纸页受力微损伤演化过程的声发射及多元统计特征

On the Characterisrics of Acoustic Emission and Multivariate Statistics in Micro-Damage Evolution Process of Paper Sheet Subjected to Force Action

纸页受载后的损伤断裂行为涉及其使用性能,对其损伤断裂过程的研究不仅有助于揭示纸页破坏行为的物理本质,而且有助于对纸页质量及其生产、加工工艺作出更加科学合理的评定。本文基于声发射(Acoustic Emission,AE)实验研究纸页内部微损伤演化过程,给出了评估纸页宏观损伤断裂性能的定量描述方法。首先,根据AE信号与微损伤事件之间存在本质上的关联性,通过采集和观测纸页试样受载过程中的AE信号来研究纸页损伤断裂的基本特征;其次,针对所采集AE信号的数据量大、蕴含信息丰富导致数据分析和处理困难的特点,本文采用多元随机变量的分析方法。利用概率熵和Andrews曲线法等统计分析手段对AE数据展开研究分析,并最终利用一条损伤状态轨迹曲线实现了对纸页微损伤演化过程的完整宏观描述。结果表明,纸页微损伤演化过程呈现明显阶段性变化特征;Andrews曲线的聚类结果有效地区分了不同损伤阶段的相似性和差异性,同时,不同损伤阶段中纸样的微观形貌观测提供了实验性的证据。本文以一种典型的牛皮箱板纸为试件,验证了上述方法的有效性。

Damage and fracture behavior of paper sheet subjected to force action involves its service performance.So,investigation on its damage and fracture process not only helps to reveal the physical nature of paper sheet damage,but also helps to more scientifically and reasonably assess the paper sheet quality,improving the production and processing technology of paper sheets.This paper presents a quantitative description method for the assessment of mirco-damage and fracture behavior of paper sheets.Firstly,according to the essential corelation between AE signal and micro-damage event,basic characteristics of paper sheet damage and fracture were studied by collecting and observing AE signals emitted during loading process.Secondly,since collected AE signals contain large amount of data and information,resulting in the difficulty in data analysis and processing,so multivariate of random damage method was adopted.AE data were analyzed by using probability entropy and Andrews curve.Finally,a complete macroscopic description of micro-damage evolution of paper sheets was achieved by using a trajectory of damage states.Results show that paper sheet micro-damage evolution presents obvious stepped change characteristics.Andrews curve clustering results effectively discriminate the similarity and difference among different damage stages.At the same time,scanning electron microscope observation of paper sheet on different damage stages provides experimental evidence.Taking typical kraftliner as a case the validity of above-mentioned method was verified.