Pub Date : 2024-10-18DOI: 10.1016/j.mechmat.2024.105184
Morteza Sadeghifar , Rene Billardon , Denis Delagnes , Henri Champliaud , Antoine Tahan , Mohammad Jahazi
In the present research, new and accurate equations were developed for the incremental plastic multiplier (IPM) and the consistent tangent operator (CTO) to solve numerical problems in thermo-elasto-plastic (TEP) processes using the finite element method (FEM). To ensure accuracy, all material hardening coefficients were treated as temperature-dependent, and no terms and their derivatives in the analytical-mathematical solution were ignored. Two UMAT (User MATerial) subroutines with temperature-independent and temperature-dependent parameters were programmed for the EP and TEP behavior, respectively. Finite element models were created using both the Abaqus® built-in material models and the newly developed UMAT subroutines, designated as the reference and new models, respectively. In the reference model, flow stress was implemented using tabulated plastic strain and temperature data available in Abaqus®, while in the new model, the flow stress (yield function) was derived and numerically calculated based on the developed formulation. The new equations were successfully validated by comparing the results from the new model with those from the reference model. The developed IPM and CTO can be used for accurate predictions of strains, stresses, and temperatures in TEP problems, making them well-suited for industrial applications.
本研究为增量塑性乘数（IPM）和一致切线算子（CTO）建立了新的精确方程，用于使用有限元法（FEM）解决热弹性塑性（TEP）过程中的数值问题。为确保准确性，所有材料硬化系数都被视为与温度有关，分析数学解法中的任何项及其导数都未忽略。针对 EP 和 TEP 行为，分别使用与温度无关和与温度有关的参数编制了两个 UMAT（User MATerial）子程序。使用 Abaqus® 内置材料模型和新开发的 UMAT 子程序创建了有限元模型，分别称为参考模型和新模型。在参考模型中，流动应力是利用 Abaqus® 中的表列塑性应变和温度数据实现的，而在新模型中，流动应力（屈服函数）是根据开发的公式推导和数值计算的。通过比较新模型和参考模型的结果，成功验证了新方程。开发的 IPM 和 CTO 可用于准确预测 TEP 问题中的应变、应力和温度，因此非常适合工业应用。
{"title":"A novel approach for accurate development of the incremental plastic multiplier and consistent tangent operator in thermo-elasto-plastic modeling of materials","authors":"Morteza Sadeghifar , Rene Billardon , Denis Delagnes , Henri Champliaud , Antoine Tahan , Mohammad Jahazi","doi":"10.1016/j.mechmat.2024.105184","DOIUrl":"10.1016/j.mechmat.2024.105184","url":null,"abstract":"<div><div>In the present research, new and accurate equations were developed for the incremental plastic multiplier (IPM) and the consistent tangent operator (CTO) to solve numerical problems in thermo-elasto-plastic (TEP) processes using the finite element method (FEM). To ensure accuracy, all material hardening coefficients were treated as temperature-dependent, and no terms and their derivatives in the analytical-mathematical solution were ignored. Two UMAT (User MATerial) subroutines with temperature-independent and temperature-dependent parameters were programmed for the EP and TEP behavior, respectively. Finite element models were created using both the Abaqus® built-in material models and the newly developed UMAT subroutines, designated as the reference and new models, respectively. In the reference model, flow stress was implemented using tabulated plastic strain and temperature data available in Abaqus®, while in the new model, the flow stress (yield function) was derived and numerically calculated based on the developed formulation. The new equations were successfully validated by comparing the results from the new model with those from the reference model. The developed IPM and CTO can be used for accurate predictions of strains, stresses, and temperatures in TEP problems, making them well-suited for industrial applications.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105184"},"PeriodicalIF":3.4,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531328","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}
Pub Date : 2024-10-16DOI: 10.1016/j.mechmat.2024.105179
Yuhan Zhao , Shaojing Dong , Xiuli Shen
The nonlinear behavior of ceramic-matrix composites is affected by interface debonding and fiber pull-out. In this paper, we propose the constituent-volume homogenization method (CVHM) to replace the conventional bundle homogenization method, in order to model the behavior of trans-element debonding in woven structures using finite element method. Based on the CVHM, we establish the elastic relation of the relative motion between the fiber and the matrix, and the elastic constitutive relations for the constituents. Methods have also been developed to calculate the microscopic local stress of bundle under pull-out and multiaxial loads. Based on the above studies, we develop a procedure to analyze the stress-strain relation of braided composites using the CVHM. To validate the proposed method, we estimate the nonlinear behavior of the 2D plain-weave ceramic-matrix composites and compare the results with experimental data. The influence of interface shear strength (ISS) and the fiber ultimate tensile strength (UTS) on the nonlinear behavior is investigated.
{"title":"Nonlinear behavior simulation of ceramic-matrix composites using constituent-volume homogenization method","authors":"Yuhan Zhao , Shaojing Dong , Xiuli Shen","doi":"10.1016/j.mechmat.2024.105179","DOIUrl":"10.1016/j.mechmat.2024.105179","url":null,"abstract":"<div><div>The nonlinear behavior of ceramic-matrix composites is affected by interface debonding and fiber pull-out. In this paper, we propose the constituent-volume homogenization method (CVHM) to replace the conventional bundle homogenization method, in order to model the behavior of trans-element debonding in woven structures using finite element method. Based on the CVHM, we establish the elastic relation of the relative motion between the fiber and the matrix, and the elastic constitutive relations for the constituents. Methods have also been developed to calculate the microscopic local stress of bundle under pull-out and multiaxial loads. Based on the above studies, we develop a procedure to analyze the stress-strain relation of braided composites using the CVHM. To validate the proposed method, we estimate the nonlinear behavior of the 2D plain-weave ceramic-matrix composites and compare the results with experimental data. The influence of interface shear strength (ISS) and the fiber ultimate tensile strength (UTS) on the nonlinear behavior is investigated.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105179"},"PeriodicalIF":3.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531330","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}
Pub Date : 2024-10-16DOI: 10.1016/j.mechmat.2024.105173
Ahmed Zouari , Mikel Bengoetxea-Aristondo , Filip Siska , Aymen Bouzid , Fabrice Gaslain , Aurélien Chopin , Houssem Eddine Chaieb , Kais Ammar , Pascal Bertho , Joost De Strycker , Jean-Michel Mataigne , Samuel Forest
Twinning is a major deformation mechanism in various materials, especially when few dislocation slip systems are operative. It is the case of zinc-rich coatings in galvanised steel sheets, made of pancake grains on a substrate and where the slip systems with a non-vanishing component along the -axis present high critical resolved shear stress values. In addition, the abrupt lattice orientation change associated to twinning, the stress relaxation during its propagation and the localised nature of its early stages make it difficult to reproduce this deformation mechanism by using classical crystal plasticity models conceived for dislocation slip. In this sense, this work proposes a hierarchy of three twinning models in combination with a dislocation slip crystal plasticity model, for the case of a ZnAlMg coating. These three models are: a relaxed-Taylor model applied to individual crystal orientations of the coating, a “pseudo-slip” model for twinning and a localised twinning model. The latter incorporates a linear softening in the material law accounting for the unstable twinning initiation and enforces twinning lattice reorientation. A microstructure portion extracted from an in-situ SEM tensile experiment on galvanised steel is used to perform 3D full-field finite element simulations within a finite strain formulation. SEM observations and EBSD acquisitions are used to compare simulation and experimental results during the different steps of the in-situ SEM test, regarding the deformation and damage modes of the zinc-rich coating. The focus is set on twinning evolution inside some individual grains, and the pros and the cons of the three models are finally discussed.
在各种材料中，扭结是一种主要的变形机制，尤其是在只有少数位错滑移系统起作用的情况下。镀锌钢板中的富锌涂层就是这种情况，它是由基底上的薄饼晶粒制成的，其中沿 c 轴的滑移系统具有非渐变分量，呈现出较高的临界分辨剪应力值。此外，与孪晶相关的突然晶格取向变化、孪晶传播过程中的应力松弛以及孪晶早期阶段的局部性，都使得使用为差排滑移设计的经典晶体塑性模型难以再现这种变形机制。因此，本研究针对 ZnAlMg 涂层的情况，提出了三种孪晶模型与位错滑移晶体塑性模型相结合的层次结构。这三种模型是：应用于涂层单个晶体取向的松弛-泰勒模型、孪晶的 "伪滑移 "模型和局部孪晶模型。后者在材料定律中加入了线性软化，用于解释不稳定的孪晶启动，并强制孪晶晶格重新定向。从镀锌钢原位 SEM 拉伸实验中提取的微观结构部分被用于在有限应变公式中执行三维全场有限元模拟。在原位 SEM 测试的不同步骤中，利用 SEM 观察和 EBSD 采集结果来比较模拟和实验结果，了解富锌涂层的变形和损坏模式。重点是一些单个晶粒内部的孪晶演变，最后讨论了三种模型的优缺点。
{"title":"Experimental and digital twinning in ZnAlMg coatings","authors":"Ahmed Zouari , Mikel Bengoetxea-Aristondo , Filip Siska , Aymen Bouzid , Fabrice Gaslain , Aurélien Chopin , Houssem Eddine Chaieb , Kais Ammar , Pascal Bertho , Joost De Strycker , Jean-Michel Mataigne , Samuel Forest","doi":"10.1016/j.mechmat.2024.105173","DOIUrl":"10.1016/j.mechmat.2024.105173","url":null,"abstract":"<div><div>Twinning is a major deformation mechanism in various materials, especially when few dislocation slip systems are operative. It is the case of zinc-rich coatings in galvanised steel sheets, made of pancake grains on a substrate and where the slip systems with a non-vanishing component along the <span><math><mi>c</mi></math></span>-axis present high critical resolved shear stress values. In addition, the abrupt lattice orientation change associated to twinning, the stress relaxation during its propagation and the localised nature of its early stages make it difficult to reproduce this deformation mechanism by using classical crystal plasticity models conceived for dislocation slip. In this sense, this work proposes a hierarchy of three twinning models in combination with a dislocation slip crystal plasticity model, for the case of a ZnAlMg coating. These three models are: a relaxed-Taylor model applied to individual crystal orientations of the coating, a “pseudo-slip” model for twinning and a localised twinning model. The latter incorporates a linear softening in the material law accounting for the unstable twinning initiation and enforces twinning lattice reorientation. A microstructure portion extracted from an in-situ SEM tensile experiment on galvanised steel is used to perform 3D full-field finite element simulations within a finite strain formulation. SEM observations and EBSD acquisitions are used to compare simulation and experimental results during the different steps of the in-situ SEM test, regarding the deformation and damage modes of the zinc-rich coating. The focus is set on twinning evolution inside some individual grains, and the pros and the cons of the three models are finally discussed.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105173"},"PeriodicalIF":3.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.mechmat.2024.105176
W.Q. Shen
The microstructure of heterogeneous materials affects importantly their macroscopic mechanical behavior. For a thermal-mechanical coupling problem, the temperature also has a significant effect. Firstly, the effect of temperature on the elastic behavior of heterogeneous material has been investigated in the present work with the consideration of its microstructure. Then, an explicit expression of the macroscopic yield criterion has been derived for the plastic behavior of porous material by using the homogenization approach. This yield criterion takes into account explicitly and simultaneously the influence of porosity and the effect of temperature on its overall mechanical behavior. To consider the pressure sensitivity of the matrix, the Drucker–Prager type criterion is adopted at the microscopic scale. After that, the heterogeneous material with a matrix reinforced by rigid inclusions has been studied. The microstructure information, such as the inclusion content, matrix property and the temperature have been considered explicitly in the obtained yield function. The influences of temperature and the confining pressure on the macroscopic material strength are captured by the obtained criterion. Then, the obtained result is applied to describe the temperature-dependent mechanical behaviors of sandstone.
{"title":"The influences of temperature on the macroscopic elastoplastic behaviors of heterogeneous materials","authors":"W.Q. Shen","doi":"10.1016/j.mechmat.2024.105176","DOIUrl":"10.1016/j.mechmat.2024.105176","url":null,"abstract":"<div><div>The microstructure of heterogeneous materials affects importantly their macroscopic mechanical behavior. For a thermal-mechanical coupling problem, the temperature also has a significant effect. Firstly, the effect of temperature on the elastic behavior of heterogeneous material has been investigated in the present work with the consideration of its microstructure. Then, an explicit expression of the macroscopic yield criterion has been derived for the plastic behavior of porous material by using the homogenization approach. This yield criterion takes into account explicitly and simultaneously the influence of porosity and the effect of temperature on its overall mechanical behavior. To consider the pressure sensitivity of the matrix, the Drucker–Prager type criterion is adopted at the microscopic scale. After that, the heterogeneous material with a matrix reinforced by rigid inclusions has been studied. The microstructure information, such as the inclusion content, matrix property and the temperature have been considered explicitly in the obtained yield function. The influences of temperature and the confining pressure on the macroscopic material strength are captured by the obtained criterion. Then, the obtained result is applied to describe the temperature-dependent mechanical behaviors of sandstone.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105176"},"PeriodicalIF":3.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531326","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}
Pub Date : 2024-10-15DOI: 10.1016/j.mechmat.2024.105175
M. Molinos , M. Ortiz , M.P. Ariza
We develop meanfield approximation and numerical quadrature schemes for the evaluation of Angular-Dependent interatomic Potentials (ADPs) for magnesium and magnesium hydrides at finite temperature (thermalization) and arbitrary atomic molar fractions (mixing) within a non-equilibrium statistical mechanical framework and derive local equilibrium relations. We numerically verify and experimentally validate the accuracy and fidelity of the resulting thermalized/mixed ADPs (TADPs) by means of selected numerical tests including free entropy, heat capacity, thermal expansion, molar volumes, equation of state and elastic constants. We show that the local equilibrium properties predicted by TADPs agree closely with those computed directly from ADP by means of Molecular Dynamics (MD).
{"title":"Thermalized and mixed meanfield ADP potentials for magnesium hydrides","authors":"M. Molinos , M. Ortiz , M.P. Ariza","doi":"10.1016/j.mechmat.2024.105175","DOIUrl":"10.1016/j.mechmat.2024.105175","url":null,"abstract":"<div><div>We develop meanfield approximation and numerical quadrature schemes for the evaluation of Angular-Dependent interatomic Potentials (ADPs) for magnesium and magnesium hydrides at finite temperature (thermalization) and arbitrary atomic molar fractions (mixing) within a non-equilibrium statistical mechanical framework and derive local equilibrium relations. We numerically verify and experimentally validate the accuracy and fidelity of the resulting thermalized/mixed ADPs (TADPs) by means of selected numerical tests including free entropy, heat capacity, thermal expansion, molar volumes, equation of state and elastic constants. We show that the local equilibrium properties predicted by TADPs agree closely with those computed directly from ADP by means of Molecular Dynamics (MD).</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105175"},"PeriodicalIF":3.4,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531327","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}
Pub Date : 2024-10-15DOI: 10.1016/j.mechmat.2024.105180
Tiankun Li , Pengfei Zhao , Fulin Shang
The elastoplastic deformation mechanisms of irradiated aluminum (Al)-doped gallium nitride (GaN) under contact loading are investigated in this work using the nanoindentation simulations, which is of great significance for understanding the mechanical properties of the Al-doped GaN and guiding the design of durable and high-performance GaN-based devices. The mechanical behaviors of the Al-doped GaN with different doping concentrations are analyzed, including the indentation hardness, Young's modulus, elastic recovery rates, phase transformations, and stress distribution. It is found that Al doping increases their hardness, Young's modulus, and elastic recovery rates, and leads to an enlargement of the phase transformation regions, which is dominated by the high coordination number (CN) phase transformations. Furthermore, the effects of low-dose neutron irradiation on their elastoplastic deformation mechanisms are studied by triggering cascade collisions within the structure. When subjected to such irradiation, structural changes occur in the Al-doped GaN, their indentation hardness, Young's modulus, and elastic recovery rates increase remarkably, and its phase transformation mechanism is changed remarkably. The dislocation behaviors of the doped and undoped GaN are different under neutron irradiation. This study is important for capturing the mechanical stability and integrity of Al-doped GaN in an irradiation environment, as well as developing GaN-based devices with superior irradiation resistance.
本研究利用纳米压痕模拟研究了辐照掺铝氮化镓（GaN）在接触载荷作用下的弹塑性变形机制，这对于理解掺铝氮化镓的力学性能以及指导设计耐用的高性能氮化镓基器件具有重要意义。研究分析了不同掺杂浓度的铝掺杂氮化镓的力学行为，包括压痕硬度、杨氏模量、弹性恢复率、相变和应力分布。结果发现，铝掺杂增加了它们的硬度、杨氏模量和弹性恢复率，并导致相变区域的扩大，其中以高配位数（CN）相变为主。此外，通过在结构内部引发级联碰撞，研究了低剂量中子辐照对其弹塑性变形机制的影响。在这种辐照下，掺铝氮化镓的结构发生了变化，其压痕硬度、杨氏模量和弹性恢复率显著增加，相变机制也发生了显著变化。在中子辐照下，掺杂和未掺杂 GaN 的位错行为有所不同。这项研究对于掌握掺铝氮化镓在辐照环境下的力学稳定性和完整性，以及开发具有优异抗辐照性能的氮化镓基器件具有重要意义。
{"title":"Low-dose neutron irradiation effects on the elastoplastic deformation mechanisms of aluminum-doped gallium nitride under contact loading","authors":"Tiankun Li , Pengfei Zhao , Fulin Shang","doi":"10.1016/j.mechmat.2024.105180","DOIUrl":"10.1016/j.mechmat.2024.105180","url":null,"abstract":"<div><div>The elastoplastic deformation mechanisms of irradiated aluminum (Al)-doped gallium nitride (GaN) under contact loading are investigated in this work using the nanoindentation simulations, which is of great significance for understanding the mechanical properties of the Al-doped GaN and guiding the design of durable and high-performance GaN-based devices. The mechanical behaviors of the Al-doped GaN with different doping concentrations are analyzed, including the indentation hardness, Young's modulus, elastic recovery rates, phase transformations, and stress distribution. It is found that Al doping increases their hardness, Young's modulus, and elastic recovery rates, and leads to an enlargement of the phase transformation regions, which is dominated by the high coordination number (CN) phase transformations. Furthermore, the effects of low-dose neutron irradiation on their elastoplastic deformation mechanisms are studied by triggering cascade collisions within the structure. When subjected to such irradiation, structural changes occur in the Al-doped GaN, their indentation hardness, Young's modulus, and elastic recovery rates increase remarkably, and its phase transformation mechanism is changed remarkably. The dislocation behaviors of the doped and undoped GaN are different under neutron irradiation. This study is important for capturing the mechanical stability and integrity of Al-doped GaN in an irradiation environment, as well as developing GaN-based devices with superior irradiation resistance.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105180"},"PeriodicalIF":3.4,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441597","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}
Pub Date : 2024-10-11DOI: 10.1016/j.mechmat.2024.105178
Shangyu Yang , Haizhou Liu , Lingtao Mao , Fangao Li , Bingjie Wei , Yang Ju , François Hild
Finite element-based digital volume correlation with mechanical regularization was utilized to measure the deformation fields in a concrete specimen under uniaxial compression based on in-situ (via microcomputed tomography) experiment. Heterogeneous and damage settings were introduced in the mechanical regularization. The mechanical response of the matrix and aggregates was investigated. The three-dimensional morphology of subvoxel microcrack openings was measured, the overall assessment and local depiction of concrete damage were quantified. Subvoxel microcrack openings greater than 0.26 vx were identified. The average maximum principal and average volumetric strains in the matrix were higher than those in the aggregates, and noticeable strain concentrations existed in the interfacial transition zone and pore edges. Microcracks initiated in the macroscopic elastic stage, whereas voxel-level crack openings were observed at 90% of the ultimate load. This study provides experimental support for further revealing the growth process of concrete damage.
{"title":"Damage quantification in concrete under uniaxial compression using microcomputed tomography and digital volume correlation with consideration of heterogeneity","authors":"Shangyu Yang , Haizhou Liu , Lingtao Mao , Fangao Li , Bingjie Wei , Yang Ju , François Hild","doi":"10.1016/j.mechmat.2024.105178","DOIUrl":"10.1016/j.mechmat.2024.105178","url":null,"abstract":"<div><div>Finite element-based digital volume correlation with mechanical regularization was utilized to measure the deformation fields in a concrete specimen under uniaxial compression based on in-situ (via microcomputed tomography) experiment. Heterogeneous and damage settings were introduced in the mechanical regularization. The mechanical response of the matrix and aggregates was investigated. The three-dimensional morphology of subvoxel microcrack openings was measured, the overall assessment and local depiction of concrete damage were quantified. Subvoxel microcrack openings greater than 0.26 vx were identified. The average maximum principal and average volumetric strains in the matrix were higher than those in the aggregates, and noticeable strain concentrations existed in the interfacial transition zone and pore edges. Microcracks initiated in the macroscopic elastic stage, whereas voxel-level crack openings were observed at 90% of the ultimate load. This study provides experimental support for further revealing the growth process of concrete damage.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105178"},"PeriodicalIF":3.4,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446675","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}
Shot peening is an established cold working process used to introduce residual compressive stresses on a surface and is extensively studied using conventional fatigue tests. However, it has not been widely studied using the self-heating method. Specifically, the heterogeneity of the dissipation field has not been estimated, with only an average approach being used. Previous investigations in the case of 300M steel demonstrated that the effect of shot peening on the high cycle fatigue properties can be either beneficial or detrimental. This study proposes to apply the self-heating method on polished 300M and to investigate the effect of mean stress and shot peening on the dissipation behavior. A modified self-heating model is proposed and calibrated for 300M steel. Combined with residual stress profiles, a method to compute and determine the shot peening effect on self-heating behavior through single point surface measurements is proposed. Application on 300M steel shows excellent results, the over-dissipation being mainly due to the sub-surface compressive residual stresses. The self-heating method has proven useful to quickly estimate fatigue properties of polished 300M steel. Based on the understanding of the self-heating curve of shot peened 300M steel, a quantification of shot-peening effect on fatigue limit is discussed.
{"title":"Influence of shot-peening on the self-heating behavior and fatigue properties of 300M steel","authors":"Pierrick Lepitre , Louis-Maël Merlet , Cédric Doudard , Matthieu Dhondt , Martin Surand , Sylvain Calloch","doi":"10.1016/j.mechmat.2024.105174","DOIUrl":"10.1016/j.mechmat.2024.105174","url":null,"abstract":"<div><div>Shot peening is an established cold working process used to introduce residual compressive stresses on a surface and is extensively studied using conventional fatigue tests. However, it has not been widely studied using the self-heating method. Specifically, the heterogeneity of the dissipation field has not been estimated, with only an average approach being used. Previous investigations in the case of 300M steel demonstrated that the effect of shot peening on the high cycle fatigue properties can be either beneficial or detrimental. This study proposes to apply the self-heating method on polished 300M and to investigate the effect of mean stress and shot peening on the dissipation behavior. A modified self-heating model is proposed and calibrated for 300M steel. Combined with residual stress profiles, a method to compute and determine the shot peening effect on self-heating behavior through single point surface measurements is proposed. Application on 300M steel shows excellent results, the over-dissipation being mainly due to the sub-surface compressive residual stresses. The self-heating method has proven useful to quickly estimate fatigue properties of polished 300M steel. Based on the understanding of the self-heating curve of shot peened 300M steel, a quantification of shot-peening effect on fatigue limit is discussed.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105174"},"PeriodicalIF":3.4,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.mechmat.2024.105177
Kseniia A. Mokhireva, Alexander L. Svistkov, Vladimir V. Shadrin
The mechanical behavior of elastomeric nanocomposites in experiments with nested stress-strain cycles and in cyclic tests with increasing strain amplitude was considered. In the proposed testing procedures, long time stops at each stage of the change in loading direction were of great importance. This revealed two significant features of the behavior of elastomeric nanocomposites that have received little attention. It was shown that material softening (the Mullins effect) should be considered not only in the elastic part of the Cauchy stress tensor, but also in its dissipative part. The second peculiarity was the difference between the characteristic relaxation time at loading and the characteristic relaxation time at unloading observed in the experiments.
This paper focuses on the behavior of highly-filled elastomeric materials based on different matrices (styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR)) and with different concentrations of carbon black (CB) or a combination of two fillers (CB and purified multi-walled carbon nanotubes (MWCNTs)).
A mathematical model of the viscoelastic behavior of elastomeric nanocomposites under finite strains is proposed. It takes into account the peculiarities of the behavior of highly filled elastomers observed in the experiments. The specificity of the model consists in a new variant of the form of the free energy potential. It is shown that the new model satisfies the thermodynamic inequality, which is a consequence of the first law of thermodynamics and the second law in the form of the Clausius-Duhem inequality. A good agreement between theoretical calculations and experimental data was obtained.
{"title":"Investigation of the strain rate and stretch level dependent behavior of elastomeric nanocomposites in complex uniaxial tests under finite strains","authors":"Kseniia A. Mokhireva, Alexander L. Svistkov, Vladimir V. Shadrin","doi":"10.1016/j.mechmat.2024.105177","DOIUrl":"10.1016/j.mechmat.2024.105177","url":null,"abstract":"<div><div>The mechanical behavior of elastomeric nanocomposites in experiments with nested stress-strain cycles and in cyclic tests with increasing strain amplitude was considered. In the proposed testing procedures, long time stops at each stage of the change in loading direction were of great importance. This revealed two significant features of the behavior of elastomeric nanocomposites that have received little attention. It was shown that material softening (the Mullins effect) should be considered not only in the elastic part of the Cauchy stress tensor, but also in its dissipative part. The second peculiarity was the difference between the characteristic relaxation time at loading and the characteristic relaxation time at unloading observed in the experiments.</div><div>This paper focuses on the behavior of highly-filled elastomeric materials based on different matrices (styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR)) and with different concentrations of carbon black (CB) or a combination of two fillers (CB and purified multi-walled carbon nanotubes (MWCNTs)).</div><div>A mathematical model of the viscoelastic behavior of elastomeric nanocomposites under finite strains is proposed. It takes into account the peculiarities of the behavior of highly filled elastomers observed in the experiments. The specificity of the model consists in a new variant of the form of the free energy potential. It is shown that the new model satisfies the thermodynamic inequality, which is a consequence of the first law of thermodynamics and the second law in the form of the Clausius-Duhem inequality. A good agreement between theoretical calculations and experimental data was obtained.</div></div>","PeriodicalId":18296,"journal":{"name":"Mechanics of Materials","volume":"199 ","pages":"Article 105177"},"PeriodicalIF":3.4,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438307","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}
Pub Date : 2024-10-05DOI: 10.1016/j.mechmat.2024.105172
Xiaotian Mao, Fulin Shang
Modeling the relaxation properties of resin matrix during cure plays an important role in predicting process-induced residual stresses and final distortions of resin-based composites. This paper develops a physical characterization model, which explains the temperature and cure-degree dependence of relaxation behaviors in terms of the size of cooperatively rearranging region, and special emphasis is placed on investigating the general physical mechanism of cure degree affecting the relaxation properties. In this model, the relaxation time is governed by a modified Adam-Gibbs equation, which is extended here to include the cure dependence. In addition, the relaxation modulus is modeled in a chemo-rheologically simple manner (CSM) based on the free volume theory. Material characterization is carried out using experimental data of two typical resins. It is shown that two cure-dependent model parameters, i.e., the smallest size of the cooperatively rearranging region and the glass transition temperature, are sufficient in accounting for the effect of cure on the relaxation modulus, and could provide a physical explanation of the influence of cure on relaxation behaviors. Furthermore, the proposed model is numerically realized by incorporating ABAQUS with UMAT subroutine, and its validity in predicting the residual stresses and final distortion of composites is also numerically verified by comparing with the results available in literature.
树脂基复合材料在固化过程中的松弛特性建模对于预测工艺引起的残余应力和最终变形具有重要作用。本文建立了一个物理表征模型，从协同重排区域的大小来解释松弛行为与温度和固化度的关系，并特别强调研究固化度影响松弛特性的一般物理机制。在该模型中，弛豫时间由修正的 Adam-Gibbs 方程控制，在此对该方程进行了扩展，以包括固化依赖性。此外，还根据自由体积理论，以化学流变学简单方式（CSM）建立了松弛模量模型。利用两种典型树脂的实验数据进行了材料表征。结果表明，两个与固化有关的模型参数，即协同重排区的最小尺寸和玻璃化转变温度，足以解释固化对弛豫模量的影响，并能为固化对弛豫行为的影响提供物理解释。此外，通过将 ABAQUS 与 UMAT 子程序相结合，对所提出的模型进行了数值计算，并通过与文献中的结果进行比较，对其在预测复合材料残余应力和最终变形方面的有效性进行了数值验证。
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