Theoretical and Applied Fracture Mechanics最新文献

{"title":"Probabilistic fatigue life prediction of small sample properties notched specimens under multiaxial loading","authors":"Ziyang Zhang ,&nbsp;Jianhui Liu ,&nbsp;Shengchuan Wu ,&nbsp;Qingjun Wu ,&nbsp;Yaobing Wei","doi":"10.1016/j.tafmec.2024.104836","DOIUrl":"10.1016/j.tafmec.2024.104836","url":null,"abstract":"<div><div>The multiaxial fatigue assessment of complex structures is a crucial issue in ensuring the structural integrity of modern equipment. However, in practical engineering, further progress is required in the study of small sample data, for the reliable evaluation of the fatigue life of notched specimens, and their impact on multiaxial fatigue damage evolution models. Firstly, the test data of smooth specimens is expanded, by integrating Bayesian theory and the Monte Carlo method, and a probabilistic fatigue model considering size effect under different loading conditions is established. Secondly, the influence of non-uniform stress fields and notch characteristics on fatigue crack initiation is defined, considering critical distance, with a correction to the stress field damage parameter. The relationship between fatigue life and damage variables under various loading conditions is explored, the virtual sub-sample augmentation method and the weakest link theory are combined, leading to the establishment of a multiaxial fatigue life prediction model, suitable for notched specimens. Finally, the prediction life using proposed method and other models are compared with the experimental life of three materials, the compared results show that the proposed method exhibits a notably heightened level of accuracy, and the fatigue life of notched specimens can be predicted by small samples of smooth specimens.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104836"},"PeriodicalIF":5.0,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130448","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":"Mechanical behaviors and permeability characteristics of granite considering through-crack inclination and seepage gas pressure","authors":"Lei Fang ,&nbsp;Xiaohan Zhou ,&nbsp;Xinrong Liu ,&nbsp;Jilu Zhang ,&nbsp;Yan Wang ,&nbsp;Lojain Suliman","doi":"10.1016/j.tafmec.2024.104829","DOIUrl":"10.1016/j.tafmec.2024.104829","url":null,"abstract":"<div><div>In the construction process of tunnel excavation in a deep stratum, the cracked surrounding rock is prone to instability, deterioration and harmful gas overflow under the action of high ground stress and high osmotic pressure. To identify the interaction and influencing mechanism between excavation unloading and high-pressure gas seepage. Firstly, mechanical tests under the coupling effect of gas seepage and triaxial loading were carried out on the specimens with different through-crack inclination angles (TCA) and seepage pressure of crack (SPC). The load and permeability of the specimens were monitored, and the strength degradation, deformation characteristics, and failure mode evolution of the specimens were analyzed. The results show that the risk of the deterioration and the damage for the cracked granite during unloading excavation is positively correlated with TCA and SPC. While, the deformation velocity of the cracked granite is negatively correlated with TCA and positively correlated with SPC. As TCA increased, the failure mode evolves from a single weak plane shear failure mode to a double parallel plane shear failure mode with end-face initiation. Furthermore, SPC accelerate the propagation and development of new cracks along the direction of the increased stress when TCA = 70°and 80°. Secondly, when TCA &lt; 90°, before the failure of the cracked rock mass a sharp increasing in the permeability during axial loading and radial unloading has been occurred. Meanwhile, the growth rate of gas permeability increased significantly during the rock mass destruction process, and the risk of toxic, gas outbursts and accumulation increased. Finally, a permeability evolution model considering the damaging effects of crack inclination, unloading confining pressure, and seepage gas pressure was established based on the Weibull distribution theory. The reliability of the proposed model was verified by combining the experimental results and the existing model, the evolution law of the specimen crack development degree’s sensitivity coefficient (β) to coupled damage was analyzed.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104829"},"PeriodicalIF":5.0,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130453","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 numerical study of the dynamic crack propagation behavior of mortar-granite specimens with different inclination interfaces","authors":"Hao Qiu ,&nbsp;Rongyuan Chen ,&nbsp;Yichao Wang ,&nbsp;Ruifeng Liu ,&nbsp;Dade Lai ,&nbsp;Feiyu Liao ,&nbsp;Yisheng Fang ,&nbsp;Fei Wang","doi":"10.1016/j.tafmec.2024.104831","DOIUrl":"10.1016/j.tafmec.2024.104831","url":null,"abstract":"<div><div>An in-depth investigation into the dynamic fracture behavior at the interface between high-strength mortar and rock was performed in this study. Utilizing a side material cleavage triangle (SMCT) configuration, this research integrated the experimental–numerical method, and crack propagation gauge (CPG) to explore the effects of varying loading speeds, interfacial inclination angles, and high-strength mortar strength on interfacial crack propagation behavior. The microstructure and thickness of the interfacial zone were analyzed. Additionally, Python scripting was employed to enable the batch embedding of cohesive elements into ABAQUS models. The results indicated that with an increase in high-strength mortar strength from 80 MPa to 100 MPa, there was a significant decrease in the thickness of the interfacial transition zone. In addition, as the interfacial inclination angle of the specimens increased from 90° to 106°, the average fracture toughness and energy in the high-strength mortar region increased by 16 % and 44 %, respectively, while the granite region increased by 15 % and 25 %, respectively. In the models, where cohesive elements were systematically embedded in batches, the crack propagation paths were found to align closely with the test results. During crack extension, the tensile stress at the crack tip was observed to be significantly greater than the shear stress.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104831"},"PeriodicalIF":5.0,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131002","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 the trigger mechanism of dynamic disturbance-induced continuous rockburst","authors":"Zhigang Yao ,&nbsp;Ruihan Li ,&nbsp;Tao Yu ,&nbsp;Jian Cui ,&nbsp;Jianfeng Wang ,&nbsp;Lang Bi ,&nbsp;Junyang He ,&nbsp;Yong Fang","doi":"10.1016/j.tafmec.2024.104827","DOIUrl":"10.1016/j.tafmec.2024.104827","url":null,"abstract":"<div><div>The continuous rockburst can cause intense harm to construction personnel and the environment in the tunnelling process. The on-site investigation indicates that continuous rockbursts are related to the fracture of the rockmass, but the associated mechanical mechanisms are still not clear. Focusing on the triggering mechanism of continuous rockburst under high stress conditions, this study investigated the fracture evolution of pre-cracked dolomite through the dynamic Cracked Chevron Notched Brazilian Disc (CCNBD) test. Combined with particle image velocimetry, acoustic emission and infrared monitoring methods, the influence of dynamic disturbance with different characteristics on the fracture failure of pre-cracked rock is studied systematically. The results indicate that the pre-cracks caused by tunnel excavation under high ground stress conditions are the prerequisite for continuous rockbursts, while the subsequent dynamic disturbance can significantly alter the propagation process of pre-crack. Overall, the behavior of pre-cracked rockmasses under dynamic disturbance can be divided into three categories: no damage, progressive failure, and abrupt failure. Further results indicate that dynamic disturbance frequency and amplitude are the key factors that influence the failure mode of pre-cracked rockmass. The increase in disturbance amplitude and frequency can reduces the fracture toughness of existing fractures and promotes the transition of pre-cracked rockmasses from fatigue failure to brittle failure. The findings provide a basis for understanding the mechanism of dynamic disturbance-induced continuous rockburst.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104827"},"PeriodicalIF":5.0,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130447","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":"Strain rate-dependent failure modes of material extrusion-based additively manufactured PETG: A study on crack deflection and penetration","authors":"Christoph Waly,&nbsp;Sandra Schulnig ,&nbsp;Florian Arbeiter","doi":"10.1016/j.tafmec.2024.104834","DOIUrl":"10.1016/j.tafmec.2024.104834","url":null,"abstract":"<div><div>The layer-by-layer nature of fused filament fabrication (FFF) introduces interfaces along the build direction (z-axis). A crack approaching an interface may deflect or penetrate subsequent layers, based on the relative strengths of the interface and the matrix. This study evaluates the applicability of the Cook &amp; Gordan (C&amp;G) model for predicting crack deflection or penetration in glycol-modified poly(ethylene terephthalate) (PETG) printed structures, considering different print orientations and layer heights. The loading rate was varied between 0.1 and 1000 <!--> <!-->mm/min to identify potential rate-dependent effects. Interface and matrix strengths were determined through tensile testing, and their ratio was used to assess the validity of the C&amp;G criterion. The results, supported by fracture mechanical validation experiments, indicate that the C&amp;G model can effectively predict crack paths in FFF-printed PETG structures, provided that the assumptions of linear elastic fracture mechanics are not significantly violated. Accurate predictions were unattainable at the lowest loading rate (0.1 mm/min). For loading rates ≥ 10 mm/min the criterion appears plausible, aligning with previous studies.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104834"},"PeriodicalIF":5.0,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130449","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":"Investigating the effects of different temperatures on the mixed-mode fracture parameters in adhesively bonded joints considering cohesive zone modeling","authors":"P. Hosseini ,&nbsp;T.N. Chakherlou ,&nbsp;H. Biglari ,&nbsp;A.Pourtaghi Marzrood","doi":"10.1016/j.tafmec.2024.104833","DOIUrl":"10.1016/j.tafmec.2024.104833","url":null,"abstract":"<div><div>This paper investigates the influence of temperature on the fracture behavior of a structural adhesive across pure and mixed loading conditions using experimental and finite element methods. The cohesive zone modeling (CZM) was employed to establish fracture parameters of the adhesive assemblies within the temperature range of −60 °C to + 60 °C. The adhesive behavior was characterized by deriving the normal and transverse (shear) CZM laws through the experimental data (compliance-based beam method) and an inverse technique, utilizing double cantilever beam (DCB) and end notch flexure (ENF) specimens. The determined CZM law parameters were then implemented in the numerically modelling of mixed mode Arcan specimens to generate load–displacement curves using ABAQUS software. It was observed that as the temperature elevates, the ductility of the adhesive also increases, resulting in higher fracture loads. The data obtained from the finite element method (FEM) were validated by comparing them to the experimental results. Furthermore, a satisfactory agreement was achieved between the numerical and experimental fracture responses at each temperature, demonstrating the reliability of the extracted CZM law parameters. This research has also confirmed the effectiveness of the cohesive zone modeling in predicting the fracture behavior of adhesive bonding that are subjected to different thermal and mixed loading states.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104833"},"PeriodicalIF":5.0,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130452","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":"Aging effects on the structural integrity of carboxyl terminated polybutadiene propellants","authors":"Mario Martínez ,&nbsp;Raúl López ,&nbsp;Jesús Rodríguez ,&nbsp;Alicia Salazar","doi":"10.1016/j.tafmec.2024.104828","DOIUrl":"10.1016/j.tafmec.2024.104828","url":null,"abstract":"<div><div>Structural integrity of composite solid propellants (CSPs) is one of the main concerns when considering the performance of CSP motors. The development of cracks in the propellant’s grain, caused by aging during the service life of the motor, is the main reason for its catastrophic failure. In addition, the fracture characterization of these viscoelastic and highly filled materials is not fully solved yet and hardly addressed for aged CSP. This manuscript presents a broad and comprehensive study on the fracture behavior of aged CSPs, where Schapery’s viscoelastic fracture mechanics (VEFM) methodology is used to effectively characterize the fracture behavior of a composite solid propellant with carboxyl-terminated polybutadiene (CTPB) binder. For that, stress relaxation, fracture and tensile tests have been performed on non-aged and aged CSP. Three different accelerated aging methods were employed (mechanical, thermal and ozone) that are related to the phenomena that deteriorate the material during the lifespan of the motor. Two main contributions are derived from this work. The first one is the understanding of the fracture processes developed in aged CSP, under different types of aging. The second most relevant contribution is that the cohesive stress, as the fracture parameter inferred from the VEFM approach, is observed to be correlated to the dewetting stress, a material measurable parameter. The results have potential implications for the design and longevity of future solid rocket propellants.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104828"},"PeriodicalIF":5.0,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130994","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":"Influences of freeze–thaw cycles (FTC) on tensile properties and mixed-mode I/II fracture response of epoxy resin materials","authors":"Jamal Bidadi,&nbsp;Hamed Saeidi Googarchin","doi":"10.1016/j.tafmec.2024.104830","DOIUrl":"10.1016/j.tafmec.2024.104830","url":null,"abstract":"<div><div>Epoxy resins (ERs) are widely used in manufacturing polymeric components. However, their mechanical properties and fracture resistance often deteriorate under fluctuating environmental conditions, particularly freeze–thaw cycles (FTC) common in rainy and snowy environments. The general understanding of the degradation process induced by FTC on the mechanical and fracture properties of ERs helps engineers develop predictive models. While a few studies have addressed the effect of FTC on the tensile properties of bulk ERs, very little research has been done to study mixed-mode I/II fracture behavior under such cycling. This work deals with the gap by studying the aging effects of 21, 42, and 63 FTC on the tensile properties and mixed-mode I/II fracture toughness of one type of ER being used frequently as a matrix phase for the manufacturing of fibrous composites. In this regard, dumbbell-shaped and cracked short-bend beam (SBB) specimens were used to obtain the tensile and mixed-mode I/II fracture responses, respectively, after exposure to FTC. All the specimens experienced FTC by thawing it in water at 25 °C for 12 h followed by storing the specimens in a freezer at −25 °C for 12 h each. The findings revealed that all aged specimens exhibited significantly lower tensile strain and higher tensile strength compared to the non-aged specimen. Opposite to the increase in tensile strength, a steady decrease of mixed-mode I/II fracture toughness with increasing number of FTC was observed, evidencing the destructive effect of FTC on residual fracture toughness for pre-cracked ER specimens. The reduction in experimental effective fracture toughness slows after the 42nd freeze–thaw cycle, forming a plateau. Therefore, the endurance limit for the tested ER can be set at 0.35 to 0.5 times the fracture toughness of a non-aged specimen. Finally, the mixed-mode I-II fracture envelope was established with regard to the GMTS criterion for both non-aged and aged specimens, by considering the deleterious effect of FTC on either the critical distance or FPZ existing near the crack tip. The GMTS theoretical predictions aligned well with the experimental results.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104830"},"PeriodicalIF":5.0,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131004","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":"Weld crack detection in spiral-welded pipes by direct current potential drop method and backpropagation neural network","authors":"Dexin Sun ,&nbsp;Yujie Chen ,&nbsp;Zhenjie Zhang ,&nbsp;Qun Li ,&nbsp;He Li ,&nbsp;Yue Zhao ,&nbsp;Junling Hou","doi":"10.1016/j.tafmec.2024.104817","DOIUrl":"10.1016/j.tafmec.2024.104817","url":null,"abstract":"<div><div>Pipelines are essential for transportation, and fractures can lead to severe accidents. Accurately detecting weld cracks is vital for supporting the safe operation of large-diameter spiral-welded pipelines. The direct current potential drop method detects cracks by observing the discontinuity of the electrical potential field caused by cracks inside a current-carrying body. The variation in crack lengths and positions significantly affects the measured potential drops. Traditional calibration curves focus on the relationship between crack length and potential drops, but detecting crack position is also essential. This research introduces an innovative method to identify the position and length of weld cracks in spiral-welded pipes by combining the direct current potential drop method and the backpropagation neural network. Finite element models of spiral-welded pipes with varying crack positions and lengths were created, and extensive simulations were conducted to collect potential drops across the weld seams. A backpropagation neural network model is constructed and trained through deep learning technology. The well-trained backpropagation neural network can precisely predict the position and length of the weld crack by scanning the potential drops of the entire weld seam. Several experiments have been conducted to validate the proposed method for detecting weld cracks.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104817"},"PeriodicalIF":5.0,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143130998","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":"Enhanced fatigue crack growth rate prediction in alloy steels using particle swarm optimized neural network","authors":"Harsh Kumar Bhardwaj ,&nbsp;Mukul Shukla","doi":"10.1016/j.tafmec.2024.104826","DOIUrl":"10.1016/j.tafmec.2024.104826","url":null,"abstract":"<div><div>In the manufacturing sector, fatigue crack growth (FCG) poses a critical challenge to the structural integrity and safety of components, with significant implications for human safety and economic impact. The relationship between stress intensity factor range (ΔK) and FCG rate (da/dN) is often nonlinear, even within the Paris region, influenced by factors like stress ratio (R-ratio), threshold values of ΔK (ΔK_th) and da/dN (da/dN_th), critical stress intensity factor (K_c), specimen geometry, mechanical properties, and alloy compositions. These complexities render traditional empirical methods inadequate for accurate FCG rate predictions. This study introduces a Particle Swarm Optimized Neural Network (PSONN) model, trained and tested across a range of alloy steels, including 316, 316 L, 316 L(N), AISI 301, AISI 302, 304, St 980, Q345qc, St-4340, and Fe 430D. The PSONN model outperforms traditional methods by delivering superior accuracy and reducing error in FCG rate prediction, highlighting its potential for improved safety and reliability in design.</div></div>","PeriodicalId":22879,"journal":{"name":"Theoretical and Applied Fracture Mechanics","volume":"136 ","pages":"Article 104826"},"PeriodicalIF":5.0,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143131000","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}