Theoretical and Applied Fracture Mechanics最新文献

{"title":"Exploring the influence of specimen types on the intralaminar fracture behavior of fiber-reinforced polymer matrix composites","authors":"","doi":"10.1016/j.tafmec.2024.104684","DOIUrl":"10.1016/j.tafmec.2024.104684","url":null,"abstract":"<div><div>The accurate determination of fracture toughness of fiber-reinforced composites is critical for the assessment of structural integrity. Although there have been many studies on the intralaminar fracture behavior of composites, satisfactory results have not yet been obtained regarding the influence of specimen types. In this paper, commonly used fracture specimens (DCT, CT, ESET, pin-loaded SENT and clamped SENT specimen) are applied to study their applicability in the fracture behaviors of composites with different orientations. And the impact of data processing methods for the area method, <em>G</em>_C-compliance and <em>G</em>_C-stress intensity factors on fracture performance was analyzed. The results showed that the above three data processing methods have obtained relatively consistent fracture properties. Different specimens obtained significantly various results, showing a gradually decreasing trend from clamped SENT, ESET, pin-loaded SENT, CT to DCT. Furthermore, considering that the clamped SENT specimen is closest to the Mode-I fracture toughness obtained from the DCB specimen, and there is no compression damage in the experiments under different orientations, this specimen type is the most recommended specimen. Finally, the failure mechanisms of carbon fiber-reinforced composite under different specimen types and orientations were revealed. As the orientation angle increases (<em>β</em> from 0° to 90°), the failure mode gradually transitions from matrix cracking and interface debonding to matrix shear and fiber fracture. The above achievements will contribute to a deeper understanding of the intralaminar fracture process and failure mechanism of fiber-reinforced composites.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311695","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":"Mean stress effect on crack propagation threshold at high stress ratios","authors":"","doi":"10.1016/j.tafmec.2024.104669","DOIUrl":"10.1016/j.tafmec.2024.104669","url":null,"abstract":"<div><p>The stress ratio effect on fatigue crack propagation threshold has been a subject of extensive investigation for decades in engineering materials. In the work, a modified mean stress correction model is proposed to predict long crack propagation threshold at high stress ratios as an extension of our previous work (Engineering Fracture Mechanics 2020, 223:106787). Moreover, the mean stress modified K-T diagram is derived based on the proposed model. Good accuracy can be achieved in terms of the experimental long fatigue crack propagation thresholds and K-T diagrams.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244105","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":"Fatigue crack growth rate under mixed-mode loading conditions (I+III) of a carbide-free bainitic steel designed for rail applications","authors":"","doi":"10.1016/j.tafmec.2024.104683","DOIUrl":"10.1016/j.tafmec.2024.104683","url":null,"abstract":"<div><div>Carbide-free bainitic steel was designed for railway infrastructure application, focusing on high-speed and heavy-loaded freight tracks. Considering the complex state of stresses occurring on the rails running surface, mode III plays a significant role in the initiation and propagation of fatigue cracks of rails during service. Thus, the Fatigue Crack Growth Rate (FCGR) under mixed-mode loading conditions (I+III) was evaluated. It was revealed, that fatigue lifetime increases with loading angle modes. In the area of fatigue fracture, transgranular cracking mechanisms dominated. For the stable fatigue crack growth, a trend was observed related to the decrease in the fraction of intergranular fracture with the increasing loading angle modes (α). Secondary cracks indicated privileged cracking directions related to the crystallographic structure of bainite. The influence of the mechanical stability of retained austenite during mixed-mode FCGR requires further in-depth research. These studies contribute to understanding the factors influencing the reliability of railway tracks in terms of designing new materials and modeling the rate of crack growth to precise assessment of the life cycle of rails.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142320431","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":"Compression-induced failure characteristics of brittle flawed rocks: Mechanical confinement-dependency","authors":"","doi":"10.1016/j.tafmec.2024.104678","DOIUrl":"10.1016/j.tafmec.2024.104678","url":null,"abstract":"<div><p>The flaw tips in brittle rocks are often the sources of crack initiation and growth due to the stress concentration, which commonly governs the rock strength. However, a unified framework identifying the compression-induced crack types, ultimate failure patterns and the cracking levels of brittle flawed rocks under different mechanical confinements is not yet available. This study conducts the laboratory compression experiments with the AE monitoring to explore the failure characteristics of flawed limestone and its confinement-dependency. Four new crack types including loop crack, secondary transverse crack, near-field transverse crack and far-field transverse crack are found experimentally, and then a modified crack type classification strategy is proposed. Four failure patterns including the <em>σ</em>₁-axisymmetric flaw-disturbed spalling for uniaxial compression, the <em>σ</em>₃-transverse-symmetric flaw-disturbed spalling for biaxial compression, the <em>σ</em>₁ −axisymmetric flaw-disturbed shearing for conventional triaxial compression, and the mixed <em>σ</em>₃-transverse-symmetric flaw-disturbed shearing and <em>σ</em>₂-transverse-symmetric flaw-disturbed spalling for true triaxial compression, are documented for the first time. Moreover, an acousto-mechanics-based classification methodology of rock cracking levels is established, as well as an AF (average frequency)-RA (rising angle)-based Kernel density estimation method for interpreting the rock cracking nature and the strength mechanism. This paper gets insights into the mechanical confinement-dependency of the rock failure characteristics incorporating the pre-existing flaws and help interpret the field observations.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244034","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 failure-dependence related stochastic crack growth modeling approach of competing cracking mode","authors":"","doi":"10.1016/j.tafmec.2024.104680","DOIUrl":"10.1016/j.tafmec.2024.104680","url":null,"abstract":"<div><div>Competing crack-induced fatigue fracture has been a typical failure mode especially in the very high cycle fatigue regime. However, the stochastic crack growth modeling related to failure-dependence has not been fully investigated. Here, a failure-dependence related stochastic crack growth modeling approach for competing cracking mode is proposed to address this issue. Firstly, copulas are used to model the dependent competing relationships among multiple fatigue fracture modes. The reliability analysis of multiple fatigue fracture modes is conducted from a copula perspective. Besides, the fatigue crack growth is modeled based on a nonlinear Wiener process, with unit-to-unit variability addressed by introducing random effects. Marginal reliability expressions are derived based on the Wiener process. Furthermore, a two-stage Bayesian inference method based on Hamiltonian Monte Carlo sampling is proposed to estimate model parameters. A Monte Carlo simulation study is conducted to validate the accuracy and robustness of the proposed inference method. Finally, the effectiveness of the proposed approach is proven through a real case study. It turns out that the ignorance of the competing relationships among multiple cracking modes leads to an underestimation of overall reliability. The accuracy of the model can be further improved with random effects considered.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311694","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 new strain-based approach to investigate the size and geometry effects on fracture resistance of rocks","authors":"","doi":"10.1016/j.tafmec.2024.104679","DOIUrl":"10.1016/j.tafmec.2024.104679","url":null,"abstract":"<div><p>In this paper, a new strain-based criterion is suggested for assessing the effects of size and geometry of specimen on the fracture resistance of rocks under mixed-mode (I/II) loading. The new approach named the modified maximum tangential strain (MMTSN) criterion is based on the classical maximum tangential strain (MTSN) criterion, in which the first non-singular term (<span><math><mi>T</mi></math></span>) of Williams series expansion is considered in addition to the singular terms (<span><math><mi>K</mi></math></span>). Furthermore, to provide more coherence, the critical distance (<span><math><msub><mi>r</mi><mi>c</mi></msub></math></span>) from the crack tip is defined according to a new strain-based failure model. Unlike similar strain-based fracture models available in the literature, the critical distance <span><math><msub><mi>r</mi><mi>c</mi></msub></math></span> in the MMTSN criterion is assumed to be size-dependent and a semi-empirical formulation is utilized for describing this size-dependency. To assess the ability of MMTSN for considering the size and geometry effects, the experimental data existing in the literature for a number of cracked Brazilian disk (CBD) and semi-circular bend (SCB) specimens manufactured from Guiting limestone are taken into account. It is demonstrated that the MMTSN criterion can predict the experimental data very well by taking into consideration the size and geometry effects without needing to calculate the other higher order terms.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244035","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":"Fracture toughness and fatigue crack growth in DMLS Co-Cr-Mo alloy: Unraveling the role of scanning strategies","authors":"","doi":"10.1016/j.tafmec.2024.104681","DOIUrl":"10.1016/j.tafmec.2024.104681","url":null,"abstract":"<div><p>Co-Cr-Mo alloy is crucial for biomedical implants and aerospace components. These parts often exhibit a high level of geometric intricacy. Direct metal laser sintering (DMLS) is ideal for these complex parts. In DMLS, choosing the right scanning strategies is vital, as it significantly affects the fatigue fracture behavior of the printed components. Thus, the present study investigates the effect of different scanning strategies (stripe, meander, and chessboard) on the fracture toughness and fatigue crack growth behavior of DMLS printed Co-Cr-Mo alloy. For each scanning strategy, fatigue crack growth tests have been performed to evaluate the threshold stress intensity factor and Paris law constants. To corroborate the obtained experimental results, microstructure analyses have been performed using electron backscattered diffraction. Further, failure mechanisms have been identified from fractographs obtained using field emission scanning electron microscopy. It is evident from the obtained test results that scanning strategies caused significant variation in fracture toughness and fatigue crack growth behavior. The stripe scanning strategy has exhibited higher resistance to fracture and fatigue crack growth. However, delayed crack initiation has been observed in the case of the chessboard scanning strategy. The present study provide the background for better selection of scanning strategies to mitigate fatigue fracture in DMLS-printed Co-Cr-Mo alloy designed for specific applications.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244020","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":"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":"Full field crack solutions in anti-plane flexoelectricity","authors":"","doi":"10.1016/j.tafmec.2024.104674","DOIUrl":"10.1016/j.tafmec.2024.104674","url":null,"abstract":"<div><p>In flexoelectric materials, strain gradients can induce electrical polarization. However, internal defects such as cracks profoundly affect the electromechanical coupling properties of flexoelectric solids. In particular, anti-plane cracks involve less physical fields, which are easier to study. In this study, we present a comprehensive and innovative investigation of the anti-plane crack problems in flexoelectric materials, including semi-infinite and finite-length anti-plane cracks. For the first time, we formulate a full-field solution for semi-infinite anti-plane cracks in flexoelectric media by applying the Wiener–Hopf technique. Furthermore, the collocation method and the Chebyshev polynomial expansion are used for the first time to derive the full-field hypersingular integral equation solution for finite-length anti-plane cracks in flexoelectric solids. In addition, a comparative analysis between the full-field and asymptotic solutions for semi-infinite cracks is performed, shedding light on the discrepancies in the representation of the electromechanical coupling behavior near the crack tip. The mixed finite element method is used to compare with the full-field solutions of finite-length cracks. The agreement between the numerical results and the full-field solutions demonstrates the rigor of our study. This research advances the knowledge of defects in flexoelectricity and provides significant insight into relevant failure mechanisms.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244019","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}