Engineering Fracture Mechanics最新文献

{"title":"An uncoupled ductile fracture criterion for a wide range of stress states in sheet metal forming failure prediction","authors":"","doi":"10.1016/j.engfracmech.2024.110464","DOIUrl":"10.1016/j.engfracmech.2024.110464","url":null,"abstract":"<div><p>In industrial production, sheet metal rupture will inevitably occur in the process of forming, especially in the shape of complex, relatively small thickness of the sheet. It is vital to accurately predict the failure of ductile metals under various working conditions. To deal with the problem, an uncoupled ductile fracture criterion (DFC) for a broad range of stress states is proposed based on the micro-mechanism of ductile fracture of metals, which redefines the relationship between the number of void nucleating and the equivalent plastic strain and takes into account the different deformation modes of the voids in the growth stage. Then, in order to verify the validity and advantages of the proposed DFC, the 3D fracture surface of AA 2024-T351 and AISI 1045 steel are constructed by the new criterion based on their fracture data under various stress states, and compared with the commonly used DF2016 criterion and Hu criterion. The prediction results show that the new criterion is better than them, both in terms of the maximum prediction error and the average prediction error. Furthermore, to further prove the effectiveness of the proposed model, five samples are designed for tension tests to calibrate the new DFC using a hybrid experimental–numerical approach, and the calibrated criterion is applied to cupping simulations of AA 6061 and compared with cupping experimental results. The results indicate that the Erichsen cupping number (IE) of the cupping simulation and experiment are 6.88 mm and 7.05 mm, respectively, and the error between them is only 2.411 %, and the location of the fracture is also basically the same. Therefore, all comparison results show that the proposed DFC can forecast the fracture problem in sheet forming more accurately under various stress states.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163998","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":"On the importance of the cracking process description for dynamic crack initiation simulation","authors":"","doi":"10.1016/j.engfracmech.2024.110473","DOIUrl":"10.1016/j.engfracmech.2024.110473","url":null,"abstract":"<div><p>A dynamic implementation of the coupled criterion under quasi-static loading, based only on the mean velocity during crack initiation, is proposed. It relies on a simultaneous node release method. It consists of computing the dynamic incremental energy release rate by simultaneously opening a crack of a finite length during a given time increment rather than progressively opening smaller crack increments following a velocity profile as in the progressive node release method. Both methods result in significantly different kinetic energy variations as a function of the crack length, and thus different incremental energy release rates for large enough crack velocities, for which the kinetic energy magnitude is similar to the elastic strain energy magnitude. Both simultaneous node release method and progressive node release method can however be equivalently used for small enough crack velocities since similar incremental energy release rates are obtained with both methods. Inverse identification of fracture properties based on dynamic crack initiation at a hole in Brazilian disk specimens yields critical energy release rates in the same order of magnitude as the one obtained based on dynamic crack propagation modeling.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167295","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":"Failure mechanism of transversely isotropic schist under Brazilian test using real-time X-ray nano tomography scanning","authors":"","doi":"10.1016/j.engfracmech.2024.110465","DOIUrl":"10.1016/j.engfracmech.2024.110465","url":null,"abstract":"<div><p>The study tries to address Brazilian tests on a transversely isotropic rock to investigate failure conditions by using digital volume correlation (DVC). For this purpose, an in-situ Brazilian apparatus in a nano- X-ray computed tomography (CT) scanner is applied to investigate the 3D progressive failure mechanism of the schist. Two different anisotropy angles are tested. CT scans are conducted at every selected loading stage before peak load. DVC analyzes the constructed X-ray CT images to determine the effect of schistosity orientation on failure mechanism, including crack initiation and propagation. A calibration method is presented to verify DVC parameters, including the half size of the correlation window and the space between two sub-volumes. Using DVC, 3D deviatoric strain field, strain contours, and displacement increment are determined at all stages of loading. A CT value-based method (VG Studio) is also applied to validate the DVC results. It is found that the layer boundaries affect the failure pattern, with the agreement between the DVC results and VG Studio results being observed. For the specimen with horizontal layers, the crack initiates at the center part at the lower density layer and finishes out of the center. Also, for the specimen with horizontal layers, the crack initiates and propagates at the boundary of two layers out of the middle line of the specimen. These asymmetry failures are due to the heterogeneity of layers. The study also shows the type of failure using DVC by monitoring displacement increment vectors near the crack location.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142149824","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":"High-temperature LCF behaviour of Gaussian-pitted high-strength high-ductility steel rebars","authors":"","doi":"10.1016/j.engfracmech.2024.110460","DOIUrl":"10.1016/j.engfracmech.2024.110460","url":null,"abstract":"<div><p>Fatigue of high-strength high-ductility steel rebars under pitting corrosion and high-temperature remains largely unknown, specifically concerning temperature-dependent pit sensitivity effects, limiting their widespread adoption despite advantages. This study performs high-temperature, low-cycle fatigue tests on Fe 500D rebars with Gaussian pits. Moreover, experimental results are compared with average strain energy density method, augmented with fractography-based, temperature-dependent parameter models, including exponential pit sensitivity function. Results show accelerated cyclic softening, with up to 94% and 91% reductions in fatigue life and energy dissipation capacity in corroded rebars, respectively. The findings enhance fatigue life predictions, aiding the design of more resilient and safer structures.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142167294","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":"Temporal-spatial evolution characteristics of defective coal fracture based on electric potential and multifractal characterization","authors":"","doi":"10.1016/j.engfracmech.2024.110443","DOIUrl":"10.1016/j.engfracmech.2024.110443","url":null,"abstract":"<div><p>The primary defects in coal are critical factors that induce geological disasters. Accurately predicting and identifying local damage in these defects is essential for the safe mining of underground engineering. In this paper, uniaxial compression tests were conducted on defective coal, and acoustic emission (AE) and electric potential (EP) were tested simultaneously. The mechanical behavior and failure characteristics were studied, the EP and AE features were analyzed, and the temporal-spatial features of the EP multifractal were revealed. The results indicate that external loads significantly stimulate both AE and EP responses in the coal sample, which correlate well with stress changes. As the defect dip angle increases, high-amplitude AE signals gradually decrease, and the main frequency distribution of AEs shifts from a full frequency range to a mid-low frequency range. The EP signals of each channel correspond closely with its corresponding strain evolutions, and the EP signals near the local damage area exhibit regions of high-value abnormal Δ<em>α</em>_e and low-value abnormal Δ<em>f</em>(<em>α</em>_e). When macroscopic fracturing occurs, Δ<em>α</em>_e shows a fluctuating increase, while Δ<em>f</em>(<em>α</em>_e) shows a fluctuating decrease. The spatiotemporal distribution of Δ<em>α</em>_e and Δ<em>f</em>(<em>α</em>_e) corresponds well with the stress levels and local damage in the sample. These research results provide significant theoretical guidance for the early warning and precise identification of geological disasters.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229875","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":"Recoverability degradation of adhesion between soft matters under uniaxial cyclic bonding–debonding: Modified cohesive interface model and numerical implementation","authors":"","doi":"10.1016/j.engfracmech.2024.110444","DOIUrl":"10.1016/j.engfracmech.2024.110444","url":null,"abstract":"<div><p>The main objective of this work is to propose a partial recoverable cohesive interface model, coupled with a bi-potential contact algorithm, to simulate the phenomenon of adhesion recoverability degradation under cyclic bonding–debonding between hyperelastic bodies. For this end, the proposed adhesion recoverability degradation model is constructed by defining the recovery of interface damage during the rebonding when two bodies come into contact, and a degradation factor related to the number of bonding–debonding cycles is introduced into the fully recoverable adhesion model to reduce energy dissipation after multiple cycles. Recoverability degradation includes adhesive stiffness and strength degradation, which is physically described as parallel, series and mixed arrays of adhesive bonds. Then, a finite element framework coupling the adhesion recoverability degradation model and the bi-potential contact algorithm is proposed, with Mooney–Rivlin hyperelastic material used to describe the soft matters. This framework is implemented in an in-house finite element code, with numerical examples demonstrating the model’s reliability. The proposed approach could be applied to investigate interfacial adhesion effects in fields such as flexible electronics and intelligent robotics.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163994","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 failure analysis of DZ125 directionally solidified superalloy under combined high and low cycle fatigue","authors":"","doi":"10.1016/j.engfracmech.2024.110459","DOIUrl":"10.1016/j.engfracmech.2024.110459","url":null,"abstract":"<div><p>Fracture failure behaviors of DZ125 directionally solidified nickel-base superalloy under combined high and low cycle fatigue (CCF) loads are investigated in this study. It is found that competitive cracking behaviors are present in DZ125 alloy while subjected to different CCF loads. An increase in the maximum low-cycle fatigue (LCF) nominal stress or high-cycle fatigue (HCF) stress amplitude results in a transition of crack initiation sites from subsurface pores or carbides to surface oxides. As the cycle ratio of HCF to LCF rises, crack initiation sites shift from subsurface carbides to surface oxides.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163996","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":"Creep reliability assessment of structural components at elevated temperatures considering the time dependent feature of representative stress","authors":"","doi":"10.1016/j.engfracmech.2024.110458","DOIUrl":"10.1016/j.engfracmech.2024.110458","url":null,"abstract":"<div><p>Creep reliability assessment of structural components at elevated temperatures is essential to guarantee the long-term safe operation of the system. Current studies are limited to continuum damage mechanics methods at the material level, while the reliability assessment method for creep design at the component level is rarely reported. In this work, the framework for creep reliability assessment of structural components is extended, where the time dependent feature of the representative stress is included. The effect of the time dependent feature of the representative stress on creep reliability assessment is discussed. Sensitivity analyses of material parameters on creep reliability assessment results are conducted based on the Sobol and Morris global methods. Results indicate that for the same creep design life, the component presents a higher failure probability when the time dependent feature of the representative stress is considered. Parameters <em>D</em> and <em>d</em> in the creep rupture life equation have more significant effects on creep rupture life than other parameters for the case studied.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142164000","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":"The role of the interfaces and cross-links on the mechanical behavior of mineralized collagen fibrils. A numerical approach","authors":"","doi":"10.1016/j.engfracmech.2024.110440","DOIUrl":"10.1016/j.engfracmech.2024.110440","url":null,"abstract":"<div><p>Mechanical properties of bone tissue are highly dependent on its hierarchical structure. The presence of microcracks and diffuse damage in lamellar bone is correlated with the failure of the collagen-mineral interface in mineralized collagen fibrils (MCF). The main goal of this work is to evaluate the mechanical behavior of the interfaces and quantify the stiffness loss of the MCF associated with different failure mechanisms, under controlled in-plane displacement. Additionally, we aim to study the role of the cross-links on the fibril mechanical response, beyond the interface failure. Inter- and intra-microfibrilar cross-links are analyzed. In order to address the first issue, a detailed representative volume of the MCF is analyzed by means of the finite element method, under the assumption of plane strain and periodic boundary conditions. In this model the interfaces between constituents are modeled with an exponential cohesive law. Enzymatic cross-links, located at the molecular terminals connecting each 4D (<span><math><mrow><mi>D</mi><mo>=</mo><mn>67</mn><mspace></mspace><mtext>nm</mtext></mrow></math></span>) staggered molecules, are represented by non-linear springs. Three in-plane controlled deformations are applied. The results of this work provide the anisotropic stiffness loss of the tissue involved in the different failure mechanisms at the nano-scale length. The initiation of microcracks and the presence of damage zones are compatible with the failure mechanisms observed at interfaces. Interface failure entails a progressive stiffness loss, bringing a non-linear behavior of bone. The strength obtained for the longitudinal maximum deformation is more than 20 times the transverse strength and 3.5 times the shear strength. The quantification of the reduction percentage in the elastic moduli and the shear stiffness when the fibril is damaged, has a potential application in improving failure criteria based on degradation of elastic constants. When longitudinal elongation is applied, the mechanical contribution of the cross-links in delaying the failure initiation of the interface is shown. Likewise, results of this work confirm the scarce influence of the cross-links in the strain range analyzed. Additionally, a three-dimensional numerical model of several microfibrils is defined with the aim of analyzing the mechanical relevance of inter- and intra-microfibrilar cross-links, beyond the interface failure. Results confirm that cross-links transfer the load when strain increases, being highlighted the mechanical competence of the trivalent cross-links.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0013794424006039/pdfft?md5=3a98d6187d260c58bc211bc076f6911c&pid=1-s2.0-S0013794424006039-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142136735","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":"Investigation on mixed mode I/II crack propagation in nitrate ester plasticized polyether propellant: Experimental and numerical study","authors":"","doi":"10.1016/j.engfracmech.2024.110457","DOIUrl":"10.1016/j.engfracmech.2024.110457","url":null,"abstract":"<div><p>The fracture of solid propellant is predominantly attributed to the existence of mixed mode cracks, so it is essential to investigate the the fracture behavior of solid propellant with mixed mode I/II crack. This paper presents fracture characteristics of nitrate ester plasticized polyether (NEPE) propellant under different crack inclination angles (<em>β</em> = 30°–90°). Based on the combination of a drawing machine and a high-speed camera, the mechanical response, crack propagation velocity and crack-path morphology were investigated. The critical equivalent stress intensity factor <em>K_eqc</em> was calculated to assess the fracture toughness of the NEPE propellant, and a potential simplified criterion related to the stress intensity factor was proposed. The experimental results demonstrated that the NEPE propellant with mixed mode I/II crack exhibited blunting fracture phenomena during crack propagation, resulting in fluctuating crack propagation velocity. As the crack inclination angle decreases, the fracture toughness of the NEPE propellant increases and then decreases, and the value of <em>K_eqc</em> reaches its maximum at <em>β</em> = 45°. Furthermore, numerical studies based on bond-based peridynamic (BBPD) were performed by modeling the crack propagation process of the NEPE propellant, including the crack phase field diagram and the load–displacement curve of the NEPE propellant. The simulation results were then compared with the experiments.</p></div>","PeriodicalId":11576,"journal":{"name":"Engineering Fracture Mechanics","volume":null,"pages":null},"PeriodicalIF":4.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142149822","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}