, 2008Co-Authors: James F. WilsonAbstract:AbstractA Bellows, or a closed thin-walled elastic tube with corrugated walls, undergoes longitudinal extension when subjected to internal fluid pressure. Investigated herein is the mechanical behavior of several pressurized Bellows in clusters, which are designed to bend and twist as well as to extend and compress longitudinally. Bellows in clusters can be employed as robotic limbs, such as manipulator arms and legs for walking machines. For limb bending, analysis shows that there is an optimal geometry for satellite Bellows, or a set of identical Bellows clustered longitudinally about a central core. For limb torsion, the Bellows are clustered in a cylindrical helix whose angle is chosen to produce the desired load–displacement relationships, for instance the highest rotation for a given torque. For both bending and torsional limbs, experimental results are included that exhibit the predicted mechanical behavior
Yong Gang Liu - One of the best experts on this subject based on the ideXlab platform.
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Research the Influence of Curved Shape on the Multilayer Bellows
Applied Mechanics and Materials, 2013Co-Authors: Yong Gang LiuAbstract:As a cylindrical thin-walled container, multilayer Bellows has greater bit shift compensation, vibration and noise reduction capabilities while the appropriate metal and viscoelastic damping materials are adopted. Finite element models are adopted to analyze the loss factor of multilayer Bellows in ANSYS. The strain energy distribution of Multilayer Bellows and viscoelsticity layer are given. According to the strain energy, the influence of structural parameters on the loss factor is studied. The results show that the loss factor can be improved by employing the curved shape with big wave height, small wall thickness, small wave pitch and diameter of Bellows.
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Simulation and Experiment on the Vibration Performance of Pre-Loaded Multi-Plies Bellows
Key Engineering Materials, 2010Co-Authors: Yong Gang Liu, Yu Jun XueAbstract:As major equipment for damping and sound insulation, Bellows are used as flexible joint and elastic element in the pipeline system of naval ships. In this paper, Finite Element Method was adopted to analyze the static and dynamic performance of Bellows. Fourply Bellows model was built, which 0~1.2MPa pressure is loaded. Then the stress, vibrating type and frequency of Bellows were gotten. The result of simulation shows that the frequency of Bellows increases linearly with the increase of pre-loaded. New equipment was produced to test the vibration performance of Bellows. The vibration performance of fourply Bellows was researched. The frequency, stiffness and damping of Bellows were gotten. Some rules were summarized. The result of experiment shows that the frequency and stiffness of Bellows increase with the increase of hydraulic pressure. In addition, while the hydraulic pressure is less than 0.8MPa, the damping of Bellows increases with the increase of hydraulic pressure. While the hydraulic pressure is more than 0.8MPa, the damping decreases with the increase of hydraulic pressure.