A dominant frequency-based hierarchical clustering method for evaluating the mode-II fracture mechanisms of shale using the acoustic emission technique

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2024-09-04 DOI:10.1016/j.tafmec.2024.104644

{"title":"A dominant frequency-based hierarchical clustering method for evaluating the mode-II fracture mechanisms of shale using the acoustic emission technique","authors":"","doi":"10.1016/j.tafmec.2024.104644","DOIUrl":null,"url":null,"abstract":"<div><p>The fracture toughness of rocks is a crucial fracture parameter in unconventional geo-energy exploitation and plays a significant role in the fields of fracture mechanics and hydraulic fracturing. This research first introduces the processing approaches of AE (acoustic emission) signals for further elucidating the fracture mechanisms. To measure the mode-II fracture toughness of Longmaxi shale, the PTS (punch-through shear) specimen is employed because it can accomplish both mode-II loading and mode-II fracturing. Interestingly, the Gaussian function provides a superb description of the distribution of AE amplitudes, and the discrepancies in AE amplitude distribution are conspicuous for PTS shale specimens with typical bedding angles. The conventional <em>RA</em>-<em>AF</em> analysis of AE signals is more appropriate for qualitative analysis of failure mechanisms. When relatively higher <em>RA</em> values are monitored, implying that the partial stress drop and large-scale or more intense cracks take place, which can adequately furnish precursory information for engineering failure diagnosis. Based on the correlation between damage mechanisms (or fracture modes) and the characteristic bands of AE dominant frequency distribution, the dominant frequency-based hierarchical clustering method is developed by this work to quantitatively identify the damage or fracture modes, then the demarcation of AE dominant frequency ranges is determined as low, intermediate, and high, with corresponding tensile, tensile-shear, and shear cracks.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0000,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Theoretical and Applied Fracture Mechanics","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S016784422400394X","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, MECHANICAL","Score":null,"Total":0}

引用次数: 0

Abstract

The fracture toughness of rocks is a crucial fracture parameter in unconventional geo-energy exploitation and plays a significant role in the fields of fracture mechanics and hydraulic fracturing. This research first introduces the processing approaches of AE (acoustic emission) signals for further elucidating the fracture mechanisms. To measure the mode-II fracture toughness of Longmaxi shale, the PTS (punch-through shear) specimen is employed because it can accomplish both mode-II loading and mode-II fracturing. Interestingly, the Gaussian function provides a superb description of the distribution of AE amplitudes, and the discrepancies in AE amplitude distribution are conspicuous for PTS shale specimens with typical bedding angles. The conventional RA-AF analysis of AE signals is more appropriate for qualitative analysis of failure mechanisms. When relatively higher RA values are monitored, implying that the partial stress drop and large-scale or more intense cracks take place, which can adequately furnish precursory information for engineering failure diagnosis. Based on the correlation between damage mechanisms (or fracture modes) and the characteristic bands of AE dominant frequency distribution, the dominant frequency-based hierarchical clustering method is developed by this work to quantitatively identify the damage or fracture modes, then the demarcation of AE dominant frequency ranges is determined as low, intermediate, and high, with corresponding tensile, tensile-shear, and shear cracks.

查看原文本刊更多论文

利用声发射技术评估页岩模态 II 断裂机制的基于主频的分层聚类方法

岩石的断裂韧性是非常规地质能源开发中的一个重要断裂参数，在断裂力学和水力压裂领域发挥着重要作用。本研究首先介绍了声发射信号的处理方法，以进一步阐明断裂机制。为了测量龙马溪页岩的模-II断裂韧性，采用了PTS（冲穿剪切）试样，因为它既能完成模-II加载，又能完成模-II压裂。有趣的是，高斯函数能很好地描述 AE 振幅的分布，而对于具有典型基底角的 PTS 页岩试样，AE 振幅分布的差异非常明显。对 AE 信号进行传统的 RA-AF 分析更适合对破坏机制进行定性分析。当监测到相对较高的 RA 值时，意味着发生了部分应力下降和大规模或更密集的裂纹，这可为工程失效诊断提供充分的先导信息。根据损伤机制（或断裂模式）与 AE 主频分布特征带之间的相关性，本研究开发了基于主频的分层聚类方法来定量识别损伤或断裂模式，然后将 AE 主频范围划分为低频、中频和高频，分别对应拉伸裂纹、拉伸-剪切裂纹和剪切裂纹。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Theoretical and Applied Fracture Mechanics 工程技术-工程：机械

CiteScore

8.40

自引率

18.90%

发文量

435

审稿时长

37 days

期刊介绍： Theoretical and Applied Fracture Mechanics'' aims & scopes have been re-designed to cover both the theoretical, applied, and numerical aspects associated with those cracking related phenomena taking place, at a micro-, meso-, and macroscopic level, in materials/components/structures of any kind. The journal aims to cover the cracking/mechanical behaviour of materials/components/structures in those situations involving both time-independent and time-dependent system of external forces/moments (such as, for instance, quasi-static, impulsive, impact, blasting, creep, contact, and fatigue loading). Since, under the above circumstances, the mechanical behaviour of cracked materials/components/structures is also affected by the environmental conditions, the journal would consider also those theoretical/experimental research works investigating the effect of external variables such as, for instance, the effect of corrosive environments as well as of high/low-temperature.