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.

Shear Strength Monitoring System Based on Measurement of Shear Wave Velocity and Moisture Content

2014 ◽  
Vol 635-637 ◽  
pp. 750-754
Author(s):  
Peng Hu ◽  
Qing Li ◽  
Yi Wei Xu ◽  
Nan Ying Shentu ◽  
Quan Yuan Peng
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Shear Wave ◽  
Monitoring System ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Bender Elements ◽  
Strength Measurement ◽  
Soil Shear Strength ◽  
The Relationship

Expound the importance of soil shear strength measurement at mudslide hidden point to release the loss caused by the disaster, explain the relationship between shear wave velocity, moisture content and shear strength, design the shear strength monitoring system combining the shear wave velocity measured by Piezoelectric bender elements and moisture content.

Preparation and Vibration Damping Characteristics of Wide Frequency Domain PVMQ/IIR Foam Materials

2012 ◽  
Vol 538-541 ◽  
pp. 2298-2303
Author(s):  
Shi Kai Luo ◽  
Guo Fang Ding ◽  
Jing Li Li ◽  
Yan Song Sha ◽  
Qing Min Cheng ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Wide Temperature Range ◽  
Damping Ratio ◽  
Vibration Damping ◽  
Simple Equation ◽  
Structural Damping ◽  
Damping Characteristics ◽  
Damping Materials ◽  
Foaming Technology ◽  
Isoprene Rubber

In this paper, we prepared foaming silicon rubber (PVMQ) /isobutylene-isoprene rubber (IIR) composites with chemical foaming technology. The DMA tests results showed that these foaming materials have effective damping characteristics in a wide temperature range. With the special vibrator, we found that the PVMQ/IIR foams that we prepared were the damping materials which has wide frequency domain, because they can keep high damping ratio in a wide frequency domain. When the preloading was between 1.0 mm and 1.7 mm, the structural damping did not change obviously. According to tests, we found that the damping ratio of these foams was fit to the simple equation .

scholarly journals INFLUENCE OF MATERIAL DAMPING ON THE RESPONSE OF UNDERGROUND STRUCTURES SUBJECTED TO EARTHQUAKE

2020 ◽  
Vol 26 ◽  
pp. 64-70
Author(s):  
Veronika Pavelcová ◽  
Tereza Poklopová ◽  
Michal Šejnoha ◽  
Tomáš Janda
Keyword(s):  
Damping Ratio ◽  
Underground Structure ◽  
Eurocode 8 ◽  
Viscous Damping ◽  
Material Damping ◽  
Underground Structures ◽  
Fixed Boundary ◽  
Design Spectrum ◽  
Rayleigh Damping ◽  
Element Simulation

The paper describes a finite element simulation of the response of a real underground structure subjected to earthquake using GEO5 FEM program. It concentrates on the influence of material damping with respect to a specific type of boundary condition prescribed at the bottom of the analyzed domain. It is seen that considering material damping is inevitable particularly in case of so called fixed boundary conditions to arrive at meaningful results. This is demonstrated on an artificial earthquake generated according to a design spectrum defined in Eurocode 8. A viscous damping ratio combined with the results of eigenvalue analysis is used to derive parameters of Rayleigh damping for three specific scenarios promoting the approach based on the lowest natural frequency as sufficiently accurate for the present task.

Surface-mounted bender elements for measuring horizontal shear wave velocity of soils

2008 ◽  
Vol 9 (11) ◽  
pp. 1490-1496 ◽  
Author(s):  
Yan-guo Zhou ◽  
Yun-min Chen ◽  
Yoshiharu Asaka ◽  
Tohru Abe
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Horizontal Shear ◽  
Bender Elements

Dielectric dispersion measurement of silica sand in frequency domain

2021 ◽  
Author(s):  
Keiichi Suzuki ◽  
Jun Ando ◽  
Taro Kusagaya ◽  
Eiichiro Nishiyama ◽  
Tadanori Goto ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Dielectric Dispersion ◽  
Silica Sand ◽  
Dispersion Measurement

Theoretical and experimental studies of a novel nested oscillator with a high-damping characteristic

2020 ◽  
pp. 107754632094378
Author(s):  
Haiping Liu ◽  
Kaili Xiao ◽  
PengPeng Zhao ◽  
Dongmei Zhu
Keyword(s):  
Resonant Frequency ◽  
Vibration Suppression ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Harmonic Balance Method ◽  
Design Parameters ◽  
Base Excitation ◽  
Oscillation System ◽  
Equivalent Damping ◽  
Vibration Transmissibility

Stiffness and damping of a structure usually show the opposite change so that the resonant frequency and the static load bearing capacity of a mechanical system often exhibit contradiction. To solve this dilemma, a novel high-damping oscillator which is constructed by a nested diamond structure with the purpose of enhancing the damping property is proposed in this study without reducing the overall systematic stiffness. The mathematical model and geometrical relationships are established at first. And then, the steady-state solutions under base excitation are derived by using the harmonic balance method and further verified by numerical simulation. In addition, the effects of some design parameters on the equivalent damping ratio for the high-damping oscillator are studied to reveal the nonlinear characteristic. Besides, the natural frequency of the nonlinear oscillator is also presented and investigated. By using the displacement transmissibility and comparing with the traditional linear isolator with the same overall stiffness, the vibration suppression performance of the high-damping oscillator is addressed. The obtained calculating results demonstrate that the vibration control performance of the high-damping oscillator outperforms the linear counterpart around resonant frequency. Moreover, the influences of systematic parameters of the high-damping oscillator for the base excitation case on the vibration transmissibility are also discussed, respectively. Finally, an experimental campaign is conducted on an in-house-built test rig to corroborate the accuracy of the analytical solutions of the high-damping oscillation system. The results discussed in this study provide a useful guideline, which can help to design this class of high-damping oscillation system.

Dynamic Response of Underground Structures in Sand: Experimental Data

2017 ◽  
Vol 33 (1) ◽  
pp. 347-372 ◽  
Author(s):  
Anne Lemnitzer ◽  
Lohrasb Keykhosropour ◽  
Yohsuke Kawamata ◽  
Ikuo Towhata
Keyword(s):  
Large Scale ◽  
Research Collaboration ◽  
Pressure Sensors ◽  
Structural Response ◽  
Silica Sand ◽  
Underground Structures ◽  
Bender Elements ◽  
Data Set ◽  
Displacement Transducers ◽  
Ground Motion Records

A densely instrumented system of large-scale underground structures consisting of two vertical shafts connected through a cut-and-cover tunnel and two independent shield tunnels was installed in an 8 m-diameter laminar soil box at the E-Defense shake table in Miki, Japan. The system was subjected to step-sine sweeps and scaled ground motion records of the Kobe (1995) earthquake. The underground structures were embedded in Albany Silica Sand with an average relative density of 54%. System instrumentation consisted of over 800 sensors, including strain gauges, accelerometers, displacement transducers, bender elements and pressure sensors. A U.S.-Japanese research collaboration was established to instrument the vertical shaft elements and record seismic soil pressures. Data records are archived at the NHERI DesignSafe Data Depot_and can be used to analyze the structural response, soil-structure interaction and other response parameters of individual subsurface components as well as the entire system. The DOI for the data set is 10.17603/DS21C78.

Sign in / Sign up

Export Citation Format

Share Document