Effects of temperature on pure mode-I and mode-Ⅱ fracture behaviors and acoustic emission characteristics of granite using a grain-based model

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL Theoretical and Applied Fracture Mechanics Pub Date : 2024-08-25 DOI:10.1016/j.tafmec.2024.104637

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Abstract

To investigate the effects of thermally induced microcracks on the pure mode-I and mode-Ⅱ fracture behaviors of the granite, a Grain-based model (GBM) was used to build cracked straight-through Brazilian disc (CSTBD) granite specimens. Splitting tests were conducted on the CSTBD specimens treated at various temperatures under pure mode-I and mode-Ⅱ loadings, and the moment tensor algorithm was utilized to record the acoustic emission (AE) events generated by fracture during loading. The results indicate that thermally induced microcracks predominantly consist of intergranular and intragranular tensile cracks, with quartz phase transition significantly increasing the number of intragranular tensile cracks. With the increase in heat-treatment temperature, thermally induced microcracks gradually guide the initiation direction of load-induced cracks, making the crack propagation path more tortuous. The AE characteristics reveal that the fracture behavior of the CSTBD specimen heat-treated at 600 ℃ transitions from brittle to ductile. Furthermore, thermally induced microcracks can constrain the propagation distance of load-induced cracks, increasing the small-scale AE events and the b-value, thereby reducing the AE magnitude during failure.

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利用基于晶粒的模型分析温度对花岗岩纯 I 模和Ⅱ模断裂行为以及声发射特性的影响

为了研究热诱导微裂纹对花岗岩纯模式-I和模式-Ⅱ断裂行为的影响，采用基于晶粒的模型（GBM）制作了开裂直通巴西圆盘（CSTBD）花岗岩试样。在不同温度下处理的 CSTBD 试样在纯 I 模式和 II 模式加载下进行了劈裂试验，并利用力矩张量算法记录了加载过程中断裂产生的声发射（AE）事件。结果表明，热诱导微裂纹主要由晶间和晶内拉伸裂纹组成，石英相变显著增加了晶内拉伸裂纹的数量。随着热处理温度的升高，热诱导微裂纹逐渐引导荷载诱导裂纹的萌发方向，使裂纹扩展路径更加曲折。AE 特性表明，在 600 ℃ 下热处理的 CSTBD 试样的断裂行为从脆性转变为韧性。此外，热诱导微裂纹会限制负载诱导裂纹的传播距离，增加小尺度 AE 事件和 b 值，从而降低破坏时的 AE 幅值。

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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.