Theoretical and Applied Fracture Mechanics最新文献

{"title":"Finite Element Ductile Fracture Simulation of Charpy and Drop Weight Tear Tests for API X52","authors":"","doi":"10.1016/j.tafmec.2024.104629","DOIUrl":"10.1016/j.tafmec.2024.104629","url":null,"abstract":"<div><p>This paper presents a systematic procedure for performing finite element (FE) impact ductile fracture simulation of Charpy (CVN) and Drop Weight Tear Tests (DWTT) with validation using test data of API X52. For deformation and fracture models, the Johnson-Cook (J-C) model is used, of which seven parameters are determined by analyzing (1) round bar tensile test data at three different temperatures (two parameters), (2) tensile test and fracture toughness test at room temperature (three parameters) and (3) instrumented Charpy test (load–displacement) data at room temperature (two parameters). FE impact fracture simulation results with the determined parameters show good agreement with instrumented CVN test data at three different temperatures (0 °C, −30 °C and −60 °C) and DWTT data at temperatures of RT and −30 °C. For DWTT simulation, an analysis of the pre-strain due to flattening is included. Additionally, sensitivity analyses for the effect of adiabatic heating and strain rate on simulation results show that, although both phenomena should be considered in simulation, the strain rate effect is more significant than the adiabatic heating effect.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rock damage and fracture characteristics considering the interaction between holes and joints","authors":"","doi":"10.1016/j.tafmec.2024.104628","DOIUrl":"10.1016/j.tafmec.2024.104628","url":null,"abstract":"<div><p>The work studied the damage and fracture characteristics of granite samples with circular holes and parallel fractures of different lengths under uniaxial compression conditions. Acoustic emission (AE) monitoring and digital image correlation (DIC) were used to analyze the dynamic changes of AE parameters, the evolution characteristics of the deformation field on the sample surface, and the correlation between the fractal dimension and the fracture geometry parameters. A computational model was proposed for evaluating the intensity factor of the fracture tip in a double-fracture structure with holes. The interaction between the fractures was considered to reveal the complex law of the intensity factor and the fracturing angle with the fracture geometry. The changes in AE parameters and fractal dimension indicated the influence of fracture extension on the damage mode of samples. Besides, the fracture length affected the micro-fracture behavior. The surface displacement and strain characteristics of samples revealed the modulation effect of the fracture length on the failure mode. The inclination angle, length, holes, and size of the fractures’ friction coefficient significantly affected the evolution of the intensity factor, which in turn regulated the changes in the fracture angle. The work offers a novel quantitative analytical approach and a theoretical framework for comprehending the damage and failure mechanisms of porous and fractured rocks through extensive experimentation and theoretical analysis. It holds significant practical relevance in geological engineering, mining, and tunnel construction.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142049305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on crack propagation mechanism and acoustic-thermal sensitivity analysis of pre-cracked weakly cemented rock","authors":"","doi":"10.1016/j.tafmec.2024.104619","DOIUrl":"10.1016/j.tafmec.2024.104619","url":null,"abstract":"<div><p>As the intensity and depth of coal mining gradually increase, environmental disturbances become more complex, and the degree of crack development in weakly cemented surrounding rocks continues to increase. In order to study the influence mechanism of crack angle on the fracture mechanism and acoustic − thermal precursor information of weakly cemented rocks, visual biaxial loading tests were conducted on pre-cracked weakly cemented rocks based on a transparent servo loading device, combined with digital speckle correlation method (DSCM), acoustic emission (AE), and infrared thermal imaging (ITI). The research results indicate that as the inclination angle of cracks increases, the initial strength, peak strength, and elastic modulus of rocks exhibit a logarithmic relationship of first decreasing and then increasing. When the inclination angle of the crack increases from &lt; 30° to &gt; 75°, the failure mode of weakly cemented rocks changes from shear to tension. The propagation path of deformation localization is consistent with the propagation trajectory of surface cracks, and the extension length and time of tensile cracks are longer than those of shear cracks. The acoustic − thermal sensitivity of weakly cemented rocks with crack inclination angle of &gt; 45° is higher than that with crack inclination angle of ≤ 30°. The research results contribute to further understanding and mastering the mechanism of crack initiation and propagation in weakly cemented rocks containing joints, and provide theoretical guidance for engineering methods to control the deformation of weakly cemented surrounding rocks.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study on evaluating fracture processes of different rocks using multiple physical parameters","authors":"","doi":"10.1016/j.tafmec.2024.104627","DOIUrl":"10.1016/j.tafmec.2024.104627","url":null,"abstract":"<div><p>To improve the accuracy of rock fracture evaluation, three types of rocks with different lithologies, namely, granite, coal, and sandstone, were processed into cuboid samples with unilateral notches for three-point bending tests. Real-time data were obtained via load, resistance, and acoustic emission (AE) monitoring. Various fracture patterns of the fractured rocks were collected, and the correlations between multiple physical parameters were determined. The results indicated that granite had the highest fracture toughness and initial fracture energy required for macroscopic fracturing, followed by sandstone, which had the lowest fracture toughness and initial fracture energy. The primary crack participated in the fracture process of coal and produced the most complex crack morphology, exhibiting the characteristics of “Progressive fracture” different from the “Instantaneous fracture” of granite and sandstone. The crack length reached 90.5 mm, which was much longer than that of sandstone. The temporal characteristics obtained from multiple physical quantities were synchronized with the fracture behavior. The resistivity increased gradually with the fracture, and the resistivity fluctuation caused by crack propagation increased. The resistivity change rate of granite was the highest when macrofractures occurred, whereas that of coal after complete fracture was the highest. Rock fracture produced a large number of AE events with small amplitude and low peak frequency, concentrated in the 100 ± 50 kHz band. The AE count corresponded to the crack propagation process, and the AE location indicated the crack complexity. The peak change rate of the resistivity was used to evaluate the fracture performance and exhibited a significant linear relationship with the peak load, fracture toughness, and initial fracture energy. The relationship between the accumulated AE energy and the fracture length was a quadratic function, which was used to evaluate the fracture complexity. The multiple physical quantity monitoring method is promising for predicting the fracture behavior of rocks.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141997792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of heat treatment on the shear fracture and acoustic emission properties of granite with thermal storage potential: A laboratory-scale test","authors":"","doi":"10.1016/j.tafmec.2024.104621","DOIUrl":"10.1016/j.tafmec.2024.104621","url":null,"abstract":"<div><p>The exploitation of geothermal resources enhances the energy structure but poses challenges related to thermal–mechanical issues. This study utilizes short core in compression (SCC) specimens of granite to investigate thermo-mechanical properties. We examined the effects of heat treatment temperature on physical properties, shear fracture toughness, as well as acoustic emission (AE) characteristics. Fracture surface morphology and microstructure of the heat-treated SCC specimens were also analyzed using 3D laser scanning and scanning electron microscopy. Results indicate that both mass loss and P-wave velocity decrease with increasing heating-treated temperature, and similar trends are observed in mechanical properties. Specifically, fracture energy and shear fracture toughness decline by 51.48 % and 61.27 %, respectively, as temperature rises from 25 °C to 750 °C. The <em>b</em>-value and proportion of shear cracks initially increase before falling, with an inflection point at 300 °C, linked to thermal-induced microstructural deterioration. Fractal dimension (D) and joint roughness coefficient (JRC) show significant increases with higher heat treatment temperatures. Microstructural degradation, including dehydration and thermal-induced microcracking, drives the reduction in shear properties of heat-treated granites. Overall, our findings offer valuable insights into determining various methods of heat storage reconstruction with great application potential.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142002209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Does double pre-notches have a greater impact than single pre-notch on the mechanical and fracture behavior of rock? Insights from three-point bending tests using the numerical approach of grain-based model","authors":"","doi":"10.1016/j.tafmec.2024.104624","DOIUrl":"10.1016/j.tafmec.2024.104624","url":null,"abstract":"<div><p>The mechanical performance of rock masses is significantly impacted by the existence of cracks. Distribution of the cracks may result in different mechanical or fracture behaviors of rock. To gain a preliminary understanding of such problems, a series of numerical tests of three-point bending (TPB) are designed and carried out with the consideration of single pre-notch and double pre-notches. The numerical method of grain-based model (GBM) approach is employed in this paper, with a validation implemented by comparing the results with previous experiments to demonstrate the reliability of this model. Afterward, a comprehensive investigation, including the mechanical behavior, strength characteristics, crack evolution and progressive failure mechanism of the above mentioned TPB tests are conducted. The conclusions are as follows: (1) During TPB tests, as the offset distance increases, the fracture mode of the single pre-notched specimens gradually transitions from Mode I to Mode II, with the peak fracture toughness occurring at a mixed Mode I-II fracture condition (2<em>p</em>/<em>s</em> = 0.4). Moreover, the failure angle, notch open degree and expansion area all tend to rise regardless of specimens of single or double pre-notches. (2) A thorough exploration of crack evolution shows that the specimens primarily fracture during the crack propagation and failure stages. Shear failure predominates among these stages, with microcracks mostly occurring inside the rock mineral grains. (3) When offset distance increases to a certain degree (2<em>p</em>/<em>s</em> = 0.8), the fracture of specimen ceases to be governed by the pre-notch; instead, it occurs directly from the middle of the beam specimen. This phenomenon can be attributed to the reduction of stress concentration at the notch tip, as inferred from analysis of the contact force chain. (4) In double pre-notched specimen, microcracks initiate at both pre-notches, but the final failure results from crack propagation at one notch tip. Compared to single pre-notched specimen, the presence of double pre-notches exhibits superior fracture resistance performance.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141997356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclic stress–strain behavior of additively manufactured gamma prime strengthened superalloy at elevated temperatures","authors":"","doi":"10.1016/j.tafmec.2024.104623","DOIUrl":"10.1016/j.tafmec.2024.104623","url":null,"abstract":"<div><p>The γ́-precipitation hardened nickel-based superalloy IN939 manufactured by laser powder bed fusion (L-PBF) was subjected to cyclic loading to determine the cyclic stress–strain curve by short-cut procedure. The effect of building on loading direction/orientation was investigated. 〈0<!--> <!-->0<!--> <!-->1〉 crystallographic texture along the building direction was observed. The cyclic stress–strain curves were measured at 800 °C and 900 °C and the differences in cyclic plasticity were revealed. The specimens prepared by L-PBF with a building direction parallel to the loading axis exhibited the highest cumulative plastic deformation at both temperatures, while L-PBF with a building direction perpendicular to the loading axis was the lowest. Elastic moduli were determined and the differences were attributed to the crystallographic texture. In addition, conventionally cast IN939 was investigated as the reference material. Minor microstructural changes due to cyclic straining were inspected by transmission electron microscopy.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142002210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Explicit phase-field material point method for thermally induced fractures","authors":"","doi":"10.1016/j.tafmec.2024.104618","DOIUrl":"10.1016/j.tafmec.2024.104618","url":null,"abstract":"<div><p>Thermally induced fractures in solids pose significant challenges in various fields, such as aerospace, deep underground, and civil engineering structures. Numerical methods are effective for addressing such problems, with recent advancements in phase-field and material point methods demonstrating notable advantages in crack simulation. This paper presents a computational approach within an explicit material point method framework for coupling the solutions of temperature, displacement, and phase (damage) fields. The displacement and phase fields are intricately linked through a history-dependent strain field and degradation function. The model incorporates temperature-induced strains from temperature gradients for coupling the temperature and displacement fields. In addition, the model accounts for the detrimental effects of cracks on heat conduction, ensuring a comprehensive representation of the coupled system. Two numerical examples involving thermomechanical coupling and dynamic crack branching were used to validate the effectiveness of the proposed method. Finally, the proposed method was applied to simulate the thermal shock and large deformations of thin circular ceramic specimens, successfully replicating the initiation and propagation of cracks observed during the experiment. The simulated thermally induced fractures exhibited periodic and hierarchical characteristics consistent with the experimental findings.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142049306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative calculation of rock strain concentration and corresponding damage evolution analysis","authors":"","doi":"10.1016/j.tafmec.2024.104615","DOIUrl":"10.1016/j.tafmec.2024.104615","url":null,"abstract":"<div><p>Understanding the critical strain and damage evolution process of sandstone can help engineers more accurately predict the failure modes and critical states of sandstone in actual engineering structures. Therefore, this article quantitatively analyzes the strain field data obtained through digital image correlation (DIC), and for the first time establishes a strain concentration calculation model (SCCM) to analyze the critical strain, compaction, and damage evolution process of sandstone under uniaxial compression conditions. The experimental results show that both elastic and plastic strain zones exist on the specimen surface. The proportion curve of strain concentration calculated by SCCM indicates that the strain field <em>ε</em>₁ generally undergoes two stages: the elastic strain fluctuation stage and the plastic strain development stage. In contrast, the strain field <em>ε</em>₂ exhibits roughly three stages: a rapid change phase, a slow change phase, and a stability phase. Microscopic strain analysis reveals an overlap between the compaction and damage processes of the specimen, and the critical strain value <em>ε_md</em> for micro-damage in the specimen is significantly smaller than values obtained by traditional discrimination methods. Specifically, when the defect width of the specimen is 15 mm and 40 mm, the mean <em>ε_md</em> vaules are approximately 0.006016 and 0.00539, respectively. In contrast, the mean critical strain values determined by traditional discrimination methods are 0.0180 and 0.0178, respectively. The above research results provide a new method for analyzing the strain field data of geotechnical materials, serving the optimization of engineering structure design.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of fissure distribution characteristics on the dynamic response of fissured Rock: Quantity and spacing","authors":"","doi":"10.1016/j.tafmec.2024.104620","DOIUrl":"10.1016/j.tafmec.2024.104620","url":null,"abstract":"<div><p>The impact test of red sandstone with different fissure distribution was carried out by Split Hopkinson Pressure Bar (SHPB). The failure process of the specimen in the time dimension was captured by high-speed camera and digital image correlation (DIC). The crushing characteristics of the specimen were discussed from the fractal dimension. Furthermore, the influence of fissure distribution characteristics (quantity and spacing of fissures) on the mechanical properties and fracture behavior of fissured red sandstone was analyzed. The experimental results show that the fissure spacing is negatively correlated with the dynamic compressive strength and peak strain of specimen, while the fissure quantity is negatively correlated with the dynamic compressive strength and positively correlated with the peak strain. Cracks are categorized into five types based on the manner of their initiation and expansion. The crack initiation and propagation are jointly affected by tensile stress and shear stress, but the tensile stress is dominant. With the increase of the fissure quantity, the failure mode changes from tensile failure to tensile-shear mixed failure. The increase of fissure spacing does not change its failure mode, but the formation mode of the main crack changes. The fractal dimension increases with the increase of the fissure quantity, and decreases with the increase of the fissure spacing, i.e., the larger the fissure quantity is, the higher the degree of fragmentation is, and the larger the fissure spacing is, the lower the degree of fragmentation is. The research results can provide a theoretical reference for the study of dynamic failure mechanism of rock mass with non-persistent discontinuities.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141993390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}