中图分类号：S781.2；S781.38 文献标识码：A DOI：10.7525/j.issn.1006-8023.2025.04.013

Abstract：Aiming at the acoustic emission （acoustic emission，AE）signals emitted from wood damage and fracture pro cess，multifractal detrended fluctuationanalysis（multifractaldetrendedfluctuationanalysis，MF-DFA）wasused toextractthecharacteristicparametersoftheAEsignals，andthentostudythefractalcharacteristicsofthe micro-and macrodamage behaviorsof wood.First，theAE signals generatedduring thethree-pointbending testof Zelkovaschneideriana specimen were collected.Then，the AE signal were intercepted bya sliding time windowand treated as a sequence of time periods. The generalized Hurst index，spectral width Δα ，singularity index α_max and α_max were calculated according to the MF-DFA method todescribe thelong-rangecorelationandtime-varying multifractal characteristicsof the AE signal.Finally，the whole process was categorized into elastic，elastoplastic and plastic stages based on the trend of Δα The results showedthattheAEsignalreleasedbythefracture processhadlong-rangecorrelationand its fluctuation was a multifractal process. And the value of α_max in the elastic stage was greatly reduced，which meant the multi-source charac teristics in the early stage of failure；the change of elastic-plastic stage α_max in a small range showed that the specimen hadacertain stiffess；the macroscopic fracture behaviorcan be predictedbythe time when the plastic stage α_min dropped suddenly.

Keywords：Wood；acoustic emission；multifractal；detrended fluctuation analysis

0 引言

木材作为一种具有多孔层状结构的生物复合材料，其特殊的纤维结构使其容易产生复杂的断裂机制和内部损伤，因此木质材料在长期使用过程中的安全监测是非常重要的。木结构的破坏通常表现为一些微观损伤随时间积累而形成宏观损伤，不同的损伤状态会造成不同程度的能量释放，因此会产生丰富的声发射（acoustic emission，AE）信号[1]。AE技术作为一种非破坏性方法[2]，具有测量完整性高、灵敏度高等特点，为木材损伤检测和识别提供了一种有效的手段，广泛应用于损伤定位[3]、信号处理[4]和损伤识别[5]等方面。

AE信号隐藏了材料在载荷作用下内部特性演变的信息[6]。因此，一些研究者开展了对AE技术在木材力学性能和损伤状态监测中的应用研究，表明AE信号的作用机理和变化规律能用于木材断裂与损伤检测[7]。尽管AE技术已广泛应用于破坏过程中损伤断裂的实时监测，但如何解释材料内部变化规律仍一直是研究热点。自分形维数和分形几何概念提出以来，分形理论已被应用于许多领域，包括损伤过程和AE监测的研究。因此，分形为更好地理解木材结构特征提供了一种新的理论。孙博等8讨论了多重分形谱宽 Δα 与损伤演化的关系，得到了基于多重分形的破坏前兆及预警时间。朴顺姬等通过计算不同区域的多尺度分形特征值，进而将奇异性较大的多尺度分形特征值提取出来，其集合即为木材缺陷的边缘。蔡江东等[10采用多重分形对声发射信号特征进行解构分析发现，可以从更深层次判断岩石内部裂纹演化过程，甚至有可能捕捉岩石破坏的前兆信息。……