Pub Date : 2025-02-15DOI: 10.1016/j.ijmecsci.2025.110067
Myung Hwan Bae , Seung Han Kim , Hong Min Seung , Joo Hwan Oh
Elastic metamaterials with nonlinearity have been actively studied recently due to their capability of bandgap tuning via wave amplitude. Nevertheless, previous approaches generally focused on tuning bandgap which was already formed without nonlinearities, so that they shared same limitations as in the linear bandgap cases. In this work, we propose a new nonlinear metamaterial that can open a non-existing bandgap or close the existing bandgap with nonlinear effect. The main idea is to utilize the transition between monoatomic and diatomic chains. To achieve the transition, we introduced alternating nonlinearity by using different bounding springs for even and odd masses. To theoretically describe the bandgap opening phenomena, we found that the general Lindstedt-Poincaré perturbation cannot be applied in the proposed metamaterial, so we applied Brillouin-Wigner perturbation. The proposed idea is validated with numerical simulation results. We expect our idea may extend the practical usability of nonlinear bandgap tunings and offer abundant new approaches to facilitate various advanced functionalities.
{"title":"Opening Bandgap in monoatomic-diatomic convertible metamaterial with nonlinearity","authors":"Myung Hwan Bae , Seung Han Kim , Hong Min Seung , Joo Hwan Oh","doi":"10.1016/j.ijmecsci.2025.110067","DOIUrl":"10.1016/j.ijmecsci.2025.110067","url":null,"abstract":"<div><div>Elastic metamaterials with nonlinearity have been actively studied recently due to their capability of bandgap tuning via wave amplitude. Nevertheless, previous approaches generally focused on tuning bandgap which was already formed without nonlinearities, so that they shared same limitations as in the linear bandgap cases. In this work, we propose a new nonlinear metamaterial that can open a non-existing bandgap or close the existing bandgap with nonlinear effect. The main idea is to utilize the transition between monoatomic and diatomic chains. To achieve the transition, we introduced alternating nonlinearity by using different bounding springs for even and odd masses. To theoretically describe the bandgap opening phenomena, we found that the general <em>Lindstedt-Poincaré</em> perturbation cannot be applied in the proposed metamaterial, so we applied <em>Brillouin-Wigner</em> perturbation. The proposed idea is validated with numerical simulation results. We expect our idea may extend the practical usability of nonlinear bandgap tunings and offer abundant new approaches to facilitate various advanced functionalities.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110067"},"PeriodicalIF":7.1,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-15DOI: 10.1016/j.ijmecsci.2025.110065
Zewei Hou , Yongmao Pei , Yuyang Lin , Hangyu Li , Linmao Fei
Selective movement, climbing, and precise sorting of multiple objects are critical for micro-robotics, mineral sorting, and biomedical handling. Typically, external forces such as optical, magnetic, vibrational and acoustic forces have been employed. Most of these methods require particles with special properties. Moreover, it is challenging to selectively manipulate large objects and separate them into different positions. Here, the selective climbing and separation of large objects have been investigated on the tilted vibrational Chladni plate. Firstly, we investigate the combined acoustic field and gravity on the tilted vibration plate. The robotic climbing and rolling down are realized. In the combined force, there is a force well near the anti-node. Particles are trapped to the forces well, which differs for different sizes. The combined forces are controllable by tuning the vibration amplitude. In doing this, multiple particles are trapped and separated to different positions. Further, the continuously tunable force well is achieved by switching the vibration anti-node. The straight uniform motion and selective climbing of particles are realized. Finally, the multiple kinds of particles are separated into large region by switching the anti-node. Most importantly, the precise separation and extraction of diamond particles are realized that leverages the region with maximum size-resolution combined force. This work pioneers a new approach for continuous tuning of acoustic forces. The tilted vibration structure provides large force for large and heavy particles, thereby enabling the selective climbing, robotic manipulation, and efficient separation and extraction of multiple kinds of particles.
{"title":"Selective particles climbing and precise separation by the tilted vibrational Chladni plate","authors":"Zewei Hou , Yongmao Pei , Yuyang Lin , Hangyu Li , Linmao Fei","doi":"10.1016/j.ijmecsci.2025.110065","DOIUrl":"10.1016/j.ijmecsci.2025.110065","url":null,"abstract":"<div><div>Selective movement, climbing, and precise sorting of multiple objects are critical for micro-robotics, mineral sorting, and biomedical handling. Typically, external forces such as optical, magnetic, vibrational and acoustic forces have been employed. Most of these methods require particles with special properties. Moreover, it is challenging to selectively manipulate large objects and separate them into different positions. Here, the selective climbing and separation of large objects have been investigated on the tilted vibrational Chladni plate. Firstly, we investigate the combined acoustic field and gravity on the tilted vibration plate. The robotic climbing and rolling down are realized. In the combined force, there is a force well near the anti-node. Particles are trapped to the forces well, which differs for different sizes. The combined forces are controllable by tuning the vibration amplitude. In doing this, multiple particles are trapped and separated to different positions. Further, the continuously tunable force well is achieved by switching the vibration anti-node. The straight uniform motion and selective climbing of particles are realized. Finally, the multiple kinds of particles are separated into large region by switching the anti-node. Most importantly, the precise separation and extraction of diamond particles are realized that leverages the region with maximum size-resolution combined force. This work pioneers a new approach for continuous tuning of acoustic forces. The tilted vibration structure provides large force for large and heavy particles, thereby enabling the selective climbing, robotic manipulation, and efficient separation and extraction of multiple kinds of particles.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110065"},"PeriodicalIF":7.1,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-15DOI: 10.1016/j.ijmecsci.2025.110064
Xun Peng , Jiale Sun , Yu Li , Zhicai Teng , Lei Hao
Shear-wave seismic vibrators have attracted increasing interest owing to their high efficiency, environmental friendliness, and safety. However, there are challenges in modeling the shear-wave vibrator-ground coupled system and in mastering its dynamics during the vibration process, which limits their practical operations. To address these issues, a reasonable shear-wave vibrator-ground coupled system dynamics model is proposed for the first time in this paper. The motion equations of the shear-wave vibrator-ground coupled system are derived, and the equivalent stiffness of the vibrator baseplate-soil interaction considering the triangular prism-shaped plate teeth is obtained innovatively based on the potential energy theory. Finite element (FE) simulation is utilized to verify the effectiveness of the presented theoretical calculation method. To reveal the shear-wave vibrator-ground coupled system dynamics, the modal frequencies, the harmonic response, and the dynamic characteristics under the sweep excitation of the coupled system are solved and investigated. In addition, the comprehensive effects of the structural parameters of the shear-wave vibrator on the coupled system dynamics are evaluated and identified utilizing the theoretical model. The results indicate that the proposed theoretical model can reveal the vibration characteristics of the shear-wave vibrator-ground coupled system, and the baseplates structure has great influences on the coupled system dynamics. This work could lay theoretical foundations for designing, optimizing, and controlling shear-wave vibrators.
{"title":"Modeling and analysis of a shear-wave vibrator-ground coupled system dynamics","authors":"Xun Peng , Jiale Sun , Yu Li , Zhicai Teng , Lei Hao","doi":"10.1016/j.ijmecsci.2025.110064","DOIUrl":"10.1016/j.ijmecsci.2025.110064","url":null,"abstract":"<div><div>Shear-wave seismic vibrators have attracted increasing interest owing to their high efficiency, environmental friendliness, and safety. However, there are challenges in modeling the shear-wave vibrator-ground coupled system and in mastering its dynamics during the vibration process, which limits their practical operations. To address these issues, a reasonable shear-wave vibrator-ground coupled system dynamics model is proposed for the first time in this paper. The motion equations of the shear-wave vibrator-ground coupled system are derived, and the equivalent stiffness of the vibrator baseplate-soil interaction considering the triangular prism-shaped plate teeth is obtained innovatively based on the potential energy theory. Finite element (FE) simulation is utilized to verify the effectiveness of the presented theoretical calculation method. To reveal the shear-wave vibrator-ground coupled system dynamics, the modal frequencies, the harmonic response, and the dynamic characteristics under the sweep excitation of the coupled system are solved and investigated. In addition, the comprehensive effects of the structural parameters of the shear-wave vibrator on the coupled system dynamics are evaluated and identified utilizing the theoretical model. The results indicate that the proposed theoretical model can reveal the vibration characteristics of the shear-wave vibrator-ground coupled system, and the baseplates structure has great influences on the coupled system dynamics. This work could lay theoretical foundations for designing, optimizing, and controlling shear-wave vibrators.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110064"},"PeriodicalIF":7.1,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-14DOI: 10.1016/j.ijmecsci.2025.110062
S. Esmizadeh , H. Haftbaradaran , A. Salvadori
Solid-state batteries are promising candidates for the next-generation energy storage technology, as they circumvent the cyclic stability and safety issues of the traditional liquid-electrolyte Li-ion technology. Solid electrolytes are less reactive and enable using Li-metal anodes, increasing the energy density of battery cells. However, Li dendrites nucleating at pores, grain boundaries, and cracks, particularly when the current density exceeds a critical level, have been found to penetrate the solid electrolyte, resulting in short circuit and battery failure. While existing fracture mechanics-based models of dendrite usually examine Li-filled cracks, recent experiments have shown that a Li dendrite formed inside a crack can induce fracture growth well before filling it. This work aims to develop a model for this largely unexplained behaviour by considering a Li dendrite as it grows inside a crack from an initially small nucleus. The model couples solid electrolyte deformation, stress-driven Li diffusion along the dendrite-electrolyte interface, and stress-dependent Butler-Volmer kinetics of Li deposition into the crack. A finite element formulation developed for solving the governing equations is applied to two types of solid electrolytes to examine simultaneous evolution of the stress profile, dendrite thickness profile, dendrite length, and the stress intensity factor. By considering a realistic range of model parameters, it is shown that dendrite thickening, as compared to lengthening, promoted by a lower interfacial diffusivity, a higher interfacial resistance, and a higher applied current density, can mediate crack growth before dendrite fills the crack. Both assumptions and predictions of the model are discussed with reference to the existing literature, and model predictions are compared to the experiments.
{"title":"Predicting solid electrolyte fracture by stress-mediated dendrite penetration in cracks","authors":"S. Esmizadeh , H. Haftbaradaran , A. Salvadori","doi":"10.1016/j.ijmecsci.2025.110062","DOIUrl":"10.1016/j.ijmecsci.2025.110062","url":null,"abstract":"<div><div>Solid-state batteries are promising candidates for the next-generation energy storage technology, as they circumvent the cyclic stability and safety issues of the traditional liquid-electrolyte Li-ion technology. Solid electrolytes are less reactive and enable using Li-metal anodes, increasing the energy density of battery cells. However, Li dendrites nucleating at pores, grain boundaries, and cracks, particularly when the current density exceeds a critical level, have been found to penetrate the solid electrolyte, resulting in short circuit and battery failure. While existing fracture mechanics-based models of dendrite usually examine Li-filled cracks, recent experiments have shown that a Li dendrite formed inside a crack can induce fracture growth well before filling it. This work aims to develop a model for this largely unexplained behaviour by considering a Li dendrite as it grows inside a crack from an initially small nucleus. The model couples solid electrolyte deformation, stress-driven Li diffusion along the dendrite-electrolyte interface, and stress-dependent Butler-Volmer kinetics of Li deposition into the crack. A finite element formulation developed for solving the governing equations is applied to two types of solid electrolytes to examine simultaneous evolution of the stress profile, dendrite thickness profile, dendrite length, and the stress intensity factor. By considering a realistic range of model parameters, it is shown that dendrite thickening, as compared to lengthening, promoted by a lower interfacial diffusivity, a higher interfacial resistance, and a higher applied current density, can mediate crack growth before dendrite fills the crack. Both assumptions and predictions of the model are discussed with reference to the existing literature, and model predictions are compared to the experiments.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"290 ","pages":"Article 110062"},"PeriodicalIF":7.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-14DOI: 10.1016/j.ijmecsci.2025.110063
Anas A. Al-Jamal , Imad Barsoum , Rashid K. Abu Al-Rub
The progression of additive manufacturing has paved the way for in-depth studies of various strut-, plate-, and sheet/shell-based cellular (meta)materials. Despite their promising mechanical properties, these metamaterials are highly sensitive to manufacturing defects. This study investigates the imperfection sensitivity of stochastic and periodic triply periodic minimal surface (TPMS) cellular materials by comparing imperfect additively manufactured samples to simulated defect-free lattices. Stochastic TPMS sheet-network lattices, using Schwarz-Diamond, Schoen−IWP, and Fischer-Koch S topologies, and their periodic counterparts, are investigated across various relative densities. Samples were additively manufactured using laser powder bed fusion of titanium alloy powder to evaluate the damage-tolerance of these cellular materials. Microstructural analysis was performed using micro-CT and SEM to assess 3D printability and defect density. Stochastic TPMS cellular materials demonstrated remarkable resistance to additive manufacturing defects compared to their periodic counterparts. In the presence of defects, stochastic TPMS sheet-based cellular materials maintain their stretching-dominated deformation behavior, whereas the deformation mode of the periodic counterparts was altered to a bending-dominated deformation. The reduced defect sensitivity allows superior mechanical performance of stochastic TPMS lattices at lower relative densities, where defects are most prominent. Numerical simulations indicate that defect-free periodic TPMS lattices display superior mechanical properties to their stochastic counterparts at all relative densities and show a clear effect of parent topology. This work expands on the understanding of the mechanical behavior of stochastic TPMS cellular materials and facilitates further improvements in their damage-tolerance and potential applications in various engineering fields.
{"title":"Defect-sensitivity of stochastic and periodic minimal surface titanium cellular materials","authors":"Anas A. Al-Jamal , Imad Barsoum , Rashid K. Abu Al-Rub","doi":"10.1016/j.ijmecsci.2025.110063","DOIUrl":"10.1016/j.ijmecsci.2025.110063","url":null,"abstract":"<div><div>The progression of additive manufacturing has paved the way for in-depth studies of various strut-, plate-, and sheet/shell-based cellular (meta)materials. Despite their promising mechanical properties, these metamaterials are highly sensitive to manufacturing defects. This study investigates the imperfection sensitivity of stochastic and periodic triply periodic minimal surface (TPMS) cellular materials by comparing imperfect additively manufactured samples to simulated defect-free lattices. Stochastic TPMS sheet-network lattices, using Schwarz-Diamond, Schoen−IWP, and Fischer-Koch S topologies, and their periodic counterparts, are investigated across various relative densities. Samples were additively manufactured using laser powder bed fusion of titanium alloy powder to evaluate the damage-tolerance of these cellular materials. Microstructural analysis was performed using micro-CT and SEM to assess 3D printability and defect density. Stochastic TPMS cellular materials demonstrated remarkable resistance to additive manufacturing defects compared to their periodic counterparts. In the presence of defects, stochastic TPMS sheet-based cellular materials maintain their stretching-dominated deformation behavior, whereas the deformation mode of the periodic counterparts was altered to a bending-dominated deformation. The reduced defect sensitivity allows superior mechanical performance of stochastic TPMS lattices at lower relative densities, where defects are most prominent. Numerical simulations indicate that defect-free periodic TPMS lattices display superior mechanical properties to their stochastic counterparts at all relative densities and show a clear effect of parent topology. This work expands on the understanding of the mechanical behavior of stochastic TPMS cellular materials and facilitates further improvements in their damage-tolerance and potential applications in various engineering fields.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110063"},"PeriodicalIF":7.1,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-13DOI: 10.1016/j.ijmecsci.2025.109976
Chenying Liu , Fufu Yang , Perla Maiolino , Zhong You
Origami, derived from the Japanese words ‘ori’ meaning fold and ‘kami (gami)’ meaning paper, has found extensive engineering applications in modern days. In the last decade, an emerging venue lies in robotics, where origami is taken as an exoskeleton of a robot to generate desired behaviours. The motions of origami are often coupled through in-built folds, leading to lower or more controllable degrees of freedom (DoFs) while still exhibiting shape-changing properties akin to those of soft materials. This unique feature enhances the compliance of robots without compromising their controllability. The prevalent use of zero-thickness sheets makes origami robots prone to fatigue, necessitating the incorporation of origami made from durable thick materials. Whilst substantial attempts have been made in the field of thick-panel origami, the concept was originally conceived for space solar panels. Hence, existing research predominantly focuses on properties such as flat foldability and kinematic equivalence. Consequently, many designs also end up with rigid panels of non-uniform thicknesses, complicating the fabrication process. As a result, roboticists, who are interested in shape-changing origami as well as its fabrication and control simplicity, often find it challenging to directly implement those thick panels in the robotic design. This work addresses these research gaps by introducing the first systematic approach to designing uniform-thickness origami capable of shape-changing, referred to as morphing surfaces. Such surfaces are enabled by a comprehensive mapping between thick-panel origami and spatial overconstrained linkages, followed by various tessellation methods. Bending, expanding, twisting, and complex motion behaviours will be realised on the proposed surfaces, all with a single DoF. The surfaces are thus readily applicable in robotics for targeted functions.
{"title":"Morphing surfaces inspired by thick-panel origami","authors":"Chenying Liu , Fufu Yang , Perla Maiolino , Zhong You","doi":"10.1016/j.ijmecsci.2025.109976","DOIUrl":"10.1016/j.ijmecsci.2025.109976","url":null,"abstract":"<div><div>Origami, derived from the Japanese words ‘ori’ meaning fold and ‘kami (gami)’ meaning paper, has found extensive engineering applications in modern days. In the last decade, an emerging venue lies in robotics, where origami is taken as an exoskeleton of a robot to generate desired behaviours. The motions of origami are often coupled through in-built folds, leading to lower or more controllable degrees of freedom (DoFs) while still exhibiting shape-changing properties akin to those of soft materials. This unique feature enhances the compliance of robots without compromising their controllability. The prevalent use of zero-thickness sheets makes origami robots prone to fatigue, necessitating the incorporation of origami made from durable thick materials. Whilst substantial attempts have been made in the field of thick-panel origami, the concept was originally conceived for space solar panels. Hence, existing research predominantly focuses on properties such as flat foldability and kinematic equivalence. Consequently, many designs also end up with rigid panels of non-uniform thicknesses, complicating the fabrication process. As a result, roboticists, who are interested in shape-changing origami as well as its fabrication and control simplicity, often find it challenging to directly implement those thick panels in the robotic design. This work addresses these research gaps by introducing the first systematic approach to designing uniform-thickness origami capable of shape-changing, referred to as morphing surfaces. Such surfaces are enabled by a comprehensive mapping between thick-panel origami and spatial overconstrained linkages, followed by various tessellation methods. Bending, expanding, twisting, and complex motion behaviours will be realised on the proposed surfaces, all with a single DoF. The surfaces are thus readily applicable in robotics for targeted functions.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 109976"},"PeriodicalIF":7.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-13DOI: 10.1016/j.ijmecsci.2025.110059
Jin-Zhao Li , Zhi-Ping Guan
Existing mechanical theories fall short in explaining the origin of delocalization behavior and the associated fluctuation phenomena observed in superplastic quasi-stable tension, which typically results in extraordinarily high fracture elongation. This study introduces a novel phenomenological model that accounts for the stick-slip effect arising from discontinuities in grain boundary sliding (GBS) during superplastic deformation. Experimental observations from uniaxial tension tests on a Zn-5Al superplastic alloy at 230 °C validate the accuracy of the simulations, which demonstrate static-kinetic coordinated deformation during each serrated fluctuation. Additionally, the simulations indicate that the stick-slip effect triggers dynamic delocalization behavior in superplastic tension, elucidating the nucleation and growth of additional micro-necks. Although this dynamic delocalization disrupts the initially stable flow, it significantly mitigates the development of macro-necks during unstable plastic flow, potentially leading to quasi-stable tensile deformation devoid of prominent macro-necks as the stick-slip effect intensifies. Notably, this study identifies for the first time the phenomenon of stress reduction during superplastic tension with jerky flow, attributable to an oscillatory stress induced by the GBS stick-slip effect superimposed on a static stress backdrop. The combined effects of GBS-induced stick-slip behavior and high strain rate sensitivity contribute to the extraordinarily large elongations observed in superplastic tension. Overall, the phenomenological model developed in this work not only clarifies the mechanical reasons behind specific phenomena in superplastic uniaxial tension, often overlooked by conventional mechanical analyses, but also proposes a new approach to enhancing superplastic deformation.
{"title":"A re-evaluation of super-high ductility mechanism in superplastic uniaxial tension","authors":"Jin-Zhao Li , Zhi-Ping Guan","doi":"10.1016/j.ijmecsci.2025.110059","DOIUrl":"10.1016/j.ijmecsci.2025.110059","url":null,"abstract":"<div><div>Existing mechanical theories fall short in explaining the origin of delocalization behavior and the associated fluctuation phenomena observed in superplastic quasi-stable tension, which typically results in extraordinarily high fracture elongation. This study introduces a novel phenomenological model that accounts for the stick-slip effect arising from discontinuities in grain boundary sliding (GBS) during superplastic deformation. Experimental observations from uniaxial tension tests on a Zn-5Al superplastic alloy at 230 °C validate the accuracy of the simulations, which demonstrate static-kinetic coordinated deformation during each serrated fluctuation. Additionally, the simulations indicate that the stick-slip effect triggers dynamic delocalization behavior in superplastic tension, elucidating the nucleation and growth of additional micro-necks. Although this dynamic delocalization disrupts the initially stable flow, it significantly mitigates the development of macro-necks during unstable plastic flow, potentially leading to quasi-stable tensile deformation devoid of prominent macro-necks as the stick-slip effect intensifies. Notably, this study identifies for the first time the phenomenon of stress reduction during superplastic tension with jerky flow, attributable to an oscillatory stress induced by the GBS stick-slip effect superimposed on a static stress backdrop. The combined effects of GBS-induced stick-slip behavior and high strain rate sensitivity contribute to the extraordinarily large elongations observed in superplastic tension. Overall, the phenomenological model developed in this work not only clarifies the mechanical reasons behind specific phenomena in superplastic uniaxial tension, often overlooked by conventional mechanical analyses, but also proposes a new approach to enhancing superplastic deformation.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110059"},"PeriodicalIF":7.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-13DOI: 10.1016/j.ijmecsci.2025.110061
Cheng Huang , Lei Shen , Wenyan Yu , Nizar Faisal Alkayem , Yan Han , Zhenghong Tian , Hao Yin , Gianluca Cusatis
Understanding mesoscopic component migration in fresh fiber-reinforced concrete (FRC) helps to control concrete construction quality. Studying of components’ movement in non-transparent flow requires a high-fidelity fluid-solid interaction method. This study employs a two-way coupled approach based on the SPH (Smoothed Particle Hydrodynamics) and DEM (Discrete Element Method) to simulate the rheological behavior of fresh FRC at mesoscale. The Herschel-Bulkley model is implemented to represent the shear thinning of mortar and aggregates settlement during vibrating compaction. With this high-fidelity framework, both the macroscale rheological behavior of fresh FRC as free surface flow and the mesoscale movements of coarse aggregate and fibers as suspended components can be well captured. After performing the high-fidelity preparations of fresh FRC, good agreements between experimental and numerical L-box tests and smart aggregate vibrating tests are reached. The proposed approach, in accordance with experimental evidence, shows that the fibers' orientation strongly depends on the flow speed. Moreover, the fibers’ orientation in high-speed flows tends to follow the same direction of flow, while fibers in low-speed flows tends to follow a random orientation pattern and block the flow.
{"title":"High-fidelity SPH-DEM framework for mesoscopic rheological behavior of fresh fiber-reinforced concrete","authors":"Cheng Huang , Lei Shen , Wenyan Yu , Nizar Faisal Alkayem , Yan Han , Zhenghong Tian , Hao Yin , Gianluca Cusatis","doi":"10.1016/j.ijmecsci.2025.110061","DOIUrl":"10.1016/j.ijmecsci.2025.110061","url":null,"abstract":"<div><div>Understanding mesoscopic component migration in fresh fiber-reinforced concrete (FRC) helps to control concrete construction quality. Studying of components’ movement in non-transparent flow requires a high-fidelity fluid-solid interaction method. This study employs a two-way coupled approach based on the SPH (Smoothed Particle Hydrodynamics) and DEM (Discrete Element Method) to simulate the rheological behavior of fresh FRC at mesoscale. The Herschel-Bulkley model is implemented to represent the shear thinning of mortar and aggregates settlement during vibrating compaction. With this high-fidelity framework, both the macroscale rheological behavior of fresh FRC as free surface flow and the mesoscale movements of coarse aggregate and fibers as suspended components can be well captured. After performing the high-fidelity preparations of fresh FRC, good agreements between experimental and numerical L-box tests and smart aggregate vibrating tests are reached. The proposed approach, in accordance with experimental evidence, shows that the fibers' orientation strongly depends on the flow speed. Moreover, the fibers’ orientation in high-speed flows tends to follow the same direction of flow, while fibers in low-speed flows tends to follow a random orientation pattern and block the flow.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110061"},"PeriodicalIF":7.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143444670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-13DOI: 10.1016/j.ijmecsci.2025.110045
Xin Liu , Shuai Chen , Bing Wang , Xiaojun Tan , Bo Cao , Liang Yu
Mechanical metamaterials with real-time tunability are an up-and-coming field with great attention. Due to its capability of realizing different mechanical properties, it provides a foundation for the development of intelligent adaptive structures. In this paper, a mechanical metamaterial with real-time tunable bandgap is proposed, exhibiting a wide range of adjustability. With a combination of theory, numerical simulation and experimental studies, the quasi-static mechanical properties and bandgap characteristics of the metamaterial under constant and changeable pressure are investigated, revealing the effect mechanism of cavity pressures on the mechanical properties. The results show that the metamaterial bandgap would move in real time as the cavity pressure changing. Meanwhile, the starting frequency of the bandgap could be varied from 29.6 Hz to 145.83 Hz, with approximately 5 times adjustment. And the bandgap width could be expanded to 5.7 times of the initial state, revealing an excellent wide range of tunable capabilities. Furthermore, the pneumatic actuation is a simple and reliable operation, enabling it to be normally employed in various extreme environments, such as the seabed. The mechanical metamaterials with a wide adjustable bandgap presented in this paper could provide a reference for the field of adaptive structures, offering a promising solution for the design of real-time adjustable mechanical metamaterials.
{"title":"A mechanical metamaterial with real-time tunable bandgap based on pneumatic actuation","authors":"Xin Liu , Shuai Chen , Bing Wang , Xiaojun Tan , Bo Cao , Liang Yu","doi":"10.1016/j.ijmecsci.2025.110045","DOIUrl":"10.1016/j.ijmecsci.2025.110045","url":null,"abstract":"<div><div>Mechanical metamaterials with real-time tunability are an up-and-coming field with great attention. Due to its capability of realizing different mechanical properties, it provides a foundation for the development of intelligent adaptive structures. In this paper, a mechanical metamaterial with real-time tunable bandgap is proposed, exhibiting a wide range of adjustability. With a combination of theory, numerical simulation and experimental studies, the quasi-static mechanical properties and bandgap characteristics of the metamaterial under constant and changeable pressure are investigated, revealing the effect mechanism of cavity pressures on the mechanical properties. The results show that the metamaterial bandgap would move in real time as the cavity pressure changing. Meanwhile, the starting frequency of the bandgap could be varied from 29.6 Hz to 145.83 Hz, with approximately 5 times adjustment. And the bandgap width could be expanded to 5.7 times of the initial state, revealing an excellent wide range of tunable capabilities. Furthermore, the pneumatic actuation is a simple and reliable operation, enabling it to be normally employed in various extreme environments, such as the seabed. The mechanical metamaterials with a wide adjustable bandgap presented in this paper could provide a reference for the field of adaptive structures, offering a promising solution for the design of real-time adjustable mechanical metamaterials.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110045"},"PeriodicalIF":7.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2025-02-12DOI: 10.1016/j.ijmecsci.2025.110035
Alexandre Mas, Anita Catapano, Marco Montemurro
Variable-stiffness composites (VSCs) can be efficiently designed, through multi-scale optimisation, to obtain thermal cloaks that can steer the heat flux to conceal the presence of an obstacle. Specifically, a general class of VSC structures characterised by variable fibres volume fraction, thickness and orthotropy orientation is considered in this work. The theoretical/numerical framework relies on the use of the polar formalism to describe the anisotropic thermal conductivity tensor of the VSC at the macroscopic scale, and on a general numerical homogenisation method to set the link between the design variables and the physical responses defined at different scales. In this context, the goal is to determine the optimal distribution of the fibres volume fraction, the orientation of the main orthotropy axis and the thickness of the VSC structure in order to design an efficient thermal cloak. The design variables fields are represented through non-uniform rational basis spline (NURBS) entities in order to achieve solutions that are compliant with standard computer-aided design software. Moreover, some properties of the NURBS entities, such as the local support property, are conveniently exploited to formally derive the gradient of the physical responses (and hence to speed-up the optimisation process), to automatically satisfy some manufacturability constraints (e.g., the continuity of the fibres-path) and to obtain mesh-independent solutions. The general nature of the proposed approach enables the concurrent optimisation of geometrical and physical variables at multiple scales, thus allowing the identification of optimised solutions that overcome the inherent limitations of the analytical solutions. The effectiveness of this approach is tested on benchmark problems taken from the literature. This entails an investigation into the impact of various factors, including the initial guess, the microscopic configuration of the constitutive phases of the composite material, the boundary conditions, the local thickness, the size and shape of the design region on the optimised solution.
{"title":"Multi-scale optimisation of variable-stiffness composites for thermal cloak","authors":"Alexandre Mas, Anita Catapano, Marco Montemurro","doi":"10.1016/j.ijmecsci.2025.110035","DOIUrl":"10.1016/j.ijmecsci.2025.110035","url":null,"abstract":"<div><div>Variable-stiffness composites (VSCs) can be efficiently designed, through multi-scale optimisation, to obtain thermal cloaks that can steer the heat flux to conceal the presence of an obstacle. Specifically, a general class of VSC structures characterised by variable fibres volume fraction, thickness and orthotropy orientation is considered in this work. The theoretical/numerical framework relies on the use of the polar formalism to describe the anisotropic thermal conductivity tensor of the VSC at the macroscopic scale, and on a general numerical homogenisation method to set the link between the design variables and the physical responses defined at different scales. In this context, the goal is to determine the optimal distribution of the fibres volume fraction, the orientation of the main orthotropy axis and the thickness of the VSC structure in order to design an efficient thermal cloak. The design variables fields are represented through non-uniform rational basis spline (NURBS) entities in order to achieve solutions that are compliant with standard computer-aided design software. Moreover, some properties of the NURBS entities, such as the local support property, are conveniently exploited to formally derive the gradient of the physical responses (and hence to speed-up the optimisation process), to automatically satisfy some manufacturability constraints (e.g., the continuity of the fibres-path) and to obtain mesh-independent solutions. The general nature of the proposed approach enables the concurrent optimisation of geometrical and physical variables at multiple scales, thus allowing the identification of optimised solutions that overcome the inherent limitations of the analytical solutions. The effectiveness of this approach is tested on benchmark problems taken from the literature. This entails an investigation into the impact of various factors, including the initial guess, the microscopic configuration of the constitutive phases of the composite material, the boundary conditions, the local thickness, the size and shape of the design region on the optimised solution.</div></div>","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"289 ","pages":"Article 110035"},"PeriodicalIF":7.1,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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