Research on Acoustic Emission Characteristics of Bending Failure of Timber with Different Service Life
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摘要: 为探究不同使用年限的木材受弯损伤过程中的声发射演化规律,制备了三组不同使用年限的木材进行三点弯曲声发射试验。研究各使用年限木材在承载过程中与声发射参数特征的关联性,并深入分析了木材失稳破坏前声发射主频演化及能量特征前兆。试验结果表明:木材的使用年限影响声发射活度,根据声发射参数变化可以反映木材内部的损伤变化,从而间接反映木材的使用状态;使用年限一定程度上影响主频分布,其主频主要分布在0~200 kHz,明显成段分布,使用年限较久的木材主频分布较为离散;各组试件在损伤过程中各频带能量的变化对应不同试件状态,中低频带占比较高时主要以弹性变形为主,高频带占比较高时以塑性变形为主,当两频带能量发生突变时预示试件发生断裂,对于预测木材断裂具有一定价值。Abstract: In order to explore the evolution law of acoustic emission in the process of bending damage of timber with different service life, three groups of wood with different service life were prepared for three-point bending acoustic emission test. The paper studied the correlation between the bearing process of timber with the characteristics of acoustic emission parameters, and deeply analyzed the evolution of acoustic emission dominant frequency and energy characteristics precursors before timber instability and failure. The test results showed that the service life of timber affected the acoustic emission activity, and the change of acoustic emission parameters could reflect the internal damage of timber, so as to indirectly reflect the service state of timber; the service life affected the main frequency distribution to a certain extent. The main frequency was mainly distributed in 0-200 kHz, which was obviously distributed in segments. The main frequency distribution of timber with long service life was relatively discrete; the change of energy in each frequency band of each group of specimens in the damage process corresponded to different specimen states. When the proportion of medium and low frequency band was relatively high, it was mainly elastic deformation, and when the proportion of high frequency band was relatively high, it indicated the fracture of specimens, which had a certain value for predicting timber fracture.
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