摘要
针对木材在重复荷载下的Kaiser效应问题,采用Felicity比辨识高低载荷状态,并通过声发射(acoustic emission,AE)信号关联维数表征不同载荷下Kaiser点的分形特征。首先,将采样频率设置为500 kHz,采集木材试件在重复载荷下的AE信号,其中载荷间隔设定为300 N。然后,依据噪声信号设定AE振铃的阈值为48 dB,参考美国增强塑料声发射检测委员会(CARP)准则定义“明显”AE信号并计算Felicity比,依此标定Kaiser和Felicity效应所对应的载荷阶段。最后,利用G-P算法计算Kaiser点处AE信号的关联维数D,作为不同阶段Kaiser点的辨识指标。结果表明:通过Felicity比能明显区分高低载荷状态,并且在Kaiser与Felicity效应两个阶段的Kaiser点AE信号的关联维数D存在显著差异;Kaiser效应阶段内,D值变化范围为0.8346~1.4895,而过渡到Felicity效应阶段后,D值变化范围增大到1.7038~3.6602。
To understand the Kaiser effect of the wood component under repeated loading,the Felicity ratio was used to identify the high and low loading states.The fractal characteristics of Kaiser point under different loading were characterized by the correlation dimension of the acoustic emission(AE)signal.Firstly,when the frequency was 500 kHz,the AE signals of the wood specimens were collected under repeated loading,where the load interval was set to 300 N.Then,according to the noise signal,the threshold of AE ringing was set as 48 dB,and the“obvious”AE signal was defined based on American Council for Acoustic Emission Testing of Reinforced Plastics criterion.The Felicity ratio was calculated to calibrate the load stages corresponding to Kaiser and Felicity effects.Finally,the correlation dimension D of AE signal at Kaiser point was calculated through G-P algorithm as the identification index of Kaiser point at different stages.The results showed that the high and low loading states could be clearly distinguished by the Felicity ratio.There was a significant difference in the correlation dimension D of AE signal at the Kaiser point of Kaiser and Felicity effects.During the Kaiser effect stage,the D value varied from 0.8346 to 1.4895,while after the transition to the Felicity effect stage,the D value varied from 1.7038 to 3.6602.
作者
黄长林
邓婷婷
杨洲凌
方赛银
丁锐
赖菲
李明
HUANG Chang-lin;DENG Ting-ting;YANG Zhou-ling;FANG Sai-yin;DING Rui;LAI Fei;LI Ming(Southwest Forestry University,Kunming 650224,Yunnan,China;Anhui Polytechnic University,Wuhu 241000,Anhui,China)
出处
《木材科学与技术》
北大核心
2022年第2期36-41,共6页
Chinese Journal of Wood Science and Technology
基金
国家自然科学基金“基于应变能波动传播特性的木材损伤断裂演化机制研究”(32160345)
“基于声发射能量模型的胶合木结构蠕变机理与演变规律研究”(31760182)。
作者简介
黄长林(1997—),硕士研究生。Email:1559684494@qq.com;通讯作者:李明,男,教授。Email:swfu_lm@swfu.edu.cn。
