• Title/Summary/Keyword: viscoelastic effect

Search Result 274, Processing Time 0.025 seconds

Porosity-dependent vibration investigation of functionally graded carbon nanotube-reinforced composite beam

  • Abdulmajeed M. Alsubaie;Ibrahim Alfaqih;Mohammed A. Al-Osta;Abdelouahed Tounsi;Abdelbaki Chikh;Ismail M. Mudhaffar;Saeed Tahir
    • Computers and Concrete
    • /
    • v.32 no.1
    • /
    • pp.75-85
    • /
    • 2023
  • This work utilizes simplified higher-order shear deformation beam theory (HSDBT) to investigate the vibration response for functionally graded carbon nanotube-reinforced composite (CNTRC) beam. Novel to this work, single-walled carbon nanotubes (SWCNTs) are distributed and aligned in a matrix of polymer throughout the beam, resting on a viscoelastic foundation. Four un-similar patterns of reinforcement distribution functions are investigated for the CNTRC beam. Porosity is another consideration taken into account due to its significant effect on functionally graded materials (FGMs) properties. Three types of uneven porosity distributions are studied in this study. The damping coefficient and Winkler's and Pasternak's parameters are considered in investigating the viscosity effect on the foundation. Moreover, the impact of different parameters on the vibration of the CNTRC beam supported by a viscoelastic foundation is discussed. A comparison to other works is made to validate numerical results in addition to analytical discussions. The findings indicate that incorporating a damping coefficient can improve the vibration performance, especially when the spring constant factors are raised. Additionally, it has been noted that the fundamental frequency of a beam increases as the porosity coefficient increases, indicating that porosity may have a significant impact on the vibrational characteristics of beams.

Plane waves in generalized magneto-thermo-viscoelastic medium with voids under the effect of initial stress and laser pulse heating

  • Othman, Mohamed I.A.;Fekry, Montaser;Marin, Marin
    • Structural Engineering and Mechanics
    • /
    • v.73 no.6
    • /
    • pp.621-629
    • /
    • 2020
  • The present paper aims to study the influence of the magnetic field and initial stress on the 2-D problem of generalized thermo-viscoelastic material with voids subject to thermal loading by a laser pulse in the context of the Lord-Shulman and the classical dynamical coupled theories. The analytical expressions for the physical quantities are obtained in the physical domain by using the normal mode analysis. These expressions are calculated numerically for a specific material and explained graphically. Comparisons are made with the results predicted by the Lord-Shulman and the coupled theories in the presence and absence of the initial stress and the magnetic field.

Numerical Computation of the Stress Itensity Factor of A Cracked Viscoelastic Body Under the Impact Load (충격하중을 받는 점탄성 균열의 응력확대계수 계산)

  • Lee Sung-Hee;Sim Woo-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.28 no.10
    • /
    • pp.1583-1589
    • /
    • 2004
  • In this paper, A new finite element method for the time domain analysis of the dynamic stress intensity factor of two-dimensional viscoelastic body with a stationary central crack under the transient dynamic load is presented, which is based on the intergrodifferential equations of motion in the isotropic linear viscoelasticity and the Galerkin's method. The vlscoelastic material is assumed to be elastic in dilatation and behaves like a standard linear solid in shear. As a numerical example, the Chen's problem in viscoelastodynamic version is solved for the parametric study about the effect of viscosity and relaxation time on the dynamic stress intensity factor.

Studies on Rheological Properties of High Solids Coating Colors (I) - Effect of Rheology Modifiers on Viscoelastic Properties -

  • Yoo, Sung-Jong;Cho, Byoung-Uk;Lee, Yong-Kyu
    • Journal of Korea Technical Association of The Pulp and Paper Industry
    • /
    • v.44 no.5
    • /
    • pp.39-45
    • /
    • 2012
  • For a fundamental study for high concentration pigment coating, the effects of alkali swellable emulsion (ASE) type rheology modifier and surface adsorption emulsion (SAE) type rheology modifier on both the stability and the viscoelastic behavior of a coating color were elucidated. The coating color prepared with SAE type rheology modifier showed superior thermal and mechanical stability than that with ASE type. In the high concentration and high speed coating process, the mechanical stability of a coating color was a key parameter since both impact force and shear force were increased with the increase of coating color concentration and coating speed, respectively.

Effect of elasticity of aqueous colloidal silica solution on chemical absorption of carbon dioxide with 2-amino-2-methyl-1-propanol

  • Park, Sang-Wook;Choi, Byoung-Sik;Lee, Jae-Wook
    • Korea-Australia Rheology Journal
    • /
    • v.18 no.3
    • /
    • pp.133-141
    • /
    • 2006
  • Carbon dioxide was absorbed into the aqueous nanometer sized colloidal silica solution of 0-31 wt% and 2-amino-2-methyl-1-propanol of $0-2kmol/m^3$ in a flat-stirred vessel with the impeller of various sizes and speeds at $25^{\circ}C$ and 0.101 MPa to measure the absorption rate of $CO_2$. The volumetric liquid-side mass transfer coefficient$(k_La)\;of\;CO_2$ was used to obtain the empirical correlation formula containing the rheological behavior of the aqueous colloidal silica solution. Reduction of the measured $k_La$ was explained by the viscoelastic properties of the aqueous colloidal silica solution. The theoretical value of the absorption rate of $CO_2$ was estimated from the model based on the film theory accompanied by chemical reaction and compared with the measured value.

Effect on the Deburring of Spring Collet Burr by Abrasive Flow System (입자유동시스템에 의한 스프링콜릿 버의 디버링 효과)

  • 김정두
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
    • /
    • 1998.10a
    • /
    • pp.192-197
    • /
    • 1998
  • Abrasive flow machining is useful to abrasive polish a internal or external surface of the free shape dimensional parts, which are used in many fields such as machine tool parts, semi-conductor, and medical component industries. The machining process is that two hydraulic cylinders, which are located surface to surface, are enforce media to the passage between workpiece and tooling part alternately, and then the abrasives included in the media pass the passage and polish the surface of workpiece. The media which is made of polymer and abrasive plays complex have workpiece by its viscoelastic characteristics. In this study, the media for AMF was made by mixing viscoelastic polymer with alumina and silicon carbide abrasive respectively. As a result, alumina include media is also the experiments of deburring the inside burr of in order to analyse the deburring machinability of abrasive flow machining according to various machining parameters which were media flow rate extrusion pressure, passage gap, media viscosity, abrasive content, and abrasive grain size.

  • PDF

An Analysis of Vibration and Sound Radiation of Sandwich Panels Using the Rayleigh-Ritz Method (Rayleigh-Ritz법을 이용한 샌드위치 패널의 진동 및 소음방사 특성 분석)

  • Kim, Dong-Kyu;Kim, Jae-Hyun;Jeon, Jin-Yong;Park, Jun-Hong
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.21 no.5
    • /
    • pp.430-436
    • /
    • 2011
  • The purpose of this study is to analyze the vibration and sound generation characteristics of the sandwich panel. Two thick panels were assumed to be separated by a compliant viscoelastic core. The transverse vibration induced by an external impact was analyzed using the Rayleigh-Ritz method. For applying arbitrary boundary condition of the panels, the edges were assumed to be supported by the translational and rotational springs. The beam functions were used as the trial functions. The effect of the boundary condition and viscoelastic core on the resulting vibration characteristics was investigated. The radiated sound power was analyzed using the proposed numerical model and the Rayleigh integral. The dynamic properties of the core and the mass-stiffness-mass resonance frequency had significant influence on the impact sound.

Visco-Elastic Fracture Analysis of IC Package under Thermal Loading (열하중하에 있는 IC 패키지의 점탄성 파괴해석)

  • 이강용;양지혁
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.15 no.1
    • /
    • pp.43-50
    • /
    • 1998
  • The purpose of the paper is to protect the damage of plastic IC package with searching the cause of the fracture due to the delamination and crack when the encapsulant of plastic IC package is on viscoelastic behavior with the effect of creep on high temperature, The model for analysis is the plastic SOJ package with dimpled diepad in the IR soldering process of surface mounting technology. The risk of delamination with calculating the distribution of viscoelastic thermal stress in the package without the crack in the surface mounting process is checked. The package model with the perfect delamination between chip and diepad is chosen to estimate the resistance against fracture in thermal loading with calculating C (t)-integrals according to the change of the design. The optimum design to depress the delamination and crack is presented.

  • PDF

A study on the flow characteristics of non-Newtonian fluid flows in dividing tubes (분기관에서 비뉴턴 유체의 유동특성에 관한 연구)

  • 이행남;하옥남;전운학
    • Journal of Ocean Engineering and Technology
    • /
    • v.10 no.4
    • /
    • pp.118-127
    • /
    • 1996
  • Flow patterns of fluid flow in dividing trbe were visualized, and the energy losses due to dividing were measured in laminar dividing flow of the viscoelastic fluid and its solution in tube junctions with dividing angles of $90^{\circ}$, $60^{\circ}$, $65^{\circ}$ and $15^{\circ}$. Two separation zones were observed. swelling of the streamline to the main tube or to lateral tube was observed. The sizes of the separation zones depend on the Reynolds number, the dividing angle and the dividing flow rate. The energy loss coefficients decrease with increasing Reynolds number, but their decreasing rate decreases with increasing Reynolds number as the sizes of the separation zone increase. The effect of dividing angle on the energy loss coefficients and separation is greater for main tube than for the lateral tube.

  • PDF

Study on Transient Flow in Pipeline with Flexible Tube (탄성관을 삽입한 관로에서의 비정상류에 관한 연구)

  • Kim, Young-Joon;Tsukamoto, Hiroshi
    • 유체기계공업학회:학술대회논문집
    • /
    • 2005.12a
    • /
    • pp.825-828
    • /
    • 2005
  • Experimental and numerical study was done to confirm the effect of the flexible tube in pipeline on transient flow oscillation. Experiment was made for a pipeline with and without deformable flexible tube using a single pumping system of main stainless pipe. The wave speeds of main pipe and flexible tube were calculated from the pipe material properties, structures, and boundary conditions. Time dependent pressure fluctuations were calculated for the pipeline using the simple and the Kelvin-Voigt viscoelastic models for the deformation of main pipe and flexible tube. Pressure calculated by the Kelvin-Voigt viscoelastic model showed better agreement with measured one than pressure by the simple model. Experimental and numerical results show that the maximum pressure as well as amplitude of pressure oscillation was decreased by inserting short flexible tube in pipeline. Hence, inserted short flexible tube to pipeline was found to be effective for the suppression of strong pressure oscillation. Moreover, the wave speed in pipe was discussed based on numerical and experimental results.

  • PDF