Journal of The Mechanics and Physics of Solids最新文献_第7页

Unified model for adhesive contact between solid surfaces at micro/nano-scale 微/纳米尺度固体表面粘接接触的统一模型

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-14 DOI: 10.1016/j.jmps.2024.106004

Yudong Zhu , Yong Ni , Chenguang Huang , Jilin Yu , Haimin Yao , Zhijun Zheng

Because of the huge specific surface area at the micro/nano scale, inter-surface adhesion and surface effects play a critical role in the behavior of solid-to-solid contact. The inter-surface adhesion originates from the intermolecular traction between two surfaces, while the surface effects, including residual surface stress and surface elasticity, result from the physical discrepancy between the surface atoms and their bulk counterparts. Despite the importance of both effects, theoretically modeling them together is still a challenging open issue because of the nonlinear coupling nature in between. This study is dedicated to the development of a unified theoretical framework with consideration of both inter-surface adhesion and surface effects based on the Gurtin–Murdoch surface elasticity theory. The two effects are integrated into a self-consistent equation concerning surface gaps and interactions, and a novel regularization method is proposed to address the oscillation and singularity of the equation. It is demonstrated that an adhesive contact problem with surface effects can be decomposed into two fundamental issues. One addresses the classical problem without considering residual surface stress or surface elasticity, and the other focuses solely on residual surface stress. Theoretical predictions show that the surface effects suppress or even eliminate the surface deformation and jumping instability during contact, effectively stiffening the solid surfaces. Three types of pull-off force transitions with surface effects are obtained, forming continuous bridges among the rigid (Bradley), soft (JKR), and liquid-like (Young–Dupre) limits. The adhesion transitions considering surface effects in this work are universal, and the existing limits or transitions can be regarded as special cases of this work. Our study provides a further understanding of the adhesive contact between micro/nano solids and may be instructive for practical applications where inter-surface adhesion and surface effects are dominant, such as nanoindentation, micro-electro-mechanical systems, and microelectronics.

由于在微/纳米尺度上具有巨大的比表面积，表面间的粘附和表面效应在固-固接触行为中起着至关重要的作用。表面间的粘附源于两个表面之间的分子间牵引力，而表面效应，包括残余表面应力和表面弹性，是由表面原子与它们的体原子之间的物理差异造成的。尽管这两种效应都很重要，但由于两者之间的非线性耦合性质，理论上将它们一起建模仍然是一个具有挑战性的开放问题。本研究致力于在Gurtin-Murdoch表面弹性理论的基础上，建立兼顾表面间粘附和表面效应的统一理论框架。将这两种效应整合到一个关于表面间隙和相互作用的自洽方程中，并提出了一种新的正则化方法来解决方程的振荡性和奇异性。结果表明，具有表面效应的胶粘剂接触问题可以分解为两个基本问题。一个解决经典问题，不考虑残余表面应力或表面弹性，而另一个只关注残余表面应力。理论预测表明，表面效应抑制甚至消除了接触过程中的表面变形和跳跃不稳定性，有效地增强了固体表面的刚度。得到了三种具有表面效应的拉脱力转换类型，在刚性（Bradley）、软（JKR）和液态（Young-Dupre）极限之间形成了连续的桥梁。本工作中考虑表面效应的附着过渡具有普遍性，现有的极限或过渡可视为本工作的特例。我们的研究提供了对微/纳米固体之间粘附接触的进一步理解，并可能对表面间粘附和表面效应占主导地位的实际应用具有指导意义，例如纳米压痕，微机电系统和微电子学。

{"title":"Unified model for adhesive contact between solid surfaces at micro/nano-scale","authors":"Yudong Zhu , Yong Ni , Chenguang Huang , Jilin Yu , Haimin Yao , Zhijun Zheng","doi":"10.1016/j.jmps.2024.106004","DOIUrl":"10.1016/j.jmps.2024.106004","url":null,"abstract":"<div><div>Because of the huge specific surface area at the micro/nano scale, inter-surface adhesion and surface effects play a critical role in the behavior of solid-to-solid contact. The inter-surface adhesion originates from the intermolecular traction between two surfaces, while the surface effects, including residual surface stress and surface elasticity, result from the physical discrepancy between the surface atoms and their bulk counterparts. Despite the importance of both effects, theoretically modeling them together is still a challenging open issue because of the nonlinear coupling nature in between. This study is dedicated to the development of a unified theoretical framework with consideration of both inter-surface adhesion and surface effects based on the Gurtin–Murdoch surface elasticity theory. The two effects are integrated into a self-consistent equation concerning surface gaps and interactions, and a novel regularization method is proposed to address the oscillation and singularity of the equation. It is demonstrated that an adhesive contact problem with surface effects can be decomposed into two fundamental issues. One addresses the classical problem without considering residual surface stress or surface elasticity, and the other focuses solely on residual surface stress. Theoretical predictions show that the surface effects suppress or even eliminate the surface deformation and jumping instability during contact, effectively stiffening the solid surfaces. Three types of pull-off force transitions with surface effects are obtained, forming continuous bridges among the rigid (Bradley), soft (JKR), and liquid-like (Young–Dupre) limits. The adhesion transitions considering surface effects in this work are universal, and the existing limits or transitions can be regarded as special cases of this work. Our study provides a further understanding of the adhesive contact between micro/nano solids and may be instructive for practical applications where inter-surface adhesion and surface effects are dominant, such as nanoindentation, micro-electro-mechanical systems, and microelectronics.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 106004"},"PeriodicalIF":5.0,"publicationDate":"2024-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142867479","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}

引用次数: 0

Characterizing dissipated energy density distribution and damage zone in double network hydrogels 双网状水凝胶耗散能量密度分布及损伤区表征

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-12 DOI: 10.1016/j.jmps.2024.106006

Jiapeng You , Chong Wang , Zhixuan Li , Zishun Liu

The double network hydrogels (DN gels) process high fracture toughness due to their considerable energy dissipation during fracture. To effectively interpret the energy dissipation, it is imperative to conduct a study on the quantitative characterization of the dissipated energy density distribution and the damage zone around the crack tip. In this study, we propose a series of tearing tests on pre-stretched DN gel specimens to quantitatively characterize the dissipated energy density distribution. According to the dissipated energy density distribution, the damage zone of the DN gel during tearing is divided into three parts: hardening zone, yielding zone and pre-yielding zone. The dissipated energy density distribution determines both the feature size and the contribution of these damage zones to the fracture toughness. We reveal that both the dissipated energy density and the feature size of the damage zones significantly influence the fracture toughness. Additionally, this study delves into the effect of the first network's cross-linking degree on the dissipated energy density distribution and damage zone. The dissipated energy density distribution, determined by tearing test, is validated by available experimental results, which show good agreement. This study proposes a quantitatively experimental method to investigate the dissipated energy density distribution and damage zone. It is anticipated that this approach will provide new insights into the energy dissipation mechanism of soft materials.

双网状水凝胶（DN凝胶）由于在断裂过程中具有相当大的能量耗散，具有较高的断裂韧性。为了有效地解释能量耗散，有必要对耗散能量密度分布和裂纹尖端周围损伤区进行定量表征研究。在本研究中，我们提出了一系列的撕裂试验预拉伸DN凝胶样品，定量表征耗散能量密度分布。根据耗散能量密度分布，将DN凝胶撕裂过程中的损伤区分为硬化区、屈服区和预屈服区三个部分。耗散能量密度分布决定了这些损伤区域的特征尺寸和对断裂韧性的贡献。结果表明，耗散能密度和损伤区特征尺寸对断裂韧性有显著影响。此外，本研究还探讨了第一网络交联度对耗散能量密度分布和损伤区域的影响。通过撕裂试验确定的耗散能密度分布与已有的实验结果吻合较好。本研究提出了一种定量实验方法来研究耗散能量密度分布和损伤区域。预计该方法将为研究软质材料的能量耗散机制提供新的见解。

{"title":"Characterizing dissipated energy density distribution and damage zone in double network hydrogels","authors":"Jiapeng You , Chong Wang , Zhixuan Li , Zishun Liu","doi":"10.1016/j.jmps.2024.106006","DOIUrl":"10.1016/j.jmps.2024.106006","url":null,"abstract":"<div><div>The double network hydrogels (DN gels) process high fracture toughness due to their considerable energy dissipation during fracture. To effectively interpret the energy dissipation, it is imperative to conduct a study on the quantitative characterization of the dissipated energy density distribution and the damage zone around the crack tip. In this study, we propose a series of tearing tests on pre-stretched DN gel specimens to quantitatively characterize the dissipated energy density distribution. According to the dissipated energy density distribution, the damage zone of the DN gel during tearing is divided into three parts: hardening zone, yielding zone and pre-yielding zone. The dissipated energy density distribution determines both the feature size and the contribution of these damage zones to the fracture toughness. We reveal that both the dissipated energy density and the feature size of the damage zones significantly influence the fracture toughness. Additionally, this study delves into the effect of the first network's cross-linking degree on the dissipated energy density distribution and damage zone. The dissipated energy density distribution, determined by tearing test, is validated by available experimental results, which show good agreement. This study proposes a quantitatively experimental method to investigate the dissipated energy density distribution and damage zone. It is anticipated that this approach will provide new insights into the energy dissipation mechanism of soft materials.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 106006"},"PeriodicalIF":5.0,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142867401","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}

引用次数: 0

A tube-based constitutive model of brain tissue with inner pressure 考虑内压的脑组织管本构模型

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-10 DOI: 10.1016/j.jmps.2024.105993

Wei Liu , Zefeng Yu , Khalil I. Elkhodary , Hanlin Xiao , Shan Tang , Tianfu Guo , Xu Guo

Many blood vessels exist in brain tissue. Their internal blood pressure plays a crucial role in physiological disorders, such as brain edema, stroke, or traumatic brain injury (concussion). Homogenized continuum mechanics-based brain tissue models can provide an attractive approach to rapidly simulate blood-pressure related physiological disorders, and traumatic brain injury. These homogenized models are much easier and faster to apply compared to finite element models that detail the microstructure. This paper thus presents a homogenized constitutive model for brain tissue in which the vascular networks and blood pressure are taken into account. The proposed model is microstructurally motivated and derived, in which the matrix of the brain tissue (gray/white matter) is modeled as hyperelastic material, while the blood vessels with their inner pressure define the microstructure. The proposed constitutive model is implemented in finite element software. Despite the simplicity of the model, we show it predicts strains and stresses comparable to finite element models with detailed microstructural representations under different loading conditions, demonstrating the potential usefulness of the model in rapidly estimating brain injury risk, hematoma formation, as well as brain tissue expansion/shrinkage.

脑组织中有许多血管。他们的内部血压在生理障碍中起着至关重要的作用，如脑水肿、中风或创伤性脑损伤（脑震荡）。基于均质连续介质力学的脑组织模型为快速模拟与血压相关的生理障碍和创伤性脑损伤提供了一种有吸引力的方法。与详细描述微观结构的有限元模型相比，这些均质化模型更容易、更快速地应用。因此，本文提出了脑组织匀质本构模型，其中血管网络和血压被考虑在内。所提出的模型是微观结构驱动和衍生的，其中脑组织基质（灰质/白质）被建模为超弹性材料，而血管及其内部压力定义了微观结构。在有限元软件中实现了所提出的本构模型。尽管该模型很简单，但我们表明，在不同的加载条件下，它预测的应变和应力与具有详细微观结构表征的有限元模型相当，这表明该模型在快速估计脑损伤风险、血肿形成以及脑组织扩张/收缩方面具有潜在的实用性。

{"title":"A tube-based constitutive model of brain tissue with inner pressure","authors":"Wei Liu , Zefeng Yu , Khalil I. Elkhodary , Hanlin Xiao , Shan Tang , Tianfu Guo , Xu Guo","doi":"10.1016/j.jmps.2024.105993","DOIUrl":"10.1016/j.jmps.2024.105993","url":null,"abstract":"<div><div>Many blood vessels exist in brain tissue. Their internal blood pressure plays a crucial role in physiological disorders, such as brain edema, stroke, or traumatic brain injury (concussion). Homogenized continuum mechanics-based brain tissue models can provide an attractive approach to rapidly simulate blood-pressure related physiological disorders, and traumatic brain injury. These homogenized models are much easier and faster to apply compared to finite element models that detail the microstructure. This paper thus presents a homogenized constitutive model for brain tissue in which the vascular networks and blood pressure are taken into account. The proposed model is microstructurally motivated and derived, in which the matrix of the brain tissue (gray/white matter) is modeled as hyperelastic material, while the blood vessels with their inner pressure define the microstructure. The proposed constitutive model is implemented in finite element software. Despite the simplicity of the model, we show it predicts strains and stresses comparable to finite element models with detailed microstructural representations under different loading conditions, demonstrating the potential usefulness of the model in rapidly estimating brain injury risk, hematoma formation, as well as brain tissue expansion/shrinkage.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 105993"},"PeriodicalIF":5.0,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142867402","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}

引用次数: 0

Topological state switches in hard-magnetic meta-structures 硬磁元结构中的拓扑状态开关

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-07 DOI: 10.1016/j.jmps.2024.106001

Quan Zhang, Stephan Rudykh

We propose a metamaterial design principle that enables the remote switching of topological states. Dynamic breaking of space-inversion symmetry is achieved through the intricate design of magnetic spring structures within the metamaterial building blocks, whose stiffness can be remotely altered using an external magnetic field. We develop a mathematical model to predict the magnetic field-induced deformation and tangential stiffness of the spring structure with hard-magnetic constituent phase. Building on the predictive model, we explore the necessary conditions – including the magnetization distribution and the direction of the actuating magnetic field – that enable magnetically tunable stiffness. To demonstrate the functionality of topological state switching, we apply the proposed magnetic spring to the topological metamaterial design where a tunable stiffness landscape is essential for reversible topological phase transition. Our mathematical modeling indicates that we can remotely modulate both the dispersion properties and the topological invariants (including Zak phase and winding number) of the underlying bands in the proposed metamaterial system. Finally, we show that this tunable capability extends to controlling topologically protected edge and interface states within the finite-sized metamaterial lattice. Our design strategy for the switching of topological state paves the way for the realization of smart and intelligent metamaterials featuring tunable and active wave dynamics. It also highlights the potential of magneto-mechanical coupling in the design of advanced functional materials.

我们提出了一种能够实现拓扑状态远程切换的超材料设计原理。空间反演对称性的动态打破是通过在超材料构件内部设计复杂的磁弹簧结构来实现的，其刚度可以通过外部磁场远程改变。我们建立了一个数学模型来预测具有硬磁成分相的弹簧结构的磁场诱导变形和切向刚度。在预测模型的基础上，我们探索了实现磁可调刚度的必要条件，包括磁化分布和驱动磁场的方向。为了证明拓扑状态切换的功能，我们将所提出的磁弹簧应用于拓扑超材料设计，其中可调刚度景观对于可逆拓扑相变至关重要。我们的数学模型表明，我们可以远程调制所提出的超材料系统中底层带的色散特性和拓扑不变量（包括Zak相位和圈数）。最后，我们证明了这种可调能力扩展到控制有限尺寸的超材料晶格中的拓扑保护边缘和界面状态。我们的拓扑状态切换设计策略为实现具有可调谐和有源波动力学的智能超材料铺平了道路。它还强调了磁-机械耦合在先进功能材料设计中的潜力。

{"title":"Topological state switches in hard-magnetic meta-structures","authors":"Quan Zhang, Stephan Rudykh","doi":"10.1016/j.jmps.2024.106001","DOIUrl":"10.1016/j.jmps.2024.106001","url":null,"abstract":"<div><div>We propose a metamaterial design principle that enables the remote switching of topological states. Dynamic breaking of space-inversion symmetry is achieved through the intricate design of magnetic spring structures within the metamaterial building blocks, whose stiffness can be remotely altered using an external magnetic field. We develop a mathematical model to predict the magnetic field-induced deformation and tangential stiffness of the spring structure with hard-magnetic constituent phase. Building on the predictive model, we explore the necessary conditions – including the magnetization distribution and the direction of the actuating magnetic field – that enable magnetically tunable stiffness. To demonstrate the functionality of topological state switching, we apply the proposed magnetic spring to the topological metamaterial design where a tunable stiffness landscape is essential for reversible topological phase transition. Our mathematical modeling indicates that we can remotely modulate both the dispersion properties and the topological invariants (including Zak phase and winding number) of the underlying bands in the proposed metamaterial system. Finally, we show that this tunable capability extends to controlling topologically protected edge and interface states within the finite-sized metamaterial lattice. Our design strategy for the switching of topological state paves the way for the realization of smart and intelligent metamaterials featuring tunable and active wave dynamics. It also highlights the potential of magneto-mechanical coupling in the design of advanced functional materials.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 106001"},"PeriodicalIF":5.0,"publicationDate":"2024-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788943","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}

引用次数: 0

A continuum model for novel electromechanical-instability-free dielectric elastomers 新型无机电不稳定介电弹性体的连续介质模型

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-07 DOI: 10.1016/j.jmps.2024.105994

Rui Xiao , Zike Chen , Ye Shi , Lin Zhan , Shaoxing Qu , Paul Steinmann

Traditional dielectric elastomers exhibit an unstable response when the electric field reaches a certain threshold, known as electro-mechanical instability, which significantly limits the broad application of these soft active materials. Recently, a bimodal-networked dielectric elastomer has been designed without suffering from the electro-mechanical instability due to a clear strain stiffening effect in the median strain regime (Science, 2022, 377, 228). In this work, we develop a constitutive model to fully describe the mechanical and electro-activated response of this novel dielectric elastomer. The free energy density consists of a time-independent hyperelastic component, time-dependent viscous components and an electrical component. A hyperelastic function dependent on both the first and second strain invariants is proposed to fully capture the stress response. The form of ideal dielectric elastomers is adopted for the electrical free energy. With further incorporation of viscous effects, the model is able to describe both static electro-actuated behavior as well as the frequency-dependent actuation performance upon a square wave voltage loading. The model is also implemented for finite element analysis to design tubular actuators which have been extensively used in the area of soft robotics.

传统的介电弹性体在电场达到一定阈值时表现出不稳定的响应，称为机电不稳定性，这极大地限制了这些软活性材料的广泛应用。最近，一种双峰网络介质弹性体被设计出来，由于在中应变状态下有明显的应变硬化效应，因此没有机电不稳定性（Science, 2022, 377,228）。在这项工作中，我们建立了一个本构模型来全面描述这种新型介电弹性体的机械和电激活响应。自由能密度由与时间无关的超弹性分量、与时间有关的粘性分量和电分量组成。提出了依赖于第一应变不变量和第二应变不变量的超弹性函数来充分捕捉应力响应。电自由能采用理想介电弹性体的形式。随着粘性效应的进一步结合，该模型能够描述静态电致动行为以及频率相关的方波电压负载下的致动性能。该模型还应用于柔性机器人领域中广泛应用的管状驱动器的有限元分析。

{"title":"A continuum model for novel electromechanical-instability-free dielectric elastomers","authors":"Rui Xiao , Zike Chen , Ye Shi , Lin Zhan , Shaoxing Qu , Paul Steinmann","doi":"10.1016/j.jmps.2024.105994","DOIUrl":"10.1016/j.jmps.2024.105994","url":null,"abstract":"<div><div>Traditional dielectric elastomers exhibit an unstable response when the electric field reaches a certain threshold, known as electro-mechanical instability, which significantly limits the broad application of these soft active materials. Recently, a bimodal-networked dielectric elastomer has been designed without suffering from the electro-mechanical instability due to a clear strain stiffening effect in the median strain regime (<em>Science, 2022, 377, 228</em>). In this work, we develop a constitutive model to fully describe the mechanical and electro-activated response of this novel dielectric elastomer. The free energy density consists of a time-independent hyperelastic component, time-dependent viscous components and an electrical component. A hyperelastic function dependent on both the first and second strain invariants is proposed to fully capture the stress response. The form of ideal dielectric elastomers is adopted for the electrical free energy. With further incorporation of viscous effects, the model is able to describe both static electro-actuated behavior as well as the frequency-dependent actuation performance upon a square wave voltage loading. The model is also implemented for finite element analysis to design tubular actuators which have been extensively used in the area of soft robotics.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 105994"},"PeriodicalIF":5.0,"publicationDate":"2024-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821092","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}

引用次数: 0

A constitutive model for amorphous solids considering intrinsic entangling of shear and dilatation, with application to studying shear-banding 考虑剪切和膨胀本征纠缠的非晶固体本构模型，并应用于剪切带研究

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-06 DOI: 10.1016/j.jmps.2024.106002

W. Rao , Y. Chen , L.H. Dai , M.Q. Jiang

In amorphous solids, shear transformations, as elementary rearrangement events operating in local regions, are intrinsically entangled with dilatation deformation, which results in the physical process of the shear band being complex. To capture such entanglement, we propose a finite-deformation continuum framework for amorphous solids by incorporating nonequilibrium thermodynamics. Within this framework, we develop a constitutive model where the thermodynamic glass is divided into the kinetic and configurational subsystems. In the model, the dilatation is attributed to an athermal expansion of configuration. As a result, the effect of shear transformation on dilatation can be considered by generating plastic cold work to change the freedom degrees of the configurational subsystem. The effect of dilatation on shear transformation can be realized through the enthalpy change of the configurational subsystem that gives rise to physical aging. Based on the proposed model, we discuss the entangling mechanism of shear and dilatation, and predict the shear-banding behaviors of metallic glasses during tensile and compressive deformations at room temperature. We reveal that due to the shear-dilatation entanglement, the elastic deformations significantly influence the evolution of configurational temperature, which plays a pivotal role in controlling the degree of strain softening and the shear-banding mode.

在非晶态固体中，剪切变换作为在局部区域发生的基本重排事件，与扩张变形有着内在的纠缠关系，这导致剪切带的物理过程非常复杂。为了捕捉这种纠缠，我们结合非平衡热力学，提出了非晶态固体的有限变形连续框架。在此框架内，我们建立了一个构成模型，其中热力学玻璃分为动力学子系统和构型子系统。在该模型中，膨胀归因于构型的热膨胀。因此，可以通过产生塑性冷作来改变构型子系统的自由度，从而考虑剪切变换对扩张的影响。扩张对剪切变换的影响可通过构型子系统的焓变来实现，而焓变会引起物理老化。基于所提出的模型，我们讨论了剪切和扩张的纠缠机制，并预测了金属玻璃在室温下拉伸和压缩变形时的剪切成带行为。我们发现，由于剪切-扩张纠缠，弹性变形会显著影响构型温度的演变，而构型温度在控制应变软化程度和剪切成带模式方面起着关键作用。

{"title":"A constitutive model for amorphous solids considering intrinsic entangling of shear and dilatation, with application to studying shear-banding","authors":"W. Rao , Y. Chen , L.H. Dai , M.Q. Jiang","doi":"10.1016/j.jmps.2024.106002","DOIUrl":"10.1016/j.jmps.2024.106002","url":null,"abstract":"<div><div>In amorphous solids, shear transformations, as elementary rearrangement events operating in local regions, are intrinsically entangled with dilatation deformation, which results in the physical process of the shear band being complex. To capture such entanglement, we propose a finite-deformation continuum framework for amorphous solids by incorporating nonequilibrium thermodynamics. Within this framework, we develop a constitutive model where the thermodynamic glass is divided into the kinetic and configurational subsystems. In the model, the dilatation is attributed to an athermal expansion of configuration. As a result, the effect of shear transformation on dilatation can be considered by generating plastic cold work to change the freedom degrees of the configurational subsystem. The effect of dilatation on shear transformation can be realized through the enthalpy change of the configurational subsystem that gives rise to physical aging. Based on the proposed model, we discuss the entangling mechanism of shear and dilatation, and predict the shear-banding behaviors of metallic glasses during tensile and compressive deformations at room temperature. We reveal that due to the shear-dilatation entanglement, the elastic deformations significantly influence the evolution of configurational temperature, which plays a pivotal role in controlling the degree of strain softening and the shear-banding mode.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 106002"},"PeriodicalIF":5.0,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821095","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}

引用次数: 0

Biomimetic Turing machine: A multiscale theoretical framework for the inverse design of target space curves 仿生图灵机：目标空间曲线反设计的多尺度理论框架

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-06 DOI: 10.1016/j.jmps.2024.105999

JiaHao Li , Xiaohao Sun , ZeZhou He , YuanZhen Hou , HengAn Wu , YinBo Zhu

Morphing ribbons and their inverse design are usually confined to plane curves, since in most cases only the curvature is considered. Given that curvature and torsion are equally important geometric characteristics of space curves, it is urgent to propose a systematic theoretical framework for the inverse design. Toward this end, we here present a multiscale theoretical framework named biomimetic Turing machine (BTM) to achieve desired target space curves, which is inspired from two microstructural regulation mechanisms behind the hydration-driven morphing of plant tissues: the graded curvature regulated by matrix volume fraction (c_m) and the helix-like morphology regulated by fibril orientation angle (FOA). By analogizing to Turing machine encoded by binary mapping, the proposed BTM can inversely encode a morphing ribbon with preset microstructural parameters (FOA and c_m) to achieve desired target space curves. The proposed theoretical framework can first bridge the microstructural fiber-matrix swelling and the macroscopic ribbon morphing as a forward problem, in which a twist field is subsequently introduced to create the kinematic map between the target space curve and the ribbon, innovatively posing the inverse design as an initial value problem. To facilitate the experimental implementation of BTM, we further propose an optimization strategy for selecting the twist field and provide design criteria as guidelines for experiments. As a conceptual display, we present a phase diagram in the c_m versus FOA plane to illustrate the complex target morphologies (e.g., hemisphere, hyperboloid, and tendril) characterized by various parameters of curvature and torsion designed rationally by the BTM theory, while in previous studies the morphing morphologies (e.g., helices, arcs, and helicoid ribbons) exhibit only constant curvature or torsion. This work presents a novel inverse design strategy for space curves with both curvature and torsion, broadening the potential for the design and fabrication of morphing materials.

变形带及其逆设计通常局限于平面曲线，因为在大多数情况下只考虑曲率。鉴于曲率和扭转是空间曲线同样重要的几何特征，迫切需要提出一个系统的反设计理论框架。为此，我们提出了仿生图灵机（BTM）的多尺度理论框架，以实现所需的目标空间曲线，该框架的灵感来自于植物组织水化变形背后的两种微观结构调节机制：由基质体积分数（cm）调节的渐变曲率和由纤维取向角（FOA）调节的螺旋状形态。该算法通过类比采用二值映射编码的图灵机，对具有预设微结构参数（FOA和cm）的变形带进行反向编码，从而获得期望的目标空间曲线。所提出的理论框架首先将微观结构纤维基质膨胀和宏观带状变形作为正演问题连接起来，随后引入扭转场来创建目标空间曲线与带状之间的运动学映射，创新地将反设计作为初值问题。为了方便BTM的实验实现，我们进一步提出了一种优化选择扭转场的策略，并提供了设计准则作为实验指导。作为一种概念性展示，我们在cm平面和FOA平面上绘制了相位图，以说明由BTM理论合理设计的各种曲率和扭转参数表征的复杂目标形态（如半球、双曲面和卷须），而在以往的研究中，变形形态（如螺旋、圆弧和螺旋带）只有恒定的曲率或扭转。本研究提出了一种具有曲率和扭转的空间曲线的新型逆设计策略，为变形材料的设计和制造拓展了潜力。

{"title":"Biomimetic Turing machine: A multiscale theoretical framework for the inverse design of target space curves","authors":"JiaHao Li , Xiaohao Sun , ZeZhou He , YuanZhen Hou , HengAn Wu , YinBo Zhu","doi":"10.1016/j.jmps.2024.105999","DOIUrl":"10.1016/j.jmps.2024.105999","url":null,"abstract":"<div><div>Morphing ribbons and their inverse design are usually confined to plane curves, since in most cases only the curvature is considered. Given that curvature and torsion are equally important geometric characteristics of space curves, it is urgent to propose a systematic theoretical framework for the inverse design. Toward this end, we here present a multiscale theoretical framework named biomimetic Turing machine (BTM) to achieve desired target space curves, which is inspired from two microstructural regulation mechanisms behind the hydration-driven morphing of plant tissues: the graded curvature regulated by matrix volume fraction (<em>c<sub>m</sub></em>) and the helix-like morphology regulated by fibril orientation angle (FOA). By analogizing to Turing machine encoded by binary mapping, the proposed BTM can inversely encode a morphing ribbon with preset microstructural parameters (FOA and <em>c<sub>m</sub></em>) to achieve desired target space curves. The proposed theoretical framework can first bridge the microstructural fiber-matrix swelling and the macroscopic ribbon morphing as a forward problem, in which a twist field is subsequently introduced to create the kinematic map between the target space curve and the ribbon, innovatively posing the inverse design as an initial value problem. To facilitate the experimental implementation of BTM, we further propose an optimization strategy for selecting the twist field and provide design criteria as guidelines for experiments. As a conceptual display, we present a phase diagram in the <em>c<sub>m</sub></em> versus FOA plane to illustrate the complex target morphologies (e.g., hemisphere, hyperboloid, and tendril) characterized by various parameters of curvature and torsion designed rationally by the BTM theory, while in previous studies the morphing morphologies (e.g., helices, arcs, and helicoid ribbons) exhibit only constant curvature or torsion. This work presents a novel inverse design strategy for space curves with both curvature and torsion, broadening the potential for the design and fabrication of morphing materials.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 105999"},"PeriodicalIF":5.0,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821094","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}

引用次数: 0

A constitutive model of monodomain liquid crystal elastomers with the thermal-mechanical-nematic order coupling

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-05 DOI: 10.1016/j.jmps.2024.105995

Weida Kang , Qian Cheng , Changyue Liu , Zhijian Wang , Dongfeng Li , Xudong Liang

Liquid crystal elastomers (LCEs) are a distinctive class of materials that combine the transformative properties of liquid crystals with the flexibility of elastomers, enabling significant reversible deformations in response to various external stimuli. This paper investigates the intricate thermal-mechanical-nematic order coupling behaviors of monodomain nematic LCEs. We propose an enhanced constitutive model that merges the established neo-classical theory with the Landau–de Gennes theory, thereby improving the model's ability to account for temperature influences effectively. Additionally, we use the concept of semi-soft elastic energy and consider the anisotropic behaviors associated with the orientations of the nematic directors, aiming to more accurately capture the nuances of their soft elastic and anisotropic properties under varied loading conditions. The present model has been numerically discretized and implemented in the commercial finite element software, facilitating precise simulations of the stress-stretch relationships and the anisotropic mechanical behaviors associated with specific director orientations. Constitutive simulations have shown a high degree of accuracy, aligning well with experimental data, especially in predicting the complex mechanical behaviors of LCEs under different thermal-mechanical conditions. Our results elucidate the necking observed during uniaxial loading and the unique director evolution during biaxial loading. Additionally, we identify a unique hole-size insensitivity in perforated LCE sheets, attributed to the compensation between anisotropic reinforcement and director orientations. These findings underscore the potential of advanced modeling techniques in exploring the dynamic properties of LCEs, paving the way for applications in artificial muscles, soft robotics, and responsive biomedical devices.

{"title":"A constitutive model of monodomain liquid crystal elastomers with the thermal-mechanical-nematic order coupling","authors":"Weida Kang , Qian Cheng , Changyue Liu , Zhijian Wang , Dongfeng Li , Xudong Liang","doi":"10.1016/j.jmps.2024.105995","DOIUrl":"10.1016/j.jmps.2024.105995","url":null,"abstract":"<div><div>Liquid crystal elastomers (LCEs) are a distinctive class of materials that combine the transformative properties of liquid crystals with the flexibility of elastomers, enabling significant reversible deformations in response to various external stimuli. This paper investigates the intricate thermal-mechanical-nematic order coupling behaviors of monodomain nematic LCEs. We propose an enhanced constitutive model that merges the established neo-classical theory with the Landau–de Gennes theory, thereby improving the model's ability to account for temperature influences effectively. Additionally, we use the concept of semi-soft elastic energy and consider the anisotropic behaviors associated with the orientations of the nematic directors, aiming to more accurately capture the nuances of their soft elastic and anisotropic properties under varied loading conditions. The present model has been numerically discretized and implemented in the commercial finite element software, facilitating precise simulations of the stress-stretch relationships and the anisotropic mechanical behaviors associated with specific director orientations. Constitutive simulations have shown a high degree of accuracy, aligning well with experimental data, especially in predicting the complex mechanical behaviors of LCEs under different thermal-mechanical conditions. Our results elucidate the necking observed during uniaxial loading and the unique director evolution during biaxial loading. Additionally, we identify a unique hole-size insensitivity in perforated LCE sheets, attributed to the compensation between anisotropic reinforcement and director orientations. These findings underscore the potential of advanced modeling techniques in exploring the dynamic properties of LCEs, paving the way for applications in artificial muscles, soft robotics, and responsive biomedical devices.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 105995"},"PeriodicalIF":5.0,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143163413","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}

引用次数: 0

Phase field fracture in elastoplastic solids: a stress-state, strain-rate, and orientation dependent model in explicit dynamics and its applications to additively manufactured metals

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-03 DOI: 10.1016/j.jmps.2024.105978

Cunyi Li , Jian Liu , Le Dong , Chi Wu , Grant Steven , Qing Li , Jianguang Fang

Phase field models have gained increasing popularity in analysing fracture behaviour of materials. However, few studies have been explored to simulate dynamic ductile fracture to date. This study aims to develop a phase field framework that considers strain rate, stress state, and orientation dependent ductile fracture under dynamic loading. Firstly, the governing equations of displacement and phase fields are formulated within an explicit finite element framework. Secondly, constitutive relations are established using a hypoelastic-plasticity framework, encompassing the influence of material orientation and strain rate on both plasticity and fracture initiation. Stress state dependent fracture initiation is also considered. Thirdly, the finite element implementation and corotational formulation of constitutive equations are derived. Finally, to validate the proposed model, additively manufactured samples, including material-level and crack propagation specimens, are tested under dynamic loading conditions. Overall, the proposed phase field model can properly reproduce the experimental force-displacement curves and crack paths. Uniaxial tension tests reveal that a higher strain rate can lead to a higher hardening curve and reduced ductility. Other material specimens further demonstrate the model's capability to predict stress state and orientation dependent dynamic fracture. To simulate dynamic crack paths accurately, it is necessary to consider anisotropic fracture initiation. Lastly, the phase field model was applied for the first time to predict the dynamic response of triply periodic minimal surface (TPMS) structures. Dynamic crack patterns were effectively captured, and the fracture mechanisms were thoroughly analysed. This study provides an explicit phase field framework for dynamic ductile fracture, with applications to additively manufactured materials and structures.

{"title":"Phase field fracture in elastoplastic solids: a stress-state, strain-rate, and orientation dependent model in explicit dynamics and its applications to additively manufactured metals","authors":"Cunyi Li , Jian Liu , Le Dong , Chi Wu , Grant Steven , Qing Li , Jianguang Fang","doi":"10.1016/j.jmps.2024.105978","DOIUrl":"10.1016/j.jmps.2024.105978","url":null,"abstract":"<div><div>Phase field models have gained increasing popularity in analysing fracture behaviour of materials. However, few studies have been explored to simulate dynamic ductile fracture to date. This study aims to develop a phase field framework that considers strain rate, stress state, and orientation dependent ductile fracture under dynamic loading. Firstly, the governing equations of displacement and phase fields are formulated within an explicit finite element framework. Secondly, constitutive relations are established using a hypoelastic-plasticity framework, encompassing the influence of material orientation and strain rate on both plasticity and fracture initiation. Stress state dependent fracture initiation is also considered. Thirdly, the finite element implementation and corotational formulation of constitutive equations are derived. Finally, to validate the proposed model, additively manufactured samples, including material-level and crack propagation specimens, are tested under dynamic loading conditions. Overall, the proposed phase field model can properly reproduce the experimental force-displacement curves and crack paths. Uniaxial tension tests reveal that a higher strain rate can lead to a higher hardening curve and reduced ductility. Other material specimens further demonstrate the model's capability to predict stress state and orientation dependent dynamic fracture. To simulate dynamic crack paths accurately, it is necessary to consider anisotropic fracture initiation. Lastly, the phase field model was applied for the first time to predict the dynamic response of triply periodic minimal surface (TPMS) structures. Dynamic crack patterns were effectively captured, and the fracture mechanisms were thoroughly analysed. This study provides an explicit phase field framework for dynamic ductile fracture, with applications to additively manufactured materials and structures.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"197 ","pages":"Article 105978"},"PeriodicalIF":5.0,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143294172","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}

引用次数: 0

A hyperelastic constitutive model for soft elastomers considering the entanglement-dependent finite extensibility 考虑纠缠相关有限可扩展性的软弹性体超弹性本构模型

IF 5 2区工程技术 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of The Mechanics and Physics of Solids

Pub Date : 2024-12-03 DOI: 10.1016/j.jmps.2024.106000

Jinglei Yang , Kaijuan Chen , Chao Yu , Kun Zhou , Guozheng Kang

In this paper, a novel hyperelastic constitutive model for soft elastomers is developed based on the concept of the tortuous tube. This model incorporates the finite extensibility of the polymer chain, the entanglement contribution to elasticity and the non-affine micro-to-macro scale transition in a unified way. To reflect the entanglement effect and its influence on the deformation of soft elastomers, the tortuous tube concept is introduced. The finite extensibility and conformational statistics of an entangled polymer chain in such a tortuous tube are clarified. By embedding the tortuous tube into the microsphere and employing the principle of minimum averaged free energy, a new non-affine scale transition rule is proposed to establish the relationship between the local deformation of a polymer chain at the microscopic scale and the overall deformation at the macroscopic scale. Based on the probability density function related to the conformational statistics, the Helmholtz free energy is established and further decoupled into a volumetric part and an isochoric part. The spatial Kirchhoff stress tensor and spatial elasticity tensor are derived from the newly established Helmholtz free energy. The proposed model is further implemented into the finite element program ABAQUS by writing a user-defined material subroutine. The prediction capability of the proposed model is verified by simulating the homogeneous and inhomogeneous deformations of soft elastomers under various loading modes, including uniaxial tension, uniaxial compression, pure shear, equi-biaxial tension, general biaxial tensile loadings, inflation and indentation. Moreover, the influence of entanglement concentration on the stretchability and stiffness of soft elastomers is predicted and discussed using the proposed model.

本文基于弯曲管的概念，建立了一种新的软弹性体超弹性本构模型。该模型统一考虑了聚合物链的有限可扩展性、缠结对弹性的贡献以及非仿射微观到宏观尺度的转变。为了反映缠结效应及其对软弹性体变形的影响，引入了扭管的概念。阐明了这种弯曲管中纠缠聚合物链的有限可拓性和构象统计。通过将弯曲管嵌入微球中，利用最小平均自由能原理，提出了一种新的非仿射尺度转换规则，建立了聚合物链在微观尺度上的局部变形与宏观尺度上的整体变形之间的关系。基于与构象统计相关的概率密度函数，建立了亥姆霍兹自由能，并进一步解耦为体积部分和等时部分。空间基尔霍夫应力张量和空间弹性张量由新建立的亥姆霍兹自由能导出。通过编写用户自定义的材料子程序，将所提出的模型进一步实现到有限元程序ABAQUS中。通过对软弹性体在单轴拉伸、单轴压缩、纯剪切、等双轴拉伸、一般双轴拉伸载荷、膨胀和压痕等不同加载模式下的均匀变形和非均匀变形进行模拟，验证了该模型的预测能力。此外，利用该模型预测并讨论了缠结浓度对软弹性体拉伸性能和刚度的影响。

{"title":"A hyperelastic constitutive model for soft elastomers considering the entanglement-dependent finite extensibility","authors":"Jinglei Yang , Kaijuan Chen , Chao Yu , Kun Zhou , Guozheng Kang","doi":"10.1016/j.jmps.2024.106000","DOIUrl":"10.1016/j.jmps.2024.106000","url":null,"abstract":"<div><div>In this paper, a novel hyperelastic constitutive model for soft elastomers is developed based on the concept of the tortuous tube. This model incorporates the finite extensibility of the polymer chain, the entanglement contribution to elasticity and the non-affine micro-to-macro scale transition in a unified way. To reflect the entanglement effect and its influence on the deformation of soft elastomers, the tortuous tube concept is introduced. The finite extensibility and conformational statistics of an entangled polymer chain in such a tortuous tube are clarified. By embedding the tortuous tube into the microsphere and employing the principle of minimum averaged free energy, a new non-affine scale transition rule is proposed to establish the relationship between the local deformation of a polymer chain at the microscopic scale and the overall deformation at the macroscopic scale. Based on the probability density function related to the conformational statistics, the Helmholtz free energy is established and further decoupled into a volumetric part and an isochoric part. The spatial Kirchhoff stress tensor and spatial elasticity tensor are derived from the newly established Helmholtz free energy. The proposed model is further implemented into the finite element program ABAQUS by writing a user-defined material subroutine. The prediction capability of the proposed model is verified by simulating the homogeneous and inhomogeneous deformations of soft elastomers under various loading modes, including uniaxial tension, uniaxial compression, pure shear, equi-biaxial tension, general biaxial tensile loadings, inflation and indentation. Moreover, the influence of entanglement concentration on the stretchability and stiffness of soft elastomers is predicted and discussed using the proposed model.</div></div>","PeriodicalId":17331,"journal":{"name":"Journal of The Mechanics and Physics of Solids","volume":"196 ","pages":"Article 106000"},"PeriodicalIF":5.0,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788946","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}

引用次数: 0