Pub Date : 2024-11-14DOI: 10.1016/j.eml.2024.102265
Hutomo Tanoto , Hanwen Fan , Donggi Ha , Catherine G. Ambrose , Eric O. Klineberg , Yuxiao Zhou
Trabecular bone, a highly porous 3D network of interconnected rods and plates known as trabeculae, plays a critical role in bone strength and integrity. Osteoporosis, a condition commonly associated with aging, leads to deteriorations in bone mass and microarchitecture, manifesting as reduced bone mineral density, thinner trabecular struts, increased trabecular spacing, and a shift from trabecular plates to rods. These microstructural alterations contribute to age-related fragility fractures. To quantitatively explore the link between microstructural changes and the mechanical properties of trabecular bone, we combined mechanical testing with micro-computed tomography (micro-CT) and digital volume correlation (DVC) to measure 3D full-field deformation in trabecular bone samples from healthy and osteoporotic human cadaver vertebrae. Our multi-step mechanical testing characterized strain concentration propagation under axial compressive loading, providing new insights into how microstructural parameters influence trabecular bone’s mechanical strength. This study demonstrates that imaging-based approaches for evaluating bone mechanical strength could serve as an alternative to traditional fracture risk assessment methods, which primarily rely on bone mineral density.
{"title":"Quantifying the relation between aging-related trabecular bone microstructure and mechanical properties with digital volume correlation approach","authors":"Hutomo Tanoto , Hanwen Fan , Donggi Ha , Catherine G. Ambrose , Eric O. Klineberg , Yuxiao Zhou","doi":"10.1016/j.eml.2024.102265","DOIUrl":"10.1016/j.eml.2024.102265","url":null,"abstract":"<div><div>Trabecular bone, a highly porous 3D network of interconnected rods and plates known as trabeculae, plays a critical role in bone strength and integrity. Osteoporosis, a condition commonly associated with aging, leads to deteriorations in bone mass and microarchitecture, manifesting as reduced bone mineral density, thinner trabecular struts, increased trabecular spacing, and a shift from trabecular plates to rods. These microstructural alterations contribute to age-related fragility fractures. To quantitatively explore the link between microstructural changes and the mechanical properties of trabecular bone, we combined mechanical testing with micro-computed tomography (micro-CT) and digital volume correlation (DVC) to measure 3D full-field deformation in trabecular bone samples from healthy and osteoporotic human cadaver vertebrae. Our multi-step mechanical testing characterized strain concentration propagation under axial compressive loading, providing new insights into how microstructural parameters influence trabecular bone’s mechanical strength. This study demonstrates that imaging-based approaches for evaluating bone mechanical strength could serve as an alternative to traditional fracture risk assessment methods, which primarily rely on bone mineral density.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102265"},"PeriodicalIF":4.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701413","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 : 2024-11-14DOI: 10.1016/j.eml.2024.102263
Solon Tsimpoukis, Stelios Kyriakides
Tensile tests on NiTi tubes at different average strain rates reveal a unique behavior resulting from interactions between the latent heat of the reversible transformations, the transformation stress and the associated localized deformation patterns. At slow rates (e.g., 10−5 s−1) transformation is by a helical band or multipronged fronts. The heat exchange with the environment dissipates the latent heat, the temperature remains at the ambient level, and the stress remains constant during transformation. At a rate of 10−2 s−1 three narrow parallel helical bands of martensite (M) nucleate simultaneously at one end. Their tips propagate at the same speed, while the stress remains constant at the level corresponding to the temperature of the transformed material behind them. Once they reach the other end, further transformation occurs by band broadening accompanied by heating and increase in the recorded stress. During unloading, three helical bands of austenite (A) covering the length of the specimen nucleate nearly simultaneously and subsequently broaden causing cooling and decrease in stress. This behavior is contrasted with that observed in strips and small diameter rods where during loading rate-induced heating results in progressive nucleation of new inclined bands of M at sites with lower temperature. The progressive nucleation of new inclined bands (of A) is repeated during unloading. The rate tube experiments have been successfully simulated numerically using coupled static displacement-transient thermal finite element analysis linked to a user material subroutine based on the thermomechanical constitutive model for SMAs of our group. The following novel features of the analysis are crucial for successful simulations: both transformations are represented by a single surface with softening introduced over their extents; the transformation stress, strain and latent heat vary with temperature; the heat exchange between the model and the environment is modeled appropriately. Overall, the results of the experiments provide a challenging platform for developing and evaluating constitutive models for phase transforming materials, while the analysis points to features that must be included.
在不同平均应变速率下对镍钛管进行的拉伸试验揭示了可逆转变潜热、转变应力和相关局部变形模式之间相互作用所产生的独特行为。在低应变速率下（例如 10-5 s-1），转变是通过螺旋带或多棱形前沿进行的。在转化过程中，与环境的热交换会耗散潜热，温度保持在环境温度水平，应力保持恒定。马氏体（M）以 10-2 s-1 的速度在一端同时形成三条狭窄的平行螺旋带。它们的尖端以相同的速度传播，而应力则保持恒定，与它们后面的转化材料的温度相对应。当它们到达另一端时，伴随着加热和记录应力的增加，通过带状扩展发生进一步转变。在卸载过程中，覆盖试样长度的三条奥氏体螺旋带（A）几乎同时成核，随后变宽，导致冷却和应力下降。这种行为与在带材和小直径棒材中观察到的行为形成鲜明对比，在带材和小直径棒材中，加载过程中速率引起的加热导致在温度较低的部位逐渐形成新的 M 倾斜带。在卸载过程中，新倾斜带（A）的逐渐成核过程会重复出现。我们使用静态位移-瞬态热耦合有限元分析法对速率管实验进行了成功的数值模拟，该分析法与基于我们课题组 SMA 热力学构成模型的用户材料子程序相连接。分析中的以下新特点对成功模拟至关重要：两种转变均由单一表面表示，并在其范围内引入软化；转变应力、应变和潜热随温度变化而变化；模型与环境之间的热交换被适当建模。总之，实验结果为开发和评估相变材料的构成模型提供了一个具有挑战性的平台，同时分析指出了必须包含的特征。
{"title":"Effect of rate on the response and localized transformation patterns in NiTi Tubes","authors":"Solon Tsimpoukis, Stelios Kyriakides","doi":"10.1016/j.eml.2024.102263","DOIUrl":"10.1016/j.eml.2024.102263","url":null,"abstract":"<div><div>Tensile tests on NiTi tubes at different average strain rates reveal a unique behavior resulting from interactions between the latent heat of the reversible transformations, the transformation stress and the associated localized deformation patterns. At slow rates (e.g., 10<sup>−5</sup> s<sup>−1</sup>) transformation is by a helical band or multipronged fronts. The heat exchange with the environment dissipates the latent heat, the temperature remains at the ambient level, and the stress remains constant during transformation. At a rate of 10<sup>−2</sup> s<sup>−1</sup> three narrow parallel helical bands of martensite (M) nucleate simultaneously at one end. Their tips propagate at the same speed, while the stress remains constant at the level corresponding to the temperature of the transformed material behind them. Once they reach the other end, further transformation occurs by band broadening accompanied by heating and increase in the recorded stress. During unloading, three helical bands of austenite (A) covering the length of the specimen nucleate nearly simultaneously and subsequently broaden causing cooling and decrease in stress. This behavior is contrasted with that observed in strips and small diameter rods where during loading rate-induced heating results in progressive nucleation of new inclined bands of M at sites with lower temperature. The progressive nucleation of new inclined bands (of A) is repeated during unloading. The rate tube experiments have been successfully simulated numerically using coupled static displacement-transient thermal finite element analysis linked to a user material subroutine based on the thermomechanical constitutive model for SMAs of our group. The following novel features of the analysis are crucial for successful simulations: both transformations are represented by a single surface with softening introduced over their extents; the transformation stress, strain and latent heat vary with temperature; the heat exchange between the model and the environment is modeled appropriately. Overall, the results of the experiments provide a challenging platform for developing and evaluating constitutive models for phase transforming materials, while the analysis points to features that must be included.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102263"},"PeriodicalIF":4.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142701312","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}
Accurate and efficient prediction of benchmark properties is essential to the discovery of diverse functional materials, but searching vast element combinatorial and bonding configurational spaces presents formidable challenges to current computational techniques. Here, we devise a large atomic partition (LAP) model featuring a scheme to partition material properties into constituent atomic attributes, which are validated by a data-driven calibration procedure and assigned to elements across the periodic table, then utilized as raw ingredients to assemble and assess targeted properties of new materials. Distinct subtypes are designated for each element based on local atomic environments such as coordination number and valence state, and the parameter count of the LAP model can be tuned widely to tailor prediction accuracy and computational efficiency. As demonstrative case studies, we explore volumetric cohesive energy, bulk modulus, and shear modulus, and the results showcase superior accuracy, efficiency, universality, and interpretability of the LAP model compared to alternative approaches. Moreover, based on the predicted elastic moduli, we discover a series of rare and highly sought-after compounds exhibiting concurrent superior hardness and toughness, highlighting the promise of the LAP model in high-throughput screening for advanced materials with targeted outstanding functionalities.
准确有效地预测基准属性对发现各种功能材料至关重要，但搜索庞大的元素组合和成键构型空间对当前的计算技术提出了严峻的挑战。在此，我们设计了一个大原子分区（LAP）模型，其特点是将材料特性划分为组成原子属性的方案，这些属性通过数据驱动的校准程序进行验证，并分配给元素周期表中的所有元素，然后利用这些元素作为原材料来组装和评估新材料的目标特性。根据配位数和价态等局部原子环境，为每种元素指定了不同的子类型，LAP 模型的参数数可进行广泛调整，以定制预测精度和计算效率。作为示范案例研究，我们探讨了体积内聚能、体积模量和剪切模量，结果表明与其他方法相比，LAP 模型具有更高的准确性、效率、通用性和可解释性。此外，根据预测的弹性模量，我们还发现了一系列稀有且备受追捧的化合物，它们同时表现出卓越的硬度和韧性，这凸显了 LAP 模型在高通量筛选具有目标性卓越功能的先进材料方面的前景。
{"title":"A large atomic partition model for materials discovery","authors":"Lintao Miao , Xiaoang Yuan , Chun Tang , Changfeng Chen , Enlai Gao","doi":"10.1016/j.eml.2024.102262","DOIUrl":"10.1016/j.eml.2024.102262","url":null,"abstract":"<div><div>Accurate and efficient prediction of benchmark properties is essential to the discovery of diverse functional materials, but searching vast element combinatorial and bonding configurational spaces presents formidable challenges to current computational techniques. Here, we devise a large atomic partition (LAP) model featuring a scheme to partition material properties into constituent atomic attributes, which are validated by a data-driven calibration procedure and assigned to elements across the periodic table, then utilized as raw ingredients to assemble and assess targeted properties of new materials. Distinct subtypes are designated for each element based on local atomic environments such as coordination number and valence state, and the parameter count of the LAP model can be tuned widely to tailor prediction accuracy and computational efficiency. As demonstrative case studies, we explore volumetric cohesive energy, bulk modulus, and shear modulus, and the results showcase superior accuracy, efficiency, universality, and interpretability of the LAP model compared to alternative approaches. Moreover, based on the predicted elastic moduli, we discover a series of rare and highly sought-after compounds exhibiting concurrent superior hardness and toughness, highlighting the promise of the LAP model in high-throughput screening for advanced materials with targeted outstanding functionalities.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102262"},"PeriodicalIF":4.3,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659221","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 : 2024-11-08DOI: 10.1016/j.eml.2024.102256
Long Liu, Quanzi Yuan
Environmental effects can determine the ductile–brittle behavior of cracks at the atomic scale, but the underlying processes remain poorly understood and contentious. Here, we report the competition between ductile and brittle behaviors at crack tips induced by the prevalent environmental effect of dissolution. Our findings reveal that this competition is driven by two fundamental deformation mechanisms related to dissolution: crack blunting and defect accumulation. Through separate evaluations of dissolution-induced cleavage and dissolution-induced plasticity, we demonstrate that these deformation mechanisms not only dominate brittle fracture toughness but also lead to dislocation slip. We have developed a theoretical model to predict the ductile and brittle behavior of cracks under dissolution, and the theory aligns well with the simulation results and remains consistent with existing experimental trends. This work will broaden the microscopic understanding of ductile and brittle fracture of cracks in complex environments.
{"title":"Atomic insights into the ductile–brittle competition of cracks under dissolution","authors":"Long Liu, Quanzi Yuan","doi":"10.1016/j.eml.2024.102256","DOIUrl":"10.1016/j.eml.2024.102256","url":null,"abstract":"<div><div>Environmental effects can determine the ductile–brittle behavior of cracks at the atomic scale, but the underlying processes remain poorly understood and contentious. Here, we report the competition between ductile and brittle behaviors at crack tips induced by the prevalent environmental effect of dissolution. Our findings reveal that this competition is driven by two fundamental deformation mechanisms related to dissolution: crack blunting and defect accumulation. Through separate evaluations of dissolution-induced cleavage and dissolution-induced plasticity, we demonstrate that these deformation mechanisms not only dominate brittle fracture toughness but also lead to dislocation slip. We have developed a theoretical model to predict the ductile and brittle behavior of cracks under dissolution, and the theory aligns well with the simulation results and remains consistent with existing experimental trends. This work will broaden the microscopic understanding of ductile and brittle fracture of cracks in complex environments.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102256"},"PeriodicalIF":4.3,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659220","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 : 2024-11-06DOI: 10.1016/j.eml.2024.102251
Yifei Ren, P.K. Purohit
Micro-scale propulsion by rotating helical flagella is of interest for the study of bacteria and robotic micro-swimmers. The propulsive thrust and torque produced by the rotating flagella are usually estimated assuming that they are rigid. In this paper we assume the flagella to be deformable elastic rods and compute propulsive forces and torques by enforcing local equilibrium of the rod within the context of resistive force theory. The torque–speed characteristics of the flagellar motor driving the rotation are taken into account. We show that the problem can be cast as a system of algebraic equations if the flagella are assumed to be helical before and after deformation when no spontaneous curvature is included. If the assumption of helical shape is dropped then we show that the propulsion problem can be cast as a system of first order differential equations that can be solved numerically. Our results in both cases agree reasonably well with experimental observations of bacterial propulsion and deviate from the predictions of Purcell depending on the mechanical properties of the flagellum.
{"title":"A model for micro-scale propulsion using flexible rotating flagella","authors":"Yifei Ren, P.K. Purohit","doi":"10.1016/j.eml.2024.102251","DOIUrl":"10.1016/j.eml.2024.102251","url":null,"abstract":"<div><div>Micro-scale propulsion by rotating helical flagella is of interest for the study of bacteria and robotic micro-swimmers. The propulsive thrust and torque produced by the rotating flagella are usually estimated assuming that they are rigid. In this paper we assume the flagella to be deformable elastic rods and compute propulsive forces and torques by enforcing local equilibrium of the rod within the context of resistive force theory. The torque–speed characteristics of the flagellar motor driving the rotation are taken into account. We show that the problem can be cast as a system of algebraic equations if the flagella are assumed to be helical before and after deformation when no spontaneous curvature is included. If the assumption of helical shape is dropped then we show that the propulsion problem can be cast as a system of first order differential equations that can be solved numerically. Our results in both cases agree reasonably well with experimental observations of bacterial propulsion and deviate from the predictions of Purcell depending on the mechanical properties of the flagellum.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102251"},"PeriodicalIF":4.3,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659219","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 : 2024-11-01DOI: 10.1016/j.eml.2024.102246
Eduardo Gutierrez-Prieto , Michael Gomez , Pedro M. Reis
We investigate the geometrically nonlinear deformation and buckling of a slender elastic beam subject to time-dependent ‘fictitious’ (non-inertial) forces arising from unsteady rotation. Using a rotary apparatus that accurately imposes an angular acceleration around a fixed axis, we demonstrate that dynamically coupled centrifugal and Euler forces can produce tunable structural deformations. Specifically, by systematically varying the acceleration ramp in a highly automated experimental setup, we show how the buckling onset of a cantilevered beam can be precisely tuned and its deformation direction selected. In a second configuration, we demonstrate that Euler forces can cause a pre-arched beam to snap-through, on demand, between its two stable states. We also formulate a theoretical model rooted in Euler’s elastica that rationalizes the problem and provides predictions in excellent quantitative agreement with the experimental data. Our findings demonstrate an innovative approach to the programmable actuation of slender rotating structures, where complex loading fields can be produced by controlling a single input parameter, the angular position of a rotating system. The ability to predict and control the buckling behaviors under such non-trivial loading conditions opens avenues for designing devices based on rotational fictitious forces.
{"title":"Harnessing centrifugal and Euler forces for tunable buckling of a rotating elastica","authors":"Eduardo Gutierrez-Prieto , Michael Gomez , Pedro M. Reis","doi":"10.1016/j.eml.2024.102246","DOIUrl":"10.1016/j.eml.2024.102246","url":null,"abstract":"<div><div>We investigate the geometrically nonlinear deformation and buckling of a slender elastic beam subject to time-dependent ‘fictitious’ (non-inertial) forces arising from unsteady rotation. Using a rotary apparatus that accurately imposes an angular acceleration around a fixed axis, we demonstrate that dynamically coupled centrifugal and Euler forces can produce tunable structural deformations. Specifically, by systematically varying the acceleration ramp in a highly automated experimental setup, we show how the buckling onset of a cantilevered beam can be precisely tuned and its deformation direction selected. In a second configuration, we demonstrate that Euler forces can cause a pre-arched beam to snap-through, on demand, between its two stable states. We also formulate a theoretical model rooted in Euler’s <em>elastica</em> that rationalizes the problem and provides predictions in excellent quantitative agreement with the experimental data. Our findings demonstrate an innovative approach to the programmable actuation of slender rotating structures, where complex loading fields can be produced by controlling a single input parameter, the angular position of a rotating system. The ability to predict and control the buckling behaviors under such non-trivial loading conditions opens avenues for designing devices based on rotational fictitious forces.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"72 ","pages":"Article 102246"},"PeriodicalIF":4.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554550","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 : 2024-10-30DOI: 10.1016/j.eml.2024.102255
Guozhan Xia
This paper establishes an analytical method for the wrinkling of compressible magnetic soft (MS) plates subject to an in-plane biaxial stretching and an out-of-plane magnetic induction field. The bifurcation analysis is performed with external Maxwell stress considered by combining the surface impedance matrix method and the Stroh formulation in terms of true magnetic field variables. We decouple the resulting bifurcation equations into antisymmetric and symmetric modes and provide the explicit expressions within a neo-Hookean ideal magnetoelastic model. Numerical examples show that the antisymmetric wrinkling usually occurs prior to the symmetric one, unless the permeability of the plates is much smaller than that of the surroundings , i.e., the normalized permeability . This observation is consistent with the previous studies on incompressible case. However, for nearly incompressible plates with , the compressible constitutive relation may impose an additional deformation constraint that noticeably limits the occurrence and extent of wrinkling in the plates. One intriguing observation in particular is that the critical stretches for the thin-plate instability exhibit a nonmonotonic character as the compressibility of plate varies. Release of compressibility plays a positive role on stabilizing the MS plates when , yet a negative role when . This phenomenon may be attributed to the coupling effect between the compressibility and the normalized permeability , suggesting a potential way to regulate wrinkling behaviors of MS materials by tuning the surrounding permeability. The present work may serve as benchmark solutions for understanding structural failures in various related functional MS-based devices.
本文建立了可压缩磁性软板（MS）在平面内双轴拉伸和平面外磁感应场作用下起皱的分析方法。在考虑外部麦克斯韦应力的情况下，结合表面阻抗矩阵法和真实磁场变量的斯特罗公式进行了分叉分析。我们将分岔方程解耦为非对称和对称模式，并在新胡克理想磁弹性模型中提供了明确的表达式。数值示例表明，除非板的渗透率μ远小于周围环境的渗透率μ′，即归一化渗透率μ/μ′→0，否则反对称起皱通常发生在对称起皱之前。这一观察结果与之前对不可压缩情况的研究结果一致。然而，对于μ/μ′>1的近不可压缩板，可压缩构成关系可能会施加额外的变形约束，从而明显限制板材皱褶的发生和程度。一个特别有趣的观察结果是，随着板的可压缩性的变化，薄板不稳定性的临界拉伸表现出非单调性。这一现象可能归因于压缩性与归一化渗透率μ/μ′之间的耦合效应，表明通过调节周围渗透率可以调节 MS 材料的起皱行为。本研究可作为了解各种基于 MS 的相关功能器件结构故障的基准解决方案。
{"title":"Wrinkling of compressible magnetic soft plates","authors":"Guozhan Xia","doi":"10.1016/j.eml.2024.102255","DOIUrl":"10.1016/j.eml.2024.102255","url":null,"abstract":"<div><div>This paper establishes an analytical method for the wrinkling of compressible magnetic soft (MS) plates subject to an in-plane biaxial stretching and an out-of-plane magnetic induction field. The bifurcation analysis is performed with external Maxwell stress considered by combining the surface impedance matrix method and the Stroh formulation in terms of true magnetic field variables. We decouple the resulting bifurcation equations into antisymmetric and symmetric modes and provide the explicit expressions within a neo-Hookean ideal magnetoelastic model. Numerical examples show that the antisymmetric wrinkling usually occurs prior to the symmetric one, unless the permeability of the plates <span><math><mi>μ</mi></math></span> is much smaller than that of the surroundings <span><math><msup><mrow><mi>μ</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span>, i.e., the normalized permeability <span><math><mrow><mrow><mi>μ</mi></mrow><mo>/</mo><mrow><msup><mrow><mi>μ</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></mrow><mo>→</mo><mn>0</mn></math></span>. This observation is consistent with the previous studies on incompressible case. However, for nearly incompressible plates with <span><math><mrow><mrow><mi>μ</mi></mrow><mo>/</mo><mrow><msup><mrow><mi>μ</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></mrow><mo>></mo><mn>1</mn></math></span>, the compressible constitutive relation may impose an additional deformation constraint that noticeably limits the occurrence and extent of wrinkling in the plates. One intriguing observation in particular is that the critical stretches for the thin-plate instability exhibit a nonmonotonic character as the compressibility of plate varies. Release of compressibility plays a positive role on stabilizing the MS plates when <span><math><mrow><mn>0</mn><mrow><mo><</mo><mrow><mrow><mi>μ</mi></mrow><mo>/</mo><mrow><msup><mrow><mi>μ</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></mrow><mo><</mo></mrow><mn>1</mn></mrow></math></span>, yet a negative role when <span><math><mrow><mrow><mi>μ</mi></mrow><mo>/</mo><mrow><msup><mrow><mi>μ</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></mrow><mo>></mo><mn>1</mn></math></span>. This phenomenon may be attributed to the coupling effect between the compressibility and the normalized permeability <span><math><mrow><mrow><mi>μ</mi></mrow><mo>/</mo><mrow><msup><mrow><mi>μ</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></mrow></math></span>, suggesting a potential way to regulate wrinkling behaviors of MS materials by tuning the surrounding permeability. The present work may serve as benchmark solutions for understanding structural failures in various related functional MS-based devices.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102255"},"PeriodicalIF":4.3,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586582","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}
Soft adhesive layers show promise in various engineering applications, including biomedicine, automotive, semiconductor, and aerospace industries. However, cavities trapped at the interface due to poor contact will significantly inhibit their adhesion capacity, leading to rapid crack-growth failure. Significant efforts in these applications within a confined contact area are focused on mitigating the effects and enhancing the debonding work of the interface without changing the materials, such as using bioinspired micropillars. However, soft adhesives with isolated contact elements face limitations due to manufacturing complexity and the collision of micropillars under large deformation. This study proposes a simple and effective method to reduce the hydrostatic pressure around the crack tips by designing a dendritic pattern within the confined area. This approach inhibited interface crack growth well and improved adhesive performance. As a result, the crack failure was delayed, with the stretch ratio enhanced by more than 36 %, while the debonding work increased by 85 % compared with the circular adhesive layer. This study demonstrates that adhesion capacity can be significantly improved while reducing material usage by designing dendritic patterns.
{"title":"Crack-growth inhibition by designing dendritic pattern for soft adhesives","authors":"Yifan Zhang , Danming Zhong , Qiuxuan Wang , Ping Rao , Shaoxing Qu","doi":"10.1016/j.eml.2024.102254","DOIUrl":"10.1016/j.eml.2024.102254","url":null,"abstract":"<div><div>Soft adhesive layers show promise in various engineering applications, including biomedicine, automotive, semiconductor, and aerospace industries. However, cavities trapped at the interface due to poor contact will significantly inhibit their adhesion capacity, leading to rapid crack-growth failure. Significant efforts in these applications within a confined contact area are focused on mitigating the effects and enhancing the debonding work of the interface without changing the materials, such as using bioinspired micropillars. However, soft adhesives with isolated contact elements face limitations due to manufacturing complexity and the collision of micropillars under large deformation. This study proposes a simple and effective method to reduce the hydrostatic pressure around the crack tips by designing a dendritic pattern within the confined area. This approach inhibited interface crack growth well and improved adhesive performance. As a result, the crack failure was delayed, with the stretch ratio enhanced by more than 36 %, while the debonding work increased by 85 % compared with the circular adhesive layer. This study demonstrates that adhesion capacity can be significantly improved while reducing material usage by designing dendritic patterns.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"73 ","pages":"Article 102254"},"PeriodicalIF":4.3,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578255","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 : 2024-10-25DOI: 10.1016/j.eml.2024.102253
Yizhou Shen , Yanlong Xu , Feng Liu , Fanglong Wang , Guan Wang , Zhichun Yang
Energy harvesting exploiting the inverse piezoelectric effect has been the subject of much attention and discussion in the field of elastic and structural dynamics. Recently, the ongoing development of elastic metamaterials and metasurfaces has opened up a new way to improve the quality of energy harvesting. Here, we proposed a new strategy for harvesting elastic energy in a plate, which is the use of the inverse piezoelectric effect to convert the elastic energy into electrical energy after the achromatic meta-grating has focused broadband flexural waves. A new theoretical method to design the achromatic meta-grating is proposed based on derived analytical expression of the phase shift of subunit. When a meta-grating, a thin plate and a piezoelectric patch are combined into an energy harvesting system, the elastic energy can be converted into electric energy by the system, and the output voltage can be amplified by twice that of the system without the meta-grating. A theoretical framework is built to analyze the performance of the energy harvesting system, and variational parametric analyses are carried out to obtain the optimal resistance, the optimal length, thickness and position of piezoelectric patch, which are , 18 mm, 0.2 mm and 30 mm, respectively. For the optimized system, the power harvested rate of the system is close to 4 in the frequency band of 6–8 kHz. Finally, the design of the system based on the wave focusing principle is extended, and energy harvesters are designed for different frequency bands, which can all work under different excitation conditions (a local and a base excitations). Our work opens up a new route for elastic energy harvesting and may have broad application prospects in the development of self-powered sensors.
{"title":"Broadband elastic energy harvesting based on achromatic meta-grating","authors":"Yizhou Shen , Yanlong Xu , Feng Liu , Fanglong Wang , Guan Wang , Zhichun Yang","doi":"10.1016/j.eml.2024.102253","DOIUrl":"10.1016/j.eml.2024.102253","url":null,"abstract":"<div><div>Energy harvesting exploiting the inverse piezoelectric effect has been the subject of much attention and discussion in the field of elastic and structural dynamics. Recently, the ongoing development of elastic metamaterials and metasurfaces has opened up a new way to improve the quality of energy harvesting. Here, we proposed a new strategy for harvesting elastic energy in a plate, which is the use of the inverse piezoelectric effect to convert the elastic energy into electrical energy after the achromatic meta-grating has focused broadband flexural waves. A new theoretical method to design the achromatic meta-grating is proposed based on derived analytical expression of the phase shift of subunit. When a meta-grating, a thin plate and a piezoelectric patch are combined into an energy harvesting system, the elastic energy can be converted into electric energy by the system, and the output voltage can be amplified by twice that of the system without the meta-grating. A theoretical framework is built to analyze the performance of the energy harvesting system, and variational parametric analyses are carried out to obtain the optimal resistance, the optimal length, thickness and position of piezoelectric patch, which are <span><math><mrow><mn>870</mn><mi>Ω</mi></mrow></math></span>, 18 mm, 0.2 mm and 30 mm, respectively. For the optimized system, the power harvested rate of the system is close to 4 in the frequency band of 6–8 kHz. Finally, the design of the system based on the wave focusing principle is extended, and energy harvesters are designed for different frequency bands, which can all work under different excitation conditions (a local and a base excitations). Our work opens up a new route for elastic energy harvesting and may have broad application prospects in the development of self-powered sensors.</div></div>","PeriodicalId":56247,"journal":{"name":"Extreme Mechanics Letters","volume":"72 ","pages":"Article 102253"},"PeriodicalIF":4.3,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535951","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}
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