Mechanics of Materials最新文献

{"title":"High speed investigation of spatio-temporal localization of plastic deformation and fracture of notched Al-Mg specimens exhibiting intermittent plasticity","authors":"M.F. Gasanov,&nbsp;A.A. Denisov,&nbsp;A.A. Shibkov,&nbsp;A.E. Zolotov,&nbsp;S.S. Kochegarov","doi":"10.1016/j.mechmat.2025.105331","DOIUrl":"10.1016/j.mechmat.2025.105331","url":null,"abstract":"<div><div>Intermittent plasticity, known as the Portevin-Le Chatelier (PLC) effect and the yield point phenomenon, is a striking example of unstable mechanical behavior of metals and alloys caused by localization of plastic deformation within the PLC and Lüders bands. In present work dynamics and morphology these bands in notched specimens of an AlMg6 (AA5059) commercial alloy under stress-rate controlled tensile tests was investigated. The strain and force responses to the formation and propagation of deformation bands were measured synchronously with high-speed video recording of the specimen surface with a time resolution of 0.2 ms. The results show that the notch is an attractor of deformation bands from the Lüders band to the neck. The notch reduces the effective size of the gauge part of the specimen to a value comparable to the width of the specimen and causes premature sudden failure, reducing the resource of strength and ductility of the alloy. The deformation bands generated by the notch tip cause strain jumps, i.e. steps in the stress-strain curve and stress drops in the complex structure of the force response. It was established that the local rate of plastic deformation in the Lüders band and the PLC band exceeds the average strain rate of the specimen by 3 and 3.5 orders of magnitude, respectively. The spatial statistical distribution of the bands has a sharp maximum in the section along which the main crack will pass. It is a shear crack (type II) that propagates viscously at a velocity of several m/s along the PLC band in the neck structure. Before the rupture the moments of PLC band nucleation self-organize into time sequence that obeys an exponential law. The role of Lüders and subsequent PLC bands in the mechanism of neck formation and failure of a notched specimen is discussed.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105331"},"PeriodicalIF":3.4,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143681516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A constitutive model for Cemented-Sand-Gravel (CSG) materials based on strength characteristics","authors":"Yingli Wu ,&nbsp;Honglei Ren ,&nbsp;Wei Li ,&nbsp;Peiran Jing ,&nbsp;Wanli Guo","doi":"10.1016/j.mechmat.2025.105313","DOIUrl":"10.1016/j.mechmat.2025.105313","url":null,"abstract":"<div><div>As a novel dam type with numerous advantages, the cemented sand and gravel (CSG) dam is increasingly crucial in water conservancy engineering construction. Extensive triaxial shear tests were conducted on specimens with varying confining pressures and gel contents to investigate the intricate mechanical properties of the CSG. Subsequently, a suitable strength criterion and constitutive model for CSG were established. The results indicated that (1) CSG exhibits certain cementation and structural characteristics, displaying significant strain softening, strong shear dilatancy, and other macroscopic mechanical properties. (2) A shear strength criterion based on binary medium theory was developed to describe strength evolution in different gel contents. (3) The shear strength criterion was judiciously transformed into the constitutive model's shear yield surface while considering the material's tensile properties based on the modified Cam-Clay model to obtain the volumetric yield surface. Additionally, the constitutive model focuses on delineating strain softening and strong shear dilatancy of CSG. (4) The stiffness matrix of the constitutive model was derived under general stress conditions with proven good fitting effects during triaxial shear testing of CSG. These findings provide enhanced theoretical guidance for stress-deformation calculations related to CSG dams.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105313"},"PeriodicalIF":3.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atomic-scale interfacial strengthening mechanism of nano intermetallic compounds in Ti-Ni bimetallic alloys","authors":"Hao Li ,&nbsp;Zhifeng Huang ,&nbsp;Daqian Xu ,&nbsp;Qiang Shen ,&nbsp;Fei Chen","doi":"10.1016/j.mechmat.2025.105329","DOIUrl":"10.1016/j.mechmat.2025.105329","url":null,"abstract":"<div><div>It is well established that cracking induced by Ti-Ni intermetallic compounds (IMCs) severely compromises the application of Ti-Ni bimetallic alloys in extreme environments. However, recent research has demonstrated that reducing the size of these originally detrimental IMCs from the micrometer to the nanometer scale can enhance the plasticity and strength of the metal. To investigate the effects of nanoscale IMCs on the deformation mechanisms of Ti-Ni bimetallic alloys under high strain, we employed molecular dynamics (MD) simulations to study the mechanical deformation mechanisms of two common IMCs at the interface of Ti-Ni bimetallic alloys, namely Ti₂Ni and TiNi₃, and their influence on the interfacial bonding strength of the alloy. Both lamellar and particulate configurations were considered.The results of uniaxial tensile tests reveal that Ti₂Ni undergoes atomic-scale rearrangement after yielding, exhibiting high ductility but low strength. In contrast, TiNi₃ is highly brittle and exhibits limited slip. In the context of Ti-Ni bimetallic alloys, the interface between lamellar Ti₂Ni and the Ti layer is highly susceptible to stress concentration due to the lack of long-range order in the Ti₂Ni structure. The semi-coherent interface between lamellar TiNi₃ and the Ti layer is the primary cause of brittleness at the Ti-Ni interface. Additionally, the presence of particulate IMCs acts as dislocation sources, activating slip in the Ni layer, thereby enhancing overall plasticity at the expense of some strength.Our simulation work provides a potential approach for designing high-performance Ti-Ni bimetallic alloys and elucidates the deformation mechanisms of Ti₂Ni and TiNi₃ within the alloy matrix.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105329"},"PeriodicalIF":3.4,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanism and prediction of screw dislocation strengthening by interstitials in advanced high-strength steels: Application to Fe–C and Fe–N alloys","authors":"Predrag Andric ,&nbsp;Sebastián Echeverri Restrepo ,&nbsp;Francesco Maresca","doi":"10.1016/j.mechmat.2025.105314","DOIUrl":"10.1016/j.mechmat.2025.105314","url":null,"abstract":"<div><div>Screw dislocations control the yield strength of low-alloyed body-centered-cubic (e.g. steels). Interstitials such as C and N play a key role in the strengthening mechanisms, yet a mechanistic theory that enables the prediction of strength of alloys over a broad range of compositions and interstitial contents is not available. Here, we provide such a theory and apply it to screw dislocations with C and N in iron, from dilute to larger concentrations. The theory, which accounts for interstitial solute segregation by Cottrell atmospheres, is validated with respect to atomistic simulations and used to predict the yield strength of a broad range of alloys, including fully ferritic, martensitic and precipitation-strengthened microstructures. By using a recent model developed by the authors to predict the dislocation density of martensite as a function of the interstitials content, we find a new scaling of the yield strength with the dislocation density, which matches experiments and differs from the commonly used Taylor equation. The demonstrated predictive power of the theory paves the way for theory-guided alloy design, based on reduced and hence more sustainable testing.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105314"},"PeriodicalIF":3.4,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A rate-dependent implicit gradient damage model with energy limiter: Ductile fracture analysis and determination of the physical length scale","authors":"Hung Thanh Tran ,&nbsp;Shunhua Chen ,&nbsp;Xiaofei Hu ,&nbsp;Tinh Quoc Bui","doi":"10.1016/j.mechmat.2025.105310","DOIUrl":"10.1016/j.mechmat.2025.105310","url":null,"abstract":"<div><div>This work presents an implicit gradient-enhanced damage theory for failure in elastoplastic solids under the quasi-static loading condition. Our previous rate-independent gradient-enhanced damage formulation based on the energy limiter concept for brittle fracture in (Tran, Bui et al, CMAME 413:116123, 2023) is extended to ductile damage analysis with the consideration of rate-dependent crack growth characteristics. The present development contains a system of equilibrium and rate-dependent gradient crack evolution equations that describe the deformation of the body and rate-dependent evolution of the smeared damage in metals, respectively. For the nonlocal damage law, it has almost the same form as the one in our mentioned reference, except for the introduced rate-dependent crack growth term. Consistently with the energy limiter idea for fracture analysis, the material constitutive elastoplastic stress–strain relation is derived from the energy limiter formulation developed for ductile crack growth modeling with the von Mises plasticity criterion for an isotropic body under the small strain regime. This study, other than numerical experiments, will present a complete procedure to determine all input parameters used in the current theory for ductile failure analysis including the value of the length scale from reference experimental tests. To the best knowledge of the authors, it will show, for the first time in the literature, that the length scale is an actual physical scalar of the simulated problem and could be estimated from experiments. On the numerical side, ductile failure analyses under the standard finite element method (FEM) with the aid of an iterative staggered algorithm with both two-dimensional (2D) plane strain and general three-dimensional (3D) crack-growth problems are conducted to reveal the performance and capability of the gradient damage formulation based on the energy limiter concept for fracture in metals.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105310"},"PeriodicalIF":3.4,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shear bands in polymer tubes under internal pressure","authors":"Tianxiang Lan ,&nbsp;Yaodong Jiang ,&nbsp;Peidong Wu ,&nbsp;Yueguang Wei","doi":"10.1016/j.mechmat.2025.105315","DOIUrl":"10.1016/j.mechmat.2025.105315","url":null,"abstract":"<div><div>The extensive emergence and frequent interaction of shear bands play a pivotal role in the behavior of ductile polymers under large deformations. This paper employs the finite element method to analyze the emergence and evolution of shear bands in polymer tubes under internal pressure. Assuming the tube is sufficiently long, plane strain conditions prevail in the axial direction. The behavior of polymers is represented by the classical elastic-viscoplastic constitutive model, which incorporates influences of pressure, strain rate and temperature on yielding and encompasses intrinsic softening and consequent orientation hardening. Simulations indicate that shear bands initially propagate in a spiral pattern, followed by widening, multiplication, and annihilation indications. These phenomena collectively contribute to the onset and expansion of necks. The competition between the propagation and multiplication of shear bands governs the unpredictability in the initiation sites of necking. Particular attention is paid to four interesting interactions between shear bands (i.e., “detour”, bifurcation, obstruction, “repulsion”) and their genesis mechanisms. The effects of material parameters, initial geometric imperfections, specimen thickness and loading method are systematically discussed. It is demonstrated that intrinsic softening facilitates the emergence and propagation of bands, while orientation hardening contributes to the widening of bands and the expansion of necks. The synergistic effect of intrinsic softening and orientational hardening modulates shear bands’ morphology, multiplication, competition and interaction. The initial imperfection wave number significantly affects the number of shear bands. Periodic symmetric imperfections result in a comparable number of clockwise and counterclockwise shear bands, followed by necks propagating bi-directionally along the specimen. Conversely, periodic asymmetric imperfections induce a unidirectional spiral configuration of shear bands, followed by necks propagating unidirectionally along the specimen. Compared with experiments, it is demonstrated that the constitutive model can qualitatively depict the onset and propagation of necks. The multiplication, bifurcation, “detour”, and obstruction of shear bands frequently observed in experiments can also be predicted well qualitatively.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105315"},"PeriodicalIF":3.4,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Batch active learning for microstructure–property relations in energetic materials","authors":"Ozge Ozbayram ,&nbsp;Daniel Olsen ,&nbsp;Maruthi Annamaraju ,&nbsp;Andreas E. Robertson ,&nbsp;Aditya Venkatraman ,&nbsp;Surya R. Kalidindi ,&nbsp;Min Zhou ,&nbsp;Lori Graham-Brady","doi":"10.1016/j.mechmat.2025.105308","DOIUrl":"10.1016/j.mechmat.2025.105308","url":null,"abstract":"<div><div>Polymer-bonded explosives (PBX) exhibit complex microstructure–property relationships, particularly in their shock-to-detonation transition (SDT) behavior. Traditionally physics-based simulations to explore these relationships are computationally expensive and time-consuming for a number of reasons. We present a material informatics framework that leverages batch active learning to efficiently investigate the intricate microstructure-macroscopic property relationships for PBX, significantly reducing simulation time. Our framework integrates multi-output Gaussian Process Regression (MOGPR) to capture complex relationships between microstructural features (including void volume fraction, shape, and distribution) and reaction response (characterized by shock pressure and run-to-detonation distance). The batch active learning component efficiently traverses the microstructure space by strategically selecting the most informative microstructures for additional simulations, maximizing information gain while minimizing computational costs. By iteratively refining the MOGPR model with the most informative samples, we accelerate the learning process and improve the predictive accuracy of the microstructure–property relationships. Our results demonstrate rapid model convergence and high predictive accuracy, with <span><math><msup><mrow><mi>r</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> scores of 0.97 for both pressure and run distance predictions in leave-one-out cross-validation after only eight iterations. This approach efficiently navigates the diverse microstructure space, uncovering key factors governing the SDT behavior in PBX. It also has the potential to significantly improve the design and optimization of PBX materials, enabling the development of tailored explosives with enhanced performance and safety characteristics.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105308"},"PeriodicalIF":3.4,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143550930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predictions of temperature-dependent material properties and auxeticity of graphene platelets","authors":"Zhouyu Zheng,&nbsp;Hui-Shen Shen,&nbsp;Bai-Wei Na,&nbsp;Yin Fan,&nbsp;Xiuhua Chen,&nbsp;Hai Wang","doi":"10.1016/j.mechmat.2025.105311","DOIUrl":"10.1016/j.mechmat.2025.105311","url":null,"abstract":"<div><div>In current engineering applications, there is a lack of a complete set of material properties for graphene platelets (GPLs). In this paper, we predict the material properties of GPLs through atomistic structural mechanics and molecular dynamics (MD) simulations. A novel spring beam-based finite element model is designed and implemented for the analysis of material properties. Numerical results of the atomistic structural mechanics model are compared with those of the MD model. In the present proposed model, the interlayer distance of GPL is varied as the number of layer increases, and the numerical results show that the varying of interlayer distance has a significant influence on the Young's moduli <em>E</em>₁₁ and <em>E</em>₂₂, and shear modulus <em>G</em>₁₂ of GPLs under AIREBO potential. The simulation results reveal that the material properties of GPLs are slightly anisotropic and in most cases GPLs have auxetic properties. The temperature-dependent material properties, including Young's moduli, shear modulus and thermal expansion coefficients of GPLs with in-plane positive and negative Poisson's ratios are obtained for the first time.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105311"},"PeriodicalIF":3.4,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A molecular dynamic investigation of cyclic strengthening mechanism of Ni-based single crystal superalloy","authors":"Bin Xie ,&nbsp;Jing Wang ,&nbsp;Yongsheng Fan ,&nbsp;Ruizhi Li","doi":"10.1016/j.mechmat.2025.105312","DOIUrl":"10.1016/j.mechmat.2025.105312","url":null,"abstract":"<div><div>Ni-based single crystal superalloys, as crucial materials in the aviation and aerospace industry, frequently encounter fatigue failure induced by cyclic loading, which is one of the primary failure modes. In this study, molecular dynamics (MD) simulations are utilized to explore the cyclic strengthening mechanisms of Ni-based single crystal superalloys, with a focus on dislocation evolution under cyclic loading. Two typical feature atomistic models of the alloys are constructed and dislocations are introduced under cyclic loading, investigating the interactions between dislocations and the γ/γ′ interface. The results highlight the excellent capacity of the interfacial dislocation network for dislocation deposition, particularly for those attempting to penetrate the γ′ phase, and capture a transition in emission dislocations slip plane from the <span><math><mrow><mo>{</mo><mn>111</mn><mo>}</mo></mrow></math></span> plane to the <span><math><mrow><mo>{</mo><mn>100</mn><mo>}</mo></mrow></math></span> plane. The dislocation absorption is driven by two primary mechanisms: the formation of stable link points at the γ/γ′ interface and the obstructive effect of the γ′ phase. Additionally, a stress stratification phenomenon at the γ/γ′ interface is observed, hindering dislocation movement during loading and leading to dislocation trapping through cross-slip during unloading. Furthermore, the simulations reveal two distinct forms of dislocation barriers pile-up within the γ phase: one arising from the decomposition of the interfacial dislocation network, which leads to the emergence of stacking faults (SFs) bands and Lomer-Cottrell lock; the other stemming from the formation of SFs bands due to the decomposition of the emission dislocations within the γ phase channel. These findings provide meaningful insights into the cyclic hardening behavior of Ni-based superalloys.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"205 ","pages":"Article 105312"},"PeriodicalIF":3.4,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143534558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The most severe imperfection governs the buckling strength of pressurized multi-defect hemispherical shells","authors":"Fani Derveni,&nbsp;Florian Choquart,&nbsp;Arefeh Abbasi ,&nbsp;Dong Yan,&nbsp;Pedro M. Reis","doi":"10.1016/j.mechmat.2025.105295","DOIUrl":"10.1016/j.mechmat.2025.105295","url":null,"abstract":"<div><div>We perform a probabilistic investigation on the effect of systematically removing imperfections on the buckling behavior of pressurized thin, elastic, hemispherical shells containing a distribution of defects. We employ finite element simulations, which were previously validated against experiments, to assess the maximum buckling pressure, as measured by the knockdown factor, of these multi-defect shells. Specifically, we remove fractions of either the least or the most severe imperfections to quantify their influence on the buckling onset. We consider shells with a random distribution of defects whose mean amplitude and standard deviation are systematically explored while, for simplicity, fixing the width of the defect to a characteristic value. Our primary finding is that the most severe imperfection of a multi-defect shell dictates its buckling onset. Notably, shells containing a single imperfection corresponding to the maximum amplitude (the most severe) defect of shells with a distribution of imperfections exhibit an identical knockdown factor to the latter case. Our results suggest a simplified approach to studying the buckling of more realistic multi-defect shells, once their most severe defect has been identified, using a well-characterized single-defect description, akin to the weakest-link setting in extreme-value probabilistic problems.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"204 ","pages":"Article 105295"},"PeriodicalIF":3.4,"publicationDate":"2025-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}