In-Plane Parametric Vibrations of Curved Bellows Subjected to Oscillating Internal Fluid Pressure Excitation

2004 ◽  
Author(s):  
Masahiro Watanabe ◽  
Eiji Tachibana ◽  
Nobuyuki Kobayashi
Keyword(s):  
Stability Analysis ◽  
Natural Frequencies ◽  
Parametric Instability ◽  
Fluid Pressure ◽  
Parametric Vibrations ◽  
Internal Fluid ◽  
Mathieu’S Equation ◽  
Stability Maps ◽  
Plane Direction ◽  
Pressure Excitation

This paper deals with the theoretical stability analysis of in-plane parametric vibrations of a curved bellows subjected to periodic internal fluid pressure excitation. The curved bellows studied in this paper are fixed at both ends rigidly, and are excited by the periodic internal fluid pressure. In the theoretical stability analysis, the governing equation of the curved bellows subjected to periodic internal fluid pressure excitation is derived as a Mathieu’s equation by using finite element method (FEM). Natural frequencies of the curved bellows are examined and stability maps are presented for in-plane parametric instability. It is found that the natural frequencies of the curved bellows decrease with increasing the static internal fluid pressure and buckling occurs due to high internal fluid pressure. It is also found that two types of parametric vibrations, longitudinal and transverse vibrations, occur to the curved bellows in-plane direction due to the periodic internal fluid pressure excitation. Moreover, effects of axis curvature on the parametric instability regions are examined theoretically.

Dynamic Stability of Flexible Bellows Subjected to Periodic Internal Fluid Pressure Excitation

2004 ◽  
Vol 126 (2) ◽  
pp. 188-193 ◽  
Author(s):  
Masahiro Watanabe ◽  
Nobuyuki Kobayashi ◽  
Yuichi Wada
Keyword(s):  
Stability Analysis ◽  
Natural Frequencies ◽  
Theoretical Calculations ◽  
Parametric Instability ◽  
Fluid Pressure ◽  
Internal Fluid ◽  
Mathieu’S Equation ◽  
Stability Maps ◽  
Instability Regions ◽  
Pressure Excitation

This paper deals with the theoretical stability analysis and experimental study of flexible bellows subjected to periodic internal fluid pressure excitation. The bellows studied in this paper are fixed at both ends rigidly, and are excited by the periodic internal fluid pressure. In the theoretical stability analysis, the basic equation of the bellows subjected to periodic internal fluid pressure excitation is derived as a Mathieu’s equation. Natural frequencies of the bellows are examined and stability maps are presented for parametric instability, computed by Bolotin’s method. It is found that the transverse natural frequencies of the bellows decrease with increasing the static internal fluid pressure and buckling occurs due to high internal fluid pressure. It is also found that primary and secondary parametric vibrations occur to the bellows in transverse direction due to the periodic internal fluid pressure excitation. Parametric instability regions are clarified and the theoretical calculations of the parametric instability boundaries are in good agreement with the experimental ones. Moreover, effects of damping and static internal fluid pressure on the parametric instability regions are examined theoretically.

In-plane Parametric Vibrations of Curved Bellows Subjected to Dynamic Internal Fluid Pressure Excitation

2003 ◽  
Vol 2003.7 (0) ◽  
pp. 289-290
Author(s):  
Eiji TACHIBANA ◽  
Masahiro WATANABE ◽  
Kensuke HARA ◽  
Nobuyuki KOBAYASHI
Keyword(s):  
Fluid Pressure ◽  
Parametric Vibrations ◽  
Internal Fluid ◽  
Pressure Excitation

Parametric Instability in Metallic Bellows Due to Internal Fluid Pressure Variation During Earthquake

2007 ◽  
Author(s):  
Nobuyuki Kobayashi ◽  
Takanori Nagai ◽  
Masahiro Watanabe
Keyword(s):  
Parametric Resonance ◽  
Parametric Instability ◽  
Fluid Pressure ◽  
Element Model ◽  
Frequency Component ◽  
Pressure Variation ◽  
Axial Stiffness ◽  
Earthquake Excitation ◽  
Internal Fluid ◽  
Stiffness Variation

This paper deals with the parametric instability of the metallic bellows filled with fluid and subjected to the earthquake excitation. The axial stiffness of the metallic bellows varies due to the internal fluid pressure variation, and this stiffness variation excites the parametric resonance in the metallic bellows. Finite element model about the metallic bellows that connected to the pipe is developed to examine that parametric resonance is excited in the metallic bellows by earthquake motion or not. Numerical simulations are carried out using past recorded earthquake motions. As the results, parametric resonance may be excited in the bellows when the pipe is close to resonance with the predominant frequency component of the earthquake though earthquake is not the harmonic motion.

Parametric Instability in Metallic Bellows Subjected to Seismic Excitation

2010 ◽  
Author(s):  
Nobuyuki Kobayashi ◽  
Keisaku Kitada ◽  
Yoshiki Sugawara
Keyword(s):  
Parametric Instability ◽  
Fluid Pressure ◽  
Element Model ◽  
Frequency Component ◽  
Seismic Excitation ◽  
Axial Stiffness ◽  
Predominant Frequency ◽  
Earthquake Motion ◽  
Static Fluid ◽  
Stiffness Variation

This paper investigates the parametric instability of a metallic bellows filled with fluid and subjected to the variance of dynamic internal pressure due to an earthquake. The axial stiffness of the bellows varies due to the variation in internal static fluid pressure, and this stiffness variation induces a parametric instability in the bellows. A finite element model describing a bellows connected to a pipe is developed to examine the question of whether parametric instability is excited in such bellows by earthquake motion, which is not the harmonic vibration. Numerical simulations and experiments were carried out using the acceleration recorded by past recorded actual earthquakes. We find that indeed parametric instability may appear in the bellows when the natural frequency of the pipe is close to the predominant frequency component of the earthquake, though the earthquake motion is not harmonic.

scholarly journals Tactile Perception for Teleoperated Robotic Exploration within Granular Media

2021 ◽  
Vol 10 (4) ◽  
pp. 1-27
Author(s):  
Shengxin Jia ◽  
Veronica J. Santos
Keyword(s):  
Granular Media ◽  
Fluid Pressure ◽  
Tactile Sensor ◽  
Tactile Perception ◽  
Test Accuracy ◽  
Contact State ◽  
Buried Objects ◽  
Media Type ◽  
Additional Information ◽  
Internal Fluid

The sense of touch is essential for locating buried objects when vision-based approaches are limited. We present an approach for tactile perception when sensorized robot fingertips are used to directly interact with granular media particles in teleoperated systems. We evaluate the effects of linear and nonlinear classifier model architectures and three tactile sensor modalities (vibration, internal fluid pressure, fingerpad deformation) on the accuracy of estimates of fingertip contact state. We propose an architecture called the Sparse-Fusion Recurrent Neural Network (SF-RNN) in which sparse features are autonomously extracted prior to fusing multimodal tactile data in a fully connected RNN input layer. The multimodal SF-RNN model achieved 98.7% test accuracy and was robust to modest variations in granular media type and particle size, fingertip orientation, fingertip speed, and object location. Fingerpad deformation was the most informative modality for haptic exploration within granular media while vibration and internal fluid pressure provided additional information with appropriate signal processing. We introduce a real-time visualization of tactile percepts for remote exploration by constructing a belief map that combines probabilistic contact state estimates and fingertip location. The belief map visualizes the probability of an object being buried in the search region and could be used for planning.

The Application of the Ritz Averaging Method to Determining the Response of Systems with Time Varying Stiffness to Harmonic Excitation

1980 ◽  
Vol 102 (2) ◽  
pp. 384-390 ◽  
Author(s):  
M. Benton ◽  
A. Seireg
Keyword(s):  
Linear System ◽  
Averaging Method ◽  
Approximate Solutions ◽  
Harmonic Excitation ◽  
Time Varying ◽  
Parametric Vibrations ◽  
Nonlinear Characteristics ◽  
Closed Form Solutions ◽  
Mathieu’S Equation ◽  
Stiffness Variation

Parametric vibrations occur in many mechanical systems such as gears where the stiffness variation and external excitations generally occur at integer multiples of the rotational speed. This paper describes a procedure based on the Ritz Averaging Method for developing closed form solutions for the response of such systems to harmonic excitations. Although the method is illustrated in the paper by the case of a linear system with harmonic stiffness fluctuation (defined by Mathieu’s equation) it can be readily applied to determine approximate solutions for systems with nonlinear characteristics and any periodic variations of parameters.

Buckling of Risers in Tension due to Internal Pressure: Nonmovable Boundaries

1983 ◽  
Vol 105 (3) ◽  
pp. 277-281 ◽  
Author(s):  
M. M. Bernitsas ◽  
T. Kokkinis
Keyword(s):  
Internal Pressure ◽  
Fluid Pressure ◽  
Critical Length ◽  
Entire Length ◽  
Tubular Columns ◽  
Internal Fluid ◽  
Static Instability

Open-ended tubular columns may buckle globally as Euler columns due to the action of internal fluid pressure even while they are in tension along their entire length. Hydraulic columns, marine drilling and production risers are, therefore, prone to such static instability. This paper explains this phenomenon, defines the critical riser length for which this instability may occur and provides graphs with values of the critical length which can readily be used for design purposes. Risers with nonmovable boundaries are considered; namely, hinged-hinged, clamped-hinged, hinged-clamped and clamped-clamped risers.

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