Yangkun Du - Academia.edu (original) (raw)
Papers by Yangkun Du
Initial residual stress is omnipresent in biological tissues and soft matter, and can affect grow... more Initial residual stress is omnipresent in biological tissues and soft matter, and can affect growth-induced pattern selection significantly. Here we demonstrate this effect experimentally by letting soft tubes grow in the presence or absence of initial residual stress and by observing different growth pattern evolutions. These experiments motivate us to model the mechanisms at play when a growing bilayer tubular organ spontaneously displays buckling patterns on its inner surface. We demonstrate that not only differential growth, geometry and elasticity, but also initial residual stress distribution, exert a notable influence on these pattern phenomena. Prescribing an initial residual stress distribution offers an alternative or a more effective way to implement pattern selection for growable bio-tissues or soft matter. The results also show promise for the design of 4D bio-mimic printing protocols or for controlling hydrogel actuators.
Residual stress is ubiquitous and indispensable in most biological and artificial materials, wher... more Residual stress is ubiquitous and indispensable in most biological and artificial materials, where it sustains and optimizes many biological and functional mechanisms. The theory of volume growth, starting from a stress-free initial state, is widely used to explain the creation and evolution of growth-induced residual stress and the resulting changes in shape, and to model how growing bio-tissues such as arteries and solid tumors develop a strategy of pattern creation according to geometrical and material parameters. This modelling provides promising avenues for designing and directing some appropriate morphology of a given tissue or organ and achieve some targeted biomedical function. In this paper, we rely on a modified, augmented theory to reveal how we can obtain growth-induced residual stress and pattern evolution of a layered artery by starting from an existing, non-zero initial residual stress state. We use experimentally determined residual stress distributions of aged bi-la...
Eye fatigue is a symptom induced by long-term work of both eyes and brains. Without proper treatm... more Eye fatigue is a symptom induced by long-term work of both eyes and brains. Without proper treatment, eye fatigue may incur serious problems such as fatigue driving, special work operating faults, or even ophthalmic diseases[1, 2, 3, 4]. Current studies on detecting eye fatigue mainly focus on computer vision detect technology. However, these methods can be very unreliable due to occasional bad visual condition[3, 4]. As a solution, we proposed a wearable conformal in vivo eye fatigue monitoring
Journal of the Mechanics and Physics of Solids
International Journal of Non-Linear Mechanics
Soft Matter
Initial residual stress is omnipresent in biological tissues and soft matter, and can affect grow... more Initial residual stress is omnipresent in biological tissues and soft matter, and can affect growth- induced pattern selection significantly. Here we demonstrate this effect experimentally by letting soft tubes grow...
Scientific Reports
Residual stress is ubiquitous and indispensable in most biological and artificial materials, wher... more Residual stress is ubiquitous and indispensable in most biological and artificial materials, where it sustains and optimizes many biological and functional mechanisms. The theory of volume growth, starting from a stress-free initial state, is widely used to explain the creation and evolution of growthinduced residual stress and the resulting changes in shape, and to model how growing bio-tissues such as arteries and solid tumors develop a strategy of pattern creation according to geometrical and material parameters. This modelling provides promising avenues for designing and directing some appropriate morphology of a given tissue or organ and achieve some targeted biomedical function. In this paper, we rely on a modified, augmented theory to reveal how we can obtain growth-induced residual stress and pattern evolution of a layered artery by starting from an existing, non-zero initial residual stress state. We use experimentally determined residual stress distributions of aged bi-layered human aortas and quantify their influence by a magnitude factor. Our results show that initial residual stress has a more significant impact on residual stress accumulation and the subsequent evolution of patterns than geometry and material parameters. Additionally, we provide an essential explanation for growth-induced patterns driven by differential growth coupled to an initial residual stress. Finally, we show that initial residual stress is a readily available way to control growth-induced pattern creation for tissues and thus may provide a promising inspiration for biomedical engineering. Many bio-tissues, such as arteries, heart, brain, intestine and some tumors, are under significant levels of residual stresses in vivo and also once unloaded 1-7. Residual stresses are used for maintaining a self-balanced state, by transferring physical signals and regulating some specific bio-functions 8-11. It is fair to say that healthy biological performances rely heavily on appropriate levels of residual stress. Hence, a greater understanding of the role played by residual stress can lead to better design of mechanical, electrical, chemical, biological and internal environments for living organisms. In biology, residual stress is widely accepted as the result of growth and remodelling processes or of other, more involved bio-interactions. Physically, by referring to the multiplicative decomposition (MD) method of plasticity theory, and by decomposing the overall growth process into two separate parts, Rodriguez et al. 12 were able to simulate the growth process and to explain growth-induced residual stress. The former step refers to the mass accumulation and incompatibility creation processes within two stress-free states called unconstrained growth; the later step refers to residual stress creation and compatibility restoration processes called elastic deformation. This MD model illuminates many related mathematical and mechanical studies on the growth of artery, brain, intestine, etc. 5,13-17. Moreover, the influence of growth factors, including differential growth extent, volume change rate, and/or growth velocity, on residual stress distribution, pattern creation and evolution has also been analysed with the MD model 5,18-20. Nonetheless, there still remain some limitations for this model due to its assumption that both the initial configuration and the natural configuration (or virtual configuration 21) remain stress-free states during the unconstrained growth process. As discussed by Johnson et al. 21 , for residually stressed materials the stress-free state is an entirely discrete state made of a collection of nearly infinitesimal volumes, which is unattainable in practice
Journal of the Mechanics and Physics of Solids
Science China Information Sciences
Eye fatigue has attracted significant interest due to its potential harm to human daily activitie... more Eye fatigue has attracted significant interest due to its potential harm to human daily activities. An ultrathin flexible piezoelectric sensor was currently designed and fabricated to detect eye fatigue by deforming together with the eyelid epidermis. Herein we develop a theoretical model to illustrate the correlation between the eyelid motion and the signals output by the piezoelectric sensor. The theoretical predictions on the eyelid motion based on the measured electrical output agree well with the in vivo observations in experiment. A simple scaling law is established to evaluate the impacts of different parameters on the function ability of the flexible piezoelectric sensor. The results may provide useful guidelines for designing and optimizing similar devices for alike biological motions.
Journal of Micromechanics and Microengineering
Theoretical and Applied Mechanics Letters
Initial residual stress is omnipresent in biological tissues and soft matter, and can affect grow... more Initial residual stress is omnipresent in biological tissues and soft matter, and can affect growth-induced pattern selection significantly. Here we demonstrate this effect experimentally by letting soft tubes grow in the presence or absence of initial residual stress and by observing different growth pattern evolutions. These experiments motivate us to model the mechanisms at play when a growing bilayer tubular organ spontaneously displays buckling patterns on its inner surface. We demonstrate that not only differential growth, geometry and elasticity, but also initial residual stress distribution, exert a notable influence on these pattern phenomena. Prescribing an initial residual stress distribution offers an alternative or a more effective way to implement pattern selection for growable bio-tissues or soft matter. The results also show promise for the design of 4D bio-mimic printing protocols or for controlling hydrogel actuators.
Residual stress is ubiquitous and indispensable in most biological and artificial materials, wher... more Residual stress is ubiquitous and indispensable in most biological and artificial materials, where it sustains and optimizes many biological and functional mechanisms. The theory of volume growth, starting from a stress-free initial state, is widely used to explain the creation and evolution of growth-induced residual stress and the resulting changes in shape, and to model how growing bio-tissues such as arteries and solid tumors develop a strategy of pattern creation according to geometrical and material parameters. This modelling provides promising avenues for designing and directing some appropriate morphology of a given tissue or organ and achieve some targeted biomedical function. In this paper, we rely on a modified, augmented theory to reveal how we can obtain growth-induced residual stress and pattern evolution of a layered artery by starting from an existing, non-zero initial residual stress state. We use experimentally determined residual stress distributions of aged bi-la...
Eye fatigue is a symptom induced by long-term work of both eyes and brains. Without proper treatm... more Eye fatigue is a symptom induced by long-term work of both eyes and brains. Without proper treatment, eye fatigue may incur serious problems such as fatigue driving, special work operating faults, or even ophthalmic diseases[1, 2, 3, 4]. Current studies on detecting eye fatigue mainly focus on computer vision detect technology. However, these methods can be very unreliable due to occasional bad visual condition[3, 4]. As a solution, we proposed a wearable conformal in vivo eye fatigue monitoring
Journal of the Mechanics and Physics of Solids
International Journal of Non-Linear Mechanics
Soft Matter
Initial residual stress is omnipresent in biological tissues and soft matter, and can affect grow... more Initial residual stress is omnipresent in biological tissues and soft matter, and can affect growth- induced pattern selection significantly. Here we demonstrate this effect experimentally by letting soft tubes grow...
Scientific Reports
Residual stress is ubiquitous and indispensable in most biological and artificial materials, wher... more Residual stress is ubiquitous and indispensable in most biological and artificial materials, where it sustains and optimizes many biological and functional mechanisms. The theory of volume growth, starting from a stress-free initial state, is widely used to explain the creation and evolution of growthinduced residual stress and the resulting changes in shape, and to model how growing bio-tissues such as arteries and solid tumors develop a strategy of pattern creation according to geometrical and material parameters. This modelling provides promising avenues for designing and directing some appropriate morphology of a given tissue or organ and achieve some targeted biomedical function. In this paper, we rely on a modified, augmented theory to reveal how we can obtain growth-induced residual stress and pattern evolution of a layered artery by starting from an existing, non-zero initial residual stress state. We use experimentally determined residual stress distributions of aged bi-layered human aortas and quantify their influence by a magnitude factor. Our results show that initial residual stress has a more significant impact on residual stress accumulation and the subsequent evolution of patterns than geometry and material parameters. Additionally, we provide an essential explanation for growth-induced patterns driven by differential growth coupled to an initial residual stress. Finally, we show that initial residual stress is a readily available way to control growth-induced pattern creation for tissues and thus may provide a promising inspiration for biomedical engineering. Many bio-tissues, such as arteries, heart, brain, intestine and some tumors, are under significant levels of residual stresses in vivo and also once unloaded 1-7. Residual stresses are used for maintaining a self-balanced state, by transferring physical signals and regulating some specific bio-functions 8-11. It is fair to say that healthy biological performances rely heavily on appropriate levels of residual stress. Hence, a greater understanding of the role played by residual stress can lead to better design of mechanical, electrical, chemical, biological and internal environments for living organisms. In biology, residual stress is widely accepted as the result of growth and remodelling processes or of other, more involved bio-interactions. Physically, by referring to the multiplicative decomposition (MD) method of plasticity theory, and by decomposing the overall growth process into two separate parts, Rodriguez et al. 12 were able to simulate the growth process and to explain growth-induced residual stress. The former step refers to the mass accumulation and incompatibility creation processes within two stress-free states called unconstrained growth; the later step refers to residual stress creation and compatibility restoration processes called elastic deformation. This MD model illuminates many related mathematical and mechanical studies on the growth of artery, brain, intestine, etc. 5,13-17. Moreover, the influence of growth factors, including differential growth extent, volume change rate, and/or growth velocity, on residual stress distribution, pattern creation and evolution has also been analysed with the MD model 5,18-20. Nonetheless, there still remain some limitations for this model due to its assumption that both the initial configuration and the natural configuration (or virtual configuration 21) remain stress-free states during the unconstrained growth process. As discussed by Johnson et al. 21 , for residually stressed materials the stress-free state is an entirely discrete state made of a collection of nearly infinitesimal volumes, which is unattainable in practice
Journal of the Mechanics and Physics of Solids
Science China Information Sciences
Eye fatigue has attracted significant interest due to its potential harm to human daily activitie... more Eye fatigue has attracted significant interest due to its potential harm to human daily activities. An ultrathin flexible piezoelectric sensor was currently designed and fabricated to detect eye fatigue by deforming together with the eyelid epidermis. Herein we develop a theoretical model to illustrate the correlation between the eyelid motion and the signals output by the piezoelectric sensor. The theoretical predictions on the eyelid motion based on the measured electrical output agree well with the in vivo observations in experiment. A simple scaling law is established to evaluate the impacts of different parameters on the function ability of the flexible piezoelectric sensor. The results may provide useful guidelines for designing and optimizing similar devices for alike biological motions.
Journal of Micromechanics and Microengineering
Theoretical and Applied Mechanics Letters