Pub Date : 2024-10-24DOI: 10.1016/j.euromechsol.2024.105476
Xin-Yu Lu , Si-Yu Guo , Yan-Gao Hu
The purpose of this study is to investigate the influence of different stages of different interfaces evolution under external forces on stress transfer within composite materials, which is crucial for analyzing reinforcement mechanisms in composite materials. Analytical solutions are derived to explore the impact of these distinct phases, both at the interfaces along the fiber length direction and at the fiber ends, on the complex stress distribution profiles within composite materials. Furthermore, the frictional effect at the interface serves to impede the debonding process in the composite. Under the same load, the debonding length of the interface decreases as the frictional effect increases. The increase in fiber aspect ratio (AR) effectively reduces the length of the damage and debonding interface and increases the axial fiber stress. Additionally, the theoretical results agree well with numerical simulation and experimental results. In essence, this model provides analytical solutions that are instrumental for analyzing stress transfer in fiber-reinforced composites during different stages of interface evolution.
{"title":"Study of the effect of interfacial damage and friction on stress transfer in short fiber-reinforced composites","authors":"Xin-Yu Lu , Si-Yu Guo , Yan-Gao Hu","doi":"10.1016/j.euromechsol.2024.105476","DOIUrl":"10.1016/j.euromechsol.2024.105476","url":null,"abstract":"<div><div>The purpose of this study is to investigate the influence of different stages of different interfaces evolution under external forces on stress transfer within composite materials, which is crucial for analyzing reinforcement mechanisms in composite materials. Analytical solutions are derived to explore the impact of these distinct phases, both at the interfaces along the fiber length direction and at the fiber ends, on the complex stress distribution profiles within composite materials. Furthermore, the frictional effect at the interface serves to impede the debonding process in the composite. Under the same load, the debonding length of the interface decreases as the frictional effect increases. The increase in fiber aspect ratio (AR) effectively reduces the length of the damage and debonding interface and increases the axial fiber stress. Additionally, the theoretical results agree well with numerical simulation and experimental results. In essence, this model provides analytical solutions that are instrumental for analyzing stress transfer in fiber-reinforced composites during different stages of interface evolution.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105476"},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142552975","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}
A family of negative Poisson's ratio honeycombs with asymmetric base units and potential applications in civil and marine industries are introduced by introducing asymmetricities to the geometry of regular re-entrant unit cell. These structures, namely the single symmetry-broken re-entrant (SSR), double symmetry-broken re-entrant (DSR), and hybrid symmetry-broken re-entrant (HSR) honeycomb lattices, are fabricated through fused filament fabrication and subjected to experimental three-point bending (TPB) experiments and simulations. The novel designs showcase exceptional specific energy absorption (SEA) attributes compared to the regular metamaterial, with the SSR structure exhibiting a remarkable 147.2% higher SEA. The asymmetric metamaterials also demonstrate higher flexural modulus (Ef) compared to the benchmark design, with the SSR and DSR models boasting approximately 29% and 19% higher Ef, respectively. Studies on design parameters show that internal angle of unit cells that creates the asymmetricity affects the flexural performance of the unique auxetic honeycombs, significantly. Finally, parametric investigation on out-of-plane bending of the honeycombs showed the dominance of all asymmetric-unit honeycombs over the benchmark due to having organized self-contact regions. The SSR and DSR structures own about 51% and 39% higher SEA than the benchmark honeycomb under out-of-plane TPB, respectively.
通过对规则再入角单元的几何形状引入不对称，介绍了一系列具有不对称基底单元的负泊松比蜂窝结构，以及在民用和海洋工业中的潜在应用。这些结构，即单对称-断裂-再入角晶胞（SSR）、双对称-断裂-再入角晶胞（DSR）和混合对称-断裂-再入角晶胞（HSR）蜂窝晶格，是通过熔融长丝制造工艺制成的，并进行了三点弯曲（TPB）实验和模拟实验。与普通超材料相比，新颖的设计显示出卓越的比能量吸收（SEA）特性，其中 SSR 结构的 SEA 显著提高了 147.2%。与基准设计相比，非对称超材料还表现出更高的弯曲模量（Ef），其中 SSR 和 DSR 模型的 Ef 分别高出约 29% 和 19%。对设计参数的研究表明，产生不对称的单元格内角对独特的辅助蜂窝材料的弯曲性能影响很大。最后，对蜂窝平面外弯曲的参数研究表明，由于具有有组织的自接触区域，所有非对称单元蜂窝都优于基准蜂窝。在平面外 TPB 条件下，SSR 和 DSR 结构的 SEA 分别比基准蜂窝高出约 51% 和 39%。
{"title":"Flexural behaviors of asymmetric Re-entrant auxetic honeycombs","authors":"Ehsan Bahmanpour , Amin Montazeri , Amirhossein Saeedi , Maryam Mahnama","doi":"10.1016/j.euromechsol.2024.105475","DOIUrl":"10.1016/j.euromechsol.2024.105475","url":null,"abstract":"<div><div>A family of negative Poisson's ratio honeycombs with asymmetric base units and potential applications in civil and marine industries are introduced by introducing asymmetricities to the geometry of regular re-entrant unit cell. These structures, namely the single symmetry-broken re-entrant (SSR), double symmetry-broken re-entrant (DSR), and hybrid symmetry-broken re-entrant (HSR) honeycomb lattices, are fabricated through fused filament fabrication and subjected to experimental three-point bending (TPB) experiments and simulations. The novel designs showcase exceptional specific energy absorption (SEA) attributes compared to the regular metamaterial, with the SSR structure exhibiting a remarkable 147.2% higher SEA. The asymmetric metamaterials also demonstrate higher flexural modulus (E<sub>f</sub>) compared to the benchmark design, with the SSR and DSR models boasting approximately 29% and 19% higher E<sub>f</sub>, respectively. Studies on design parameters show that internal angle of unit cells that creates the asymmetricity affects the flexural performance of the unique auxetic honeycombs, significantly. Finally, parametric investigation on out-of-plane bending of the honeycombs showed the dominance of all asymmetric-unit honeycombs over the benchmark due to having organized self-contact regions. The SSR and DSR structures own about 51% and 39% higher SEA than the benchmark honeycomb under out-of-plane TPB, respectively.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105475"},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538787","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}
Pub Date : 2024-10-24DOI: 10.1016/j.euromechsol.2024.105472
Ved Prakash , Mohammad Masiur Rahaman , Debasish Roy
Micro-cracks, micro-voids and other such defects, which typically coalesce to form macroscopic cracks, could be represented through incompatible, local rotations of material points, i.e. micro-regions. Specifically, based on a micropolar or Cosserat continuum-like hypothesis that requires attaching directors to material points, we track the evolving frame rotation and hence the microstructural orientation during quasi-brittle damage. We introduce a critical energy release rate incorporating the wryness tensor, which in turn is a function of the micro-rotation field and its gradient within the damaged region. The (pseudo) rotation field appears as additional degrees of freedom to describe a frame field, whose evolution is particularly significant within a diffused region of evolving damage as obtained through a phase-field formulation of brittle fracture. We emphasize that, unlike micropolar continua where it contributes to elastic energy, the wryness tensor appears only in the fracture energy in our approach. Thus, without damage, the solid conforms to the classical continuum. By making suitable modifications to the terms within the elastic energy and applying the principle of virtual work, we arrive at the governing partial differential equations (PDEs). For assessing the proposed framework, we choose a specific form of energy density and demonstrate, through numerical examples, the effect of the newly introduced parameters. The classical phase-field model is readily recovered by switching off the micro-rotation. Additionally, we explore a potential application of this model in representing and propagating initial defects.
{"title":"A microstructural defect-orientation informed phase field model","authors":"Ved Prakash , Mohammad Masiur Rahaman , Debasish Roy","doi":"10.1016/j.euromechsol.2024.105472","DOIUrl":"10.1016/j.euromechsol.2024.105472","url":null,"abstract":"<div><div>Micro-cracks, micro-voids and other such defects, which typically coalesce to form macroscopic cracks, could be represented through incompatible, local rotations of material points, i.e. micro-regions. Specifically, based on a micropolar or Cosserat continuum-like hypothesis that requires attaching directors to material points, we track the evolving frame rotation and hence the microstructural orientation during quasi-brittle damage. We introduce a critical energy release rate incorporating the wryness tensor, which in turn is a function of the micro-rotation field and its gradient within the damaged region. The (pseudo) rotation field appears as additional degrees of freedom to describe a frame field, whose evolution is particularly significant within a diffused region of evolving damage as obtained through a phase-field formulation of brittle fracture. We emphasize that, unlike micropolar continua where it contributes to elastic energy, the wryness tensor appears only in the fracture energy in our approach. Thus, without damage, the solid conforms to the classical continuum. By making suitable modifications to the terms within the elastic energy and applying the principle of virtual work, we arrive at the governing partial differential equations (PDEs). For assessing the proposed framework, we choose a specific form of energy density and demonstrate, through numerical examples, the effect of the newly introduced parameters. The classical phase-field model is readily recovered by switching off the micro-rotation. Additionally, we explore a potential application of this model in representing and propagating initial defects.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105472"},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572761","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}
Pub Date : 2024-10-22DOI: 10.1016/j.euromechsol.2024.105474
Alexandru-Viorel Coșa , Radu Negru , Dan-Andrei Șerban
This study is concerned with the development of an innovative beam geometry based on a tessellation of Kagome unit cells and the improvement of its geometry with the aim of increasing its flexural properties. This aspect was achieved by generating a functionally graded metamaterial structure based on a novel approach that considers the well-established analytical beam theory models as the basis of for the optimization of the structural parameters of the unit cells at an individual level. The starting premise is that the optimal strut thickness variation with the height of the beam will cause the material to yield uniformly in the critical cross-section. Preliminary studies were conducted in order to numerically determine the variation of the stiffness and the strength of the Kagome structure with the thickness of its struts. Considering the equivalent stress distribution during bending in the critical cross-section, an optimal variation of the stiffness with the height of the beam was evaluated. Based on these results, different values for the strut diameter were imposed at corresponding coordinates relative to the neutral axis, assuring a continuous transition across the height of the beam. The flexural properties of the developed functionally graded structure were evaluated using finite element analyses and determined superior characteristics when compared with the data obtained from simulations performed on an uniform Kagome beam with of the same mass. The investigated structures were manufactured through stereolithography and subjected to three-point bending tests, the results being in agreement with the numerical data, thus validating the design.
{"title":"Development of Kagome-based functionally graded beams optimized for flexural loadings","authors":"Alexandru-Viorel Coșa , Radu Negru , Dan-Andrei Șerban","doi":"10.1016/j.euromechsol.2024.105474","DOIUrl":"10.1016/j.euromechsol.2024.105474","url":null,"abstract":"<div><div>This study is concerned with the development of an innovative beam geometry based on a tessellation of Kagome unit cells and the improvement of its geometry with the aim of increasing its flexural properties. This aspect was achieved by generating a functionally graded metamaterial structure based on a novel approach that considers the well-established analytical beam theory models as the basis of for the optimization of the structural parameters of the unit cells at an individual level. The starting premise is that the optimal strut thickness variation with the height of the beam will cause the material to yield uniformly in the critical cross-section. Preliminary studies were conducted in order to numerically determine the variation of the stiffness and the strength of the Kagome structure with the thickness of its struts. Considering the equivalent stress distribution during bending in the critical cross-section, an optimal variation of the stiffness with the height of the beam was evaluated. Based on these results, different values for the strut diameter were imposed at corresponding coordinates relative to the neutral axis, assuring a continuous transition across the height of the beam. The flexural properties of the developed functionally graded structure were evaluated using finite element analyses and determined superior characteristics when compared with the data obtained from simulations performed on an uniform Kagome beam with of the same mass. The investigated structures were manufactured through stereolithography and subjected to three-point bending tests, the results being in agreement with the numerical data, thus validating the design.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105474"},"PeriodicalIF":4.4,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528956","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}
Pub Date : 2024-10-19DOI: 10.1016/j.euromechsol.2024.105473
Hao Xu , Hai-Tao Liu , Guo-Feng Li
Based on conventional re-entrant auxetic honeycomb (CRAH), a multi-arc re-entrant auxetic honeycomb (MARAH) is proposed. The mechanical properties of the honeycomb can be significantly improved by introducing multiple arcs. Through theoretical analysis, finite element analysis, and experiment, the influence of arc radius, arc angle, and cell wall thickness on effective Poisson's ratio, effective Young's modulus, energy absorption, and stress level are investigated. There are significant differences between MARAH and CRAH in Poisson's ratio, deformation mode, stress level, and energy absorption. Compared with CRAH, MARAH has a better negative Poisson's ratio effect, wider Poisson's ratio adjustable range, better energy absorption, and superior stability. In addition, the reduction of the yield stress can effectively reduce the damage of impact load on the honeycomb. The research results can provide new ideas for the design and application of new metamaterials.
{"title":"In-plane characteristics of a multi-arc re-entrant auxetic honeycomb with enhanced negative Poisson's ratio effect and energy absorption","authors":"Hao Xu , Hai-Tao Liu , Guo-Feng Li","doi":"10.1016/j.euromechsol.2024.105473","DOIUrl":"10.1016/j.euromechsol.2024.105473","url":null,"abstract":"<div><div>Based on conventional re-entrant auxetic honeycomb (CRAH), a multi-arc re-entrant auxetic honeycomb (MARAH) is proposed. The mechanical properties of the honeycomb can be significantly improved by introducing multiple arcs. Through theoretical analysis, finite element analysis, and experiment, the influence of arc radius, arc angle, and cell wall thickness on effective Poisson's ratio, effective Young's modulus, energy absorption, and stress level are investigated. There are significant differences between MARAH and CRAH in Poisson's ratio, deformation mode, stress level, and energy absorption. Compared with CRAH, MARAH has a better negative Poisson's ratio effect, wider Poisson's ratio adjustable range, better energy absorption, and superior stability. In addition, the reduction of the yield stress can effectively reduce the damage of impact load on the honeycomb. The research results can provide new ideas for the design and application of new metamaterials.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105473"},"PeriodicalIF":4.4,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528954","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}
Pub Date : 2024-10-18DOI: 10.1016/j.euromechsol.2024.105471
Jundong Wang , Xiangqian Xu , Hao Lu , Lu Zhang , Yeda Lian , Zhixun Wen , Zhufeng Yue
Nickel-based single crystal superalloys (Ni-SXs) are widely used in turbine blades of aircraft engines. With the increasing demand for higher temperature-bearing capacity, the introduction of film cooling holes, impingement holes, and trailing edge slots for cooling induces stress concentration, which compromises the structural integrity of the blades, generates complex multiaxial stress states, and adversely affects their operational performance. In this study, Ni-SXs, DD6, was utilized to investigate the influence of stress ratios on fatigue performance under complex stress states. Low cycle fatigue (LCF) tests were carried out at different stress ratios with stress concentration coefficient Kt = 1.0, 2.0 and 3.0. The results indicate that the notched specimens exhibit a significant fatigue notch strengthening effect under high stress ratios. The fracture surface and microstructure also indicate that under high stress ratios loading, the notches exhibit significant creep failure characteristics. This means that the main cause of fatigue notch strengthening is similar to creep notch strengthening effect. A macroscopic anisotropic constitutive model coupled with damage was developed and applied to finite element analysis of notched specimens. The results demonstrate that as the stress ratio rises, the stress relaxation effect at the notch becomes more pronounced, yet the level of damage diminishes. Additionally, a stress-equivalent model based on Bridgman stress was proposed, which effectively unifies the lifetime trends of notched and smooth specimens, predicting lifetimes within a threefold error band.
{"title":"Fatigue notch strengthening effect of nickel-based single crystal superalloys under different stress ratios","authors":"Jundong Wang , Xiangqian Xu , Hao Lu , Lu Zhang , Yeda Lian , Zhixun Wen , Zhufeng Yue","doi":"10.1016/j.euromechsol.2024.105471","DOIUrl":"10.1016/j.euromechsol.2024.105471","url":null,"abstract":"<div><div>Nickel-based single crystal superalloys (Ni-SXs) are widely used in turbine blades of aircraft engines. With the increasing demand for higher temperature-bearing capacity, the introduction of film cooling holes, impingement holes, and trailing edge slots for cooling induces stress concentration, which compromises the structural integrity of the blades, generates complex multiaxial stress states, and adversely affects their operational performance. In this study, Ni-SXs, DD6, was utilized to investigate the influence of stress ratios on fatigue performance under complex stress states. Low cycle fatigue (LCF) tests were carried out at different stress ratios with stress concentration coefficient K<sub>t</sub> = 1.0, 2.0 and 3.0. The results indicate that the notched specimens exhibit a significant fatigue notch strengthening effect under high stress ratios. The fracture surface and microstructure also indicate that under high stress ratios loading, the notches exhibit significant creep failure characteristics. This means that the main cause of fatigue notch strengthening is similar to creep notch strengthening effect. A macroscopic anisotropic constitutive model coupled with damage was developed and applied to finite element analysis of notched specimens. The results demonstrate that as the stress ratio rises, the stress relaxation effect at the notch becomes more pronounced, yet the level of damage diminishes. Additionally, a stress-equivalent model based on Bridgman stress was proposed, which effectively unifies the lifetime trends of notched and smooth specimens, predicting lifetimes within a threefold error band.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105471"},"PeriodicalIF":4.4,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528953","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}
Pub Date : 2024-10-16DOI: 10.1016/j.euromechsol.2024.105468
Longda Liu, Xiang Liu, Xifeng Liang
In multilayered structures, delamination not only reduces local strength but also induces buckling instability, compromising structural safety even before reaching the critical buckling load. This paper introduces a novel model for buckling analysis of structures with delamination damage. The model utilizes exact stiffness formulations derived from Timoshenko theory, enabling precising modeling of beam-like structures with through-thickness delamination. The Wittrick–Williams algorithm is utilized to calculate the critical buckling loads, which are validated against results from the finite element software ANSYS. Additionally, a modified Euler buckling formula for the approximate yet closed-form critical buckling load of delaminated beam-like structures is proposed, with comparisons made to the exact stiffness method results. The study investigates the effects of position and length of delamination and boundary conditions of beam on the critical buckling loads. The findings indicate that the buckling reduction factors of delaminated beam is primarily influenced by the thickness-wise position of the delamination, followed by the delamination length, and then the length-wise position of the delamination. Furthermore, the impact of boundary conditions becomes more significant when the delamination is near the beam’s end. This research provides practical guidelines for preventing buckling instability in delaminated beam-like structures.
{"title":"Buckling instability analysis of delaminated beam-like structures by using the exact stiffness method","authors":"Longda Liu, Xiang Liu, Xifeng Liang","doi":"10.1016/j.euromechsol.2024.105468","DOIUrl":"10.1016/j.euromechsol.2024.105468","url":null,"abstract":"<div><div>In multilayered structures, delamination not only reduces local strength but also induces buckling instability, compromising structural safety even before reaching the critical buckling load. This paper introduces a novel model for buckling analysis of structures with delamination damage. The model utilizes exact stiffness formulations derived from Timoshenko theory, enabling precising modeling of beam-like structures with through-thickness delamination. The Wittrick–Williams algorithm is utilized to calculate the critical buckling loads, which are validated against results from the finite element software ANSYS. Additionally, a modified Euler buckling formula for the approximate yet closed-form critical buckling load of delaminated beam-like structures is proposed, with comparisons made to the exact stiffness method results. The study investigates the effects of position and length of delamination and boundary conditions of beam on the critical buckling loads. The findings indicate that the buckling reduction factors of delaminated beam is primarily influenced by the thickness-wise position of the delamination, followed by the delamination length, and then the length-wise position of the delamination. Furthermore, the impact of boundary conditions becomes more significant when the delamination is near the beam’s end. This research provides practical guidelines for preventing buckling instability in delaminated beam-like structures.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105468"},"PeriodicalIF":4.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528955","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}
Pub Date : 2024-10-15DOI: 10.1016/j.euromechsol.2024.105465
Anna Mariya Shajan , Raghu Piska , Sundararajan Natarajan
This work presents a phase field model for dynamic fracture under thermo-mechanical loads to analyze functionally graded material (FGM). Coupled governing equations are derived by minimizing the total energy consisting of kinetic energy and elastic strain energy, along with the energy due to the external heat source. To overcome the computational expense associated with the standard finite element analysis for implementing the phase field model, an adaptive approach based on the quadtree algorithm is employed that enhances computational efficiency while preserving accuracy. The hanging nodes within the element are treated as polygonal elements. The governing equations are solved using a staggered solution algorithm, following a hybrid phase field implementation strategy. The notch location, temperature variation, and gradation profile of FGM are carefully examined and investigated using numerous examples. It is observed that these parameters significantly influence the behavior of FGM. The results align well with the existing literature, validating our methodology within the examples explored. Additionally, the computational efficiency of adaptive meshing techniques is assessed, demonstrating the significant reductions in computational overhead while preserving accuracy and versatility in handling multi-physics fracture scenarios.
{"title":"Dynamic thermal shock resilience of functionally graded materials: An adaptive phase-field approach","authors":"Anna Mariya Shajan , Raghu Piska , Sundararajan Natarajan","doi":"10.1016/j.euromechsol.2024.105465","DOIUrl":"10.1016/j.euromechsol.2024.105465","url":null,"abstract":"<div><div>This work presents a phase field model for dynamic fracture under thermo-mechanical loads to analyze functionally graded material (FGM). Coupled governing equations are derived by minimizing the total energy consisting of kinetic energy and elastic strain energy, along with the energy due to the external heat source. To overcome the computational expense associated with the standard finite element analysis for implementing the phase field model, an adaptive approach based on the quadtree algorithm is employed that enhances computational efficiency while preserving accuracy. The hanging nodes within the element are treated as polygonal elements. The governing equations are solved using a staggered solution algorithm, following a hybrid phase field implementation strategy. The notch location, temperature variation, and gradation profile of FGM are carefully examined and investigated using numerous examples. It is observed that these parameters significantly influence the behavior of FGM. The results align well with the existing literature, validating our methodology within the examples explored. Additionally, the computational efficiency of adaptive meshing techniques is assessed, demonstrating the significant reductions in computational overhead while preserving accuracy and versatility in handling multi-physics fracture scenarios.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105465"},"PeriodicalIF":4.4,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528952","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}
Pub Date : 2024-10-13DOI: 10.1016/j.euromechsol.2024.105469
Sergey Aksenov, Vadim Mikolaenko
The design of superplastic forming technologies requires accurate description of material flow behaviour. Furthermore, as the flow curves reflect the deformation mechanisms and microstructure evolution of a material, their accurate determination is an important aspect of material science. The standard experimental method for determining superplastic flow curves is the tensile test, which encounters a significant challenge known as a gripping problem. In superplastic forming conditions, utilizing an extensometer proves difficult, leading to strain determination solely based on crosshead positions. This oversight neglects the non-uniform deformation of a specimen and the material flow occurring in the gripping region. This study presents a novel technique aimed at addressing this issue during the analysis of tensile test data, thereby establishing a reliable material model. The proposed technique was applied to construct the flow behaviour model of an aluminium alloy of the Al–Mg–Fe–Ni system at 460 °C based on the results of tensile tests in the strain rate range of . The material model was developed using the hyperbolic sine equation with strain-dependent parameters, employing sequential polynomial approximation to reduce the number of utilized coefficients. This model was then used in simulations of tensile tests with various geometries to validate its accuracy.
超塑性成形技术的设计需要准确描述材料的流动行为。此外，由于流动曲线反映了材料的变形机制和微观结构演变，因此准确测定流动曲线是材料科学的一个重要方面。确定超塑性流动曲线的标准实验方法是拉伸试验，这种方法会遇到一个被称为 "夹持问题 "的重大挑战。在超塑性成形条件下，使用拉伸计很困难，导致应变测定只能基于十字头位置。这种疏忽忽略了试样的非均匀变形和夹持区域的材料流动。本研究提出了一种新技术，旨在解决拉伸测试数据分析过程中的这一问题，从而建立可靠的材料模型。根据应变率范围为 0.002-0.06s-1 的拉伸试验结果，提出的技术被用于构建铝-镁-铁-镍系铝合金在 460 °C 下的流动行为模型。该材料模型是利用双曲正弦方程和应变相关参数建立的，采用了序列多项式近似方法来减少使用系数的数量。该模型随后用于各种几何形状的拉伸试验模拟，以验证其准确性。
{"title":"Accurate determination of uniaxial flow behaviour of superplastic materials","authors":"Sergey Aksenov, Vadim Mikolaenko","doi":"10.1016/j.euromechsol.2024.105469","DOIUrl":"10.1016/j.euromechsol.2024.105469","url":null,"abstract":"<div><div>The design of superplastic forming technologies requires accurate description of material flow behaviour. Furthermore, as the flow curves reflect the deformation mechanisms and microstructure evolution of a material, their accurate determination is an important aspect of material science. The standard experimental method for determining superplastic flow curves is the tensile test, which encounters a significant challenge known as a gripping problem. In superplastic forming conditions, utilizing an extensometer proves difficult, leading to strain determination solely based on crosshead positions. This oversight neglects the non-uniform deformation of a specimen and the material flow occurring in the gripping region. This study presents a novel technique aimed at addressing this issue during the analysis of tensile test data, thereby establishing a reliable material model. The proposed technique was applied to construct the flow behaviour model of an aluminium alloy of the Al–Mg–Fe–Ni system at 460 °C based on the results of tensile tests in the strain rate range of <span><math><mrow><mn>0.002</mn><mo>−</mo><mn>0.06</mn><msup><mrow><mspace></mspace><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>. The material model was developed using the hyperbolic sine equation with strain-dependent parameters, employing sequential polynomial approximation to reduce the number of utilized coefficients. This model was then used in simulations of tensile tests with various geometries to validate its accuracy.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105469"},"PeriodicalIF":4.4,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432349","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}
Pub Date : 2024-10-10DOI: 10.1016/j.euromechsol.2024.105462
Zhaozhan Zhang , Anshuai Wang , Qingyu Lin , Yongtao Sun , Bin Wang , Liang Wang , Shuo Wang , Yansen Wu , Yunxiang Ma , Qian Ding
The paper designed two novel tooth-shaped metamaterials based on the tooth-shaped characteristics, including the first order tooth-shaped metamaterial (FOTM) and the second order tooth-shaped metamaterial (SOTM). The SOTM produces an ultra-low band gaps (102.6 Hz) compare of the value of the FOTM (184.5 Hz). Among the first 24 order dispersion curves, the band gap coverages of the FOTM and SOTM can reach 68.5% and 74.1%. Even band gap coverages below 500 Hz still reach 34.1% and 44.8%. While the FOTM owns the maximum bandwidths (688.4 Hz). Next, the band gap generation mechanism of tooth-shaped metamaterials is analyzed according vibration modes. The rotational vibrations in its central part and tooth-shaped ligament parts dissipate the elastic wave energy and generate the band gap by analyzing the iso-frequency contour, group velocity and phase velocity. Finally, the influence of the core tooth-shaped ligaments width and length on the band structure of the FOTM and SOTM are studied. For the FOTM and SOTM, increasing the core tooth-shaped ligament height results in a decrease of the band gap. The design exhibits excellent band gap properties and meets the requirements for lightweight design, and it provides a novel solution for multi-low-frequency wide band.
{"title":"Study on the multi-low-frequency band gaps and vibration reduction performance of the tooth-shaped acoustic metamaterial","authors":"Zhaozhan Zhang , Anshuai Wang , Qingyu Lin , Yongtao Sun , Bin Wang , Liang Wang , Shuo Wang , Yansen Wu , Yunxiang Ma , Qian Ding","doi":"10.1016/j.euromechsol.2024.105462","DOIUrl":"10.1016/j.euromechsol.2024.105462","url":null,"abstract":"<div><div>The paper designed two novel tooth-shaped metamaterials based on the tooth-shaped characteristics, including the first order tooth-shaped metamaterial (FOTM) and the second order tooth-shaped metamaterial (SOTM). The SOTM produces an ultra-low band gaps (102.6 Hz) compare of the value of the FOTM (184.5 Hz). Among the first 24 order dispersion curves, the band gap coverages of the FOTM and SOTM can reach 68.5% and 74.1%. Even band gap coverages below 500 Hz still reach 34.1% and 44.8%. While the FOTM owns the maximum bandwidths (688.4 Hz). Next, the band gap generation mechanism of tooth-shaped metamaterials is analyzed according vibration modes. The rotational vibrations in its central part and tooth-shaped ligament parts dissipate the elastic wave energy and generate the band gap by analyzing the iso-frequency contour, group velocity and phase velocity. Finally, the influence of the core tooth-shaped ligaments width and length on the band structure of the FOTM and SOTM are studied. For the FOTM and SOTM, increasing the core tooth-shaped ligament height results in a decrease of the band gap. The design exhibits excellent band gap properties and meets the requirements for lightweight design, and it provides a novel solution for multi-low-frequency wide band.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"109 ","pages":"Article 105462"},"PeriodicalIF":4.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432350","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}
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