Theoretical and Applied Fracture Mechanics最新文献

{"title":"Microstructure – Fracture toughness relationship in a sub-zero treated 0.9C-7.8Cr sub-ledeburitic tool steel","authors":"","doi":"10.1016/j.tafmec.2024.104670","DOIUrl":"10.1016/j.tafmec.2024.104670","url":null,"abstract":"<div><p>The Sleipner steel (0.9C-7.8Cr sub-ledeburitic tool steel) is a widely utilized tool steel currently being adopted to produce tools used in fine blanking, shearing, forming, coining, deep drawing, and others. In these branches, tailoring the final mechanical properties, such as hardness and toughness, to specific application is highly appreciated. The Sleipner steel was subjected to sub-zero treatments (at –140 °C for 17 h and 36 h) in the current work. The resulting microstructures, hardness variations, and changes in fracture toughness were analyzed and discussed. It was observed that sub-zero treatments reduced the retained austenite amounts by 14–15 % and slightly refined the martensite. However, the impact of this treatment on carbide count was marginal. The hardness of the sub-zero treated steel increased when tempered at temperatures up to 400 °C, but it decreased after tempering at 520 °C compared to cryogenically treated specimens.</p><p>Sub-zero treatment reduced the fracture toughness in the steel tempered up to a temperature of 400 °C, but an increment in this property was found after 520 °C tempering. Nevertheless, the obtained results indicate that it is impossible to simultaneously enhance both the hardness and fracture toughness of this particular steel grade. Therefore, it is necessary to carefully choose the principal goal of the treatment (either hardness or toughness) even before subjecting the tools to the heat/sub-zero treatment.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142232801","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 determination of crack growth resistance curves of high-strength steel using thin clamped SENT specimens","authors":"","doi":"10.1016/j.tafmec.2024.104651","DOIUrl":"10.1016/j.tafmec.2024.104651","url":null,"abstract":"<div><p>Martensitic stainless steels (MSS) are known for their high mechanical strength and moderate corrosion resistance across various environments. However, their martensitic structure imposes limitations on fracture toughness. By employing heat treatments like quenching and partitioning, it becomes feasible to augment the presence of residual austenite in the material. This microstructural change enables the material to better absorb energy during fracture, thereby increasing its fracture toughness. The development of high-strength steels with good fracture toughness could influence the project and design of structural components, potentially resulting in reduced structural thickness. Experimental determination of crack growth resistance curves and fracture toughness for thin high-strength steels is challenging because most standardized methodologies were developed for thicker samples. The American Society for Testing and Materials has published a standard test method for the determination of resistance to stable crack extension under low-constraint conditions (ASTM E2472) in terms of critical crack-tip-opening angle (CTOA, <em>ψ</em>_c) and/or critical opening displacement at the original crack tip (<em>δ</em>₅), involving the use of thin compact tension C(T) and middle-tension M(T) specimens. However, this method requires specific instrumentation, relatively large specimens, and additional experimental devices such as anti-buckling guides. In this context, this paper evaluates the applicability of the elastic unloading compliance technique for determining crack growth resistance curves in terms of <em>J</em>-integral of MSS using relatively small, non-standard thin clamped SENT specimens with thickness of 1 mm. The proposed methodology, based on a combination of BS 8571 standard and the compliance, stress intensity factor, and <em>η</em>_pl factor solutions from the literature, has proven to be suitable for evaluating toughness in thin clamped SENT specimens and could be useful for assessing fracture toughness in high-strength steels of small thickness.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167649","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":"Analytical expressions for Jk-integrals of orthotropic/isotropic interface cracks","authors":"","doi":"10.1016/j.tafmec.2024.104643","DOIUrl":"10.1016/j.tafmec.2024.104643","url":null,"abstract":"<div><p>This paper presents new analytical expressions for <span><math><msub><mi>J</mi><mi>k</mi></msub></math></span> integrals in terms of the stress intensity factors (SIF) of an in-plane traction free interface crack in an orthotropic/isotropic bimaterial. Using the sextic formalism of Stroh and Muskhelishvili formulation, a general solution for the stress and displacement fields near the interface crack of this bimaterial are derived. This paper also presents an analytical expression for the SIFs of a finite interface crack in an infinite orthotropic/isotropic bimaterial subject to in-plane remote stresses. For validation of the presented theory, the analytical <span><math><msub><mi>J</mi><mi>k</mi></msub></math></span> integrals, crack opening displacements and stresses along the interface of an infinite orthotropic/ aluminum plate with a finite interface crack subject to tension are compared with the corresponding numerical results obtained using the boundary element method. For the orthotropic material, different fibre reinforced polymers are considered. The results show that a metal/fibre composite can be tailored to crack growth resistance. This study provides explicit analytical expressions for fracture parameters of cracks between isotropic and orthotropic materials which are not currently available in the SIF handbooks.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0167844224003938/pdfft?md5=6eda03d9e9f65d0679f8e9d4707c7b2d&pid=1-s2.0-S0167844224003938-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Notch sensitivity analysis of a 2205 duplex stainless steel in a gaseous hydrogen environment","authors":"","doi":"10.1016/j.tafmec.2024.104655","DOIUrl":"10.1016/j.tafmec.2024.104655","url":null,"abstract":"<div><p>Austenitic stainless steels are typically used in hydrogen environments due to their resistance to hydrogen embrittlement, though their mechanical strength is only medium to low. To explore the use of high-strength materials, their susceptibility to hydrogen embrittlement must be studied. Duplex stainless steels, featuring both austenitic and ferritic phases, are among the promising candidates due to their enhanced mechanical properties. They exhibit good mechanical properties but, due to the presence of the ferritic phase, they are sensitive in hydrogen environment. In this study, the notch sensitivity of 2205 duplex is analyzed, both in air and hydrogen environment (at a pressure of 140 bar). Three different specimens are designed with different notch radii, varying the stress concentration factor from K_t = 2 to K_t = 6. A numerical simulation has been carried out in order to calculate the stress and deformation conditions for each configuration and the failure mechanisms have been analyzed for all the cases, establishing the behavior of this material against different types of notches in air and in a hydrogen environment. Moreover, a coupled diffusion-deformation model has been developed using Comsol finite element software. The model is focused on hydrogen transport and incorporates lattice hydrogen diffusion and a stress-assisted diffusion term to account for the influence of mechanical stress on the diffusion process. The results show a high notch sensitivity of this material in the tensile strength embrittlement index, as a consequence of the high hydrogen susceptibility of the ferritic phase enhanced by the high stress–strain states at the notch tip.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0167844224004051/pdfft?md5=dc23f7bec7db0ca027016187175cbf9f&pid=1-s2.0-S0167844224004051-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanical properties and cracking strength estimation of high-strength engineered cementitious composites considering the fracture process zone","authors":"","doi":"10.1016/j.tafmec.2024.104647","DOIUrl":"10.1016/j.tafmec.2024.104647","url":null,"abstract":"<div><p>In the present study, the effect of flaws on the mechanical properties of high-strength engineered cementitious composites (HS-ECC) was investigated. Compressive tests, tensile tests, and electron microscope scanning microscopic tests were designed to explore the influence mechanism of flaws on mechanical properties. The results show that the compressive failure of HS-ECC was primarily characterized by a high density of vertical micro-cracks, and the specimen maintained exceptional structural integrity. All tested mix ratios demonstrated tensile strain hardening. Notably, the test groups with an 18 mm fiber length exhibited superior crack width control, with an average crack width of less than 30 μm. A new fiber bridging model was proposed, informed by microstructural analysis and crack opening displacement observations. A theoretical formula for the cracking strength of HS-ECC was developed based on the fracture process zone concept. The calculated initial crack strength closely matches the experimental values, with a discrepancy range of [0, 17 %]. This close agreement provides robust validation for the accuracy and reliability of the enhanced cracking strength calculation theory, thereby supporting its application in the design of ECC.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163701","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":"An examination of techniques based on two strain gages for the determination of mode I stress intensity factor in orthotropic composite materials","authors":"","doi":"10.1016/j.tafmec.2024.104653","DOIUrl":"10.1016/j.tafmec.2024.104653","url":null,"abstract":"<div><p>In this work, we have examined the single strain gage technique proposed by Chakraborty et al. (2014) (CMC1) for the accurate determination of mode I stress intensity factor (SIF) in orthotropic composite materials. Numerical simulations carried out on single edge crack specimen with different values of the height to width ratio (<span><math><mrow><mi>h</mi><mo>/</mo><mi>b</mi></mrow></math></span>) and of the crack length to width ratio (<span><math><mrow><mi>a</mi><mo>/</mo><mi>b</mi></mrow></math></span>) have shown the limits of this technique and that the use of a single strain gage is not always reliable to provide precise measurements of SIF, <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>I</mi></mrow></msub></math></span>. To avoid such a situation, we have proposed two new techniques based on two strain gages named CMC2 and M_CMC2. The CMC2 technique is a natural extension of the CMC1 technique and the M_CMC2 technique is a modification of the CMC2 technique. Accordingly, general finite element approaches are developed to estimate the extent of the valid region of these two techniques. The results of the numerical simulations show that the two techniques CMC2 and the M_CMC2 can give a very accurate value of <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>I</mi></mrow></msub></math></span> when the two strain gages are placed within valid region. Also, these results show that these two techniques provide good solutions to ensure an accurate measurement of <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>I</mi></mrow></msub></math></span> when the technique of CMC1 fails to provide the desired precision and accuracy of <span><math><msub><mrow><mi>K</mi></mrow><mrow><mi>I</mi></mrow></msub></math></span>. In addition, the results derived from experimental data (Chakraborty et al., 2017) proved the effectiveness of the CMC2 technique.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142164906","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":"Syncretic investigation on size effect in fracture behavior of dam concrete with physical experiment and mesoscale simulation","authors":"","doi":"10.1016/j.tafmec.2024.104649","DOIUrl":"10.1016/j.tafmec.2024.104649","url":null,"abstract":"<div><p>Understanding and predicting mechanical properties in large-scale structures such as dams poses a significant challenge, largely due to the inherent size effect in concrete materials. This study presents a mesoscopic investigation into the size effect on fracture behavior in dam concrete under three-point bending, employing both physical experiments and mesoscale simulation. Meso-structures of dam concrete specimens, including prefabricated cracks, are initially generated using a novel method tailored for three-point bending experiments. Subsequently, model parameters and solver settings for the phase field method are calibrated based on laboratory experiments. The fracture behavior and mechanical response of dam concrete under three-point bending are systematically modeled and analyzed, with different parameters including loading positions, maximum aggregate sizes, crack-height ratios, and specimen dimensions. Furthermore, a significant size effect is observed in both fracture resistance and flexural strength, as evidenced by computational outputs. Three classical models proposed by Bažant, Carpinteri, and Kim are adopted, to capture the influence of different maximum aggregate sizes and crack-height ratios on flexural strength, and a favorable consistency is observed across a range of specimen heights from 80 to 500 mm. The presented computational analysis provides valuable insights for the application of experimental and numerical outputs in practical engineering scenarios.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142228902","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":"Investigating the effects of aging and New Jig Coal Tailings (NJCT) on mixed-mode I/II fracture behavior of asphalt mixture modified with BituSul","authors":"","doi":"10.1016/j.tafmec.2024.104654","DOIUrl":"10.1016/j.tafmec.2024.104654","url":null,"abstract":"<div><p>Moisture susceptibility and cracking resistance of asphalt pavement made with sulfur additive are two important failures of this type of asphalt mixture that should be considered. Recently, researchers have been trying to improve the mechanical performance of sulfur asphalt mixtures by modifying the asphalt mixture manufacturing method, modifying sulfur manufacturing technology, and applying laboratory conditioning. In this laboratory work, an attempt was made to improve the mechanical properties of an asphalt mixture made with a type of sulfur material called BituSul by different methods. The first method was the moisture susceptibility test and the second method was the fracture test. In the first step, 30 % of PG70-10 bitumen was replaced with BituSul, and a moisture susceptibility test was performed. After estimating the minimum moisture susceptibility of the BituSul-reinforced asphalt mixture, the fracture test was performed on the asphalt mixture without additives, BituSul-reinforced asphalt mixture, and BituSul-reinforced asphalt mixture containing New Jig Coal Tailings (NJCT) (with a replacement ratio of 50 % filler). To compare the fracture behavior of the mixtures over time, two conditions, including one freeze–thaw cycle (FTC) and about fifty-six hours of the aging period, which was equivalent to four years of failure, were applied to the mentioned samples separately. Finally, the samples were tested under mixed mode I/II at −12 °C and + 24 °C. The findings showed that the manufacturing technology used in this research, including how to design and manufacture the samples, the type of bitumen used, and the type of sulfur used (BituSul), caused a 2 % decrease in moisture susceptibility compared to the base sample. The fracture resistance results showed that the application of 0 and one cycle of FTC decreased the fracture indices of the mixture reinforced with BituSul at −12 °C and + 24 °C. Also, the results showed that the fracture stiffness improved for samples containing BituSul at −12 °C and + 24 °C. Finally, the results showed that applying aging to BituSul mixtures and BituSul mixtures reinforced with NJCT improved fracture resistance, fracture flexibility, and fracture stiffness. However, NJCT could not compensate for the improvement of fracture indices of asphalt mixture caused by the presence of BituSul; therefore, the application of aging was reported to be a suitable option to improve the fracture indices of BituSul-reinforced mixtures.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172839","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":"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":"10.1016/j.tafmec.2024.104644","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":5.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163700","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":"Numerical implementation and comparison study on simulating thermo-elastic fracture using adaptive phase-field method combined with BFGS algorithm and AM algorithm","authors":"","doi":"10.1016/j.tafmec.2024.104650","DOIUrl":"10.1016/j.tafmec.2024.104650","url":null,"abstract":"<div><p>In this paper, the computational performance of alternate minimization (AM) and Broyden–Fletcher–Goldfarb–Shanno (BFGS) to solve the coupled partial differential equations arising within the framework of the phase field method is numerically studied. Both the numerical approaches are employed on an adaptive phase field method. In the case of BFGS, a double-loop recursive algorithm in combination with a line search is implemented. The local refinement is based on a pre-defined threshold on the damage variable and element size. The incompatible nodes due to adaptive refinement are handled by variable-node elements. The performance of the solution algorithm is numerically studied for a few problems with different loading conditions, viz., pure mechanical, pure thermal and combined thermo-mechanical. From the study, it is opined that the BFGS algorithm is 2<span><math><mo>∼</mo></math></span>5 times faster than the AM approach, which is typically used for adaptive phase field framework. In addition, the detailed numerical implementation is presented.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148031","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}