Engineering Fracture Mechanics最新文献_第4页

An evaluation method for the hygrothermal effect on fatigue crack propagation in CFRP–strengthened RC beam

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110760

Dongyang Li , Guang Qin , Jiaying Su , Minglang Xue , Zhanbiao Chen , Wen Li , Jiaxiang Lin , Peiyan Huang

Hygrothermal effects on the fatigue crack propagation behavior of Carbon fiber reinforced polymer (CFRP)–strengthened reinforced concrete (RC) beam was studied based on experimental and numerical methods. Quasi-static tests and hygrothermal fatigue tests of RC beams were conducted to investigate the coupling effect of the hygrothermal environment and fatigue load on the crack propagation behavior. Digital image correlation (DIC) method was applied to track the whole process of fatigue main crack initiation and propagation in real time, in order to obtain the fatigue crack length and crack propagation rate. Stress intensity factor (SIF) of main crack was calculated through finite element method considering material nonlinearity and hygrothermal influence. Results showed that SIF considering hygrothermal influence slightly increased compared to that at indoor atmospheric environment, and the influence of temperature on SIF was greater than that of relative humidity. The fatigue crack propagation curves showed a segmented phenomenon and different fitting function were adopted. It was found that the fatigue crack propagation rate increased with the increase of temperature at the same maximum stress intensity factor K_max. However, the increase of relative humidity had a limited effect on the fatigue crack propagation curves, showing less influence on the fatigue crack propagation behavior compared with that of temperature. Finally, environmental equations based on Paris Law were proposed to quantify the effect of temperature and humidity on fatigue crack propagation in RC beams strengthened with CFRP.

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引用次数: 0

Closed-form solution to the debonding of embedded Through-Section FRP bar-to-concrete joints with interfacial defects

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110708

Kaiming Pan , Yanjie Wang , Hongbo Liu , Zhimin Wu , Mengdi Jia , Yifeng Chen

The Embedded Through-Section (ETS) technique has recently received significant attention in strengthening existing reinforced concrete (RC) structures through the use of fibre-reinforced polymer (FRP) bars inserted into predrilled holes in concrete using adhesive. Interfacial bond defects are easily observed in practical applications of ETS FRP bar-to-concrete joints due to poor construction or environmental deterioration, resulting in degradations in both local bond behavior and global performance of ETS-strengthened concrete systems. This paper presents a closed-form analytical solution to evaluate the effect of interfacial defects on the debonding response of ETS- FRP bar-to-concrete joints and examine the interfacial defect criticality from size and location aspects. A set of closed-form solutions for the load-slip curve, debonding load, interfacial bond stress, tensile stress as well as effective bond length are derived throughout the debonding process. After validating the analytical solutions with self-conducted test results and existing experimental and numerical data, a parametric analysis is performed to quantify the influence of interfacial defects on the load responses. The results show that the analytical predictions can accurately describe the debonding behavior of ETS FRP bar-to-concrete joints with different defect lengths and locations. It is revealed that bond defects adversely affect both the debonding load and maximum load; however, enhancing the bond strength and embedded length can alleviate such a detrimental impact. Furthermore, defects near the loading point in short joints or close to the embedded end in long joints can maximize the load-bearing capacity. These findings emphasize the critical role of interfacial defects in the debonding analysis and practical design of RC beams strengthened with FRP bars using the ETS technique.

{"title":"Closed-form solution to the debonding of embedded Through-Section FRP bar-to-concrete joints with interfacial defects","authors":"Kaiming Pan , Yanjie Wang , Hongbo Liu , Zhimin Wu , Mengdi Jia , Yifeng Chen","doi":"10.1016/j.engfracmech.2024.110708","DOIUrl":"10.1016/j.engfracmech.2024.110708","url":null,"abstract":"<div><div>The Embedded Through-Section (ETS) technique has recently received significant attention in strengthening existing reinforced concrete (RC) structures through the use of fibre-reinforced polymer (FRP) bars inserted into predrilled holes in concrete using adhesive. Interfacial bond defects are easily observed in practical applications of ETS FRP bar-to-concrete joints due to poor construction or environmental deterioration, resulting in degradations in both local bond behavior and global performance of ETS-strengthened concrete systems. This paper presents a closed-form analytical solution to evaluate the effect of interfacial defects on the debonding response of ETS- FRP bar-to-concrete joints and examine the interfacial defect criticality from size and location aspects. A set of closed-form solutions for the load-slip curve, debonding load, interfacial bond stress, tensile stress as well as effective bond length are derived throughout the debonding process. After validating the analytical solutions with self-conducted test results and existing experimental and numerical data, a parametric analysis is performed to quantify the influence of interfacial defects on the load responses. The results show that the analytical predictions can accurately describe the debonding behavior of ETS FRP bar-to-concrete joints with different defect lengths and locations. It is revealed that bond defects adversely affect both the debonding load and maximum load; however, enhancing the bond strength and embedded length can alleviate such a detrimental impact. Furthermore, defects near the loading point in short joints or close to the embedded end in long joints can maximize the load-bearing capacity. These findings emphasize the critical role of interfacial defects in the debonding analysis and practical design of RC beams strengthened with FRP bars using the ETS technique.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110708"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164587","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}

引用次数: 0

Creep-fatigue crack growth behavior under mean stress effect in polymer electrolyte membrane: Experimental analysis and numerical crack growth modeling

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110789

Liang Cai , Wei Li , Pilin Song , Ibrahim Elbugdady , Gang Liu , Zhenduo Sun

The creep-fatigue crack growth behavior of polymer electrolyte membrane under cyclic loading with distinct mean stress is investigated. The crack under cyclic loading with higher mean stress displays enhanced propagation rate. Identical cyclic plastic zone size is found under different stress ratios, implying that the fatigue damage primarily depends on stress amplitude. The creep damage leads to the occurrence of crack-front micropores, thereby accelerating crack growth. The enlargement of hydrophobic domain is detected at high stress ratio, which reveals the creep effect on failure process from phase morphology aspect. A damage-based numerical model is established to predict creep-fatigue crack growth.

引用次数: 0

A physics-enhanced deep learning approach for prediction of stress intensity factors in bimaterial interface cracks

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110720

Luyang Zhao , Qian Shao

Stress intensity factors (SIFs) are pivotal in understanding cracking behaviors and predicting crack propagation in layered materials. This study introduces a physics-enhanced deep learning approach for the efficient prediction of SIFs in bimaterial interface fracture problems. Guided by linear elastic fracture mechanics theory, three sets of features are designed and extracted to comprehensively represent the influential factors determining SIFs, including loads, boundary conditions, crack patterns, and material properties. Specifically, loads and boundary conditions are represented by stress fields on the crack-free configuration obtained from coarse finite element simulations, while crack characterization is achieved through level set functions. The inherent heterogeneity of multi-layered structures is addressed by spatially distributing material properties, such as Young’s modulus and Poisson’s ratio, throughout the domain. Subsequently, a compact convolutional neural network is trained on labeled data to map these features to SIFs of bimaterial interface cracks. The predictive performance and generalization capability of the proposed model are demonstrated across diverse problem settings, encompassing various interfaces, loads, boundary conditions, and crack patterns. Effective knowledge extraction and transfer are showcased between problems with distinct loading modes, highlighting the good explainability of the proposed model. Moreover, the model demonstrates efficacy in scenarios with large or irregular geometries by focusing on a localized region surrounding the crack. This strategy not only enhances the adaptability of the proposed model to diverse geometries but also reduces the data collection and model training costs.

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引用次数: 0

Very-high-cycle-fatigue behaviour of ultrasonic-assisted TIG welded TC4 joints: Microcrack initiation and life prediction influenced by dislocations and oxides under shear stress

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110746

Hailong Deng , Yufan Sun , Mingkai Li , Yupeng Guo , Jie Liu , Jianhang Kong , Xiangxin He , Yu Huan

Titanium alloy welded structures are commonly applied in aircraft industry manufacturing. Therefore, the behaviour of Ti-6Al-4 V (TC4) welded joints was investigated at very-high-cycle-fatigue (VHCF) conditions using ultrasonic-assisted tungsten inert gas (TIG) welding, aims to reveal the mechanism of crack initiation and fine granular area (FGA) formation, as well as to develop a model for predicting fatigue life. In particular, the data suggest that S-N curves are single-linear at both stress ratios, while three failure modes and three defect types were found. Transmission electron microscopy (TEM) analysis combined with image processing method revealed the presence of dislocation structures in FGA, indicating that stress concentration effect led to the generation of high-density dislocations, the produces lattice distortion and crystal slip at maximum ά martensitic Schmidt factor plane, concludes that the dislocation piles up together with oxides produced by oxygen aggregation promotes the microcrack initiation. Meanwhile, the cracks near fatal defect were driven by tensile and shear stresses with the propagation mode of Mode I + Mode II, and the region was observed to consist of discontinuous nano fine grain layers and broken martensitic laths. Additionally, the S-N curves with higher point-to-line convergence are reconstructed based on the defect size and defect depth. Finally, based on failure mechanism and linear elastic deformation theory, a VHCF life prediction model is developed by considering the modified maximum shear stress, mean stress and stress intensity factors (SIF) value with the effect of Schmidt factor mean value and defect features, which can improve the safety of structures.

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引用次数: 0

The electrical discharge characteristics and ignition mechanism of coal mine roof fracture under stress

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110744

Chenguang Wang , Deming Wang , Haihui Xin , Wei Zhang , Tengfei Chen , Kang Zhang

Underground goaf is a high-risk area of thermodynamic disaster accidents in coal mines, and the thermodynamic disaster accidents occurring in goaf may be inextricably linked with the activities of the roof. This paper conducts in-depth research on the instantaneous electrical discharge characteristics and ignition mechanism induced in the process of rock damage by building a force-electric ignition experimental system. The results showed that the electric discharge generated by rocks during the fracture process could penetrate air and produce the photoelectric effect. The instantaneous electric discharge capacity and luminous intensity generated during rock fracturing were mainly affected by the quartz content and compressive strength of the rock, and the experiment confirmed that the electrical discharge of rocks during the fracture process can ignite methane-air. The piezoelectric effect during the loading process of rocks can significantly enhance their electric discharge capacity. In this paper, the viewpoint that the electric discharge of coal seam roof in the process of fracturing ignites the methane in goaf and causes disasters was proposed. The research results explored the synergistic discharge mechanism during rock fracture process, and elucidated the enhancing effect of piezoelectric effect in rock fracture discharge process. The research can provide a theoretical basis for the disaster-causing mechanism in the process of roof fracturing caused by mine pressure in goaf.

{"title":"The electrical discharge characteristics and ignition mechanism of coal mine roof fracture under stress","authors":"Chenguang Wang , Deming Wang , Haihui Xin , Wei Zhang , Tengfei Chen , Kang Zhang","doi":"10.1016/j.engfracmech.2024.110744","DOIUrl":"10.1016/j.engfracmech.2024.110744","url":null,"abstract":"<div><div>Underground goaf is a high-risk area of thermodynamic disaster accidents in coal mines, and the thermodynamic disaster accidents occurring in goaf may be inextricably linked with the activities of the roof. This paper conducts in-depth research on the instantaneous electrical discharge characteristics and ignition mechanism induced in the process of rock damage by building a force-electric ignition experimental system. The results showed that the electric discharge generated by rocks during the fracture process could penetrate air and produce the photoelectric effect. The instantaneous electric discharge capacity and luminous intensity generated during rock fracturing were mainly affected by the quartz content and compressive strength of the rock, and the experiment confirmed that the electrical discharge of rocks during the fracture process can ignite methane-air. The piezoelectric effect during the loading process of rocks can significantly enhance their electric discharge capacity. In this paper, the viewpoint that the electric discharge of coal seam roof in the process of fracturing ignites the methane in goaf and causes disasters was proposed. The research results explored the synergistic discharge mechanism during rock fracture process, and elucidated the enhancing effect of piezoelectric effect in rock fracture discharge process. The research can provide a theoretical basis for the disaster-causing mechanism in the process of roof fracturing caused by mine pressure in goaf.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110744"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143165000","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}

引用次数: 0

Effect of temperature and geometry on the brittle failure of an 18MND5 steel in the lower part of the ductile to brittle transition

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110745

Emmanuelle Catel , Aboubakr Amzil , Eric Lorentz , Anna Dahl , Jacques Besson

Tests on cracked CT and SENT specimens (152 tests) extracted from a nuclear pressure vessel steel (18MND5) were conducted between

- 150

^{\circ}

C and

- 50

^{\circ}

C together with tests on smooth and notched bars. Tests on tensile bars were used to calibrate a temperature-dependent hardening law. Tests on cracked specimens that exhibited brittle failure only were analyzed using the Beremin model. Special care was taken to evaluate local stresses using enhanced mixed finite elements. The Beremin model was able to represent the entire database provided the reference failure stress

σ_{u}

increases with temperature. Finally, the results were also interpreted using the Master Curve approach, which was adapted to account for different stress states using the

Q

-parameter.

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引用次数: 0

Mesh-independent proportional method to obtain ISSF and singularity index at the interface corner of three-dimensional dissimilar structures

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110624

Tatsujiro Miyazaki , Hibiki Fukuda , Nao-Aki Noda

An efficient analysis method is proposed for the intensity of singular stress field (ISSF) as well as the singularity index (SI) at the interface corner of three dimensional (3D) bonded joints by using the finite element method (FEM). By varying the minimum mesh size

e_{m i n}

, the FEM stresses

σ_{FEM}

obtained from the FEM are investigated around the corner singular point. Then, mesh-independent expressions such as

σ_{FEM} (r) \cdot {(e_{m i n})}^{1 - λ} = c o n s t .

are derived for ISSF and SI based on the proportional stress fields in prismatic joints having similar FEM mesh pattern. Previously analyzed results coincide with the present mesh-independent results to the three digits for ISSF and SI in 3D corners. The experimental results show that the critical singular stress distributions causing debonding are almost identical at the interface corner and at the interface edge independent of the adhesive thickness. This is confirmed for the ABA joint denoting the 3D prismatic butt joints whose similar adherends A are bonded by resin B. Under a constant load, the ABC joint whose dissimilar adherends A and C are bonded by resin B has larger ISSF than the ABA joints. This ISSF difference increases with decreasing the adhesive thickness

h

, and this ISSF difference is more remarkable at the interface corner than at the interface edge. The debonding failure criterion is discussed by using the previous experiment conducted for ABA-, ABC-butt joints and ABA-, ABC- three step lap joints. It is found that the adhesive strength of the ABC joint can be expressed as a constant critical ISSF at the interface corner and the constant value coincides with the value of the 3D ABA joints. Those new findings show that the proposed 3D mesh-independent proportional method is especially useful for evaluating the debonding strength of the adhesive ABC joints.

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引用次数: 0

Adaptive phase-field modeling of fracture propagation in layered media: Effects of mechanical property mismatches, layer thickness, and interface strength

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110672

Salman Khan , Ishank Singh , Chandrasekhar Annavarapu , Antonio Rodríguez-Ferran

Fracture propagation in layered media is investigated using an adaptive phase-field method. We focus on the interplay between cracks and interfaces, considering both perfectly and imperfectly bonded interfaces. For perfectly bonded interfaces, three-layer models are analyzed to study the effects of mechanical property mismatches, layer thickness, and confinement pressure on crack growth. Results reveal that critical energy release rate mismatch significantly influences the crack geometry, leading to single through-going fractures, middle layer fragmentation, or delamination. There is an inverse relationship between layer thickness and fragmentation, and between confinement pressure and delamination. For imperfectly bonded interfaces, a phase-field method incorporating an interface energy term is introduced and validated with benchmark examples. This model is used to study the combined effects of mechanical property mismatch and interface strength on crack growth. Our findings demonstrate that the interface strength strongly influences the dominant failure mechanism, with high strength favoring mechanical property mismatch-driven fracture and low strength leading to interfacial failure. Finally, the robustness of the proposed method is illustrated through a complex seven-layer model. This study provides valuable insights into the various factors influencing macroscopic failure mechanisms in layered materials.

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引用次数: 0

Life evaluation method for nickel-based directionally solidified turbine blade-like specimens under near-service conditions

IF 4.7 2区工程技术 Q1 MECHANICS

Engineering Fracture Mechanics

Pub Date : 2025-02-07 DOI: 10.1016/j.engfracmech.2024.110787

Tianxiao Sui , Yang Gan , Qinzheng Yang , Shunpeng Zhu , Wenjun Wang , Dong Mi , Zhengming Qian , Xiaoan Hu

Life assessment of turbine blades is a challenging issue due to the complexity of their structural designs and operational loads. To address the issue, a life evaluation method for turbine blade-like specimens under near-service conditions was investigated. First, creep and creep-fatigue tests were conducted on these specimens to replicate operational environments, with the nominal load of the critical section set at 950 °C/273 MPa. Next, the coupled-damage Norton-Bailey model was used to simulate the creep behavior at 760 °C, 850 °C and 980 °C. Electromagnetic-thermal coupling simulations were then carried out in COMSOL with a 120A alternating current, yielding the temperature distribution for the blade-like specimen. The mechanical response of these specimens under creep and creep-fatigue conditions was simulated based on the Norton-Bailey model. Finally, a life prediction model was developed by introducing a weight function into the critical distance method. The results indicated that the introduction of film-cooling holes and cyclic loading reduced the specimens’ life by 43 % and 42 %, respectively. Elevated temperatures (942–965 °C) at the leading edge caused crack initiation in non-holed specimens, while high stress (maximum stress of 1103 MPa) around the holes led to crack initiation in holed specimens. A comparative analysis with traditional cross-sectional averaging methods demonstrated that the proposed model achieves higher predictive accuracy, with all predictions falling within a twofold scatter band.

{"title":"Life evaluation method for nickel-based directionally solidified turbine blade-like specimens under near-service conditions","authors":"Tianxiao Sui , Yang Gan , Qinzheng Yang , Shunpeng Zhu , Wenjun Wang , Dong Mi , Zhengming Qian , Xiaoan Hu","doi":"10.1016/j.engfracmech.2024.110787","DOIUrl":"10.1016/j.engfracmech.2024.110787","url":null,"abstract":"<div><div>Life assessment of turbine blades is a challenging issue due to the complexity of their structural designs and operational loads. To address the issue, a life evaluation method for turbine blade-like specimens under near-service conditions was investigated. First, creep and creep-fatigue tests were conducted on these specimens to replicate operational environments, with the nominal load of the critical section set at 950 °C/273 MPa. Next, the coupled-damage Norton-Bailey model was used to simulate the creep behavior at 760 °C, 850 °C and 980 °C. Electromagnetic-thermal coupling simulations were then carried out in COMSOL with a 120A alternating current, yielding the temperature distribution for the blade-like specimen. The mechanical response of these specimens under creep and creep-fatigue conditions was simulated based on the Norton-Bailey model. Finally, a life prediction model was developed by introducing a weight function into the critical distance method. The results indicated that the introduction of film-cooling holes and cyclic loading reduced the specimens’ life by 43 % and 42 %, respectively. Elevated temperatures (942–965 °C) at the leading edge caused crack initiation in non-holed specimens, while high stress (maximum stress of 1103 MPa) around the holes led to crack initiation in holed specimens. A comparative analysis with traditional cross-sectional averaging methods demonstrated that the proposed model achieves higher predictive accuracy, with all predictions falling within a twofold scatter band.</div></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":"314 ","pages":"Article 110787"},"PeriodicalIF":4.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164580","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}

引用次数: 0