Theoretical and Applied Fracture Mechanics最新文献

{"title":"Study on crack propagation behaviors of three-point bending concrete beams with small span-depth ratios","authors":"","doi":"10.1016/j.tafmec.2024.104638","DOIUrl":"10.1016/j.tafmec.2024.104638","url":null,"abstract":"<div><p>Three-point bending (TPB) beams with small span-depth ratios, i.e. TPB beams with the same span of 400 mm but various depths (100 mm, 150 mm and 200 mm), were tested to study the crack propagation behaviors of concrete. The evaluations of crack extension resistance curve (<em>K</em>_R-curve), fracture process zone (FPZ) length, <em>l</em>_FPZ, and crack tip opening displacement (<em>CTOD</em>) were studied. The digital image correlation (DIC) technique was utilized to monitor the entire loading process. Moreover, the effects of strain rates (10⁻⁵/s, 10⁻⁴/s, 10⁻³/s and 10⁻²/s) on the fracture process of TPB beams with small span-depth ratios (2, 2.5 and 3) were discussed based on findings in literature. The results shown that (1) with the increase of specimen depth from 100 mm to 200 mm, the obtained <em>K</em>_R-curves and initial fracture toughness were not influenced by the small span-depth ratios, while different increase trends were observed for the unstable fracture toughness, the average maximum value of <em>l</em>_FPZ and the value of <em>CTOD</em>. (2) With the loading rate increasing from 10⁻⁵/s to 10⁻²/s, the obtained <em>K</em>_R-curve and the maximum length of FPZ increased slightly, while the evolution of <em>CTOD</em> was not affected by the loading rate.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142099476","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":"Effects of temperature on pure mode-I and mode-Ⅱ fracture behaviors and acoustic emission characteristics of granite using a grain-based model","authors":"","doi":"10.1016/j.tafmec.2024.104637","DOIUrl":"10.1016/j.tafmec.2024.104637","url":null,"abstract":"<div><p>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 <em>b</em>-value, thereby reducing the AE magnitude during failure.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142076261","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 and analytical study on non-tip initiation behavior of three-dimensional non-planar cracks in rock-like materials","authors":"","doi":"10.1016/j.tafmec.2024.104626","DOIUrl":"10.1016/j.tafmec.2024.104626","url":null,"abstract":"<div><p>The presence of fractures, joints, bedding planes, and faults within rock masses results in their inherent heterogeneity and discontinuity. These structural defects alter the mechanical properties of rock masses, reducing their structural strength and stiffness, and contributing to anisotropy. In addition to planar cracks, non-planar cracks are frequently found within rock masses due to geological evolution and local stress variations. While the mechanisms of planar crack propagation and fracture in both two-dimensional and three-dimensional spaces have been extensively studied and understood, research on non-planar cracks has largely been confined to two-dimensional aspects. This study addresses the limitations by successfully creating brittle solid specimens with three-dimensional non-planar internal cracks. Uniaxial compression tests and numerical simulations were conducted to investigate the propagations and fracture behaviors of various shapes of three-dimensional non-planar internal cracks. The experiments identified two primary macroscopic failure modes: symmetric non-planar internal cracks exhibiting non-tip initiation failure, and asymmetric non-planar internal cracks displaying tip initiation on the upper side and non-tip initiation on the lower side. The failure strengths of non-planar internal cracks were significantly higher than those of planar cracks, and the size of the cracks had minimal effect on their failure strengths. Notably, from initiation to failure, symmetric non-planar internal cracks did not generate any wing cracks, whereas asymmetric non-planar internal cracks were accompanied by petal-shaped cracks, wing cracks, and lance-shaped cracks. Under uniaxial compression, non-planar internal cracks propagated at extremely high speeds, resulting in rough and uneven fracture surfaces. In addition to Type III lance-shaped cracks, dynamic fracture characteristic areas and Wallner lines were also observed on the fracture surfaces. This study provides valuable insights into the fracture behavior of three-dimensional non-planar cracks and a reference basis for understanding their propagation and failure mechanisms.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142088971","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":"Progressive failure analysis of laminar composites under compression using smeared crack-band damage model and full layerwise theory","authors":"","doi":"10.1016/j.tafmec.2024.104635","DOIUrl":"10.1016/j.tafmec.2024.104635","url":null,"abstract":"<div><p>This paper presents an original finite element (FE) model that integrates the smeared crack band (SCB) approach and full layerwise plate theory (FLWT). The model enhances the computational efficiency of progressive failure analysis (PFA) of laminar composites in compression, by utilizing the layerwise approach which reduces a 3D model to a 2D one. The model distributes damage throughout the FE domain, with fracture mechanisms represented by material stiffness degradation controlled by damage variables (based on equivalent strains specifically defined for each failure mode). Mesh dependency issues are addressed by scaling fracture energy using a characteristic element length, and failure initiation and modes are determined using the 3D Hashin failure criterion.</p><p>Accurately describing lamina response in fiber direction under compression requires linear-brittle softening with a stress plateau. The study showed that a model considering 30 % of residual stress accurately predicts maximum stress regardless of mesh refinement, demonstrating results’ minor dependence from the selected element size.</p><p>The model accuracy has been confirmed by comparing the obtained results against experimental and benchmark data from the literature. The size effect study demonstrated a decrease in maximum stress of the open-hole laminates in compression with increasing specimen in-plane size. This trend is consistent with experimental and reference numerical observations, confirming the model accuracy and applicability even for relatively coarse meshes. Therefore, computational efficiency is improved, with preserved accuracy of conventional solid finite element models.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0167844224003859/pdfft?md5=d1469081394d67586c438c712425bcad&pid=1-s2.0-S0167844224003859-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142099475","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":"Effects of fissure locations on the crack propagation morphologies of 3D printing tunnel models: Experiments and numerical simulations","authors":"","doi":"10.1016/j.tafmec.2024.104631","DOIUrl":"10.1016/j.tafmec.2024.104631","url":null,"abstract":"<div><p>Hidden fissures widely exist in the surrounding rock of tunnels, and the propagations and interactions of the fissures will directly affect the safety and stability of tunnels. However, experimental and numerical simulation studies are scarce on the tunnel-fissure interactions under complex stress conditions. Based on this background, circular tunnel specimens with different prefabricated fissure locations are prepared by three-dimensional (3D) printing technology. Uniaxial compression fracture tests are conducted utilizing Digital Image Correlation (DIC) technology to obtain strain distributions. An improved Smoothed Particle Hydrodynamics (SPH) method is employed to simulate the crack propagation processes of the tunnel-fissure interactions. The results demonstrate the following: 1) Upper main cracks, upper side cracks, and lower side cracks are produced around the tunnel, and wing cracks initiate from the prefabricated fissure tips. 2) For the different intersection positions, wing crack propagation length decreases as the intersection position moves upward, while the lower side crack propagation length increases. 3) For different distances <em>d</em>, upper side crack does not appear, and the propagation length of upper main crack increases with the increase of the distance <em>d</em>. 4) For different fissure inclination angles <em>α</em>, upper main crack does not appear when <em>α</em> = 15°. The propagation length of wing crack increases with the increase of inclination angle <em>α</em>. 5) The peak stress increases as the intersection position moves upward, while it decreases with the increase of inclination angle <em>α</em>. With increasing distance <em>d</em>, the peak stress initially increases and then decreases. Finally, the crack initiation mechanisms under different fissure orientations and inclinations are discussed. These research findings provide valuable insights into the tunnel-fissure interaction mechanisms under complex stress conditions and the applications of the SPH method in underground engineering simulations.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041180","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":"T-stress extraction in arbitrarily cracked orthotropic composites with the numerical manifold method and Stroh formalism","authors":"","doi":"10.1016/j.tafmec.2024.104632","DOIUrl":"10.1016/j.tafmec.2024.104632","url":null,"abstract":"<div><p>The escalating utilization of composites over the past decades has necessitated the fracture investigation of orthotropic materials. The T-stress, namely, the first non-singular term of the normal stress parallel to the crack in William’s expansion, is of great significance for fracture analysis. In this work, the numerical manifold method (NMM) is advanced to assess the T-stress of arbitrary-shaped cracks (including non-intersecting cracks and multi-branched cracks) in two-dimensional orthotropic composites. Attributing to the bi-cover systems, the NMM can conveniently discretize the physical domain and naturally accommodate the discontinuity across crack surface. Meanwhile, the singularity at crack tip can be well captured by the wise choice of local approximation function. Through the application of interaction integral technology in the NMM postprocessing, the T-stress is extracted with the Stroh-form auxiliary fields. The accuracy of the proposed method is verified by comparing with reference solutions and then applied to arbitrarily branched and intersecting cracks. The results indicate that the present approach has convincing accuracy and also considerable convenience in T-stress evaluation. Additionally, the impacts of material orientations, crack geometries and loading conditions on the T-stress are also investigated.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142076262","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":"Solution of a Dugdale–Barenblatt crack in an infinite strip by a hyper-singular integral equation","authors":"","doi":"10.1016/j.tafmec.2024.104625","DOIUrl":"10.1016/j.tafmec.2024.104625","url":null,"abstract":"<div><p>This work treats the case of a Dugdale–Barenblatt crack within an infinite strip through the resolution of a hyper singular integral equation. The crack is perpendicular to the strip boundaries and located at its center. The solution approach is based on second order Chebyshev polynomials and requires meticulous treatment of the jump discontinuities within the loading distribution along the crack faces. The relationship between the width of the strip and the length of the cohesive zone has been established. The variation in applied load with the increase in crack length, considering different ratios of the initial crack length to the strip width is illustrated. Furthermore, the crack propagation is simulated. Validation of our approach is achieved through comparison with both the infinite medium case and the work of H. Tada et al. <em>“The Stress Analysis of Cracks Handbook, Del Research Corporation, Hellertown, Pennsylvania. 1973”</em>.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083392","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":"Modeling the effect of material heterogeneity on the thermo-mechanical behavior of concrete using mesoscale and stochastic field approaches","authors":"","doi":"10.1016/j.tafmec.2024.104622","DOIUrl":"10.1016/j.tafmec.2024.104622","url":null,"abstract":"<div><p>The adverse impact of high temperatures on concrete is a well-recognized issue that can lead to significant mechanical deterioration and structural integrity loss. Factors such as aggregate type, cement composition, temperature, duration of exposure, and moisture content can substantially influence the fire resistance of concrete. To simulate and better understand the effects arising from the heterogeneity of concrete in a fire situation, a mesoscale approach is proposed, using the Mesh Fragmentation Technique (MFT) to assess the complex thermo-mechanical behavior of concrete. The MFT introduces high aspect ratio interface elements to model crack propagation and interfacial transition zones by means of an appropriated tensile damage constitutive law. In this extended framework, a fully-coupled thermo-mechanical model is proposed. The modeling approach includes considerations of both macroscopic and mesoscopic scales, in which the coarse aggregate, mortar matrix and interfacial transition zones are represented. Besides, a stochastic distribution is assumed for the material properties to account for the lower scale heterogeneity. The main novelty proposed in this study consists in the synergy of mesoscale and stochastic approaches that are herein combined to model the effect of heterogeneity on the concurrent macro-mesoscale thermo-mechanical behavior of concrete. To validate the numerical model’s capabilities in capturing thermally induced cracks, benchmark cases and a simulation of a bending beam exposed to elevated temperatures are presented. The results demonstrate the potential of the proposed approach in predicting the behavior of concrete subjected to thermal loading and the role played by heterogeneity in the thermally induced cracking.</p></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142076260","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":"Flexural and fracture performance of fiber reinforced self compacting alkali activated concrete– A DOE approach","authors":"","doi":"10.1016/j.tafmec.2024.104630","DOIUrl":"10.1016/j.tafmec.2024.104630","url":null,"abstract":"<div><p>Owing to their much-reduced carbon footprint and lower embodied energy, compared to conventional Portland Cement (OPC-based) Concrete mixes, Alkali Activated Concrete (AAC) mixes represent a pivotal advancement towards achieving sustainability goals. The fracture properties were investigated using Three-Point Bending Tests (3-PBT) under the mode I failure mechanism. This study utilises Taguchi analysis to analyse and optimise Self-Compacting Alkali-Activated Concrete (SAAC), focusing mainly on its flexural strength and fracture characteristics. An L-16 orthogonal array of experiments with three input parameters − replacement of Blast Furnace Slag (BFS) with Fly ash (FA) (0 %, 30 %, 40 %, and 50 %), Steel Fibers (SF) volume content (0 %, 0.25 %, 0.5 % and 0.75 %) and Notch to Depth (a₀/d) ratio (0.2,0.3,0.4 and 0.5), at four levels each, was adopted. The Work of Fracture Method (WFM) and Double K Fracture Criterion (DKFC) were utilised to determine the Fracture Energy (G_F) and fracture toughness, respectively. The results obtained from all the sixteen mixes showed that the F0-S0.75-N0.5 mix demonstrated better values in several parameters, such as flexural strength of 7.82 MPa,<span><math><mrow><mspace></mspace><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span> of 0.928 MPa√m, <span><math><mrow><msubsup><mrow><mspace></mspace><mtext>K</mtext></mrow><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 6.99 MPa√m and <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>/ <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 0.133. A maximum G_F of 2350 N/m was obtained with F50-S0.75-N0.2 mix. However, all the inferior values of these parameters were observed with F50-S0-N0.5 mix, which recorded a flexural strength of 4.90 MPa, <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span> of 0.612 MPa√m,<span><math><mrow><msubsup><mrow><mspace></mspace><mtext>K</mtext></mrow><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 1.16 MPa√m, <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>/ <span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>uns</mtext></msubsup></mrow></math></span> of 0.528 and G_F of 125 N/m. Through Taguchi analysis, the optimal combination for flexural strength was identified as FA 0 %, SF 0.75 %, and a₀/d 0.5 and for both Initial Fracture Toughness (<span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>IC</mtext></mrow><mtext>ini</mtext></msubsup></mrow></math></span>) and Unstable Fracture Toughness (<span><math><mrow><msubsup><mtext>K</mtext><mrow><mtext>I","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":5.0,"publicationDate":"2024-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041179","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":"Comments on standard EN-10371 and proposals for standard follow up","authors":"","doi":"10.1016/j.tafmec.2024.104617","DOIUrl":"10.1016/j.tafmec.2024.104617","url":null,"abstract":"<div><p>The small punch test technique was developed in the USA in the 1980 s, followed shortly by Japan and introduced to Europe in the 1990 s. CEN organized Workshop 21 to summarize more than ten years of research results and formulate the first technical guidelines CWA 15627. The specification work for European standard started in 2015 and the first European standard EN-10371 was published in 2022. The EN-10371 standardized the specimen size and test apparatus. It also specifies the test procedure and characteristic parameters for small punch test (SP) and small punch creep test (SPC). Nine annexes allows estimation of the values normally obtained using classical standard size uniaxial or fracture mechanics specimens. In order to make the standard perfect and usable, the standard working group proposed a five year “standard follow up” project in 2019. Responding to the proposed project, authors carefully re-examined the specification, and found some shortcomings in the standard. Proposals are put forward to improve the current methodology and extend the standard scope to include the latest development.</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":"142088970","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}