Sensitivity Analysis For Estimation Of Complex Modulus Of Viscoelastic Materials By Non-resonance Method

Ahn, Tae-Kil; Kim, K.-J.

doi:10.1006/jsvi.1994.1395

Cited by 12 publications

(4 citation statements)

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“…The dynamic properties of polymers are often measured using rodlike specimens excited to longitudinal vibrations. [15][16][17] However, it is difficult to induce a controlled vibration of a granular material formed into a rod because the material will collapse. If a container such as a tube is used to hold the specimen in the shape of the rod, the friction between the granular material and the container significantly affects material's vibration characteristics.…”

Section: A Measurement Setupmentioning

confidence: 99%

“…The measurement procedures based on this longitudinal vibration of the specimen are well established. [15][16][17] In the transfer function method, a standing wave is analyzed to estimate the wave number from the measured transfer functions. From the measured wave number in the solid, the complex stiffness and the wave speed were obtained:…”

Section: B Wave Propagations In Granular and Porous Mediamentioning

confidence: 99%

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Measurements of the frame acoustic properties of porous and granular materials

Park

2005

The Journal of the Acoustical Society of America

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For porous and granular materials, the dynamic characteristics of the solid component (frame) are important design factors that significantly affect the material’s acoustic properties. The primary goal of this study was to present an experimental method for measuring the vibration characteristics of this frame. The experimental setup was designed to induce controlled vibration of the solid component while minimizing the influence from coupling between vibrations of the fluid and the solid component. The Biot theory was used to verify this assumption, taking the two dilatational wave propagations and interactions into account. The experimental method was applied to measure the dynamic properties of glass spheres, lightweight microspheres, acoustic foams, and fiberglass. A continuous variation of the frame vibration characteristics with frequency similar to that of typical viscoelastic materials was measured. The vibration amplitude had minimal effects on the dynamic characteristics of the porous material compared to those of the granular material. For the granular material, materials comprised of larger particles and those under larger vibration amplitudes exhibited lower frame wave speeds and larger decay rates.

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Section: A Measurement Setupmentioning

confidence: 99%

Section: B Wave Propagations In Granular and Porous Mediamentioning

confidence: 99%

Measurements of the frame acoustic properties of porous and granular materials

Park

2005

The Journal of the Acoustical Society of America

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“…Ahn and Kim [6] analyzed the sensitivity for estimation of complex modulus by dynamic stiffness method. If the specimen is cylindrical, of length L and cross-section area A, then the modulus E is obtained, provided that the specimen is not so short that corrections must be applied, nor so long that creep or toppling occurs.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Many different mechanical testing techniques have been developed over years, such as creep and relaxation test under tension, indentation method [7][8][9], free decay method [10,11], forced vibrated method (dynamic mechanical analysis) [3,6,[12][13][14][15][16][17], resonance method [18][19][20][21], and wave propagation method [22][23][24]. There are also a lot of standards for testing the mechanical properties of viscoelastic materials.…”

Section: Introductionmentioning

confidence: 99%

A new method for identifying mechanical impedence of soft viscoelastic materials

Yin¹

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Following the wider use of viscoelastic materials in industries over the past few decades, being able to characterize mechanical properties of such materials experimentally has become increasing important. However, existing dynamic testing methods such as free decay method, forced vibration method, resonant method and wave propagation method share a common drawback. Each of these methods requires the use of sensors and actuators in exciting and measuring the load and deformation which renders the loading effect of sensors for small samples and the mass effect of sensors at high frequency testing inevitable. Furthermore, installation of sensors and actuators is difficult when the space is small. Samples preparation is also a major problem to overcome in applying the existing methods. Moreover, they are not suitable for in situ testing. Is this study, a new method, transduction matrix method, for testing complex modulus and loss factor of soft viscoelastic materials is designed by using Simultaneous Sensing and Actuating (SSA) technique. In transduction matrix method the actuator is described by a 2x2 transduction matrix which allows the mechanical impedance of the output port of the actuator to be detected from the electrical impedance of the input port while the actuator works as a sensor simultaneously. The detected mechanical impedance can then be analyzed to provide mechanical properties of viscoelastic materials. Transduction matrix method was first applied on electrodynamic actuators. The theoretical model of the shaker was then derived and proved to be the closed form of the four transduction functions based on some simplification on the shaker. Transduction matrix ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library 2.2.4 Wave propagation method 19 2.2.5 Comparison of the methods 22 2.3 Mechanical properties of human tissues 24 2.3.1 In vitro mechanical properties of human tissues 24 2.3.2 In vivo mechanical properties of human skin 25 2.3.3 Equipment for testing mechanical properties of human skin 28 2.4 Summary 31 3. Transduction matrix method and its application on shaker 3.1 3.4.4 Adding mass method 54 3.5 Actuating and sensing capability of shaker 64 3.5.1 Actuating capability of shaker 64 3.5.2 Sensing capability of shaker 65 3.6 Decoupling effect of the transduction matrix method 73 v

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