Boundary Conditions Analysis of Circular Capacitive Micromachined Ultrasonic Transducer (CMUT) Devices

2021 ◽  
Vol 15 ◽  
Author(s):  
Jiujiang Wang ◽  
Yuanyu Yu ◽  
Jiangming Kuang ◽  
Shuang Zhang ◽  
Jing Xu ◽  
...  
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Integrated Circuit ◽  
Ultrasonic Transducer ◽  
Equilibrium Conditions ◽  
Elastic Boundary ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
New Type ◽  
Release Method ◽  
Fixed Boundary Condition

Background: Capacitive micromachined ultrasonic transducer (CMUT) is a new type ultrasound transducer which has gained more and more research interests in ultrasound imaging because of its wider bandwidth, higher receiving sensitivity and more likely to be integrated with integrated circuit (IC). Analytical solution is intuitive, fast and convergent among simulation methods. The membrane deflection is important to the CMUT performance. The deformation for a circular CMUT under an external force can be described by von Kármán equations. Objective: To find suitable boundary conditions that are crucial for the governing equations to be properly solved to get the analytical solutions for membrane deformation. Methods: Features of two commonly used CMUT fabrication methods, sacrificial release method (SR) and wafer bonding (WB) method, are introduced. The force and moment equilibrium conditions of the supporting post are analyzed to get the boundary condition equations. Results: The analytical results match well with finite element method (FEM) results for the fixed boundary condition while there are still some difference for the elastic boundary condition. Conclusion: The boundary conditions for SR fabricated devices are elastic support while the boundary conditions for WB fabricated devices are fixed.

Full Sliding Adhesive-Like Contact of V-Belts

2002 ◽  
Vol 124 (4) ◽  
pp. 706-712 ◽  
Author(s):  
Go¨ran Gerbert ◽  
Francesco Sorge
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Power Transmission ◽  
A Priori ◽  
Belt Drive ◽  
Natural Boundary ◽  
Condition Problem ◽  
New Type ◽  
Wrap Angle ◽  
Natural Boundary Conditions

Analysis of power transmission in a belt drive consisting of, e.g., two pulleys might be treated as a boundary value problem. Tight side tension FT, slack side tension FS and the wrap angle α are the three natural boundary conditions. In the literature, theories are developed where seating and unseating as well as the power transmitting part of the contact are considered. The solutions presented so far don’t fulfill the boundary conditions properly, since a certain tension ratio FT/FS is associated with a certain contact angle and not an a priori specified one. It appears that a new type of full sliding solution must be introduced to handle the boundary condition problem. During part of the contact there is almost no tension variation in spite of the full sliding conditions. The designation adhesive-like solution is here introduced for that part. Conditions and character of the adhesive-like solution are outlined in the paper.

Reception characteristics investigation and measurement of capacitive micromachined ultrasonic transducer

Sensor Review ◽  
2019 ◽  
Vol 40 (2) ◽  
pp. 237-246
Author(s):  
Hongliang Wang ◽  
Xiangjun Wang ◽  
Changde He ◽  
Chenyang Xue
Keyword(s):  
Ultrasonic Transducer ◽  
State Equation ◽  
Structure Design ◽  
Pressure Amplitude ◽  
Analysis Model ◽  
Content Type ◽  
Lumped Parameter ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
New Type ◽  
The Time Domain

Purpose As a new type of ultrasonic transducer with significant advantages, capacitive micromachined ultrasonic transducer (CMUT) has good application prospect. The reception characteristic of the CMUT is one of the important factors determining the application effect. This paper aims to study the reception characteristics of CMUT. Design/methodology/approach In this paper, the state equation is deduced and the analysis model is established in SIMULINK environment based on the lumped parameter system model of the CMUT cell. Based on this analysis model, the influencing factors of CMUT reception characteristics are studied and investigated, and the time-domain and frequency-domain characteristics are investigated in detail. Findings The analysis results show that parameters directly affect the reception characteristics of the CMUT, such as direct current (DC) bias voltage, input sound pressure amplitude and frequency. At the same time, the measurement system is built and the reception characteristics are verified. Originality/value This paper provides an effective method for rapid analyzing the reception characteristics of CMUT. These results provide an important theoretical basis and reference for further optimization of CMUT structure design, and lay a good foundation for the practical application measurement.

A seepage outlet boundary condition in hemodynamics modeling

2017 ◽  
Vol 62 (5) ◽  
Author(s):  
Fan He ◽  
Lu Hua ◽  
Li-jian Gao
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Shear Stresses ◽  
Arterial Circulation ◽  
Cfd Models ◽  
Fluctuation Range ◽  
New Type ◽  
Computational Fluid Dynamics Cfd ◽  
Methodological Paper ◽  
Outlet Boundary Condition

AbstractBackground:In computational fluid dynamics (CFD) models for hemodynamics applications, boundary conditions remain one of the major issues in obtaining accurate fluid flow predictions.Objective:As an important part of the arterial circulation, microcirculation plays important roles in many aspects, such as substance exchange, interstitial fluid generation and inverse flow. It is necessary to consider microcirculation in hemodynamics modeling. This is a methodological paper to test and validate a new type of boundary condition never applied to microcirculation before.Methods:In order to address this issue, we introduce microcirculation as a seepage outlet boundary condition in computational hemodynamics. Microcirculation is treated as a porous medium in this paper. Numerical comparisons of the seepage and traditional boundary conditions are made.Results:The results show that the seepage boundary condition has significant impacts on numerical simulation. Under the seepage boundary condition, the fluctuation range of the pressures progressively rises in the artery zone. The results obtained from the traditional boundary condition show that the pressure fluctuation range gradually falls. In addition, the wall shear stresses under the traditional outlet boundary condition are much higher than those under the seepage outlet boundary condition.Conclusions:The proposed boundary condition is more suitable in hemodynamics modeling.

The sensibility on dynamic characteristics of pre-pressure thin-wall pipe under elastic boundary conditions

2016 ◽  
Vol 231 (6) ◽  
pp. 995-1009 ◽  
Author(s):  
Li Chaofeng ◽  
Tang Qiansheng ◽  
Miao Boqing ◽  
Wen Bangchun
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Natural Frequency ◽  
Forced Vibration ◽  
Vibration Response ◽  
Spring Stiffness ◽  
Pressure Pipe ◽  
Elastic Boundary ◽  
Elastic Boundary Conditions ◽  
Distributed Pressure

Consideration is given to dynamic behavior of cylindrical pressure pipe with elastic boundary conditions. Based on Sanders’ shell theory and Hamilton principle, the system equations are established for integrating the uniform distributed pressure into the elastic boundary condition. In the analytical formulation, the Rayleigh–Ritz method with a set of displacement shape functions is used to deduce mass, damping, and stiffness matrices of the pipe system. The displacements in three directions are represented by the characteristic orthogonal polynomial series and trigonometric functions which are satisfied with the elastic boundary conditions, which are represented as four sets of independent springs placed at the ends including three sets of linear springs and one set of rotational spring. The pressure pipe always suffers a uniform distributed pressure in radial direction. To verify the accuracy and reliability of the present method, several numerical examples with classical boundary condition, including free and simply supported supports are listed and comparisons are made with open literature. Then the influences of boundary restraint stiffness and the distributed pressure on natural frequency and the forced vibration response are studied: The natural frequencies increase significantly as the restraint stiffness or the distributed pressure increases. Compared to the rotational spring stiffness, the stiffnesses of axial, radial, and circumferential springs have more significant effect on natural frequency. And the lower modes are more sensitive on restraint stiffness than higher modes. But the variation of natural frequency with respect to the spring stiffness decreases monotonically with the increasing distributed pressure. The forced vibration response is also affected by the restraint stiffness.

Analysis of Structure Dynamic Characteristics of a Metal Plate

2012 ◽  
Vol 268-270 ◽  
pp. 1075-1079
Author(s):  
Chen Zhang ◽  
Zhi Gang Yang ◽  
Yin Zhi He
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Modern Method ◽  
Metal Plate ◽  
Mode Shapes ◽  
Structure Dynamic ◽  
Fixed Boundary Condition

Modal analysis is a modern method to study structure dynamic characteristics. In this paper, computational modal analysis with Finite Element Method is applied to simulate an aluminum plate with the dimension of 160mm*240mm*1.5mm under different boundary conditions (Including free boundary condition and fixed boundary condition). The results of structure natural frequencies and mode shapes of this plate show obvious difference between the two boundary conditions.

Full Sliding “Adhesive-Like” Contact of V-Belts

2000 ◽  
Author(s):  
Göran Gerbert ◽  
Francesco Sorge
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Power Transmission ◽  
A Priori ◽  
Belt Drive ◽  
Natural Boundary ◽  
Condition Problem ◽  
New Type ◽  
Wrap Angle ◽  
Natural Boundary Conditions

Abstract Analysis of power transmission in a belt drive consisting of e. g. two pulleys might be treated as a boundary value problem. Tight side tension FT, slack side tension FS and the wrap angle α are the three natural boundary conditions. In the literature, theories are developed where seating and unseating as well as the power transmitting part of the contact are considered. The solutions presented so far don’t fulfil the boundary conditions properly, since a certain tension ratio FT/FS is associated with a certain contact angle and not an a priori specified one. It appears that a new type of full sliding solution must be introduced to handle the boundary condition problem. During part of the contact there is almost no tension variation in spite of the full sliding conditions. The designation adhesive like solution is here introduced for that part. Conditions and character of the adhesive like solution are outlined in the paper.

Sturm-Liouville Problem for Stationary Differential Operator with Nonlocal Two-Point Boundary Conditions

2006 ◽  
Vol 11 (1) ◽  
pp. 47-78 ◽  
Author(s):  
S. Pečiulytė ◽  
A. Štikonas
Keyword(s):  
Boundary Condition ◽  
Differential Operator ◽  
Boundary Conditions ◽  
Nonlocal Boundary Condition ◽  
Nonlocal Boundary ◽  
Liouville Problem ◽  
Complex Case ◽  
Qualitative Behavior ◽  
Point Boundary ◽  
Sturm Liouville

The Sturm-Liouville problem with various types of two-point boundary conditions is considered in this paper. In the first part of the paper, we investigate the Sturm-Liouville problem in three cases of nonlocal two-point boundary conditions. We prove general properties of the eigenfunctions and eigenvalues for such a problem in the complex case. In the second part, we investigate the case of real eigenvalues. It is analyzed how the spectrum of these problems depends on the boundary condition parameters. Qualitative behavior of all eigenvalues subject to the nonlocal boundary condition parameters is described.

Design and Experiment of Capacitive Micromachined Ultrasonic Transducer Array for High-Frequency Underwater Imaging

2020 ◽  
Vol 13 ◽  
Author(s):  
Yuanyu Yu ◽  
Jiujiang Wang ◽  
Xin Liu ◽  
Sio Hang Pun ◽  
Weibao Qiu ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
High Frequency ◽  
Ultrasonic Transducer ◽  
Center Frequency ◽  
Design Parameters ◽  
Underwater Imaging ◽  
Release Process ◽  
Steel Wires ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
Frequency Ultrasound

Background:: Ultrasound is widely used in the applications of underwater imaging. Capacitive micromachined ultrasonic transducer (CMUT) is a promising candidate to the traditional piezoelectric ultrasonic transducer. In underwater ultrasound imaging, better resolutions can be achieved with a higher frequency ultrasound. Therefore, a CMUT array for high-frequency ultrasound imaging is proposed in this work. Methods:: Analytical methods are used to calculate the center frequency in water and the pull-in voltage for determining the operating point of CMUT. Finite element method model was developed to finalize the design parameters. The CMUT array was fabricated with a five-mask sacrificial release process. Results:: The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional bandwidth of 123 %. The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment was carried out with the target of three steel wires. Conclusion:: In this study, we have developed CMUT for high-frequency underwater imaging. The experiment showed that the CMUT can detect the steel wires with the diameter of 100 μm and the axial resolution was 0.582 mm, which is close to one wavelength of ultrasound in 2.6 MHz.

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