Pub Date : 2024-09-06DOI: 10.1016/j.ijsolstr.2024.113059
In this paper, we investigate wave propagation in cubic periodic architectured materials. We analyse three different types of unit cells, with distinct symmetries (centrosymmetric, non-centrosymmetric chiral and non-centrosymmetric achiral) with the aim of investigating the consequences of such symmetries on the elastodynamic behaviour of the architectured material. To this end, numerical simulations are performed on unit cells representative of the three types, to extract phase velocities and polarisations of waves along different directions. It is shown that some unconventional couplings between the different eigensolutions give rise to circular or elliptically polarised waves, associated with dispersive effects (acoustical activity). Subsequently, a theoretical analysis using a generalised equivalent continuum model (strain gradient elasticity) is performed to analyse these results and unveil the links between the symmetries of the architecture and the macroscopic elastodynamic behaviour. Indeed, it is shown that strain gradient elasticity is able to discriminate between the three symmetry classes, that are seen as equivalent by a classic continuum theory.
{"title":"Elastic wave propagation in cubic non-centrosymmetric and chiral architectured materials: Insights from strain gradient elasticity","authors":"","doi":"10.1016/j.ijsolstr.2024.113059","DOIUrl":"10.1016/j.ijsolstr.2024.113059","url":null,"abstract":"<div><p>In this paper, we investigate wave propagation in cubic periodic architectured materials. We analyse three different types of unit cells, with distinct symmetries (centrosymmetric, non-centrosymmetric chiral and non-centrosymmetric achiral) with the aim of investigating the consequences of such symmetries on the elastodynamic behaviour of the architectured material. To this end, numerical simulations are performed on unit cells representative of the three types, to extract phase velocities and polarisations of waves along different directions. It is shown that some unconventional couplings between the different eigensolutions give rise to circular or elliptically polarised waves, associated with dispersive effects (acoustical activity). Subsequently, a theoretical analysis using a generalised equivalent continuum model (strain gradient elasticity) is performed to analyse these results and unveil the links between the symmetries of the architecture and the macroscopic elastodynamic behaviour. Indeed, it is shown that strain gradient elasticity is able to discriminate between the three symmetry classes, that are seen as equivalent by a classic continuum theory.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020768324004189/pdfft?md5=eae4b1d20f1a7b36eda3f7a25c32fb04&pid=1-s2.0-S0020768324004189-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142239781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-04DOI: 10.1016/j.ijsolstr.2024.113058
Peeling the front-side film from the flexible and ultra-thin wafer is a critical procedure for the fabrication of ultra-thin chips. For a successful peeling process, the following conditions are required simultaneously: the interface between the film and the wafer is debonded, the interface between the wafer and the substrate remains undelaminated, and the wafer stays intact. However, there are relatively few studies focusing on the underlying mechanism in this peeling process. Here, a theoretical model is developed to investigate the competing behavior of interface delamination and wafer cracking for the bilayer film-substrate system. Based on the constant-stress (Dugdale) cohesive law and Euler-Bernoulli beam theory, both the competing interface delamination criterion and the wafer cracking criterion are determined. The corresponding competing maps of interface delamination and wafer cracking are obtained, in which the interface delamination path and the wafer safety status can be predicted. The effect of several dimensionless parameters on the competing behavior of interface delamination and wafer cracking is examined systematically, including the property of the geometry, the material, and the interface of the bilayer film-substrate system. The theoretical model is validated by both finite element analysis (FEA) and experimental results. This research aims to provide some guidance for optimizing the peeling parameters and contribute to a higher success rate of peeling process.
{"title":"Competing behavior of interface delamination and wafer cracking during peeling film from ultra-thin wafer","authors":"","doi":"10.1016/j.ijsolstr.2024.113058","DOIUrl":"10.1016/j.ijsolstr.2024.113058","url":null,"abstract":"<div><p>Peeling the front-side film from the flexible and ultra-thin wafer is a critical procedure for the fabrication of ultra-thin chips. For a successful peeling process, the following conditions are required simultaneously: the interface between the film and the wafer is debonded, the interface between the wafer and the substrate remains undelaminated, and the wafer stays intact. However, there are relatively few studies focusing on the underlying mechanism in this peeling process. Here, a theoretical model is developed to investigate the competing behavior of interface delamination and wafer cracking for the bilayer film-substrate system. Based on the constant-stress (Dugdale) cohesive law and Euler-Bernoulli beam theory, both the competing interface delamination criterion and the wafer cracking criterion are determined. The corresponding competing maps of interface delamination and wafer cracking are obtained, in which the interface delamination path and the wafer safety status can be predicted. The effect of several dimensionless parameters on the competing behavior of interface delamination and wafer cracking is examined systematically, including the property of the geometry, the material, and the interface of the bilayer film-substrate system. The theoretical model is validated by both finite element analysis (FEA) and experimental results. This research aims to provide some guidance for optimizing the peeling parameters and contribute to a higher success rate of peeling process.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142173307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-03DOI: 10.1016/j.ijsolstr.2024.113056
This paper presents a topology optimization framework utilizing a deformation plasticity model to approximate the isotropic hardening von-Mises incremental elastoplasticity model under monotone proportional loading. One advantage of the model is that it is based on a yield surface allowing for precise matching to uniaxial elastoplastic isotropic hardening response. The deformation plasticity model and the incremental plasticity model coincides for proportional loading and since the deformation plasticity model is path-independent, the computational cost and implementation complexity reduce significantly compared to the conventional incremental elastoplasticity. To investigate the deformation plasticity model combined with topology optimization, we compare three common elastoplastic optimization objectives: stiffness, strain energy and plastic work. The possibility to limit the peak local plastic work while maximizing the strain energy is also investigated. The consistent analytical sensitivity analysis which only requires the terminal state is derived using adjoint method. Numerical examples demonstrate that the proportionality assumption is reasonable and the deformation plasticity model combined with topology optimization is a competitive alternative to cumbersome incremental elastoplasticity.
{"title":"A “poor-man’s” deformation plasticity based approach to topology optimization of elastoplastic structures","authors":"","doi":"10.1016/j.ijsolstr.2024.113056","DOIUrl":"10.1016/j.ijsolstr.2024.113056","url":null,"abstract":"<div><p>This paper presents a topology optimization framework utilizing a deformation plasticity model to approximate the isotropic hardening von-Mises incremental elastoplasticity model under monotone proportional loading. One advantage of the model is that it is based on a yield surface allowing for precise matching to uniaxial elastoplastic isotropic hardening response. The deformation plasticity model and the incremental plasticity model coincides for proportional loading and since the deformation plasticity model is path-independent, the computational cost and implementation complexity reduce significantly compared to the conventional incremental elastoplasticity. To investigate the deformation plasticity model combined with topology optimization, we compare three common elastoplastic optimization objectives: stiffness, strain energy and plastic work. The possibility to limit the peak local plastic work while maximizing the strain energy is also investigated. The consistent analytical sensitivity analysis which only requires the terminal state is derived using adjoint method. Numerical examples demonstrate that the proportionality assumption is reasonable and the deformation plasticity model combined with topology optimization is a competitive alternative to cumbersome incremental elastoplasticity.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142157712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-02DOI: 10.1016/j.ijsolstr.2024.113047
Additive manufacturing (AM) of high-temperature alloys through processes such as laser powder bed fusion (LPBF) has gained significant interest and is rapidly expanding due to its exceptional design freedom, which enables the fabrication of complex parts that contribute to the increased efficiency of aerospace and energy systems. The materials produced through this process exhibit unique microstructures and mechanical properties, which necessitate dedicated study and characterization. In this context, our research focuses on the experimental characterization of the isothermal cyclic viscoplastic mechanical response of Hastelloy X (HX) over the temperature range of 22 to 1000 °C and at various strain rates, addressing a current gap in the literature. Recognizing the need for material models that can accurately represent the cyclic mechanical response of LPBF HX across a broad temperature range, we developed a robust extension of the viscoplastic isotropic-kinematic hardening Chaboche model, intended for applications in the thermomechanical simulation of the LPBF process for the analysis of residual stress and distortion, as well as for assessing the mechanical integrity of LPBF components. The extension involves expressing the entire set of model parameters explicitly with analytical functions to account for their temperature dependence. Consequently, the model includes a relatively large number of parameters to represent the isotropic-kinematic hardening viscoplastic response of the alloy over a wide temperature range, and hence to overcome the endeavor of its systematic calibration, a dedicated calibration approach was introduced. The model ultimately demonstrated its capability to precisely represent the isothermal response of the alloy over the examined temperatures and strain rates. To evaluate the model’s predictiveness for non-isothermal conditions, out-of-phase thermomechanical cyclic experiments were also conducted as independent benchmark tests, where the model’s predictions were fairly consistent with the experimental results. As a part of this study, the derived material model has been integrated into the UMAT subroutine, complete with an analytical derivation of the consistent Jacobian matrix.
通过激光粉末床熔融(LPBF)等工艺对高温合金进行增材制造(AM),由于其设计自由度极高,可制造出有助于提高航空航天和能源系统效率的复杂零件,因而受到了广泛关注,并正在迅速发展。通过这种工艺生产的材料具有独特的微观结构和机械性能,因此有必要对其进行专门的研究和表征。在此背景下,我们的研究重点是对哈氏合金 X (HX) 在 22 至 1000 °C 的温度范围内和各种应变速率下的等温循环粘塑性机械响应进行实验表征,以填补目前文献中的空白。我们认识到需要能够准确表示 LPBF HX 在广泛温度范围内的循环机械响应的材料模型,因此开发了粘塑性各向同性运动硬化 Chaboche 模型的稳健扩展,旨在应用于 LPBF 过程的热机械模拟,以分析残余应力和变形,以及评估 LPBF 组件的机械完整性。该模型的扩展包括用分析函数明确表达整套模型参数,以考虑其温度依赖性。因此,该模型包含了相对较多的参数,以表示合金在较宽温度范围内的各向同性运动硬化粘塑性响应。该模型最终证明了它有能力在所考察的温度和应变率范围内精确表示合金的等温响应。为了评估该模型对非等温条件的预测能力,还进行了相外热机械循环实验作为独立的基准测试,模型的预测结果与实验结果相当一致。作为本研究的一部分,已将推导出的材料模型集成到 UMAT 子程序中,并对一致的雅各布矩阵进行了分析推导。
{"title":"Cyclic mechanical response of LPBF Hastelloy X over a wide temperature and strain range: Experiments and modelling","authors":"","doi":"10.1016/j.ijsolstr.2024.113047","DOIUrl":"10.1016/j.ijsolstr.2024.113047","url":null,"abstract":"<div><p>Additive manufacturing (AM) of high-temperature alloys through processes such as laser powder bed fusion (LPBF) has gained significant interest and is rapidly expanding due to its exceptional design freedom, which enables the fabrication of complex parts that contribute to the increased efficiency of aerospace and energy systems. The materials produced through this process exhibit unique microstructures and mechanical properties, which necessitate dedicated study and characterization. In this context, our research focuses on the experimental characterization of the isothermal cyclic viscoplastic mechanical response of Hastelloy X (HX) over the temperature range of 22 to 1000 °C and at various strain rates, addressing a current gap in the literature. Recognizing the need for material models that can accurately represent the cyclic mechanical response of LPBF HX across a broad temperature range, we developed a robust extension of the viscoplastic isotropic-kinematic hardening Chaboche model, intended for applications in the thermomechanical simulation of the LPBF process for the analysis of residual stress and distortion, as well as for assessing the mechanical integrity of LPBF components. The extension involves expressing the entire set of model parameters explicitly with analytical functions to account for their temperature dependence. Consequently, the model includes a relatively large number of parameters to represent the isotropic-kinematic hardening viscoplastic response of the alloy over a wide temperature range, and hence to overcome the endeavor of its systematic calibration, a dedicated calibration approach was introduced. The model ultimately demonstrated its capability to precisely represent the isothermal response of the alloy over the examined temperatures and strain rates. To evaluate the model’s predictiveness for non-isothermal conditions, out-of-phase thermomechanical cyclic experiments were also conducted as independent benchmark tests, where the model’s predictions were fairly consistent with the experimental results. As a part of this study, the derived material model has been integrated into the UMAT subroutine, complete with an analytical derivation of the consistent Jacobian matrix.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020768324004062/pdfft?md5=a0067fd251b0fcba368e7225e8b11e0b&pid=1-s2.0-S0020768324004062-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-09-02DOI: 10.1016/j.ijsolstr.2024.113040
A stable deformation mode is highly desired for mechanical metamaterials, especially when coupled with a negative Poisson’s ratio. However, such metamaterials often face challenges in terms of scalability toward large deformation or strain. In response, we propose a multi-step hierarchical auxetic metamaterial design paradigm, incorporating a series of incrementally scaled-down structures with same scale factor into a re-entrant framework. This design enables instability regulation and multi-step deformation capabilities while preserving auxetic behavior, even under significant strain. Such multi-step metamaterials exhibit excellent properties, including tailored multi-phase compression modulus and strength, along with an enhanced energy absorption capacity that is as large as 2.1 times that of the original auxetic metamaterial. Experiments and simulations demonstrate that the deformation mechanism and compression response of the proposed multi-step auxetics are strongly influenced by the reduction factor and the order of the inner structure. A particularly intriguing observation is that the incorporation of embedded microstructures can restore stable deformation, even in the presence of significant initial instability, particularly with a reduction factor of . At high relative density, its specific energy absorption stands out favorably compared to other configurations, highlighting the success of the recoverable buckling mechanism. This work paves the way for designing multi-step mechanical metamaterials for use in impact resistance and body protection.
{"title":"A multi-step auxetic metamaterial with instability regulation","authors":"","doi":"10.1016/j.ijsolstr.2024.113040","DOIUrl":"10.1016/j.ijsolstr.2024.113040","url":null,"abstract":"<div><p>A stable deformation mode is highly desired for mechanical metamaterials, especially when coupled with a negative Poisson’s ratio. However, such metamaterials often face challenges in terms of scalability toward large deformation or strain. In response, we propose a multi-step hierarchical auxetic metamaterial design paradigm, incorporating a series of incrementally scaled-down structures with same scale factor <span><math><mi>α</mi></math></span> into a re-entrant framework. This design enables instability regulation and multi-step deformation capabilities while preserving auxetic behavior, even under significant strain. Such multi-step metamaterials exhibit excellent properties, including tailored multi-phase compression modulus and strength, along with an enhanced energy absorption capacity that is as large as 2.1 times that of the original auxetic metamaterial. Experiments and simulations demonstrate that the deformation mechanism and compression response of the proposed multi-step auxetics are strongly influenced by the reduction factor and the order of the inner structure. A particularly intriguing observation is that the incorporation of embedded microstructures can restore stable deformation, even in the presence of significant initial instability, particularly with a reduction factor of <span><math><mrow><mn>1</mn><mo>/</mo><mn>5</mn></mrow></math></span>. At high relative density, its specific energy absorption stands out favorably compared to other configurations, highlighting the success of the recoverable buckling mechanism. This work paves the way for designing multi-step mechanical metamaterials for use in impact resistance and body protection.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-08-31DOI: 10.1016/j.ijsolstr.2024.113049
To understand the influence of friction on the shear-slip behavior of heterogeneous brittle composites, a novel cohesive interlayer model that can effectively capture the friction effect was proposed based on the classical Park-Paulino-Roesler model. Meanwhile, the unified potential energy function governing the interface tangential and normal behaviors was introduced to realize the mechanical interaction between Mode I fracture and Mode II fracture, and a smooth friction growth function was added in the elastic deformation stage for calculating the accurate contact pressure and friction force. Furthermore, the capability of the proposed model in addressing unloading and reloading was improved, and the fracture energy can vary accordingly during cyclic loading. To verify the effectiveness of the proposed model, it was examined by modelling the shear behavior of a masonry wallette. The results show that the relative error of the proposed model is 14.92% which is much lower than those of the other three pre-existing models when calculating the displacement corresponding to peak shear stress. Meanwhile, in terms of peak shear stress and initial displacement at residual stage, the relative errors of the proposed model are only 1.82% and 5.04%, respectively, indicating the high accuracy. Besides, the tangent stiffness determined by the second-order integration of the potential energy function is also continuous and smooth, which ensures the effective convergence of the proposed cohesive model.
为了解摩擦对异质脆性复合材料剪切滑移行为的影响,在经典的 Park-Paulino-Roesler 模型基础上,提出了一种能有效捕捉摩擦效应的新型内聚层间模型。同时,引入了支配界面切向行为和法向行为的统一势能函数,以实现模式 I 断裂和模式 II 断裂之间的力学相互作用,并在弹性变形阶段添加了平滑摩擦增长函数,以计算精确的接触压力和摩擦力。此外,所提出模型在处理卸载和重载方面的能力也得到了提高,在循环加载过程中,断裂能量也会相应变化。为了验证所提模型的有效性,我们对砌体围檩的剪切行为进行了建模检验。结果表明,在计算峰值剪应力对应的位移时,所提出模型的相对误差为 14.92%,远低于其他三个已有模型。同时,在计算峰值剪应力和残余阶段的初始位移时,所提出模型的相对误差分别仅为 1.82% 和 5.04%,表明其精度较高。此外,势能函数二阶积分确定的切线刚度也是连续平滑的,这确保了所提出内聚模型的有效收敛性。
{"title":"A novel cohesive interlayer model considering friction","authors":"","doi":"10.1016/j.ijsolstr.2024.113049","DOIUrl":"10.1016/j.ijsolstr.2024.113049","url":null,"abstract":"<div><p>To understand the influence of friction on the shear-slip behavior of heterogeneous brittle composites, a novel cohesive interlayer model that can effectively capture the friction effect was proposed based on the classical Park-Paulino-Roesler model. Meanwhile, the unified potential energy function governing the interface tangential and normal behaviors was introduced to realize the mechanical interaction between Mode I fracture and Mode II fracture, and a smooth friction growth function was added in the elastic deformation stage for calculating the accurate contact pressure and friction force. Furthermore, the capability of the proposed model in addressing unloading and reloading was improved, and the fracture energy can vary accordingly during cyclic loading. To verify the effectiveness of the proposed model, it was examined by modelling the shear behavior of a masonry wallette. The results show that the relative error of the proposed model is 14.92% which is much lower than those of the other three pre-existing models when calculating the displacement corresponding to peak shear stress. Meanwhile, in terms of peak shear stress and initial displacement at residual stage, the relative errors of the proposed model are only 1.82% and 5.04%, respectively, indicating the high accuracy. Besides, the tangent stiffness determined by the second-order integration of the potential energy function is also continuous and smooth, which ensures the effective convergence of the proposed cohesive model.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020768324004086/pdfft?md5=c8cc2ff1f52a818faea2f9fee413f190&pid=1-s2.0-S0020768324004086-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-08-30DOI: 10.1016/j.ijsolstr.2024.113054
In this study, we investigate the effect of Van der Waals and Casimir forces on the mathematical model of nano-electromechanical systems (NEMS) such as nano-beam actuators that contain cantilever and double cantilever beams. The singular nonlinear boundary value problem governing the beam-type actuators, including geometric nonlinearity is solved by using an intelligent strength of feedforward artificial neural networks (ANNs) and hybridization of optimization algorithms such as arithmetic optimization algorithm (AOA) and active set algorithm (ASA). The proposed ANN-AOA-AS algorithm is employed to quantify the effect of changes in applied voltage, dispersion forces, geometric nonlinearity parameters, and initial axial strain on the deflection of the beam. Furthermore, to validate the results obtained by the proposed algorithm, statistical analyses are conducted to compare the approximate solutions with state-of-the-art methodologies available in the latest literature. In addition, performance indicators are defined such as mean square error (MSE), Nash–Sutcliffe efficiency (NSE), mean absolute deviations (MAD), root mean square error (RMSE), and Error in Nash–Sutcliffe efficiency (ENSE) to study the accuracy and efficiency of the solutions. The results show that these indicators’ mean percentage values lie around to which reflects the perfect modeling of the approximate solutions.
{"title":"ANN based optimization of nano-beam oscillations with intermolecular forces and geometric nonlinearity","authors":"","doi":"10.1016/j.ijsolstr.2024.113054","DOIUrl":"10.1016/j.ijsolstr.2024.113054","url":null,"abstract":"<div><p>In this study, we investigate the effect of Van der Waals and Casimir forces on the mathematical model of nano-electromechanical systems (NEMS) such as nano-beam actuators that contain cantilever and double cantilever beams. The singular nonlinear boundary value problem governing the beam-type actuators, including geometric nonlinearity is solved by using an intelligent strength of feedforward artificial neural networks (ANNs) and hybridization of optimization algorithms such as arithmetic optimization algorithm (AOA) and active set algorithm (ASA). The proposed ANN-AOA-AS algorithm is employed to quantify the effect of changes in applied voltage, dispersion forces, geometric nonlinearity parameters, and initial axial strain on the deflection of the beam. Furthermore, to validate the results obtained by the proposed algorithm, statistical analyses are conducted to compare the approximate solutions with state-of-the-art methodologies available in the latest literature. In addition, performance indicators are defined such as mean square error (MSE), Nash–Sutcliffe efficiency (NSE), mean absolute deviations (MAD), root mean square error (RMSE), and Error in Nash–Sutcliffe efficiency (ENSE) to study the accuracy and efficiency of the solutions. The results show that these indicators’ mean percentage values lie around <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> which reflects the perfect modeling of the approximate solutions.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142097039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-08-30DOI: 10.1016/j.ijsolstr.2024.113053
An artificial intelligence machine learning-based design framework is proposed to design lattice-based metamaterials with hexagonal symmetry that deliver wide band gaps at user-desired frequency ranges between 0 and 1000 kHz. The design approach starts by selecting a traditional, easy-to-manufacture parent lattice-based material that does not necessarily exhibit wide or functional band gaps. Subsequently, the parent lattice is transformed into a band-gap-rich lattice by superposing periodic triangular-shaped perturbations (i.e., zigzag-sine-based curvatures) with controllable frequencies and magnitudes on its ligaments. Finally, the frequency and magnitude parameters needed to deliver a specific band gap between 0 and 1000 kHz are determined using a hybrid intelligent framework, developed based on an Adaptive Neuro-Fuzzy Inference Systems (ANFIS). The ANFIS network integrates fuzzy logic expert models and artificial neural networks’ machine learning capabilities. Such a hybrid network is known for its ability to model strongly nonlinear and complex data. The data used in training the ANFIS models is generated using parametric finite element-based simulations where band gaps corresponding to a wide range of perturbation frequencies and magnitudes are computationally determined. The parametric study showed a nonlinear and complex topology-band gap characteristic relation; however, the Adaptive Neuro-Fuzzy Inference System (ANFIS) proved capable of modeling the observed complex topology-band gap behavior efficiently. The accuracy of the ANFIS models exceeded 99 % in several design ranges (i.e., perturbation parameters ranges). These were designated as high-accuracy design regions and were highlighted in the proposed design approach. Using multiple case studies with different band gap requirements, the ANFIS-based design framework proved effective in delivering customized lattice-based metamaterials with user-defined band gap frequencies.
{"title":"Hybrid intelligent framework for designing band gap-rich 2D metamaterials","authors":"","doi":"10.1016/j.ijsolstr.2024.113053","DOIUrl":"10.1016/j.ijsolstr.2024.113053","url":null,"abstract":"<div><p>An artificial intelligence machine learning-based design framework is proposed to design lattice-based metamaterials with hexagonal symmetry that deliver wide band gaps at user-desired frequency ranges between 0 and 1000 kHz. The design approach starts by selecting a traditional, easy-to-manufacture parent lattice-based material that does not necessarily exhibit wide or functional band gaps. Subsequently, the parent lattice is transformed into a band-gap-rich lattice by superposing periodic triangular-shaped perturbations (i.e., zigzag-sine-based curvatures) with controllable frequencies and magnitudes on its ligaments. Finally, the frequency and magnitude parameters needed to deliver a specific band gap between 0 and 1000 kHz are determined using a hybrid intelligent framework, developed based on an Adaptive Neuro-Fuzzy Inference Systems (ANFIS). The ANFIS network integrates fuzzy logic expert models and artificial neural networks’ machine learning capabilities. Such a hybrid network is known for its ability to model strongly nonlinear and complex data. The data used in training the ANFIS models is generated using parametric finite element-based simulations where band gaps corresponding to a wide range of perturbation frequencies and magnitudes are computationally determined. The parametric study showed a nonlinear and complex topology-band gap characteristic relation; however, the Adaptive Neuro-Fuzzy Inference System (ANFIS) proved capable of modeling the observed complex topology-band gap behavior efficiently. The accuracy of the ANFIS models exceeded 99 % in several design ranges (i.e., perturbation parameters ranges). These were designated as high-accuracy design regions and were highlighted in the proposed design approach. Using multiple case studies with different band gap requirements, the ANFIS-based design framework proved effective in delivering customized lattice-based metamaterials with user-defined band gap frequencies.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142128627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-08-30DOI: 10.1016/j.ijsolstr.2024.113052
This paper extends the reduced Yld2004 (rYld2004) function to present the anisotropic hardening behavior for body-centered cubic and face-centered cubic metals under the proportional loading conditions based on neural network. The parameters of the rYld2004 anisotropic hardening model (AH_rYld2004) are determined by the uniaxial tensile yield stresses along , , , , , and from the rolling direction as well as equibiaxial tension. The evolution of anisotropic parameters are described by the back propagation neural network optimized by ant colony optimization algorithm. The predicted data by AH_rYld2004 and some common anisotropic models are compared with the experimental results to verify the precision of the AH_rYld2004 in characterizing anisotropic hardening. The comparison proves that the AH_rYld2004 precisely characterize the anisotropic evolution with increasing plastic deformation for AA 3003-O and QP980. Simultaneously, the AH_rYld2004 function based on neural network is used to accurately simulate of circular cup deep drawing for AA 3003-O and uniaxial tension for QP980. The results indicate that the AH_rYld2004 model is capable to accurately represent the plastic anisotropic evolution for uniaxial tension along seven loading directions and equibiaxial tension.
{"title":"Neural network based rYld2004 anisotropic hardening model under non-associated flow rule for BCC and FCC metals","authors":"","doi":"10.1016/j.ijsolstr.2024.113052","DOIUrl":"10.1016/j.ijsolstr.2024.113052","url":null,"abstract":"<div><p>This paper extends the reduced Yld2004 (rYld2004) function to present the anisotropic hardening behavior for body-centered cubic and face-centered cubic metals under the proportional loading conditions based on neural network. The parameters of the rYld2004 anisotropic hardening model (AH_rYld2004) are determined by the uniaxial tensile yield stresses along <span><math><msup><mrow><mtext>0</mtext></mrow><mo>°</mo></msup></math></span>, <span><math><msup><mrow><mtext>15</mtext></mrow><mo>°</mo></msup></math></span>, <span><math><msup><mrow><mtext>30</mtext></mrow><mo>°</mo></msup></math></span>, <span><math><msup><mrow><mtext>45</mtext></mrow><mo>°</mo></msup></math></span>, <span><math><msup><mrow><mtext>60</mtext></mrow><mo>°</mo></msup></math></span>, <span><math><msup><mrow><mtext>75</mtext></mrow><mo>°</mo></msup></math></span> and <span><math><msup><mrow><mtext>90</mtext></mrow><mo>°</mo></msup></math></span> from the rolling direction as well as equibiaxial tension. The evolution of anisotropic parameters are described by the back propagation neural network optimized by ant colony optimization algorithm. The predicted data by AH_rYld2004 and some common anisotropic models are compared with the experimental results to verify the precision of the AH_rYld2004 in characterizing anisotropic hardening. The comparison proves that the AH_rYld2004 precisely characterize the anisotropic evolution with increasing plastic deformation for AA 3003-O and QP980. Simultaneously, the AH_rYld2004 function based on neural network is used to accurately simulate of circular cup deep drawing for AA 3003-O and uniaxial tension for QP980. The results indicate that the AH_rYld2004 model is capable to accurately represent the plastic anisotropic evolution for uniaxial tension along seven loading directions and equibiaxial tension.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2024-08-30DOI: 10.1016/j.ijsolstr.2024.113050
We investigate the propagation of harmonic flexural waves in periodic two-phase phononic multi-supported continuous beams whose elementary cells are designed according to the quasicrystalline standard Fibonacci substitution rule. The resulting dynamic frequency spectra are studied with the aid of a trace-map formalism which provides a geometrical interpretation of the recursive rule governing traces of the relevant transmission matrices: the traces of three consecutive elementary cells can be represented as a point on the surface defined by an invariant function of the square root of the circular frequency, and the recursivity implies the description of a discrete orbit on the surface. In analogy with the companion axial problem, we show that, for specific layouts of the elementary cell (the canonical configurations), the orbits are almost periodic. Likewise, for the same layouts, the stop-/pass-band diagrams along the frequency domain are almost periodic. Several periodic orbits exist and each corresponds to a self-similar portion of the dynamic spectra whose scaling law can be investigated by linearising the trace map in the neighbourhood of the orbit. The obtained results provide a new piece of theory to better understand the dynamic behaviour of two-phase flexural periodic waveguides whose elementary cell is obtained from quasicrystalline generation rules.
{"title":"Flexural wave propagation in canonical quasicrystalline-generated waveguides","authors":"","doi":"10.1016/j.ijsolstr.2024.113050","DOIUrl":"10.1016/j.ijsolstr.2024.113050","url":null,"abstract":"<div><p>We investigate the propagation of harmonic flexural waves in periodic two-phase phononic multi-supported continuous beams whose elementary cells are designed according to the quasicrystalline standard Fibonacci substitution rule. The resulting dynamic frequency spectra are studied with the aid of a trace-map formalism which provides a geometrical interpretation of the recursive rule governing traces of the relevant transmission matrices: the traces of three consecutive elementary cells can be represented as a point on the surface defined by an invariant function of the square root of the circular frequency, and the recursivity implies the description of a discrete orbit on the surface. In analogy with the companion axial problem, we show that, for specific layouts of the elementary cell (the <em>canonical</em> configurations), the orbits are almost periodic. Likewise, for the same layouts, the stop-/pass-band diagrams along the frequency domain are almost periodic. Several periodic orbits exist and each corresponds to a self-similar portion of the dynamic spectra whose scaling law can be investigated by linearising the trace map in the neighbourhood of the orbit. The obtained results provide a new piece of theory to better understand the dynamic behaviour of two-phase flexural periodic waveguides whose elementary cell is obtained from quasicrystalline generation rules.</p></div>","PeriodicalId":14311,"journal":{"name":"International Journal of Solids and Structures","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0020768324004098/pdfft?md5=6e9f92d86384657bf287795703c5725f&pid=1-s2.0-S0020768324004098-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142151144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}