Abstract In this study, a hybrid MMC-AABH plus approach is developed for the fast optimal design of shell-graded-infill structures. The key idea is to use a proper description about the graded microstructural infill and the coating shell. To this end, a set of moving morphable components is adopted to represent the boundary of the coating shell, while the graded infill is embodied by spatially varying orthotropic porous configurations. Under such a treatment, with a small number of design variables, both the boundary of the coating shell and the graded microstructure infill can be optimized simultaneously. Other attractive features of the present study are summarized as follows. Firstly, the smooth variation across the microstructural infill can be automatically satisfied based on the proposed approach compared with other similar method. Secondly, with the use of the extreme value principle of Laplace equation, the minimum feature size can be explicit controlled during the optimization. Thirdly, compared with other methods in the frontier, the approach proposed in the present study enjoys considerable reduction in the computation cost and can obtain near-optimal design of coating structure. The effectiveness of the proposed approach is further demonstrated with numerical examples.
{"title":"FAST OPTIMAL DESIGN OF SHELL-GRADED-INFILL STRUCTURES WITH EXPLICIT BOUNDARY BY A HYBRID MMC-AABH PLUS APPROACH","authors":"Yikang Bi, Shaoshuai Li, Yichao Zhu","doi":"10.1115/1.4064035","DOIUrl":"https://doi.org/10.1115/1.4064035","url":null,"abstract":"Abstract In this study, a hybrid MMC-AABH plus approach is developed for the fast optimal design of shell-graded-infill structures. The key idea is to use a proper description about the graded microstructural infill and the coating shell. To this end, a set of moving morphable components is adopted to represent the boundary of the coating shell, while the graded infill is embodied by spatially varying orthotropic porous configurations. Under such a treatment, with a small number of design variables, both the boundary of the coating shell and the graded microstructure infill can be optimized simultaneously. Other attractive features of the present study are summarized as follows. Firstly, the smooth variation across the microstructural infill can be automatically satisfied based on the proposed approach compared with other similar method. Secondly, with the use of the extreme value principle of Laplace equation, the minimum feature size can be explicit controlled during the optimization. Thirdly, compared with other methods in the frontier, the approach proposed in the present study enjoys considerable reduction in the computation cost and can obtain near-optimal design of coating structure. The effectiveness of the proposed approach is further demonstrated with numerical examples.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"95 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135390865","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}
Abstract Head injuries induced by tennis ball impacts are computationally studied. The impact of a two-piece tennis ball on a human head is simulated by using an established full body model and a newly constructed tennis ball model. The new tennis ball model is validated against existing experimental data. The frontal impact of a tennis ball on a human head at a velocity of 25 m/s is first studied as the baseline case. The effects of the impact location, velocity, and angle as well as the ball spinning are then examined. It is revealed that the lateral impact results in a higher risk of head injury than the frontal and crown impacts. In addition, it is found that the impact force and von Mises stress in the skull, the intracranial pressure and first principal strain in the brain, and the translational and rotational accelerations at the center of gravity of the head all increase with the increase of the impact velocity. Moreover, the normal (90-deg) impact has the highest risk of head injury, which is followed by the 60-deg, 45-deg and 30-deg impacts. Further, it is observed that the spinning of the tennis ball has insignificant effects on the head response. The simulation results show that there will be no skull fracture or mild brain injury in the baseline case. However, traumatic brain injuries may occur after the impact velocity exceeds 40 m/s. The findings of the current study provide new insights into the risks of head injuries induced by tennis ball impacts.
{"title":"Head Injuries Induced by Tennis Ball Impacts: A Computational Study","authors":"Yongqiang Li, Xin-Lin Gao","doi":"10.1115/1.4063814","DOIUrl":"https://doi.org/10.1115/1.4063814","url":null,"abstract":"Abstract Head injuries induced by tennis ball impacts are computationally studied. The impact of a two-piece tennis ball on a human head is simulated by using an established full body model and a newly constructed tennis ball model. The new tennis ball model is validated against existing experimental data. The frontal impact of a tennis ball on a human head at a velocity of 25 m/s is first studied as the baseline case. The effects of the impact location, velocity, and angle as well as the ball spinning are then examined. It is revealed that the lateral impact results in a higher risk of head injury than the frontal and crown impacts. In addition, it is found that the impact force and von Mises stress in the skull, the intracranial pressure and first principal strain in the brain, and the translational and rotational accelerations at the center of gravity of the head all increase with the increase of the impact velocity. Moreover, the normal (90-deg) impact has the highest risk of head injury, which is followed by the 60-deg, 45-deg and 30-deg impacts. Further, it is observed that the spinning of the tennis ball has insignificant effects on the head response. The simulation results show that there will be no skull fracture or mild brain injury in the baseline case. However, traumatic brain injuries may occur after the impact velocity exceeds 40 m/s. The findings of the current study provide new insights into the risks of head injuries induced by tennis ball impacts.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"174 S402","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135775138","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}
Abstract Bandgaps, or frequency ranges of forbidden wave propagation, are a hallmark of phononic crystals (PnCs). Unlike their lattice counterparts, PnCs taking the form of continuous structures exhibit an infinite number of bandgaps of varying location, bandwidth, and distribution along the frequency spectrum. While these bandgaps are commonly predicted from benchmark tools such as the Bloch-wave theory, the conditions that dictate the patterns associated with bandgap symmetry, attenuation, or even closing in multi-bandgap PnCs remain an enigma. In this work, we establish these patterns in one-dimensional rods undergoing longitudinal motion via a canonical transfer-matrix-based approach. In doing so, we connect the conditions governing bandgap formation and closing to their physical origins in the context of the Bragg condition (for infinite media) and natural resonances (for finite counterparts). The developed framework uniquely characterizes individual bandgaps within a larger dispersion spectrum regardless of their parity (i.e., odd versus even bandgaps) or location (low versus high-frequency), by exploiting dimensionless constants of the PnC unit cell which quantify the different contrasts between its constitutive layers. These developments are detailed for a bi-layered PnC and then generalized for a PnC of any number of layers by increasing the model complexity. We envision this mathematical development to be a future standard for the realization of hierarchically structured PnCs with prescribed and finely tailored bandgap profiles.
{"title":"The role of frequency and impedance contrasts in bandgap closing and formation patterns of axially-vibrating phononic crystals","authors":"Hasan B. Al Ba'ba'a, Mostafa Nouh","doi":"10.1115/1.4063815","DOIUrl":"https://doi.org/10.1115/1.4063815","url":null,"abstract":"Abstract Bandgaps, or frequency ranges of forbidden wave propagation, are a hallmark of phononic crystals (PnCs). Unlike their lattice counterparts, PnCs taking the form of continuous structures exhibit an infinite number of bandgaps of varying location, bandwidth, and distribution along the frequency spectrum. While these bandgaps are commonly predicted from benchmark tools such as the Bloch-wave theory, the conditions that dictate the patterns associated with bandgap symmetry, attenuation, or even closing in multi-bandgap PnCs remain an enigma. In this work, we establish these patterns in one-dimensional rods undergoing longitudinal motion via a canonical transfer-matrix-based approach. In doing so, we connect the conditions governing bandgap formation and closing to their physical origins in the context of the Bragg condition (for infinite media) and natural resonances (for finite counterparts). The developed framework uniquely characterizes individual bandgaps within a larger dispersion spectrum regardless of their parity (i.e., odd versus even bandgaps) or location (low versus high-frequency), by exploiting dimensionless constants of the PnC unit cell which quantify the different contrasts between its constitutive layers. These developments are detailed for a bi-layered PnC and then generalized for a PnC of any number of layers by increasing the model complexity. We envision this mathematical development to be a future standard for the realization of hierarchically structured PnCs with prescribed and finely tailored bandgap profiles.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"174 S403","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135775137","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}
Mohammad Nazmus Saquib, Richard Larson, Siavash Sattar, Jiang Li, Sergey Kravchenko, Oleksandr Kravchenko
Abstract A novel approach for microstructure reconstruction using artificial intelligence (MR-AI) was proposed to non-destructively measure the through-thickness average stochastic fiber orientation distribution (FOD) in a prepreg platelet molded composite (PPMC) plate. MR-AI approach uses thermal strain components on the surfaces of a PPMC plate as input to the deep learning model, which allows to predict a distribution of local through-thickness average fiber orientation state in the entire PPMC volume. The experimental setup with a heating stage and digital image correlation (DIC) was used to measure thermal strains on the surface of PPMC plate. Optical microscopy was then used to measure FOD in the cross-section of PPMC plate. FOD measurements from optical microscopy imagery compared favorably with FOD prediction by MR-AI. The proposed methodology opens the opportunity for rapid, non-destructive inspection of manufacturing induced FOD in molded composites.
{"title":"Experimental Validation of Reconstructed Microstructure via Deep Learning in Discontinuous Fiber Platelet Composite","authors":"Mohammad Nazmus Saquib, Richard Larson, Siavash Sattar, Jiang Li, Sergey Kravchenko, Oleksandr Kravchenko","doi":"10.1115/1.4063983","DOIUrl":"https://doi.org/10.1115/1.4063983","url":null,"abstract":"Abstract A novel approach for microstructure reconstruction using artificial intelligence (MR-AI) was proposed to non-destructively measure the through-thickness average stochastic fiber orientation distribution (FOD) in a prepreg platelet molded composite (PPMC) plate. MR-AI approach uses thermal strain components on the surfaces of a PPMC plate as input to the deep learning model, which allows to predict a distribution of local through-thickness average fiber orientation state in the entire PPMC volume. The experimental setup with a heating stage and digital image correlation (DIC) was used to measure thermal strains on the surface of PPMC plate. Optical microscopy was then used to measure FOD in the cross-section of PPMC plate. FOD measurements from optical microscopy imagery compared favorably with FOD prediction by MR-AI. The proposed methodology opens the opportunity for rapid, non-destructive inspection of manufacturing induced FOD in molded composites.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"18 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135934443","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}
Abstract Studies have reported that the electromigration induced void growth velocity in metal thin films is inversely related to the adhesion strength of the metal thin film with the base and passivation layers. It was also observed that the contribution of interface adhesion strength to electromigration resistance decreases with increase in temperature. In this study an expression is derived for the diffusive void growth velocity induced by electromigration from a generalized thermodynamically consistent continuum-based theory for reaction-diffusion driven solid state interface evolution. This relation captures the effect of adhesion with the base and passivation layers on electromigration resistance of thin metal films. Electromigration experiments were carried out at elevated temperatures and high current density to induce voiding in thin Cu metal film deposited on a base layer of TiN and passivated with TiN or SiNx. The degradation of interface adhesion strength with temperature is modeled using an Andrade-type of relationship. The void growth rates characterized in these experiments are combined with the expression for void growth rate to estimate the interface adhesion strength for the Cu-TiN and Cu-SiNx interfaces. The methodology for estimating the adhesion strength of the metal-passivation layer interface is validated through comparison with interface adhesion strengths from mechanical de-adhesion tests reported in literature.
{"title":"A Non-contact Method for Estimating Thin Metal Film Adhesion Strength through Current Induced Void Growth","authors":"Sudarshan Prasad, Pavan Kumar Vaitheeswaran, Yuvraj Singh, Pei-En Chou, Huanyu Liao, Ganesh Subbarayan","doi":"10.1115/1.4063948","DOIUrl":"https://doi.org/10.1115/1.4063948","url":null,"abstract":"Abstract Studies have reported that the electromigration induced void growth velocity in metal thin films is inversely related to the adhesion strength of the metal thin film with the base and passivation layers. It was also observed that the contribution of interface adhesion strength to electromigration resistance decreases with increase in temperature. In this study an expression is derived for the diffusive void growth velocity induced by electromigration from a generalized thermodynamically consistent continuum-based theory for reaction-diffusion driven solid state interface evolution. This relation captures the effect of adhesion with the base and passivation layers on electromigration resistance of thin metal films. Electromigration experiments were carried out at elevated temperatures and high current density to induce voiding in thin Cu metal film deposited on a base layer of TiN and passivated with TiN or SiNx. The degradation of interface adhesion strength with temperature is modeled using an Andrade-type of relationship. The void growth rates characterized in these experiments are combined with the expression for void growth rate to estimate the interface adhesion strength for the Cu-TiN and Cu-SiNx interfaces. The methodology for estimating the adhesion strength of the metal-passivation layer interface is validated through comparison with interface adhesion strengths from mechanical de-adhesion tests reported in literature.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"251 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135320579","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}
Zouqing Tan, Yang Feng, Xiaohao Shi, Yanmei Yue, Neng-Hui Zhang
Abstract Highly compliant structures such as microbeams can deform substantially in response to interactions between molecules adsorbed on their surface. To understand such systems and improve their detection signals, a mechano-electro-chemical coupling model for mechanical deformations of the microbeams immobilized single stranded DNA (ssDNA) is established due to flexoelectricity. The governing equations and corresponding boundary conditions of ssDNA-microbeams are derived by using the variational principle. The bending deformations of ssDNA-microbeams (one for cantilever beam and another for simply supported beam) are derived. The electric potential in the regions inside and outside the ssDNA layer is obtained by linear Poisson-Boltzmann equation for different electrolyte solutions. The analytical expressions to quantify the beam deflection and the potential difference of ssDNA layer are presented. The theoretical predictions are compared with the experimental data to validate the applicability of the present model. Numerical results reveal that the solution types, thickness and elastic modulus of substrate materials have obvious influence on the deflections of ssDNA-microbeams. Therefore, the present model can help to improve the reading of the bending deformation signal of the microbeam biosensors.
{"title":"A mechano-electro-chemical coupling model for bending analysis of single-stranded DNA-microbeam biosensors due to flexoelectricity","authors":"Zouqing Tan, Yang Feng, Xiaohao Shi, Yanmei Yue, Neng-Hui Zhang","doi":"10.1115/1.4063949","DOIUrl":"https://doi.org/10.1115/1.4063949","url":null,"abstract":"Abstract Highly compliant structures such as microbeams can deform substantially in response to interactions between molecules adsorbed on their surface. To understand such systems and improve their detection signals, a mechano-electro-chemical coupling model for mechanical deformations of the microbeams immobilized single stranded DNA (ssDNA) is established due to flexoelectricity. The governing equations and corresponding boundary conditions of ssDNA-microbeams are derived by using the variational principle. The bending deformations of ssDNA-microbeams (one for cantilever beam and another for simply supported beam) are derived. The electric potential in the regions inside and outside the ssDNA layer is obtained by linear Poisson-Boltzmann equation for different electrolyte solutions. The analytical expressions to quantify the beam deflection and the potential difference of ssDNA layer are presented. The theoretical predictions are compared with the experimental data to validate the applicability of the present model. Numerical results reveal that the solution types, thickness and elastic modulus of substrate materials have obvious influence on the deflections of ssDNA-microbeams. Therefore, the present model can help to improve the reading of the bending deformation signal of the microbeam biosensors.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"48 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135321116","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}
Abstract In this work, closed-form expressions of shear correction factor (SCF) have been derived for beams with functionally graded material (FGM), through variational asymptotic method (VAM). An energy equivalence approach has been adopted between VAM and Timoshenko model, for estimating the SCF. A planar FGM beam has been considered and the calculation for SCF has been carried out. The formulation has been derived in a functional form that permits solutions for a large class of gradation models of FGM. In the limiting case when the material becomes homogeneous the estimated SCF matches exactly with that of the literature, thus validating the solution. A detailed discussion has been carried out on the results and conclusions have been drawn.
{"title":"Closed form Expressions of Shear Correction Factor for Functionally Graded Beams","authors":"None Amandeep, Anup Kumar Pathak, Srikant Sekhar Padhee","doi":"10.1115/1.4063817","DOIUrl":"https://doi.org/10.1115/1.4063817","url":null,"abstract":"Abstract In this work, closed-form expressions of shear correction factor (SCF) have been derived for beams with functionally graded material (FGM), through variational asymptotic method (VAM). An energy equivalence approach has been adopted between VAM and Timoshenko model, for estimating the SCF. A planar FGM beam has been considered and the calculation for SCF has been carried out. The formulation has been derived in a functional form that permits solutions for a large class of gradation models of FGM. In the limiting case when the material becomes homogeneous the estimated SCF matches exactly with that of the literature, thus validating the solution. A detailed discussion has been carried out on the results and conclusions have been drawn.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"15 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135768364","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}
Abstract Magneto-mechanical metamaterials possess unique and tunable properties by adjusting their shape configurations in response to an external magnetic field. Their designs and functionalities are diverse and are utilized in a wide variety of applications, such as highly tunable elastic and electromagnetic wave filters and targeted shape morphing. In this perspective, we examine the general background of magneto-mechanical metamaterials and their diverse applications. The possible future directions in the field are also thoroughly discussed.
{"title":"Magneto-Mechanical Metamaterials: A Perspective","authors":"Jay Sim, Ruike Renee Zhao","doi":"10.1115/1.4063816","DOIUrl":"https://doi.org/10.1115/1.4063816","url":null,"abstract":"Abstract Magneto-mechanical metamaterials possess unique and tunable properties by adjusting their shape configurations in response to an external magnetic field. Their designs and functionalities are diverse and are utilized in a wide variety of applications, such as highly tunable elastic and electromagnetic wave filters and targeted shape morphing. In this perspective, we examine the general background of magneto-mechanical metamaterials and their diverse applications. The possible future directions in the field are also thoroughly discussed.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"24 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135769508","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}
Dezhong Tong, MD Khalil, Matthew Justin Silva, Guanjin Wang, Bashir Khoda, Mohammad Khalid Jawed
Abstract The fisherman's knot, renowned for its strength and reliability, finds applications in engineering and medicine. However, a comprehensive understanding of its mechanics remains limited in scientific literature. In this paper, we present a systematic study of the tightening behavior of the fisherman's knot through a combined approach of tabletop experiments and Discrete Elastic Rods simulations. Our experimental setup involves gradually applying tension to the two ends of the fisherman's knot until it fractures. We observed a correlation between the knot's material properties and its behavior during tightening, leading up to fracture. The tightening process of the fisherman's knot exhibits distinct ``sliding' or ``stretching' motions, influenced by factors such as friction and elastic stiffness. Furthermore, the failure modes of the knot (material fracture and topological failure) are determined by an interplay between elastic stiffness, friction, and initial conditions. This study sheds light on the underlying mechanics of the fisherman's knot and provides insight into its behavior during the tightening process, contributing to the broader understanding of the mechanics of knots in practical applications.
{"title":"Mechanical Response of Fisherman's Knots during Tightening","authors":"Dezhong Tong, MD Khalil, Matthew Justin Silva, Guanjin Wang, Bashir Khoda, Mohammad Khalid Jawed","doi":"10.1115/1.4063895","DOIUrl":"https://doi.org/10.1115/1.4063895","url":null,"abstract":"Abstract The fisherman's knot, renowned for its strength and reliability, finds applications in engineering and medicine. However, a comprehensive understanding of its mechanics remains limited in scientific literature. In this paper, we present a systematic study of the tightening behavior of the fisherman's knot through a combined approach of tabletop experiments and Discrete Elastic Rods simulations. Our experimental setup involves gradually applying tension to the two ends of the fisherman's knot until it fractures. We observed a correlation between the knot's material properties and its behavior during tightening, leading up to fracture. The tightening process of the fisherman's knot exhibits distinct ``sliding' or ``stretching' motions, influenced by factors such as friction and elastic stiffness. Furthermore, the failure modes of the knot (material fracture and topological failure) are determined by an interplay between elastic stiffness, friction, and initial conditions. This study sheds light on the underlying mechanics of the fisherman's knot and provides insight into its behavior during the tightening process, contributing to the broader understanding of the mechanics of knots in practical applications.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"40 6-7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134909045","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}
Abstract This paper presents comprehensive numerical studies on the instability behavior of metamaterial-based cylindrical shells (meta-shells) under axial compression. The cylindrical meta-shells are comprised of lattice-like metamaterial unit cells including house unit cells and their variants, cuboid braced, octet truss, and octahedron. Their buckling and post-buckling behavior, effects of dimensional variations, structural mass efficiency in carrying axial compression, and the influences from damaged units are studied in this work. The results show that cylindrical meta-shells can exhibit benign or multi-stable post-buckling behavior rather than catastrophic unstable post-buckling commonly seen for conventional cylindrical shells with continuous surfaces. This work finds that the critical buckling loads scale with the meta-shell dimensions following a quadratic relation. However, the meta-shells' structural mass efficiencies in carrying axial load do not change or slightly increase as their sizes proportionally increase. The study on the effects of defects shows that the critical buckling loads linearly decrease with respect to the mass of total damaged units.
{"title":"Instability of Metamaterial-based Thin Cylindrical Shells under Axial Compression","authors":"Mitansh Doshi, Xin Ning","doi":"10.1115/1.4063898","DOIUrl":"https://doi.org/10.1115/1.4063898","url":null,"abstract":"Abstract This paper presents comprehensive numerical studies on the instability behavior of metamaterial-based cylindrical shells (meta-shells) under axial compression. The cylindrical meta-shells are comprised of lattice-like metamaterial unit cells including house unit cells and their variants, cuboid braced, octet truss, and octahedron. Their buckling and post-buckling behavior, effects of dimensional variations, structural mass efficiency in carrying axial compression, and the influences from damaged units are studied in this work. The results show that cylindrical meta-shells can exhibit benign or multi-stable post-buckling behavior rather than catastrophic unstable post-buckling commonly seen for conventional cylindrical shells with continuous surfaces. This work finds that the critical buckling loads scale with the meta-shell dimensions following a quadratic relation. However, the meta-shells' structural mass efficiencies in carrying axial load do not change or slightly increase as their sizes proportionally increase. The study on the effects of defects shows that the critical buckling loads linearly decrease with respect to the mass of total damaged units.","PeriodicalId":54880,"journal":{"name":"Journal of Applied Mechanics-Transactions of the Asme","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134909362","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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