林业工程学报2025，Vol.10Issue(3)：25-32,8.DOI:10.13360/j.issn.2096-1359.202405003
弯曲载荷下含预制裂纹杉木梁细观损伤特征与识别
Microscopic damage characteristics and identification of prefabricated crack-containing Chinese fir beams under bending load
摘要
Abstract
In practical engineering applications,as the primary load-bearing components of timber structures,the failure mode of wood beams mainly involves bending damage.Unlike the singularity of microscopic damage forms observed tension or compression,the bending damage process progresses through different stages,each characterized by various types of damage,often involving multiple microscopic damage forms within the same stage.Compared to singular damage,identifying and determining damage in such complex mechanical behavior becomes significantly more challenging.The microscopic damage of wood can be classified into four main types:cell wall buckling and collapse,microcrack damage,delamination and fiber bundle fracture.The peak frequency of the damage characteristic signal can be used to distinguish these microscopic damage types.In this study,by focusing on fir(Cunninghamia lanceolate)wood,experiments were designed to monitor and collect acoustic emission signals during the three-point bending damage process.Noise in the acoustic emission signals obtained from the damage tests was eliminated using the wavelet packet threshold method.The experimental acoustic emission signals of wood damage were then processed and analyzed using the empirical mode decomposition-wavelet packet energy entropy signal processing method.According to the different stages of the damage process,based on the empirical modal decomposition,the feature signals were extracted and separated from the original signals,which can characterize the damage.Then,the wavelet packet energy entropy of the extracted feature signals was utilized as the damage index to identify the different types of damage at each stage of the damage process.Through the cross-correlation coefficient between the feature signals and the original signals,the percentage of damage types in each stage of damage was quantitatively characterized,and the different types and percentages of microscopic damage corresponding to each stage were determined.The results showed that the empirical mode decomposition-wavelet packet energy entropy method can effectively determine the type and composition of the microscopic damage occurring at different stages of the three-point bending process,while the correlation coefficients between the intrinsic mode function(IMF)components of the acoustic emission signals and the original signals were capable of determining the proportions of the microscopic damage corresponding to the different stages of damage in the three-point bending process of fir.This study proposed a method for identifying the microscopic damage of wooden beams under bending loads capable of inducing various types of microscopic damage.This method provides robust theoretical support for studying the damage mechanisms of wood beams and monitoring the health of wooden structures in service.关键词
木材损伤识别/预制裂纹/弯曲载荷/多细观损伤/声发射/小波包能量熵/经验模态分解Key words
wood damage identification/pre-existing crack/bending load/multiple microscopic damage/acoustic emission/wavelet packet energy entropy/empirical modal decomposition(EMD)分类
林学引用本文复制引用
马荣宇,赵东,于立川,赵健,刘嘉辉..弯曲载荷下含预制裂纹杉木梁细观损伤特征与识别[J].林业工程学报,2025,10(3):25-32,8.基金项目
北京市自然科学基金(2182045). （2182045）
