COMSOL Multiphysics Modeling of Architected Acoustic Transducers in Oil Drilling

MRS Advances ◽  
2016 ◽  
Vol 1 (24) ◽  
pp. 1755-1760 ◽  
Author(s):  
Runkun Jiang ◽  
Lei Mei ◽  
Q. M. Zhang
Keyword(s):  
Epoxy Resin ◽  
Wave Velocity ◽  
Acoustic Pressure ◽  
Solid Mechanics ◽  
Velocity Shear ◽  
Comsol Multiphysics ◽  
Voltage Response ◽  
Oil Drilling ◽  
Acoustic Transducers ◽  
Piezoelectric Elements

ABSTRACTIn the oil and gas industry, acoustic transducers have been found to provide valuable geological sonic information such as compressional wave velocity, shear wave velocity, and rock formation slowness. These data can be used to indicate lithology, determine porosity, detect over-pressured formation zones, and check well to well correlation. One category of such acoustic transducers is equipped with piezoelectric elements. Conventional piezoelectric transducers are packaged by epoxy resin. Because of the liquid nature of uncured epoxy resin, it is difficult to position the piezoelectric elements accurately. The introduction of polyether ether ketone (PEEK) as the packaging material solved this issue. Due to the ease of machining on solid form, architectures of the composite acoustic transducers can be devised with great flexibility and creativity. These designs can be modeled with finite element methods (FEM) and the best design for the oil drilling application can be finalized and fabricated.COMSOL Multiphysics® solves problems in a programming environment that integrates relevant physics. In this case, it includes electrical circuit, solid mechanics, acoustics, and piezoelectricity. Here a compete model and procedure to study the performance of an architected composite acoustic transducer is provided. The displacement analysis gives insights into the resonance modes of the piezoelectric elements. The acoustics analysis gives the necessary information on the acoustic performance of the transducers, such as acoustic pressure spatial distribution, acoustic pressure frequency response, transmitting voltage response, and directivity. These are important criteria to judge the effectiveness of an architected transducer.

An Epoxy Bonding Apparatus for Applications under Extreme Environment

MRS Advances ◽  
2016 ◽  
Vol 1 (21) ◽  
pp. 1525-1530
Author(s):  
Runkun Jiang ◽  
Lei Mei ◽  
Q. M. Zhang
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Epoxy Resin ◽  
Bonding Strength ◽  
Extreme Environment ◽  
Oil Drilling ◽  
Resin Layer ◽  
Trapped Air ◽  
Acoustic Transducers ◽  
Epoxy Bonding

ABSTRACTA number of electrical components and devices work in extreme environment such as high temperature, high pressure, strong vibration, corrosive chemicals, etc. A common practice to protect them is to shield them in materials that are mechanically and chemically resistant to these harsh conditions. In this scenario, epoxy bonding is preferred and it is crucial to have high bonding strength. One example is the acoustic transducers used in oil drilling. The temperature can reach 200 °C and the pressure can reach 140 MPa. The piezoelectric ceramic parts cannot withstand these conditions so different packaging materials are used such as polyether ether ketone (PEEK).Here an epoxy bonding apparatus is presented that has demonstrated ultrahigh bonding strength. Though epoxy resin is degassed before applying, which gets rid of air bubbles generated in the mixing process, there is trapped air when two surfaces are closed together. This trapped air has minuscule effect for applications in ambient environment, but under extreme environment, it compromises the bonding strength majorly. We devised a vacuum system that contains a motorized stage with the bonding parts attached. After the epoxy is applied and the system is pumped to 1% vacuum, a computer controls the motor to move the bonding parts into contact. Since the entire operation is in vacuum, it leaves no trapped air and results in increased bonding strength. This apparatus confirmed the importance of surface preparation, including removal of air by starting the cure in vacuum (5 mm Hg) and subsequently releasing the vacuum [1].Another technique to improve the bonding strength utilizes the finding that a uniform epoxy resin layer between 50 µm and 150 µm [2] results in the optimal bonding strength. Here we applied spacers such as optic fiber (125 µm in diameter) or glass fiber fabric (150 µm in thickness) in between the bonding surfaces. These spacers ensure that the epoxy resin layer is of uniform thickness. It also utilizes the principle of glass-epoxy compositing to increase mechanical strength by fiber reinforcement and load distribution [3, 4].The above bonding apparatus has been proven to increase the bonding strength by experiments. Acoustic transducers bonded with this technique passed the high pressure, high temperature tests resembling the oil drilling conditions.

Simulation-based assessment of coupled frequency response of magneto-electro-elastic auxetic multifunctional structures subjected to various electromagnetic circuits

2021 ◽  
pp. 146442072110219
Author(s):  
Vinyas Mahesh ◽  
Vishwas Mahesh ◽  
Dineshkumar Harursampath ◽  
Ahmed E Abouelregal
Keyword(s):  
Electric Fields ◽  
Solid Mechanics ◽  
Natural Frequencies ◽  
Comsol Multiphysics ◽  
Simulation Based ◽  
Electric And Magnetic Fields ◽  
Auxetic Structures ◽  
Triangular Elements ◽  
Benchmark Solutions ◽  
Free Vibration Response

This article deals with the modeling of magneto-electro-elastic auxetic structures and developing a methodology in COMSOL Multiphysics® to assess the free vibration response of such structures when subjected to various electromagnetic circuit conditions. The triple energy interaction between elastic, magnetic, and electric fields are established in the COMSOL Multiphysics® using structural mechanics and electromagnetic modules. The multiphase magneto-electro-elastic material with different percentages of piezoelectric and piezomagnetic phases are used as the material. In the solid mechanics module, the piezoelectric and piezomagnetic materials were created in stress-charge and stress-magnetization forms, respectively. The electric and magnetic fields are defined in COMSOL Multiphysics® through electromagnetic equations. Further, the customized controlled meshing constituted of free tetrahedral and triangular elements is adapted to trade-off between the accuracy and the computational expenses. The eigenvalue analysis is performed to obtain the natural frequencies of the MEE re-entrant auxetic structures. Also, the efficiency of smart auxetic structures over conventional honeycomb structures is presented throughout the manuscript. In addition, the discrepancy in the natural frequencies of the structures considering coupled and uncoupled state is also illustrated. It is believed that the modeling procedure and its outcomes serve as benchmark solutions for further design and analysis of smart auxetic magneto-electro-elastic structures.

The Finite Analysis of the Piezoelectric Shell Stack Transducer

2012 ◽  
Vol 430-432 ◽  
pp. 1890-1893 ◽  
Author(s):  
Yu Lu ◽  
Li Kun Wang ◽  
Lei Qin ◽  
Da Ke Cai
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Resonance Frequency ◽  
Epoxy Resin ◽  
Radial Direction ◽  
Experimental Results ◽  
Voltage Response ◽  
Element Analysis ◽  
Analytical Results ◽  
Piezoelectric Shell

Novel piezoelectric shell stack in radial direction had been developed. The shell stack was composed of inner and outer shells which are bonded with each other by epoxy resin. The vibration and electromechanical characteristics of the piezoelectric shell stack were modeled and simulated by Finite Element Analysis (FEA). The send voltage response (SV) of both single and double shells under water were computed. Particularly the analytical results of shell stack presented in resonance frequency varying with the radius and thickness had been compared with experiments. The computations show agreement with the experimental results, and the errors are less than 1.28%.

Development of a novel pulse wave velocity measurement system: Using dual piezoelectric elements

2014 ◽  
Vol 36 (7) ◽  
pp. 927-932 ◽  
Author(s):  
Kei-ichiro Kitamura ◽  
Ryuya Takeuchi ◽  
Kazuhiro Ogai ◽  
Zhu Xin ◽  
Wenxi Chen ◽  
...  
Keyword(s):  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Measurement System ◽  
Velocity Measurement ◽  
Pulse Wave ◽  
Piezoelectric Elements ◽  
Pulse Wave Velocity Measurement

Measurement of low-strain material damping and wave velocity with bender elements in the frequency domain

1998 ◽  
Vol 35 (6) ◽  
pp. 1032-1040 ◽  
Author(s):  
Diego Brocanelli ◽  
Victor Rinaldi
Keyword(s):  
Resonant Frequency ◽  
Frequency Domain ◽  
Wave Velocity ◽  
Damping Ratio ◽  
Velocity Shear ◽  
Silica Sand ◽  
Material Damping ◽  
Bender Elements ◽  
Triaxial Cell ◽  
Cell Components

This paper discusses the application of piezoceramic bender elements for measurement of damping ratio in the frequency domain in a triaxial cell under isotropic confinement. The emitter was excited with a constant voltage and varied frequency sine signal while the phase difference and amplitude in the receiver were measured. The resonant frequency and dynamic characteristics of cell components were analyzed to study the influence of possible additional modes when the modal analysis of a soil sample is performed. Damping ratio and shear wave velocity were determined in a sample of dry silica sand at different confinements from the first resonant mode of the sample. A relationship was found between measured travel time and resonant frequency that satisfies the solution for the general wave equation. The measured damping ratio compares very well with approximated empirical models. It is concluded that the methodology assumed in this work performs satisfactory when the dynamic response of the cell components is properly identified.Key words: wave velocity, shear modulus, material damping, bender elements, frequency analysis, silica sand.

Solid-state explosion simulation in COMSOL Multiphysics

2019 ◽  
Vol 14 (4) ◽  
pp. 253-261
Author(s):  
A.V. Belov ◽  
O.V. Kopchenov ◽  
A.O. Skachkov ◽  
D.E. Ushakov
Keyword(s):  
Solid Mechanics ◽  
Equations Of Motion ◽  
Solid Material ◽  
Normal Pressure ◽  
Steel Grade ◽  
Blast Waves ◽  
Comsol Multiphysics ◽  
Initial Moment ◽  
Steel Tank ◽  
Solving Equations

In this work, the propagation of blast waves in a rock mass caused by a short-term load is considered. Such loads are typical in the construction of tunnels and other excavations using blasting. For modeling by the finite element method, the cross-platform software COMSOL Multiphysics 5.4 was used. The explosion is reproduced in a steel tank whose steel grade is EN 1.7220 4CrMo4. The medium in the tank has the properties of granite rock (Young’s modulus E = 50 GPa, Poisson’s ratio ν = 2/7, Density ρ = 2700 kg/m3 ). The sphere is also a body having the properties of granite. Set to clarify the geometry of the explosion and the area where the mesh is indicated. The tank has dimensions: 10.39 m in length and diameter 2.9 m. The wall thickness of the tank is 0.01 m. To model the explosion, the Solid Mechanics interface was used, located in the Structural Mechanics branch, based on solving equations of motion together with a model for solid material. Results such as displacement, stress, and strain are calculated. The force per unit volume (Fv) is specified by the normal pressure in the sphere. Also, the tensile strength was calculated for this steel grade: upon reaching a certain pressure in the tank (7.26 MPa), the simulation stops, and the system notifies at what point in time the destruction occurred. A Time Dependent Study is used. Seconds are used as a unit of time. The task is calculated from 0 seconds (initial moment of time) to 0.003 seconds (final moment of time) with a construction step of 0.00005.

scholarly journals Viscoelastic Biomarkers of Ex Vivo Liver Samples via Torsional Wave Elastography

Diagnostics ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 111 ◽  
Author(s):  
Inas H. Faris ◽  
Juan Melchor ◽  
Antonio Callejas ◽  
Jorge Torres ◽  
Guillermo Rus
Keyword(s):  
Soft Tissue ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Ex Vivo ◽  
Torsional Wave ◽  
Velocity Shear ◽  
P Waves ◽  
Shear Moduli ◽  
Viscoelastic Parameters

The clinical ultrasound community demands mechanisms to obtain the viscoelastic biomarkers of soft tissue in order to quantify the tissue condition and to be able to track its consistency. Torsional Wave Elastography (TWE) is an emerging technique proposed for interrogating soft tissue mechanical viscoelastic constants. Torsional waves are a particular configuration of shear waves, which propagate asymmetrically in-depth and are radially transmitted by a disc and received by a ring. This configuration is shown to be particularly efficient in minimizing spurious p-waves components and is sensitive to mechanical constants, especially in cylinder-shaped organs. The objective of this work was to validate (TWE) technique against Shear Wave Elasticity Imaging (SWEI) technique through the determination of shear wave velocity, shear moduli, and viscosity of ex vivo chicken liver samples and tissue mimicking hydrogel phantoms. The results of shear moduli for ex vivo liver tissue vary 1.69–4.0kPa using TWE technique and 1.32–4.48kPa using SWEI technique for a range of frequencies from 200 to 800Hz. Kelvin–Voigt viscoelastic parameters reported values of μ = 1.51kPa and η = 0.54Pa·s using TWE and μ = 1.02kPa and η = 0.63Pa·s using SWEI. Preliminary results show that the proposed technique successfully allows reconstructing shear wave velocity, shear moduli, and viscosity mechanical biomarkers from the propagated torsional wave, establishing a proof of principle and warranting further studies.

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