Acquisition and Analysis of Continuous Acoustic Emission Waveform for Classification of Damage Sources in Ceramic Fiber Mat

Abstract

Waveforms of acoustic emission (AE) events come close and sometimes overlap each other when AE activity is very high. Conventional AE measurement systems which handle discrete AE events are not suitable for this situation because miss-detection of AE event occurs frequently. A new AE measurement system named as Continuous Wave Memory (CWM) was developed to solve this problem by recording the AE waveforms continuously to hard disks for several hours throughout the testing time. This new system enabled multiple analysis of one waveform with different filtering parameters. Short time Fourier transform (STFT) gave the time-frequency-magnitude characteristic of continuous AE waveforms and useful information for evaluation of degradation of materials. In this study, the degradation of ceramic fiber mat during cyclic compression test and the effect of binder-addition were evaluated by this new system. STFT results clearly showed the classification of degradation of the mat; breakage of fibers was the main source in the early compression cycles and sporadic friction between fibers became the main source of AE in the later compression cycles. The effect of organic binder to prevent the degradation of the mat was also estimated. It was observed that the friction signal disappeared and the breakage signal weakened in the binder-added specimens.

<i>In-Situ</i> Evaluation of Detwinning Behavior in Extruded AZ31 Mg Alloy by AE

“…In addition, AE measurement was simultaneously performed using Continuous Wave Memory (CWM) which was developed by our group. 11) CWM memorizes all AE waveforms continuously at a sampling rate of 10 MHz. Four AE sensors (M304A, Fuji Ceramics, Japan) having a frequency band of 1001000 kHz were used in all the experiments.…”

Investigation of Static and Fatigue Behavior of Periodic Mesh Plates Using Acoustic Emission Method

“…In addition, AE measurement was performed using Continuous Wave Memory (CWM) developed by our group. 13) A piezoelectric transducer (M304 Fuji Ceramics, Japan) with a resonant frequency of 300 kHz was used in all experiments. The signal was amplified and filtered by a highpass filter of 100 kHz to remove the noises from environment.…”

“…They also have been particularly studied in medical application as implants for the healing of mandibular fractures due to their excellent biocompatibility and their adaptability to the complex shape of the bone. 13) To ensure an efficient bone reconstruction mechanical properties of bone and implant have to be close in order to prevent bone atrophy due to excessive stress-shielding. 4) Therefore, the evaluation of mechanical properties plays a crucial role for the development of efficient implant.…”

Effect of Confinement Layer on Laser Ablation and Cavitation Bubble during Laser Shock Peening

“…Since the sensor was soaked in the tank, the cable of the sensor was covered by waterproof sealant paste. AE waveforms was recorded by using Continuous Wave Memory (CWM) 12) , which was been developed by our research group and is capability to memorize all waveforms continuously at the sampling rate of 10 MHz. The times of both AE measurement and high speed camera were synchronized providing a correct relationship of phenomena observed by high speed camera with detected AE waveforms.…”