Evaluation of destructive processes in FRC composites using time-frequency analysis of AE signals

Modern fiber-cement boards currently used in construction are made of natural raw materials such as cement, cellulose fibers and of polyvinyl alcohol (PVA) and water. They replaced the eternitic plates, which were harmful to health, originated by Ludwig Hatschek. Materials made of fiber-cement are used in construction industry as a building and finishing material for facades, internal walls and roofs. Therefore, they are exposed to environmental conditions including rainfall and temperature changes, and in particular to frequent temperature transition through 0°C in a 24-hour cycle (cyclic freezing-thawing). In addition, fibrous cement materials, primarily used as cladding elements, are exposed to exceptional conditions, which include the high temperature caused by fire. The article presents the results of experimental tests of flexural strength of cement fiber boards subjected to exceptional conditions, to which the operation of fire belongs. The paper also presents a proposal to use a non-destructive method of acoustic emission based on time-frequency analysis for testing fiber-cement boards. Interesting research results were obtained that allowed to trace the differences in the mechanisms of material destruction under the influence of the changing time of external factors.

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Time-frequency analysis of acoustic emission signals generated by cement-fiber boards during bending test

MATEC Web of Conferences ◽

10.1051/matecconf/201817402020 ◽

2018 ◽

Vol 174 ◽

pp. 02020 ◽

Cited By ~ 1

Author(s):

Anna Adamczak-Bugno ◽

Grzegorz Świt ◽

Aleksandra Krampikowska

Keyword(s):

Acoustic Emission ◽

Frequency Analysis ◽

Building Materials ◽

Bending Strength ◽

Raw Materials ◽

Experimental Tests ◽

Nondestructive Method ◽

Bending Test ◽

Time Frequency Analysis ◽

Time Frequency

Fiber-cement building materials have been used in civil engineering for over one hundred years. Contemporary fiber-cement boards are made of natural raw materials such as cement, cellulose fibers, PVA and water. Materials made of fiber-cement are used in construction as a building and finishing material for elevations, internal walls and roofs, hence are exposed to environmental conditions such as rainfall and temperature changes, in particular, frequent temperature transition through 0°C in a 24 hour cycle (cyclic freezing-thawing). In addition, fibrous cement materials, primarily used as cladding elements, are exposed to exceptional conditions, which include the high temperature caused by fire. The article presents the results of experimental tests of bending strength of cement-fiber boards subjected to environmental factors and exceptional factors. The paper also presents a proposal to use a nondestructive method of acoustic emission (AE) based on time-frequency analysis for testing fiber-cement boards. Interesting research results were obtained, which allowed to trace the differences in the mechanisms of material destruction under the influence of various factors.

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Application of Joint-Time Frequency Analysis Methods for Nondestructive Evaluation

10.1115/imece1999-0890 ◽

1999 ◽

Author(s):

Ki-Woo Nam ◽

Kun-Chan Lee ◽

Jeong-Hwan Oh

Keyword(s):

Crack Propagation ◽

Nondestructive Evaluation ◽

Frequency Analysis ◽

Cyclic Fatigue ◽

Frequency Characteristics ◽

Time Frequency Analysis ◽

Ultrasonic Signals ◽

Time Frequency ◽

Analysis Methods ◽

Ae Signals

Abstract Application of signal processing techniques to nondestructive evaluation (NDE) in general and acoustic emission (AE) studies in particular has become a standard tool in determining the frequency characteristics of the signals and relating these characteristics to the integrity of the structure under consideration. Recent studies have shown that the frequency characteristics of ultrasonic signals from evolving damage during cyclic (fatigue) and dynamic loads change with time; in other words, the signals are nonstationary, and that these changes can be related to the nature of the damage taking place during loading. A joint time-frequency analysis such as Short Time Fourier Transform (STFT) and Wigner-Ville distribution (WVD), can in principle be used to determine the time dependent frequency characteristics of nonstationary signals in presence of background noise. In this study these techniques are applied to analyze AE signals from fatigue crack propagation in 5083 aluminum alloys and ultrasonic signals in degraded austenitic 316 stainless steels, to study the evolution of damage in these materials. It is demonstrated that the nonstationary characteristics of both AE and ultrasonic signals could be analyzed effectively by these methods. STFT was found to be more effective in analyzing AE signals, and WVD was more effective for analyzing the attenuation and frequency characteristics of degraded materials through ultrasonics. It is indicated that the time-frequency analysis methods should also be useful in evaluating crack propagation and final fracture process resulting from various damages and defects in structural members.

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Damage Detection in RAPTOR Telescope Systems Using Time-Frequency Analysis Methods

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.588.43 ◽

2013 ◽

Vol 588 ◽

pp. 43-53 ◽

Cited By ~ 1

Author(s):

Ifigeneia Antoniadou ◽

Keith Worden ◽

Graeme Manson ◽

Nikolaos Dervilis ◽

S.G. Taylor ◽

...

Keyword(s):

Frequency Analysis ◽

Gamma Ray ◽

Energy Operator ◽

Experimental Tests ◽

Energy Separation ◽

Driving Mechanism ◽

Time Frequency Analysis ◽

Time Frequency ◽

Remote Locations ◽

Analysis Methods

The RAPTOR telescope systems are astronomical observatories that operate in remote locations in New Mexico searching for astrophysical transients called gamma-ray bursts. Their operating condition should remain at good levels in order to have accurate observations. Currently, the first component of the RAPTOR telescopes to fail is a capstan driving mechanism that operates in a run-to failure mode. The capstans wear relatively frequently because of their manufacturing material and can cause damage to other more expensive components, such as the drive wheels and the telescope optics. Monitoring the condition of these systems seems a reasonable solution since the unpredictable rate at which the capstans experience wear, in combination with the remote locations and high duty cycles of these telescope systems, make it unprofitable to choose a strategy of replacing the capstans at chosen intervals. Experimental tests of the telescope systems reported here recorded vibration signals during clockwise and counterclockwise rotations, similar to a motion known as "homing-sequence". The Empirical Mode Decomposition (EMD) method in combination with the Hilbert Transform (HT) and a new alternative method for the estimation of the instantaneous features of a signal that applies an energy tracking operator, called Teager-Kaiser Energy operator, and an energy separation algorithm to the data being analysed, are the time-frequency analysis methods used for analysis here.

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A time–frequency analysis based internal leakage detection method for hydraulic actuators

Advances in Mechanical Engineering ◽

10.1177/1687814016685058 ◽

2017 ◽

Vol 9 (1) ◽

pp. 168781401668505 ◽

Cited By ~ 5

Author(s):

Zhikai Yao ◽

Jian Tang ◽

Ting Rui ◽

Jinhui Duan

Keyword(s):

Wavelet Transform ◽

Frequency Analysis ◽

Continuous Wavelet Transform ◽

Control Valve ◽

Experimental Tests ◽

Continuous Wavelet ◽

Time Frequency Analysis ◽

Hydraulic Actuators ◽

Time Frequency ◽

Pressure Signal

Internal leakage in the hydraulic actuators is concerned in this article, which is caused by seal damage, resulting in the limited performance of the system. To study the issue, this article proposes a method based on time–frequency analysis for the detection in hydraulic actuators. First, the pressure signal after filtering of the actuator in one side is collected when the control valve is affected by sinusoidal-like inputs. Second, the time–frequency image of pressure signal in a period at different leakage levels is obtained after continuous wavelet transform. Third is the sum of pixels in the time–frequency image. It is shown that the feature pattern is established by the sum of pixels in the time–frequency image that internal leakage and its severity could be detected effectively. The proposed method required two baselines and premeasured the pressure signal at 11 leakage levels. Once the sum of pixels in the time–frequency image values, obtained from the time–frequency image by continuous wavelet transform based on wavelet Cmor1-1 in subsequent offline tests, are greater than the first baseline, a leakage alarm is triggered. Furthermore, a severe leakage alarm is triggered when the value is greater than the second baseline. Experimental tests show the accuracy of the proposed scheme at different mother wavelets, and it is done without knowing the model of actuator or leakage.

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