Pub Date : 2025-01-08DOI: 10.1016/j.ijmecsci.2025.109957
Mingxiang Ling, Jie Zhu, Shilei Wu, Lei Yuan, Xianmin Zhang
Lagrange's equation is usually combined with the compliance matrix method to solve the dynamics of compliant mechanisms that belongs to a time-domain approach. In contrast, we introduce a dynamic compliance matrix method (DCM) for both kinetostatics and vibration analyses of small-deformation compliant mechanisms in the frequency domain. We discuss in detail under what preconditions the so-called dynamic compliance matrix is valid and how it can be correctly transferred between flexure building blocks. Then, we propose a generalized procedure for the dynamic compliance modeling of serial-parallel chains by virtue of mechanical networks. In essence, such a new concept of DCM has a similar modeling process to traditional static compliance matrix method by mass grounding, but it enables both kinetostatic and dynamic modeling of compliant mechanisms in a pseudo-static way switched by setting the circular frequency to zero as needed. It relies on a matrix summation operation without the requirements of internal force analysis and kinematic calculation, hence is modeling-concise and programming-friendly for complex serial-parallel compliant mechanisms. Two case studies are presented to validate the proposed DCM and discuss its application scopes.
{"title":"A dynamic compliance matrix method for modeling compliant mechanisms","authors":"Mingxiang Ling, Jie Zhu, Shilei Wu, Lei Yuan, Xianmin Zhang","doi":"10.1016/j.ijmecsci.2025.109957","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109957","url":null,"abstract":"Lagrange's equation is usually combined with the compliance matrix method to solve the dynamics of compliant mechanisms that belongs to a time-domain approach. In contrast, we introduce a dynamic compliance matrix method (DCM) for both kinetostatics and vibration analyses of small-deformation compliant mechanisms in the frequency domain. We discuss in detail under what preconditions the so-called dynamic compliance matrix is valid and how it can be correctly transferred between flexure building blocks. Then, we propose a generalized procedure for the dynamic compliance modeling of serial-parallel chains by virtue of mechanical networks. In essence, such a new concept of DCM has a similar modeling process to traditional static compliance matrix method by mass grounding, but it enables both kinetostatic and dynamic modeling of compliant mechanisms in a pseudo-static way switched by setting the circular frequency to zero as needed. It relies on a matrix summation operation without the requirements of internal force analysis and kinematic calculation, hence is modeling-concise and programming-friendly for complex serial-parallel compliant mechanisms. Two case studies are presented to validate the proposed DCM and discuss its application scopes.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"75 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975234","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 : 2025-01-07DOI: 10.1016/j.ijmecsci.2025.109918
Lianzhou Wang, Hao Huang, Chenyu Huang, Xinyu Liu
Improved Delayed Detached Eddy Simulation (IDDES) method on a 48 million grid is utilized to numerically simulate the E779A propeller wake, with a focus on comparing the evolution mechanisms and dynamics of wake topology instability under varying loading conditions. A tip vortex identification method is employed to extract and analyze the evolution trajectories along with the core positions of the tip vortices. Based on this, a Lumley map is established to visualize the development of the turbulence anisotropy at the tip and hub vortex cores. Detailed discussions of the turbulent energy spectra across various regions of the wake are also conducted. In addition, mode structures are analyzed using a reduced order strategy, emphasizing variations under different loading conditions. As tip vortices evolve downstream, the distorted and deformed trailing edge vortices undergo mutual induction with adjacent downstream tip vortices, signaling the onset of elliptical instability and the beginning of vortex system destabilization. Eventually, turbulence anisotropy gradually takes up in the vortex core. Similarity in the turbulence energy spectra can be observed under all loading conditions, in terms of both the energy injection scale and the inertial subrange. Additionally, mode decomposition results of reduced order modeling are examined, focusing on spatial flow patterns and characteristic temporal frequencies. The results show that the circumferential and radial deformation significantly contributes to vortex instability. The present paper aims to provide an insightful perspective and valuable reference for understanding the key mechanisms of propeller wake dynamics.
{"title":"Investigation on the vortex dynamics in the wake of a rotating propeller","authors":"Lianzhou Wang, Hao Huang, Chenyu Huang, Xinyu Liu","doi":"10.1016/j.ijmecsci.2025.109918","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109918","url":null,"abstract":"Improved Delayed Detached Eddy Simulation (IDDES) method on a 48 million grid is utilized to numerically simulate the E779A propeller wake, with a focus on comparing the evolution mechanisms and dynamics of wake topology instability under varying loading conditions. A tip vortex identification method is employed to extract and analyze the evolution trajectories along with the core positions of the tip vortices. Based on this, a Lumley map is established to visualize the development of the turbulence anisotropy at the tip and hub vortex cores. Detailed discussions of the turbulent energy spectra across various regions of the wake are also conducted. In addition, mode structures are analyzed using a reduced order strategy, emphasizing variations under different loading conditions. As tip vortices evolve downstream, the distorted and deformed trailing edge vortices undergo mutual induction with adjacent downstream tip vortices, signaling the onset of elliptical instability and the beginning of vortex system destabilization. Eventually, turbulence anisotropy gradually takes up in the vortex core. Similarity in the turbulence energy spectra can be observed under all loading conditions, in terms of both the energy injection scale and the inertial subrange. Additionally, mode decomposition results of reduced order modeling are examined, focusing on spatial flow patterns and characteristic temporal frequencies. The results show that the circumferential and radial deformation significantly contributes to vortex instability. The present paper aims to provide an insightful perspective and valuable reference for understanding the key mechanisms of propeller wake dynamics.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"90 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975236","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 : 2025-01-07DOI: 10.1016/j.ijmecsci.2025.109938
Yulin Sun, Leon Mishnaevsky Jr.
Healable polymer blends with phase-separated thermoset/thermoplastic (TS/TP) microstructures have gained significant interest for their high potential in sustainable structural applications. To better understand the damage and healing behavior of these materials, an isotropic continuum cohesive damage-healing model specific to the healable TS/TP blends is first presented within the framework of finite element method. Traction–separation laws of cohesive models are integrated into regular finite elements, where damage variables of each element can be achieved by explicit modeling of crack evolution. A parabolic damage evolution law is derived for elastoplastic polycaprolactone (PCL) based on its experimental stress–strain behavior. Temperature-dependent material properties and time-dependent loading are incorporated in the model. The phase change of PCL is characterized by linking its modulus to crystallinity. The proposed model is validated by applying the model prediction for epoxy/PCL blends consisting of epoxy particles and PCL matrix and comparing the results with experimental data in available literature. Representative volume element (RVE) models of epoxy/PCL blends are developed from realistic micrographs through image-based model generation to capture true microstructures. The proposed model provides a good starting basis for understanding the damage and healing mechanisms in healable TS/TP polymer blends.
{"title":"Healable polymer blends: Computational analysis of damage and healing mechanisms","authors":"Yulin Sun, Leon Mishnaevsky Jr.","doi":"10.1016/j.ijmecsci.2025.109938","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109938","url":null,"abstract":"Healable polymer blends with phase-separated thermoset/thermoplastic (TS/TP) microstructures have gained significant interest for their high potential in sustainable structural applications. To better understand the damage and healing behavior of these materials, an isotropic continuum cohesive damage-healing model specific to the healable TS/TP blends is first presented within the framework of finite element method. Traction–separation laws of cohesive models are integrated into regular finite elements, where damage variables of each element can be achieved by explicit modeling of crack evolution. A parabolic damage evolution law is derived for elastoplastic polycaprolactone (PCL) based on its experimental stress–strain behavior. Temperature-dependent material properties and time-dependent loading are incorporated in the model. The phase change of PCL is characterized by linking its modulus to crystallinity. The proposed model is validated by applying the model prediction for epoxy/PCL blends consisting of epoxy particles and PCL matrix and comparing the results with experimental data in available literature. Representative volume element (RVE) models of epoxy/PCL blends are developed from realistic micrographs through image-based model generation to capture true microstructures. The proposed model provides a good starting basis for understanding the damage and healing mechanisms in healable TS/TP polymer blends.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"51 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975233","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 : 2025-01-07DOI: 10.1016/j.ijmecsci.2025.109947
Lingyue Ma, Hagit Sagi, Rami Eliasy, Dov Sherman
We report on a new, cost-effective, and relatively simple experimental method to evaluate the Griffith barrier, initiation, and arrest energies in cracked brittle specimens under Mode-I conditions, by a stable crack propagation under displacement control conditions. Obreimoff's experiment inspired the new method, and thus we termed it the Obreimoff-inspired Coefficient of Thermal Expansion Mismatch (OCTEM) method. It includes inserting a 10 mm by diameter low angle conic aluminum pin into a perfectly matched conic hole in a rectangular thin precracked brittle specimen. Upon heating the assembly on top of an electrical heating stage, the thermal expansion coefficients mismatch between the aluminum pin and specimen generated sufficient deformation until the crack propagates stably. Silicon specimens, where the cracks propagated on the (110)[11¯0] low energy cleavage system, were used as a model material. Cracks propagated stably in cycles of initiation, propagation, and arrest. Measuring the specimens’ temperatures during the experiments and depicting the temporal crack lengths allowed us to evaluate a set of initiation and arrest energies using linear elastic, plane stress, and contact problems with friction finite element analysis. The cleavage energy decreased as crack length grew in a stable propagation, similar to what we observed in unstable cracks. We show the importance of the gradient of the strain energy release rate (SERR), Θ¯dG0/da, on the cleavage energies. Finally, we compared the cleavage energy at initiation vs. Θ¯ for stable and unstable conditions.
{"title":"The Griffith barrier, initiation, and arrest energies by stable cracks","authors":"Lingyue Ma, Hagit Sagi, Rami Eliasy, Dov Sherman","doi":"10.1016/j.ijmecsci.2025.109947","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109947","url":null,"abstract":"We report on a new, cost-effective, and relatively simple experimental method to evaluate the Griffith barrier, initiation, and arrest energies in cracked brittle specimens under Mode-I conditions, by a stable crack propagation under displacement control conditions. Obreimoff's experiment inspired the new method, and thus we termed it the Obreimoff-inspired Coefficient of Thermal Expansion Mismatch (OCTEM) method. It includes inserting a 10 mm by diameter low angle conic aluminum pin into a perfectly matched conic hole in a rectangular thin precracked brittle specimen. Upon heating the assembly on top of an electrical heating stage, the thermal expansion coefficients mismatch between the aluminum pin and specimen generated sufficient deformation until the crack propagates stably. Silicon specimens, where the cracks propagated on the (110)[1<mml:math altimg=\"si2.svg\"><mml:mover accent=\"true\"><mml:mn>1</mml:mn><mml:mo>¯</mml:mo></mml:mover></mml:math>0] low energy cleavage system, were used as a model material. Cracks propagated stably in cycles of initiation, propagation, and arrest. Measuring the specimens’ temperatures during the experiments and depicting the temporal crack lengths allowed us to evaluate a set of initiation and arrest energies using linear elastic, plane stress, and contact problems with friction finite element analysis. The cleavage energy decreased as crack length grew in a stable propagation, similar to what we observed in unstable cracks. We show the importance of the gradient of the strain energy release rate (SERR), <mml:math altimg=\"si3.svg\"><mml:mrow><mml:mover accent=\"true\"><mml:mstyle mathvariant=\"normal\"><mml:mi>Θ</mml:mi></mml:mstyle><mml:mo>¯</mml:mo></mml:mover><mml:mspace width=\"0.16em\"></mml:mspace><mml:mspace width=\"0.28em\"></mml:mspace></mml:mrow></mml:math><ce:glyph name=\"tbnd\"></ce:glyph><ce:italic>dG<ce:inf loc=\"post\">0</ce:inf>/</ce:italic>da, on the cleavage energies. Finally, we compared the cleavage energy at initiation vs. <mml:math altimg=\"si3.svg\"><mml:mrow><mml:mover accent=\"true\"><mml:mstyle mathvariant=\"normal\"><mml:mi>Θ</mml:mi></mml:mstyle><mml:mo>¯</mml:mo></mml:mover><mml:mspace width=\"0.16em\"></mml:mspace><mml:mspace width=\"0.28em\"></mml:mspace></mml:mrow></mml:math> for stable and unstable conditions.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"41 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975238","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}
Soft pneumatic actuators have attracted considerable interest in recent years due to their high output force, large deflection and safe operation features. Despite extensive research, achieving a balance between the simplicity of the structural design and the performance of the actuator motion remains a significant challenge. This study introduces an elastic-soft hybrid pneumatic actuator, which integrates an origami chamber and an elastic plate. Unlike traditional symmetric cylindrical origami chamber based on hyperelastic material, the proposed chamber is made of soft but unstretchable fabric, which incorporates an asymmetric quadrilateral geometric configuration, enabling the generation of high output forces and large deflection capabilities. The elastic plate is strategically affixed to the chamber, serving to establish stiffness anisotropy and to induce controlled directional bending. A fabrication method based on 3D printing technology is proposed as a means of enabling the rapid and high-precision manufacturing of the actuator. This design exhibits high motion accuracy, low dead weight, and delivers significant output force. Moreover, a kineto-static analytical model is further established based on the principle of virtual work and discretization method. This model enables precise predict of the actuator, thereby enhancing the control performance of the system. The experimental validation of the motion performance of the actuator prototype and the theoretical model’s accuracy is presented. Additionally, a parallel pneumatic manipulator is developed to demonstrate the actuator’s capability in executing precise manipulation tasks. This research offers a novel perspective on the design and application of straightforward, high-performance soft pneumatic actuators with origami structures.
{"title":"A high-performance elastic-soft hybrid pneumatic actuator with origami structure","authors":"Yongzhou Long, Xingyue Zhu, Pu Shi, Qingyu Liu, Yanjun Wang, Hao Wang, Genliang Chen","doi":"10.1016/j.ijmecsci.2025.109935","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109935","url":null,"abstract":"Soft pneumatic actuators have attracted considerable interest in recent years due to their high output force, large deflection and safe operation features. Despite extensive research, achieving a balance between the simplicity of the structural design and the performance of the actuator motion remains a significant challenge. This study introduces an elastic-soft hybrid pneumatic actuator, which integrates an origami chamber and an elastic plate. Unlike traditional symmetric cylindrical origami chamber based on hyperelastic material, the proposed chamber is made of soft but unstretchable fabric, which incorporates an asymmetric quadrilateral geometric configuration, enabling the generation of high output forces and large deflection capabilities. The elastic plate is strategically affixed to the chamber, serving to establish stiffness anisotropy and to induce controlled directional bending. A fabrication method based on 3D printing technology is proposed as a means of enabling the rapid and high-precision manufacturing of the actuator. This design exhibits high motion accuracy, low dead weight, and delivers significant output force. Moreover, a kineto-static analytical model is further established based on the principle of virtual work and discretization method. This model enables precise predict of the actuator, thereby enhancing the control performance of the system. The experimental validation of the motion performance of the actuator prototype and the theoretical model’s accuracy is presented. Additionally, a parallel pneumatic manipulator is developed to demonstrate the actuator’s capability in executing precise manipulation tasks. This research offers a novel perspective on the design and application of straightforward, high-performance soft pneumatic actuators with origami structures.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"51 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975248","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}
This paper introduces a novel arc curved crease origami (ACCO) metamaterial based on Miura origami, that shows improved specific energy absorption, indicating a major advancement over traditional Miura origami. The quasi-static mechanical properties and energy absorption characteristics of the ACCO metamaterials were studied through experiments and finite element analysis. Results reveal that the ACCO metamaterials’ tailored inter-shell angles ensure consistent enhanced performance and energy absorption across all compression directions, offering lightweight and durable structures with versatile anisotropic properties. The bi-directional graded design of ACCO metamaterials, featuring adjustable shell angles, central angles, and cell thicknesses, has resulted in a new class of lightweight, high-energy-absorptive metamaterials. Our research confirms that advanced ACCO metamaterials optimize energy absorption efficiency and possess an enhanced energy dissipation system, outperforming traditional origami metamaterials. These findings suggest that ACCO metamaterials are promising for energy absorption applications and provide valuable design principles for origami-based energy absorption devices.
{"title":"Quasi-static mechanical behaviors of arc curved crease origami metamaterials","authors":"Jianzhang Huang, Jing Lin, Liwei Huang, Yijie Liu, Xinmei Xiang, Yingjing Liang","doi":"10.1016/j.ijmecsci.2025.109939","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109939","url":null,"abstract":"This paper introduces a novel arc curved crease origami (ACCO) metamaterial based on Miura origami, that shows improved specific energy absorption, indicating a major advancement over traditional Miura origami. The quasi-static mechanical properties and energy absorption characteristics of the ACCO metamaterials were studied through experiments and finite element analysis. Results reveal that the ACCO metamaterials’ tailored inter-shell angles ensure consistent enhanced performance and energy absorption across all compression directions, offering lightweight and durable structures with versatile anisotropic properties. The bi-directional graded design of ACCO metamaterials, featuring adjustable shell angles, central angles, and cell thicknesses, has resulted in a new class of lightweight, high-energy-absorptive metamaterials. Our research confirms that advanced ACCO metamaterials optimize energy absorption efficiency and possess an enhanced energy dissipation system, outperforming traditional origami metamaterials. These findings suggest that ACCO metamaterials are promising for energy absorption applications and provide valuable design principles for origami-based energy absorption devices.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"26 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142975249","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}
To understand the material removal and damage evolution mechanisms of GaN crystals involved in graphene oxide (GO) lubrication-assisted grinding, molecular dynamics (MD) simulations of single-grit grinding were performed under different GO concentrations. The findings demonstrated that the GO nanosheets presented a favorable dispersion behavior in the low-concentration coolant; however, at excessively high concentrations, they exhibited severe agglomeration, which hindered the effective interaction between GO nanosheets and the workpiece. With the increase in GO concentration, the material removal rate, elastic recovery amount, normal grinding stress, surface roughness, and subsurface damage depth initially decreased and subsequently increased. Grinding assisted by GO lubrication at an appropriate GO concentration effectively minimized the grinding force, friction coefficient, grinding temperature, grinding stress, elastic recovery, and dislocation density compared to dry grinding and pure water-lubricated grinding, thereby enhancing both surface and subsurface quality. In addition, appropriately reducing the grinding depth and increasing the grinding speed effectively minimized the subsurface damage depth. However, an excessively high grinding speed would lead to an increase in both grinding temperature and surface roughness. These findings not only enhance our understanding of the atomic-scale removal mechanisms of GaN substrates facilitated by GO nanosheets in abrasive machining process, but also present a novel strategy for the efficient and ultra-precision machining of other brittle solids.
{"title":"Atomic-scale understanding of graphene oxide lubrication-assisted grinding of GaN crystals","authors":"Chen Li, Guangyin Liu, Chenxi Gao, Rui Yang, Oleg Zakharov, Yuxiu Hu, Yongda Yan, Yanquan Geng","doi":"10.1016/j.ijmecsci.2025.109934","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109934","url":null,"abstract":"To understand the material removal and damage evolution mechanisms of GaN crystals involved in graphene oxide (GO) lubrication-assisted grinding, molecular dynamics (MD) simulations of single-grit grinding were performed under different GO concentrations. The findings demonstrated that the GO nanosheets presented a favorable dispersion behavior in the low-concentration coolant; however, at excessively high concentrations, they exhibited severe agglomeration, which hindered the effective interaction between GO nanosheets and the workpiece. With the increase in GO concentration, the material removal rate, elastic recovery amount, normal grinding stress, surface roughness, and subsurface damage depth initially decreased and subsequently increased. Grinding assisted by GO lubrication at an appropriate GO concentration effectively minimized the grinding force, friction coefficient, grinding temperature, grinding stress, elastic recovery, and dislocation density compared to dry grinding and pure water-lubricated grinding, thereby enhancing both surface and subsurface quality. In addition, appropriately reducing the grinding depth and increasing the grinding speed effectively minimized the subsurface damage depth. However, an excessively high grinding speed would lead to an increase in both grinding temperature and surface roughness. These findings not only enhance our understanding of the atomic-scale removal mechanisms of GaN substrates facilitated by GO nanosheets in abrasive machining process, but also present a novel strategy for the efficient and ultra-precision machining of other brittle solids.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"3 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929188","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}
Terahertz (THz) metalenses have attracted significant attention due to their potentials in advanced imaging, sensing, and communication applications, offering compact, lightweight designs and superior focusing capabilities compared to the conventional lenses. However, few studies have focused on polarization-independent bifocal metalenses in this frequency range. In this work, we design and demonstrate a transmissive all-dielectric bifocal metalens (ADBM), studied through simulation, optimization, fabrication, testing, and imaging methods. The metalens, composed of cross-shaped microrod phase elements made of high-resistivity silicon (Si), features low absorption, high transmission, and a simplified fabrication process. It generates distinct focal lengths for incident waves in transverse electric (TE) and transverse magnetic (TM) polarization states. They are 19.93 mm and 37.98 mm in TE and TM modes, respectively, enabling bifocal functionality. To enhance focusing performances, an error evaluation function is introduced to reduce phase errors during polarization multiplexing. The impact of different parameters in the error evaluation function on focusing performances is also discussed. ADBM achieves high Strehl ratios of 0.87 and 0.92 in TE and TM modes, respectively, indicating diffraction-limited focusing performances. Additionally, ADBM exhibits broadband focusing performances across the 0.70 THz to 1.10 THz spectra range for both polarizations. The fabricated ADBM exhibits high-resolution imaging capabilities, whihc are in agreement with simulations. This innovative design provides a new strategy for controlling orthogonal polarization states, promising broad applications in advanced optical imaging and communication.
{"title":"All-dielectric bifocal metalens with diffraction-limited focusing and polarization-dependent characteristics","authors":"Xuyang Gao, Yuxin Liu, Hao Chen, Yu-Sheng Lin, Xuequan Chen","doi":"10.1016/j.ijmecsci.2025.109916","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109916","url":null,"abstract":"Terahertz (THz) metalenses have attracted significant attention due to their potentials in advanced imaging, sensing, and communication applications, offering compact, lightweight designs and superior focusing capabilities compared to the conventional lenses. However, few studies have focused on polarization-independent bifocal metalenses in this frequency range. In this work, we design and demonstrate a transmissive all-dielectric bifocal metalens (ADBM), studied through simulation, optimization, fabrication, testing, and imaging methods. The metalens, composed of cross-shaped microrod phase elements made of high-resistivity silicon (Si), features low absorption, high transmission, and a simplified fabrication process. It generates distinct focal lengths for incident waves in transverse electric (TE) and transverse magnetic (TM) polarization states. They are 19.93 mm and 37.98 mm in TE and TM modes, respectively, enabling bifocal functionality. To enhance focusing performances, an error evaluation function is introduced to reduce phase errors during polarization multiplexing. The impact of different parameters in the error evaluation function on focusing performances is also discussed. ADBM achieves high Strehl ratios of 0.87 and 0.92 in TE and TM modes, respectively, indicating diffraction-limited focusing performances. Additionally, ADBM exhibits broadband focusing performances across the 0.70 THz to 1.10 THz spectra range for both polarizations. The fabricated ADBM exhibits high-resolution imaging capabilities, whihc are in agreement with simulations. This innovative design provides a new strategy for controlling orthogonal polarization states, promising broad applications in advanced optical imaging and communication.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"20 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929191","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 : 2025-01-02DOI: 10.1016/j.ijmecsci.2025.109931
Ruisen Fu, Chenlu Wang, Nusrat Shahneela, Rahman Ud Din, Haisheng Yang
The mechanical adaptive responses of bone are affected by various parameters of the loading, such as magnitude, rate, frequency, number of cycles, and recovery time. However, the precise relationships between different loading parameters and bone adaptation as well as their governing mechanism remain unclear. Here, we developed a novel multi-scale model of whole bone-lacunocanalicular network (LCN)-osteocyte characterizing whole-bone deformation-produced fluid flow within a large LCN as well as responses of osteocytes to fluid shear stress (FSS) via opening, closing, or inactivating mechanosensitive ion channels (MSIC). The model was next used to examine the effects of loading magnitude, frequency, cycle numbers, and recovery time on the responses of osteocytes. Results showed that the load magnitude and frequency mainly affected the proportion of open MSIC by changing FSS on the osteocytes. When the load-induced FSS increased, the proportion of open osteocyte MSIC was enhanced. With an increase in the cycle number, MSIC transformed gradually from an open state into an inactivated state, resulting in saturation in response to continuous FSS. Interestingly, a short-term recovery time restored the MSIC to a closed state which could turn into an open state following subsequent loading, while a long-term recovery time was helpful for recovering the mechanical sensitivity of the osteocytes. These computational results largely replicated the mechanical responses of bone as observed in in vivo animal loading experiments, suggesting the importance of osteocyte MSIC in response to different loading parameters. This multi-scale model considering osteocyte MSIC could provide mechanistic insights into bone adaptation to distinct mechanical stimuli.
{"title":"A whole bone-lacunocanalicular network-osteocyte model examining bone adaptation to distinct loading parameters","authors":"Ruisen Fu, Chenlu Wang, Nusrat Shahneela, Rahman Ud Din, Haisheng Yang","doi":"10.1016/j.ijmecsci.2025.109931","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2025.109931","url":null,"abstract":"The mechanical adaptive responses of bone are affected by various parameters of the loading, such as magnitude, rate, frequency, number of cycles, and recovery time. However, the precise relationships between different loading parameters and bone adaptation as well as their governing mechanism remain unclear. Here, we developed a novel multi-scale model of whole bone-lacunocanalicular network (LCN)-osteocyte characterizing whole-bone deformation-produced fluid flow within a large LCN as well as responses of osteocytes to fluid shear stress (FSS) via opening, closing, or inactivating mechanosensitive ion channels (MSIC). The model was next used to examine the effects of loading magnitude, frequency, cycle numbers, and recovery time on the responses of osteocytes. Results showed that the load magnitude and frequency mainly affected the proportion of open MSIC by changing FSS on the osteocytes. When the load-induced FSS increased, the proportion of open osteocyte MSIC was enhanced. With an increase in the cycle number, MSIC transformed gradually from an open state into an inactivated state, resulting in saturation in response to continuous FSS. Interestingly, a short-term recovery time restored the MSIC to a closed state which could turn into an open state following subsequent loading, while a long-term recovery time was helpful for recovering the mechanical sensitivity of the osteocytes. These computational results largely replicated the mechanical responses of bone as observed in <ce:italic>in vivo</ce:italic> animal loading experiments, suggesting the importance of osteocyte MSIC in response to different loading parameters. This multi-scale model considering osteocyte MSIC could provide mechanistic insights into bone adaptation to distinct mechanical stimuli.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"27 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929189","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}
The linear transformation has been successfully used to characterize the anisotropic ductile fracture, whereas the physical background of the transformed anisotropic stress state or the equivalent plastic strain becomes somewhat vague. This deficiency in the linear-transformation model might overlook the microscopic mechanisms of the anisotropic ductile fracture related to various stress states and loading direction. Therefore, this paper proposes an advanced linear-transformation-free anisotropic ductile fracture modeling framework that is dependent on stress triaxiality and the Lode angle, two state variables intimately related to microscopic fracture mechanisms. Notably, the model introduces the critical principal stress direction to account for the dependency on loading direction. The stress state variables and principal stress direction correspond to the geometry and sampling direction straightforwardly, which significantly facilitates the calibration of fracture parameters. Furthermore, compared to traditional linear-transformation-based anisotropic models, the proposed model is underpinned by a clear physical basis and accurately captures the relationships between triaxiality, Lode angle and material ductility with respect to varying loading directions. This model has been calibrated and validated based on the testing program on aluminum alloy 6061-T6 rolled plates under various stress states, considering both in-plane and out-of-plane anisotropies. The accurate prediction in terms of the softening initiation and failure modes for all testing cases demonstrate the validity of the proposed anisotropic ductile fracture model, as evidenced by the low averaged percentage of damage indicator at softening initiation at 4.6 %.
{"title":"Linear-transformation-free anisotropic ductile fracture model based on critical principal-stress-direction","authors":"Peihua Zhu, Weigang Zhao, Zhiyang Xie, Shitong Chen","doi":"10.1016/j.ijmecsci.2024.109914","DOIUrl":"https://doi.org/10.1016/j.ijmecsci.2024.109914","url":null,"abstract":"The linear transformation has been successfully used to characterize the anisotropic ductile fracture, whereas the physical background of the transformed anisotropic stress state or the equivalent plastic strain becomes somewhat vague. This deficiency in the linear-transformation model might overlook the microscopic mechanisms of the anisotropic ductile fracture related to various stress states and loading direction. Therefore, this paper proposes an advanced linear-transformation-free anisotropic ductile fracture modeling framework that is dependent on stress triaxiality and the Lode angle, two state variables intimately related to microscopic fracture mechanisms. Notably, the model introduces the critical principal stress direction to account for the dependency on loading direction. The stress state variables and principal stress direction correspond to the geometry and sampling direction straightforwardly, which significantly facilitates the calibration of fracture parameters. Furthermore, compared to traditional linear-transformation-based anisotropic models, the proposed model is underpinned by a clear physical basis and accurately captures the relationships between triaxiality, Lode angle and material ductility with respect to varying loading directions. This model has been calibrated and validated based on the testing program on aluminum alloy 6061-T6 rolled plates under various stress states, considering both in-plane and out-of-plane anisotropies. The accurate prediction in terms of the softening initiation and failure modes for all testing cases demonstrate the validity of the proposed anisotropic ductile fracture model, as evidenced by the low averaged percentage of damage indicator at softening initiation at 4.6 %.","PeriodicalId":56287,"journal":{"name":"International Journal of Mechanical Sciences","volume":"25 1","pages":""},"PeriodicalIF":7.3,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142929212","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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