摘 要：以2种针叶材、2种阔叶材为试材，研究无缺陷试件和含横纹裂纹试件在弯曲破坏过程中材料内部微结构演化的声发射特性，并利用声发射特征参数对几种损伤类型进行辨识。结果表明：1）无缺陷试件在加载初期声发射事件发展较为缓慢，且出现的主要是一些低振幅的AE信号，而大量高振幅AE信号出现在峰值载荷附近及韧性断裂阶段；2）利用声发射监测含裂纹试件在三点弯曲载荷下的损伤并断裂全过程，可以明显地识别裂纹尖端启裂和扩展的不同阶段；3）声发射信号的特征与损伤模式有关，胞壁断裂对应的AE特征为高幅值、高能量及长持续时间，而胞壁界面损伤与层裂损伤和细胞屈服与压溃损伤对应的AE特征为低幅度、低能量及短持续时间；4）木试件在低载荷水平下呈现Kaiser效应，而在高载荷水平下呈现Felicity效应，应用Felicity比能够较好地反映木结构的损伤程度。
Abstract: Take two softwoods and two hardwoods as test materials, studied on microstructure evolves of non-flaw and crosswise crack-contained specimens under bending break process by acoustic emission (AE) technology, and using the AE characteristic parameters to distinguish several damaged types. The results indicate: the ratio of AE hits occurred of non-flaw specimens were small during the initiation of loading,and mainly appears low amplitude and low energy AE signals. As the load reached the peak and during the fracture stage, a large number of AE hits occurred and its amplitude and energy were high. Using the AE set monitor the entire damage-fracture process of crack-contained specimens under three-point-bended, may distinguish the crack tip to sidewise initiation and expansion on different stages obviously. AE signal characteristic related to damage pattern, the AE signals are large amplitude,large energy and long duration when cell-wall break, but AE signals are low amplitude, low energy and short duration as cell-wall interface damage,interlaminar fracture, cell yield and collapse damage. The Kaiser effect appears at lower loading level, but the Felicity effect appears at lower loading level.
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