Impact Damage Detection in Composite Chiral Sandwich Panels

2012 ◽  
Vol 518 ◽  
pp. 160-167 ◽  
Author(s):  
Andrzej Klepka ◽  
Wieslaw Jerzy Staszewski ◽  
T. Uhl ◽  
Dario di Maio ◽  
Fabrizio Scarpa ◽  
...  
Keyword(s):  
Damage Detection ◽  
Ultrasonic Wave ◽  
High Frequency ◽  
Impact Damage ◽  
Low Frequency ◽  
Nonlinear Acoustics ◽  
Composite Panel ◽  
Chiral Structures ◽  
Low Frequency Vibration ◽  
Vibration Wave

This paper demonstrates impact damage detection in a composite sandwich panel. The panel is built from a chiral honeycomb and two composite skins. Chiral structures are a subset of auxetic solids exhibiting counterintuitive deformation mechanism and rotative but not reflective symmetry. Damage detection is performed using nonlinear acoustics,involves combined vibro-acoustic interaction of high-frequency ultrasonic wave and low-frequency vibration excitation. High-and low-frequency excitations are introduced to the panel using a low-profile piezoceramic transducer and an electromagnetic shaker, respectively. Vibro-acoustic modulated responses are measured using laser vibrometry. The methods used for impact damage detection clearly reveal de-bonding in the composite panel. The high-frequency weak ultrasonic wave is also modulated by the low-frequency strong vibration wave when nonlinear acoustics is used for damage detection. As a result frequency sidebands can be observed around the main acoustic harmonic in the spectrum of the ultrasonic signal.

Sensor Location Analysis in Nonlinear Acoustics Used for Damage Detection in Composite Chiral Sandwich Panels

2012 ◽  
Vol 83 ◽  
pp. 223-231 ◽  
Author(s):  
Andrzej Klepka ◽  
Wieslaw Jerzy Staszewski ◽  
Dario di Maio ◽  
Fabrizio Scarpa ◽  
Kong Fah Tee ◽  
...  
Keyword(s):  
Damage Detection ◽  
High Frequency ◽  
Low Frequency ◽  
Nonlinear Acoustics ◽  
Location Analysis ◽  
Sensor Location ◽  
Ultrasonic Sensing ◽  
Low Profile ◽  
Frequency Excitation ◽  
Vibration Wave

This paper demonstrates damage detection in a smart sandwich panel with integrated piezoceramic transducers. The panel is built from a chiral honeycomb and two composite skins. A low-profile, surface-bonded piezoceramic transducer is used for high-frequency ultrasonic excitation. Low-frequency excitation is performed using a piezoceramic stack actuator. Ultrasonic sensing is performed using laser vibrometry. Nonlinear acoustics is applied for damage detection. The study is focused on sensor location analysis with respect to vibro-acoustic wave modulations. The paper demonstrates that when structure is damaged, the high-frequency “weak” ultrasonic wave is modulated by the low-frequency “strong” vibration wave. As a result frequency sidebands can be observed around the main acoustic harmonic in the spectrum of the ultrasonic signal. However, intensity of modulation strongly depends on sensor location.

In Situ Measurement of Ground Vibration Induced by Inter-City Express Train

2012 ◽  
Vol 204-208 ◽  
pp. 502-507 ◽  
Author(s):  
Quan Min Liu ◽  
Xun Zhang ◽  
Zhi Jun Zhang ◽  
Xiao Zhen Li
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Ground Vibration ◽  
Vertical Vibration ◽  
Test Results ◽  
Low Frequency Vibration ◽  
Express Train ◽  
Environmental Vibration ◽  
Logarithmic Relationship

On the basis of the measured ground borne vibration of some inter-city express railway viaduct, test results analysis shows that: the test environmental vibration is under the limit set by standard of environmental vibration in urban area; whether transverse or vertical vibration, a rapid attenuation of the peak acceleration with the distance to the up-track center is observed, however the vibration at 7.5m appears to be amplified; the ground vibration with the distance conforms to a logarithmic relationship; the horizontal ground vibration at 7.5m caused by the elevated rail transit is larger 3.6cm/s2 than the vertical vibration; low-frequency vibration transfers farther than high frequency vibration; the eccentric effect of two-track viaduct is obvious.

Analysis of Vibro-Acoustic Modulations in Nonlinear Acoustics Used for Impact Damage Detection - Numerical and Experimental Study

2013 ◽  
Vol 558 ◽  
pp. 341-348 ◽  
Author(s):  
Łukasz Pieczonka ◽  
Andrzej Klepka ◽  
Wieslaw Jerzy Staszewski ◽  
Tadeusz Uhl ◽  
Francesco Aymerich
Keyword(s):  
Experimental Study ◽  
Finite Element ◽  
Composite Plate ◽  
Natural Frequencies ◽  
Impact Damage ◽  
Low Frequency ◽  
Fe Modeling ◽  
Low Frequency Vibration ◽  
Frequency Excitation ◽  
Nonlinear Acoustic

The paper investigates experimentally the effect of low-frequency vibration on nonlinear vibro-acoustic wave modulations applied to the detection of Barely Visible Impact Damage (BVID) in a composite plate. Finite Element (FE) modeling was used in a pretest stage to identify different motion scenarios of delaminated surfaces and relate them to natural frequencies of the damaged plate. In particular the opening-closing and frictional sliding actions of the defected interfaces have been considered. Subsequently, the identified frequencies have been used for low frequency excitation in nonlinear acoustic experiments on a composite plate with impact damage.

scholarly journals Stiffness-based Spring Design Optimization using Taguchi Method to reduce Low-Frequency Vibration

2019 ◽  
Vol 5 (2) ◽  
Author(s):  
Ahmad Yusuf Ismail ◽  
Al Munawir ◽  
Noerpamoengkas A
Keyword(s):  
Taguchi Method ◽  
High Frequency ◽  
Vibration Isolation ◽  
Low Frequency ◽  
Stiffness Coefficient ◽  
Frequency Range ◽  
High Noise ◽  
Low Frequency Vibration ◽  
Optimization Variable ◽  
Vibration Transmissibility

Low-frequency vibration has been troublesome for a mechanical system. Despite the measurement difficulties, low-frequency vibration also creates several environmental effects such as high noise level that is harmful to the human body. One of the methods to reduce vibration is tuning the vibration isolation i.e. spring and damping coefficient. However, the latter method is found to be effective only for the mid-high frequency range. Therefore, this paper proposes an optimization of the spring a.k.a. stiffness coefficient in order to reduce the low-frequency vibration. The Taguchi method is used as an optimization tool since it offers simplicity yet powerful for any field of application, particularly in engineering. Two significant parameters in the spring geometry were selected as the optimization variable in the Taguchi method and evaluated using vibration transmissibility concept. The result shows that the Taguchi method has been successfully obtained the optimum value for the spring geometry purposely to reduce the vibration transmissibility.

scholarly journals On the Role of Acoustical Improvement and Surface Morphology of Seashell Composite Panel for Interior Applications in Buildings

Buildings ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 71 ◽  
Author(s):  
Erni Setyowati ◽  
Gagoek Hardiman ◽  
Purwanto ◽  
Mochamad Budihardjo
Keyword(s):  
Surface Morphology ◽  
High Frequency ◽  
Transmission Loss ◽  
Low Frequency ◽  
Composite Panel ◽  
Material Structure ◽  
Perna Viridis ◽  
Fibrous Layer ◽  
Anadara Granosa

This manuscript focuses on the acoustical behaviors and surface morphology of seashell waste filler reinforced polyester (SFRP) coverings Anadara granosa Linn, Perna viridis Linn, and Placuna placenta Linn and applications in buildings. Their acoustical performances were observed using an impedance tube using a technique with two and four microphones based on ASTM E1050-98 and ASTM E2611-09. The improvements of acoustical performance were conducted by a coupled resonator inclusion with addition of a fibrous dacron layer and back cavity. The experimental results showed that the resonators and back cavity on the material structure were able to shift the absorption ability at low frequency. The promising wide broadband frequencies performance occurred when the 15 mm Placuna placenta FRP treated with front-tailed cavity without any additional fibrous layer and air gap started from 0.2 at 2.0 kHz. The combination of resonators and fibrous layer on the material structure was able to stabilize the sound transmission loss (STL) in 52–56 dB at a high frequency. On the observation of the simple surface morphology material, it was found that Placuna placenta Linn had the highest damping performances due to the smallest pores and the most carbon compound compared to the others. Therefore, this finding is very useful for building applications.

Factors Influencing Acousto-Ultrasonic Approach to Impact Damage in Composite Materials

2011 ◽  
Vol 393-395 ◽  
pp. 97-101
Author(s):  
Huan Ping Kong ◽  
Zheng Zhang ◽  
Li Fei Li
Keyword(s):  
Composite Materials ◽  
Damage Detection ◽  
Rapid Detection ◽  
Impact Damage ◽  
Low Frequency ◽  
Factors Influencing ◽  
Frequency Transducer ◽  
Ultrasonic Parameters ◽  
Early Damage

This paper studied factors influencing AU detection results on different damage specimens, including simulation frequency, transducer modes and transducer location. Correlation between acousto-ultrasonic parameters (AUP1, AUP2) and impact damage severity in composite was investigated. The results showed that as damage severity increased, AUP1 and AUP2 of three different transducers decreased. Applying low frequency transducer, the variation of AUP1 may indicate a more rapid detection prospect. In addition, applying S1-transducer and WD-transducer, AUP2 was more effective for the early damage detection. Varying transducer’s location, S1-transducer applying 500khz simulation frequency presented a valuable results.

Dynamic Variational-Asymptotic Procedure for Laminated Composite Shells—Part II: High-Frequency Vibration Analysis

2008 ◽  
Vol 76 (1) ◽  
Author(s):  
Chang-Yong Lee ◽  
Dewey H. Hodges
Keyword(s):  
High Frequency ◽  
Vibration Analysis ◽  
Shell Theory ◽  
Low Frequency ◽  
Normal Displacement ◽  
Difficult Situation ◽  
Long Wavelength ◽  
First Approximation ◽  
Low Frequency Vibration ◽  
Characteristic Wavelength

Shell theories intended for low-frequency vibration analysis are frequently constructed from a generalization of the classical shell theory in which the normal displacement (to a first approximation) is constant through the thickness. Such theories are not suitable for the analysis of complicated high-frequency effects in which displacements may change rapidly along the thickness coordinate. Clearly, to derive by asymptotic methods, a shell theory suitable for high-frequency behavior requires a different set of assumptions regarding the small parameters associated with the characteristic wavelength and timescale. In Part I such assumptions were used to perform a rigorous dimensional reduction in the long-wavelength low-frequency vibration regime so as to construct an asymptotically correct energy functional to a first approximation. In Part II the derivation is extended to the long-wavelength high-frequency regime. However, for short-wavelength behavior, it becomes very difficult to represent the three-dimensional stress state exactly by any two-dimensional theory; and, at best, only a qualitative agreement can be expected. To rectify this difficult situation, a hyperbolic short-wave extrapolation is used. Unlike published shell theories for this regime, which are limited to homogeneous and isotropic shells, all the formulas derived herein are applicable to shells in which each layer is made of a monoclinic material.

Velocity Filter Based Tissue Elasticity Imaging for Low Frequency Vibration Wave Method

2013 ◽  
Vol 534 ◽  
pp. 267-272
Author(s):  
Takashi Miwa ◽  
Yuki Yoshihara ◽  
Yoshiki Yamakoshi
Keyword(s):  
Low Frequency ◽  
Simulated Data ◽  
Medical Application ◽  
Wave Number ◽  
Imaging Method ◽  
Elasticity Imaging ◽  
Tissue Elasticity ◽  
Low Frequency Vibration ◽  
Vibration Wave ◽  
Velocity Filtering

An elasticity imaging method using continuous vibration wave excitation is expected to be a safe and quantitative technique. A velocity map is successfully produced by running wave number spectrum analysis of the 2D displacement map of the shear wave propagation. However, a problem is still remained that the accuracy and resolution is not sufficient for medical application. This paper presents an elasticity imaging method based on velocity filtering to clear the boundary of a hard target. We demonstrate an effectiveness of this method through the simulated data.

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