Semianalytical finite element analysis of active constrained layer damping in cylindrical shells of revolution
TL;DR: In this article, a three noded, isoparametric, multilayered, semianalytical finite element is developed and used for active constrained layer damping in cylindrical shells of revolution.
About: This article is published in Computers & Structures.The article was published on 2001-04-01. It has received 19 citations till now. The article focuses on the topics: Constrained-layer damping & Damping ratio.
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TL;DR: In this paper, a multi-point multipole virtual source simulation method is proposed for solving the acoustic radiation problem of a submerged ACLD shell, where some virtual point sources are assumed to be evenly distributed on the axial line of the cylindrical shell, and the sound pressure could be written in the form of the sum of the wave functions series with the undetermined coefficients, is demonstrated to be accurate to achieve the radiation acoustic pressure of the pulsating and oscillating spheres respectively.
Abstract: Based on the transfer matrix method of exploring the circular cylindrical shell treated with active constrained layer damping (i.e., ACLD), combined with the analytical solution of the Helmholtz equation for a point source, a multi-point multipole virtual source simulation method is for the first time proposed for solving the acoustic radiation problem of a submerged ACLD shell. This approach, wherein some virtual point sources are assumed to be evenly distributed on the axial line of the cylindrical shell, and the sound pressure could be written in the form of the sum of the wave functions series with the undetermined coefficients, is demonstrated to be accurate to achieve the radiation acoustic pressure of the pulsating and oscillating spheres respectively. Meanwhile, this approach is proved to be accurate to obtain the radiation acoustic pressure for a stiffened cylindrical shell. Then, the chosen number of the virtual distributed point sources and truncated number of the wave functions series are discussed to achieve the approximate radiation acoustic pressure of an ACLD cylindrical shell. Applying this method, different radiation acoustic pressures of a submerged ACLD cylindrical shell with different boundary conditions, different thickness values of viscoelastic and piezoelectric layer, different feedback gains for the piezoelectric layer and coverage of ACLD are discussed in detail. Results show that a thicker thickness and larger velocity gain for the piezoelectric layer and larger coverage of the ACLD layer can obtain a better damping effect for the whole structure in general. Whereas, laying a thicker viscoelastic layer is not always a better treatment to achieve a better acoustic characteristic.
2 citations
01 Jan 2023
TL;DR: In this paper , the development and evolution of the constitutive equations for real viscoelastic solid materials in terms of their mechanics and physical behaviors are discussed and reviewed, and more than 14 classical and fundamental types/categories of constitutive models are discussed.
Abstract: Mathematical constitutive models are crucially important for the real viscoelastic solid materials in academic investigation and engineering application. The viscoelastic solid materials and their composites are extensively applied in practice engineering, including biomechanics, aviation, aerospace, and geology, and it has captured more and more attention in recent years. Proper application and selection for the constitutive models of the solid viscoelastic materials will be directly influenced by the investigation accuracy in analysis. The aim of this monograph is to essentially describe the development and evolution of the constitutive equations for viscoelastic solid materials in terms of their mechanics and physical behaviors. For isotropic viscoelastic material, its physical behaviors and mechanical properties are influenced by the environmental effects and external exaction factors. In this report, more than 14 classical and fundamental types/categories of the constitutive models for the real viscoelastic solid material are discussed and reviewed. Physical and mechanics behaviors in the time-, temperature-, moisture-, and frequency-domain are provided. Moreover, the development of the time-temperature-, frequency-temperature-, temperature-moisture-, and pressure-time-dependent constitutive models are also presented. We intend to illustrate and emphasize the mathematical and graphical aspects related to the constitutive models for the real viscoelastic solid material, serving as a foundation reference in future academic investigation and practical application.
10 Jan 2019
TL;DR: It is confirmed that the World Anti-Doping Agency (WSA) has approved the use of nanofiltration membranes for the recovery of phosphorous-contaminated wastewater from the Mediterranean Sea.
Abstract: هلاقم تاعلاطا هدیکچ لماک یشهوژپ هلاقم :تفایرد 14 نمهب 1396 :شریذپ 04 تشهبیدرا 1397 هئارا رد تیاس : 10 دادرخ 1397 رد ،قیقحت نیا لرتنک تاشاعترا وتسا لناپ ا هن هلیسوب یکیمانید راب تحت هیلادنچ بکرم یا راب نیلوا یارب هنیهب کیرتکلاوزیپ رگلمع هلصو ب .تسا هدش یسررب ه ،هدش هدافتسا دودحم ناملا شور زا ،کیرتکلاوزیپ هلصو اب هزاس کیمانید تلاداعم لح روظنم یروئت تایضرف ساسارب هک و لوا هبترم یشرب لکش رییغت رییغت اب لداعم هیلا لدم لکش یاه هیواز رب مکاح تلاداعم .تسا هتفای هعسوت وزیپ هلصو و هتسوپ یارب توافتم یا یم تسد هب نوتلیمه لصا قیرط زا وزیپ هلصو اب لناپ تشه ناملا زا هدافتسا اب و دنیآ یهرگ یم هیزجت هتسوپ ینایم هیلا یور هاگتسد ات دنوش ش لصاح یسیرتام تلاداعم لرتنک رثکادح رایعم زا کیرتکلاوزیپ رگلمع یارب هنیهب هزادنا و لحم نتفای یارب .دو قبط .تسا هدش هدافتسا یریذپ هفلوم دنیآرب اب بسانتم کیرتکلاوزیپ هلصو هب هدش لامعا ژاتلو ،هدافتسا دروم یلرتنک نوناق یم رگسح بصن لحم هطقن رد تعرس یاه .دشاب هحص تهج ومرف درکلمع یراذگ هب جیاتن ،دودحم ناملا لدم و یدنبل لناپ یعیبط سناکرف یارب هدمآ تسد هناوتسا یا اب هلصو نودب هیلا دنچ هدش هسیاقم دوجوم عجارم هب هتسب و زاب هقلح یلرتنک تلااح یارب یسناکرف خساپ ،هدش هنیهب متسیس کیمانید نتشاد اب سپس .دنا هدمآ تسد هرهب ریداقم ریثات اهتنا رد و تسا هدش هتشاذگ شیامن هب تاشاعترا ندش اریم تعرس و ینامز خساپ یور هلصو و لناپ یسدنه داعبا و یلرتنک .تسا :ناگژاو دیلک لناپ وتسا ا هن یا هیلادنچ بکرم کیرتکلاوزیپ رگلمع هلصو دودحم ناملا تاشاعترا لرتنک
TL;DR: In this article, the damping characteristics of an actively constrained viscoelastic material layer are examined because of the inclusion of dispersed graphite particles within the viscous material layer.
Abstract: In this work, the damping characteristics of an actively constrained viscoelastic material layer are examined because of the inclusion of dispersed graphite particles within the viscoelastic materi...
Cites background from "Semianalytical finite element analy..."
...A majority of the research articles on ACLD treatment address its mathematical modelling (Lam et al., 1995; Park and Baz, 2001; Ray and Baz, 1997; Saravanan et al., 2001; Vasques et al., 2006)....
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References
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TL;DR: Piezoelectric crystals and their application to ultrasonics were discussed in this paper, where the authors proposed a method for the extraction of the ultrasonic properties of these crystals.
Abstract: Piezoelectric crystals and their application to ultrasonics , Piezoelectric crystals and their application to ultrasonics , دانشگاه تهران
1,057 citations
TL;DR: In this paper, a finite element formulation which includes the piezoelectric or electroelastic effect is given, a strong analogy is exhibited between electric and elastic variables, and a stiffness finite element method is deduced.
Abstract: A finite element formulation which includes the piezoelectric or electroelastic effect is given. A strong analogy is exhibited between electric and elastic variables, and a ‘stiffness’ finite element method is deduced. The dynamical matrix equation of electroelasticity is formulated and found to be reducible in form to the well-known equation of structural dynamics, A tetrahedral finite element is presented, implementing the theorem for application to problems of three-dimensional electroelasticity.
972 citations
TL;DR: In this article, a hybrid damping design that integrates active and passive dampings through intelligent constrained layer (ICL) treatments is proposed, which consists of a viscoelastic shear layer sandwiched between a piezoelectric constraining cover sheet and the structure to be damped.
Abstract: This paper is to propose a viable hybrid damping design that integrates active and passive dampings through intelligent constrained layer (ICL) treatments. This design consists of a viscoelastic shear layer sandwiched between a piezoelectric constraining cover sheet and the structure to be damped. According to measured vibration response of the structure, a feedback controller regulates axial deformation of the piezoelectric layer to perform active vibration control. In the meantime, the viscoelastic shear layer provides additional passive damping. The active damping component of this design will produce adjustable and significant damping. The passive damping component of this design will increase gain and phase margins, eliminate spillover, reduce power consumption, improve robustness and reliability of the system, and reduce vibration response at high frequency ranges where active damping is difficult to implement. To model the dynamics of ICL, an eighth-order matrix differential equation governing bending and axial vibrations of an elastic beam with the ICL treatment is derived. The observability, controllability, and stability of ICL are discussed qualitatively for several beam structures. ICL may render the system uncontrollable or unobservable or both depending on the boundary conditions of the system. Finally, two examples are illustrated in this paper. The first example illustrates how an ICL damping treatment, which consists of an idealized, distributed sensor and a proportional-plus-derivative feedback controller, can reduce bending vibration of a semi-infinite elastic beam subjected to harmonic excitations. The second example is to apply an ICL damping treatment to a cantilever beam subjected to combined axial and bending vibrations. Numerical results show that ICL will produce significant damping.
172 citations
TL;DR: In this paper, a finite element model is developed to analyze the dynamics and control of flat plates which are partially treated with multi-patches of active constrained layer damping (ACLD) treatments.
Abstract: Bending vibration of flat plates is controlled using patches of active constrained layer damping (ACLD) treatments. Each ACLD patch consists of a visco-elastic damping layer which is sandwiched between two piezo-electric layers. The first layer is directly bonded to the plate to sense its vibration and the second layer acts as an actuator to actively control the shear deformation of the visco-elastic damping layer according to the plate response. With such active/passive control capabilities the energy dissipation mechanism of the visco-elastic layer is enhanced and the damping characteristics of the plate vibration is improved. A finite element model is developed to analyze the dynamics and control of flat plates which are partially treated with multi-patches of ACLD treatments. The model is validated experimentally using an aluminum plate which is 0.05 cm thick, 25.0 cm long and 12.5 cm wide. The plate is treated with two ACLD patches, each of which is made of SOUNDCOAT (Dyad 606) visco-elastic layer sandwiched between two layers of AMP/polyvinylidene fluoride (PVDF) piezo-electric films. The piezo-electric axes of the patches are set at zero degrees relative to the plate longitudinal axis to control the bending mode. The effect of the gain of a proportional control action on the system performance is presented. Comparison between the theoretical predictions and the experimental results suggest the validity of the developed finite element model. Also, comparisons with the performance of conventional passive constrained layer damping clearly demonstrate the merits of the ACLD as an effective means for suppressing the vibration of flat plates.
146 citations
TL;DR: In this paper, the design parameters and control gains of the resulting Active Constrained Layer Damping (ACLD) treatments are optimally selected, in order to maximize the modal damping ratios and minimize the total weight of the damping treatment.
Abstract: Conventional Passive Constrained Layer Damping (PCLD) treatments with viscoelastic cores are provided with built-in sensing and actuation capabilities to actively control and enhance their vibration damping characteristics. The design parameters and control gains of the resulting Active Constrained Layer Damping (ACLD) treatments are optimally selected, in this paper, for fully-treated beams using rational design procedures. The optimal thickness and shear modulus of the passive visco-elastic core are determined first to maximize the modal damping ratios and minimize the total weight of the damping treatment. The control gains of the ACLD are then selected using optimal control theory to minimize a weighted sum of the vibrational and control energies. The theoretical performance of beams treated with the optimally selected ACLD treatment is determined at different excitation frequencies and operating temperatures. Comparisons are made with the performance of beams treated with optimal PCLD treatments and untreated beams which are controlled only by conventional Active Controllers (AC). The results obtained emphasize the potential of the optimally designed ACLD as an effective means for providing broad-band attenuation capabilities over wide range or operating temperatures as compared to PCLD treatments.
141 citations