Abstract The near-field logarithmic singularities in the field quantities associated with the acceleration of an arbitrarily moving edge dislocation are calculated based on a conservation law involving the dynamic energy-momentum tensor integrated over a domain enclosed by a multi-scale contour (an annulus of inner radius ϵ02 and outer radius ϵ0). The existence of the logarithmic singularities is obtained solely from the conservation law and the leading 1/r terms in the near fields of the stress and the velocity (which are those of the steady-state motion with velocity the instantaneous velocity in the accelerating motion). From the equations of motion and the symmetry in the second partial derivatives of the displacements for y≠0 we obtain that all six logarithmic terms of the near-field expansions are independent of the angle in the polar coordinates. All logarithmic terms in the near-field expansion of the strains and velocity in an arbitrarily moving edge dislocation (subsonically) are evaluated.
{"title":"The Dynamic Energy-Momentum Tensor and the Logarithmic Singularity of a Generally Accelerating Edge Dislocation","authors":"Luqun Ni, Xanthippi Markenscoff","doi":"10.1115/1.4062629","DOIUrl":"https://doi.org/10.1115/1.4062629","url":null,"abstract":"Abstract The near-field logarithmic singularities in the field quantities associated with the acceleration of an arbitrarily moving edge dislocation are calculated based on a conservation law involving the dynamic energy-momentum tensor integrated over a domain enclosed by a multi-scale contour (an annulus of inner radius ϵ02 and outer radius ϵ0). The existence of the logarithmic singularities is obtained solely from the conservation law and the leading 1/r terms in the near fields of the stress and the velocity (which are those of the steady-state motion with velocity the instantaneous velocity in the accelerating motion). From the equations of motion and the symmetry in the second partial derivatives of the displacements for y≠0 we obtain that all six logarithmic terms of the near-field expansions are independent of the angle in the polar coordinates. All logarithmic terms in the near-field expansion of the strains and velocity in an arbitrarily moving edge dislocation (subsonically) are evaluated.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135938175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurately predicting the hyperelastic response of soft materials under complex loading conditions has been a long-standing challenge. Previous developments have shown that incorporating the entanglement effect can significantly improve the model performance. In this work, we compare the performances of different entanglement models in simulating the stress responses through either fitting uniaxial data alone or uniaxial and equibiaxial data simultaneously. Results show that the entanglement models do not exhibit satisfactory predictive ability with parameters calibrated through uniaxial data. This disadvantage can be overcome through a newly proposed Biot chain model, which inherently incorporates the entanglement effect though a new chain stretch determination that considers the contribution of all surrounding chains. As multiple pairs of experimental data are used to calibrate the model parameter, the Davidson-Goulbourne model provides the best performance. It is also demonstrated that the entanglement effect varies with the deformation mode and plays a more critical role in biaxial deformation than that in the uniaxial deformation. This study can provide a better understanding of entanglement models, including their capabilities and limitations, facilitating the development of more accurate and reliable predictive models toward various applications.
{"title":"A comparative study of the entanglement models toward simulating hyperelastic behaviors","authors":"Lingrui Zhu, Lin Zhan, Rui Xiao","doi":"10.1115/1.4063348","DOIUrl":"https://doi.org/10.1115/1.4063348","url":null,"abstract":"\u0000 Accurately predicting the hyperelastic response of soft materials under complex loading conditions has been a long-standing challenge. Previous developments have shown that incorporating the entanglement effect can significantly improve the model performance. In this work, we compare the performances of different entanglement models in simulating the stress responses through either fitting uniaxial data alone or uniaxial and equibiaxial data simultaneously. Results show that the entanglement models do not exhibit satisfactory predictive ability with parameters calibrated through uniaxial data. This disadvantage can be overcome through a newly proposed Biot chain model, which inherently incorporates the entanglement effect though a new chain stretch determination that considers the contribution of all surrounding chains. As multiple pairs of experimental data are used to calibrate the model parameter, the Davidson-Goulbourne model provides the best performance. It is also demonstrated that the entanglement effect varies with the deformation mode and plays a more critical role in biaxial deformation than that in the uniaxial deformation. This study can provide a better understanding of entanglement models, including their capabilities and limitations, facilitating the development of more accurate and reliable predictive models toward various applications.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49033915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, a new inertia modulated meta-structure is proposed to enable time-dependent inertia parameters, and thereby realize non-reciprocal wave propagation via spatiotemporal modulation. The designed cell structure is composed of an oscillatory disk and a mass that slides in a guide embedded in the disk frictionlessly with prescribed motion. Effective moment of inertia and damping coefficients of the rocking motion of the cell structure are rendered time-dependent due to the inertia and Coriolis forces of the periodically sliding mass, which allows us to implement the expected spatiotemporal modulation upon a super-cell. Non-reciprocal propagation behavior of the proposed meta-structure is verified via theoretical solution of the dispersion relation as well as dynamic response of a finite array. Effects of modulation parameters, including the frequency, amplitude, and phase, on the unidirectional propagation characteristic are thoroughly investigated.
{"title":"Inertia Modulated Meta-structure with Time-Varying Inertia Amplification","authors":"Hao Gao, Junzhe Zhu, Y. Qu, Guang Meng","doi":"10.1115/1.4063347","DOIUrl":"https://doi.org/10.1115/1.4063347","url":null,"abstract":"\u0000 In this work, a new inertia modulated meta-structure is proposed to enable time-dependent inertia parameters, and thereby realize non-reciprocal wave propagation via spatiotemporal modulation. The designed cell structure is composed of an oscillatory disk and a mass that slides in a guide embedded in the disk frictionlessly with prescribed motion. Effective moment of inertia and damping coefficients of the rocking motion of the cell structure are rendered time-dependent due to the inertia and Coriolis forces of the periodically sliding mass, which allows us to implement the expected spatiotemporal modulation upon a super-cell. Non-reciprocal propagation behavior of the proposed meta-structure is verified via theoretical solution of the dispersion relation as well as dynamic response of a finite array. Effects of modulation parameters, including the frequency, amplitude, and phase, on the unidirectional propagation characteristic are thoroughly investigated.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43597460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamics of the electroactive membranes are being studied extensively due to their vast application at the current time. However, the effect of the mechanical behavior of the compliant electrode needs to be addressed. This paper presents the non-linear analysis of an electrically actuated membrane, considering the inertia of the electrode. The membrane is modeled as a hyperelastic material and is assumed to be incompressible, homogeneous, and isotropic. The proposed analysis is discussed in a generalized way for both the compression and suspension phases. Since the membrane is vulnerable to pull-in instability, the conditions to prevent electromechanical instability are defined. Further, an analytical relation is established for breakdown voltage and is validated with experimental data. The analytical solution of axial vibration is presented in the form of elliptic integrals and by the use of multiple scale method in a generalised way for both the phases. The resultant motions and their various physical aspects under suspension and compression phases for general initial conditions are described through graphical results to comprehend the proposed analysis. Also, parameter values are quantified analytically, for which the system executes reverse behaviour in a given configuration.
{"title":"Effect of electrode on the dynamics of electroactive membrane","authors":"R. Ranjan, S. Sarangi","doi":"10.1115/1.4063346","DOIUrl":"https://doi.org/10.1115/1.4063346","url":null,"abstract":"\u0000 The dynamics of the electroactive membranes are being studied extensively due to their vast application at the current time. However, the effect of the mechanical behavior of the compliant electrode needs to be addressed. This paper presents the non-linear analysis of an electrically actuated membrane, considering the inertia of the electrode. The membrane is modeled as a hyperelastic material and is assumed to be incompressible, homogeneous, and isotropic. The proposed analysis is discussed in a generalized way for both the compression and suspension phases. Since the membrane is vulnerable to pull-in instability, the conditions to prevent electromechanical instability are defined. Further, an analytical relation is established for breakdown voltage and is validated with experimental data. The analytical solution of axial vibration is presented in the form of elliptic integrals and by the use of multiple scale method in a generalised way for both the phases. The resultant motions and their various physical aspects under suspension and compression phases for general initial conditions are described through graphical results to comprehend the proposed analysis. Also, parameter values are quantified analytically, for which the system executes reverse behaviour in a given configuration.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46831279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The spatial variation of the coefficient of restitution for frictionless impacts along the length of a circular beam is investigated using a continuous impact model. The equations of motion are obtained using the finite element method and direct time integration is used to simulate the collision on a fast time scale. For collision of a pinned beam with a fixed cylinder, the spatial variation of the coefficient of restitution, impulse magnitude, duration of collision, energetics, and the role of damping are investigated. In the absence of significant external damping, the kinematic and kinetic definitions of the coefficient of restitution provide identical results. Experiments validate the results from simulation which indicate that the coefficient of restitution is sensitive to the location of impact.
{"title":"Spatial Variation of the Coefficient of Restitution for Frictionless Impacts on Circular Beams","authors":"Aakash Khandelwal, R. Mukherjee","doi":"10.1115/1.4063218","DOIUrl":"https://doi.org/10.1115/1.4063218","url":null,"abstract":"\u0000 The spatial variation of the coefficient of restitution for frictionless impacts along the length of a circular beam is investigated using a continuous impact model. The equations of motion are obtained using the finite element method and direct time integration is used to simulate the collision on a fast time scale. For collision of a pinned beam with a fixed cylinder, the spatial variation of the coefficient of restitution, impulse magnitude, duration of collision, energetics, and the role of damping are investigated. In the absence of significant external damping, the kinematic and kinetic definitions of the coefficient of restitution provide identical results. Experiments validate the results from simulation which indicate that the coefficient of restitution is sensitive to the location of impact.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41317600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liquid crystal elastomers (LCEs) are made of liquid crystal molecules linked into rubber-like polymer networks. An LCE exhibits both the thermotropic property of liquid crystals and large deformation of elastomers. It can be monodomain or polydomain in the nematic phase and transforms to an isotropic phase at elevated temperature. These features have enabled various applications of LCEs in robotics and other fields. However, despite substantial research and development in recent years, thermomechanical coupling in polydomain LCEs remains poorly studied, such as their temperature-dependent mechanical response and stretch-influenced isotropic-nematic phase transition. This knowledge gap limits the fundamental understanding of the structure-property relationship, as well as future developments of LCEs with precisely controlled material behaviors. Here we construct a theoretical model to investigate thermomechanical coupling in polydomain LCEs, which includes a quasi-convex elastic energy of the polymer network and a free energy of mesogens. We study working conditions where a polydomain LCE is subjected to various prescribed planar stretches and temperatures. The quasi-convex elastic energy enables a “mechanical phase diagram” that describes the macroscopic effective mechanical response of the material, and the free energy of mesogens governs their first-order nematic-isotropic phase transition. Evolution of the mechanical phase diagram and the order parameter with temperature is predicted and discussed. Temperature-dependent mechanical behaviors of the polydomain LCE that have never been reported before are shown in their stress-stretch curves. These results are hoped to motivate future fundamental studies and applications of thermomechanical LCEs.
{"title":"Thermomechanical Coupling in Polydomain Liquid Crystal Elastomers","authors":"Zhengxuan Wei, Peixun Wang, Ruobing Bai","doi":"10.1115/1.4063219","DOIUrl":"https://doi.org/10.1115/1.4063219","url":null,"abstract":"\u0000 Liquid crystal elastomers (LCEs) are made of liquid crystal molecules linked into rubber-like polymer networks. An LCE exhibits both the thermotropic property of liquid crystals and large deformation of elastomers. It can be monodomain or polydomain in the nematic phase and transforms to an isotropic phase at elevated temperature. These features have enabled various applications of LCEs in robotics and other fields. However, despite substantial research and development in recent years, thermomechanical coupling in polydomain LCEs remains poorly studied, such as their temperature-dependent mechanical response and stretch-influenced isotropic-nematic phase transition. This knowledge gap limits the fundamental understanding of the structure-property relationship, as well as future developments of LCEs with precisely controlled material behaviors. Here we construct a theoretical model to investigate thermomechanical coupling in polydomain LCEs, which includes a quasi-convex elastic energy of the polymer network and a free energy of mesogens. We study working conditions where a polydomain LCE is subjected to various prescribed planar stretches and temperatures. The quasi-convex elastic energy enables a “mechanical phase diagram” that describes the macroscopic effective mechanical response of the material, and the free energy of mesogens governs their first-order nematic-isotropic phase transition. Evolution of the mechanical phase diagram and the order parameter with temperature is predicted and discussed. Temperature-dependent mechanical behaviors of the polydomain LCE that have never been reported before are shown in their stress-stretch curves. These results are hoped to motivate future fundamental studies and applications of thermomechanical LCEs.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44179931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The J-integral is applied to the single cantilever beam (SCB) and double cantilever beam (DCB) test specimens subjected to both mixed mode I and II loading and large displacements. The methods proposed and resulting closed form theoretical equations allow for the instantaneous evaluation of J during laboratory tests, requiring only the applied load and angular rotation of the specimen loading link, loading points and remaining ligament. These measurands can be acquired using a common load cell and markers, digital video camera, and video analysis software. In general, the equations do require knowledge of the specimen elastic moduli and shear moduli, as well as the specimen linear dimensions. Since the test data can be analyzed and J determined throughout the test instantaneously, and since, due to geometric non-linearities, the ratio of mode I and mode II loading will likely vary significantly throughout the test, each specimen can be used to generate multiple data points. If crack length is determined throughout the test, presumably by directly measuring the crack length optically, then when the crack advances, critical values of J for mixed mode loading can be determined using the methods and results presented. It is noted that moderate to large translational and rotational displacements actually improve the accuracy of the results using these methods. The results are applicable to standard purely mode I or purely mode II SCB and DCB tests as well and reduce to known equations in those special cases.
{"title":"Single and Double Cantilever Beam Large Displacement Mixed Mode Fracture Toughness Test Methods and J-integral Analyses","authors":"A. Paris","doi":"10.1115/1.4063216","DOIUrl":"https://doi.org/10.1115/1.4063216","url":null,"abstract":"The J-integral is applied to the single cantilever beam (SCB) and double cantilever beam (DCB) test specimens subjected to both mixed mode I and II loading and large displacements. The methods proposed and resulting closed form theoretical equations allow for the instantaneous evaluation of J during laboratory tests, requiring only the applied load and angular rotation of the specimen loading link, loading points and remaining ligament. These measurands can be acquired using a common load cell and markers, digital video camera, and video analysis software. In general, the equations do require knowledge of the specimen elastic moduli and shear moduli, as well as the specimen linear dimensions. Since the test data can be analyzed and J determined throughout the test instantaneously, and since, due to geometric non-linearities, the ratio of mode I and mode II loading will likely vary significantly throughout the test, each specimen can be used to generate multiple data points. If crack length is determined throughout the test, presumably by directly measuring the crack length optically, then when the crack advances, critical values of J for mixed mode loading can be determined using the methods and results presented. It is noted that moderate to large translational and rotational displacements actually improve the accuracy of the results using these methods. The results are applicable to standard purely mode I or purely mode II SCB and DCB tests as well and reduce to known equations in those special cases.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44490754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiangyu Xu, Jiayi Xu, Jie Liu, Chaohui Jiang, Liangfei Tian, Yingke Xu, Dechang Li, B. Ji
Finger-like structures take crucial roles in migration behaviors of collective cells. However, the mechanics of the finger-like structure has not been fully understood. Here, we constructed a two-dimensional collective cell migration model, and quantitatively analyzed the cellular mechanics of finger-like structures during the collective cell migration through experimental study and numerical simulation. We found that substrate stiffness, cell density, cell prestress, and mechanical loading significantly influence the generation and behaviors of the finger-like structures through regulating the lamellipodia spreading area, cellular traction force, and collectivity of cell motility. We showed that the regions with the higher maximum principal stress tend to produce larger finger-like structures. Increasing the spreading area of lamellipodia and the velocity of leader cells could promote the generation of higher finger-like structures. For a quantitative understanding of the mechanisms of the effects of these mechanical factors, we adopted a coarse-grained cell model based on the traction-distance law. Our numerical simulation recapitulated the cell velocity distribution, cell motility integrity, cell polarization, and the stress distribution in the cell layer observed in the experiment. These analyses reveal the cellular mechanics of the finger-like structure and its roles in collective cell migration. This study provides useful insights into the collective cell behaviors in tissue engineering and regenerative medicine for biomedical applications.
{"title":"Cellular mechanics of finger-like structures of collective cell migration","authors":"Xiangyu Xu, Jiayi Xu, Jie Liu, Chaohui Jiang, Liangfei Tian, Yingke Xu, Dechang Li, B. Ji","doi":"10.1115/1.4063217","DOIUrl":"https://doi.org/10.1115/1.4063217","url":null,"abstract":"\u0000 Finger-like structures take crucial roles in migration behaviors of collective cells. However, the mechanics of the finger-like structure has not been fully understood. Here, we constructed a two-dimensional collective cell migration model, and quantitatively analyzed the cellular mechanics of finger-like structures during the collective cell migration through experimental study and numerical simulation. We found that substrate stiffness, cell density, cell prestress, and mechanical loading significantly influence the generation and behaviors of the finger-like structures through regulating the lamellipodia spreading area, cellular traction force, and collectivity of cell motility. We showed that the regions with the higher maximum principal stress tend to produce larger finger-like structures. Increasing the spreading area of lamellipodia and the velocity of leader cells could promote the generation of higher finger-like structures. For a quantitative understanding of the mechanisms of the effects of these mechanical factors, we adopted a coarse-grained cell model based on the traction-distance law. Our numerical simulation recapitulated the cell velocity distribution, cell motility integrity, cell polarization, and the stress distribution in the cell layer observed in the experiment. These analyses reveal the cellular mechanics of the finger-like structure and its roles in collective cell migration. This study provides useful insights into the collective cell behaviors in tissue engineering and regenerative medicine for biomedical applications.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49067649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 studies the dynamic deployment of cylindrical thin-shell structures with open cross-section and attached to a rigid support. The structures are elastically folded and then released. Previous experiments have shown that the total energy of these structures decreases while a fold moves back and forth along the shell, which was explained in terms of energy losses related to the fold “bouncing” against the boundary. This paper uses a rigorous numerical simulation, based on an in-house isogeometric shell finite element code that simultaneously eliminates shear locking and hourglassing without any intrinsic energy dissipation, to show that the total energy of the system is conserved during deployment. The discrepancy with the previous results is explained by showing that en- ergy transfers from low-frequency, “rigid body” modes to higher frequency modes, which were not measured.
{"title":"Rigorous Analysis of Energy Conservation during Dynamic Deployment of Elastic Thin-Shell Structures","authors":"F. G. Canales, S. Pellegrino","doi":"10.1115/1.4063220","DOIUrl":"https://doi.org/10.1115/1.4063220","url":null,"abstract":"\u0000 This paper studies the dynamic deployment of cylindrical thin-shell structures with open cross-section and attached to a rigid support. The structures are elastically folded and then released. Previous experiments have shown that the total energy of these structures decreases while a fold moves back and forth along the shell, which was explained in terms of energy losses related to the fold “bouncing” against the boundary. This paper uses a rigorous numerical simulation, based on an in-house isogeometric shell finite element code that simultaneously eliminates shear locking and hourglassing without any intrinsic energy dissipation, to show that the total energy of the system is conserved during deployment. The discrepancy with the previous results is explained by showing that en- ergy transfers from low-frequency, “rigid body” modes to higher frequency modes, which were not measured.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47248349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Biohybrid actuators aim to leverage the various advantages of biological cells over artificial components to build novel compliant machines with high performance and autonomy. Significant advances have been made in bio-fabrication technologies, enabling the realization of muscle-powered bio-actuators. However, the mechanics of muscle-scaffold coupling has been relatively understudied, limiting the development of bio-actuators to intuitive or biomimetic designs. Here, we consider the case of implementing muscle-based actuation for soft robotic swimmers operating at low Reynolds number. We develop an analytical model to describe the elasto-hydrodynamic problem and identify key design parameters. Muscle contraction dynamics is characterized experimentally and the implications of nonlinear amplitude-frequency relationship of muscle-based actuation are discussed. We show that a novel bio-actuator with high performance can be developed by introducing compliant flexural mechanisms undergoing large deflection. Geometric nonlinearities are accounted for in the analysis of the force-deflection relationship for the flexural mechanism. Our results show that for expected muscle contraction forces, this novel bio-actuator can outperform previous muscle-powered swimmers by up to two orders of magnitude in swimming speed.
{"title":"Incorporating Geometric Nonlinearity in Theoretical Modeling of Muscle-Powered Soft Robotic Bio-Actuators","authors":"Onur Aydin, Kenta Hirashima, M. Saif","doi":"10.1115/1.4063146","DOIUrl":"https://doi.org/10.1115/1.4063146","url":null,"abstract":"\u0000 Biohybrid actuators aim to leverage the various advantages of biological cells over artificial components to build novel compliant machines with high performance and autonomy. Significant advances have been made in bio-fabrication technologies, enabling the realization of muscle-powered bio-actuators. However, the mechanics of muscle-scaffold coupling has been relatively understudied, limiting the development of bio-actuators to intuitive or biomimetic designs. Here, we consider the case of implementing muscle-based actuation for soft robotic swimmers operating at low Reynolds number. We develop an analytical model to describe the elasto-hydrodynamic problem and identify key design parameters. Muscle contraction dynamics is characterized experimentally and the implications of nonlinear amplitude-frequency relationship of muscle-based actuation are discussed. We show that a novel bio-actuator with high performance can be developed by introducing compliant flexural mechanisms undergoing large deflection. Geometric nonlinearities are accounted for in the analysis of the force-deflection relationship for the flexural mechanism. Our results show that for expected muscle contraction forces, this novel bio-actuator can outperform previous muscle-powered swimmers by up to two orders of magnitude in swimming speed.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41661114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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