力学进展

Progress in turbulent thermal convection in the past decade and outlook

XIE Yichao, ZHANG Lu, DING Guangyu, CHEN Xin, XI Hengdong, XIA Keqing

2023, 53(1): 1-47. doi: 10.6052/1000-0992-22-024

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Turbulent convection is ubiquitous in nature and industry. Turbulent Rayleigh-Bénard convection (RBC) is a model system for studying various turbulent convection phenomena. One of the characteristics of turbulent RBC is the formation of coherent structures of different scales, i.e., large-scale circulation and thermal plumes. These structures interact with the thermal and viscous boundary layers. As a result, they inevitably affect the transport properties of the system. Thus, understanding the formation, evolution, and interaction of coherent structures plays a vital role in understanding the transport properties in turbulent convection. This review summarizes progress in the spatial and temporal evolution of coherent structures and their effects on heat transport in the past decade. Special attention was paid to the progress in controlling turbulent convection and its extension to nontraditional cases, such as turbulent convection with rotation, viscoelastic turbulent convection, multiphase turbulent convection, inclined convection, and horizontal convection. A short outlook into future research directions will be given.

Cellular mechanobiology: Mediated by force-sensitive adhesion receptors

ZHANG Huan, ZHAO Guoqing, FENG Jinteng, LIN Min

2023, 53(1): 48-153. doi: 10.6052/1000-0992-22-029

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As the interface between cells and their external environment for materials and energy exchange, the cell membrane is an important structure that regulates cellular activities. Representative transmembrane force-sensitive receptors, such as integrins and cadherins, are found to play key roles in mediating cellular interactions with the ECM or adjacent cells. These interactions will then transduce mechanical stimuli into biochemical signals, which in turn activate a series of intracellular signaling cascade, and ultimately affect cell growth, differentiation, proliferation, migration and apoptosis etc. The investigation of cellular mechanobiology regulated by force-sensitive adhesion receptors has thus become the key to explore the mechanobiological mechanisms of cellular actively in response to complex mechanical microenvironments. This provides valuable theoretical and experimental basis for further understanding of the changes in cell functions under physiological and pathological conditions, as well as for revealing the mechanism of disease development. This review summarizes the cutting-edge progresses in cellular mechanobiology regulated force-sensitive adhesion receptors. This review begins by introducing the structure and function of force-sensitive receptors at the adhesion interface, and followed by elaborating systematic mathematical models of how cells sense and respond to mechanical signals mediated by these receptors. It also outlines the processes of mechanical signal transduction through force-sensitive receptors, and the mechanobiological mechanism of adhesion-mediated changes in cell functions. In addition, the techniques for constructing of in vitro mechanical microenvironment that mimic cell-ECM (via integrin ligation) and cell-cell (via cadherin ligation) interactions are described. Finally, we identify the future directions of mechanobiology in terms of force-sensitive receptors regulated cell functions.

Review on origami kinematics

CHEN Yan, GU Yuanqing

2023, 53(1): 154-197. doi: 10.6052/1000-0992-22-040

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Origami is no longer a folk art with the development of origami engineering in this century, in which a lot of previous work of mathematicians has surfaced and the engineering applications present new challenges to describe the folding process of rigid origami. Meanwhile, origami is not limited to the thin sheet, the folding and unfolding of thick panels have always hindered their related engineering applications. Recently, the development of metamaterials has brought a leap from toys to high technology for modular origami. How to coordinately set up the origami modules to enable the entire structure with excellent and tunable performance is a new hotspot in modular origami. Hence, origami kinematics has played a decisive role in many applications and explorations. This review focuses on the developed mechanism theories and their applications in the analysis and design of origami structures, which hopefully could be able to provide the theoretical foundation for origami engineering.

Advances and challenges in sports biomechanics

LIU Chenglin, HAO Weiya, HUO Bo

2023, 53(1): 198-238. doi: 10.6052/1000-0992-22-030

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The early concept of sports biomechanics refers to biomechanics in sports, which mainly solves the problems of performance enhancement and injury prevention. With the integrated development of related disciplines, the research of sports biomechanics has been extended to the fields of biology, medicine, mechanics, et al. The advance of intelligent testing, big data and artificial intelligence technologies greatly promotes the experimental measurement technologies and simulation methods of sports biomechanics. The renewal of technology and method has gradually expanded and deepened the research content and direction of this discipline and also offered new challenges. This review summarizes the recent advances and points out the development trends and key issues in sports biomechanics. The muscle constitutive theory and calculation of muscle force are the key points in the theoretical modeling and simulation calculation of sports biomechanics. The new testing methods play important role in the competitive sports. Among them the human key point detection algorithm based on deep learning has made a breakthrough in solving the non-contact measurement of competitive sports. The macroscopic damage mechanism of bone, ligament, cartilage, muscle and other tissues has been clarified, but the prediction of their early damage and the mechanism of cross-scale damage still need to be further studied. Intelligent wearable equipment, artificial intelligence and other new technologies have been applied to the research of sports biomechanics and become the hot topics. This review shows that the current research of sports biomechanics is developing towards intelligence, individualization and quantification, integrating with the related disciplines, and continuously promoting the development of scientific and technological innovation in sports, health, medical and other fields.

Study on epoxy-based shape memory polymer composites for Mars explorations

ZHANG Dou, LIU Liwu, XU Pengfei, ZHAO Yinzhong, LI Qifeng, LAN Xin, ZHANG Fenghua, WANG Linlin, WAN Xue, ZOU Xin, ZENG Chengjun, XIN Xiaozhou, DAI Wenxu, LI Ying, HE Yanchun, LIU Yanju, LENG Jinsong

2023, 53(1): 239-255. doi: 10.6052/1000-0992-22-041

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The Mars exploration mission is a major landmark project in building a powerful aerospace country and a milestone project for China's aerospace to move further into deep space. Advanced materials integrating structures with functions can do a favor. Shape memory polymers and their composites, as typical smart materials, can effectively reduce the payload while achieving autonomous deformation, and have been successfully applied to geosynchronous orbit. Therefore, we investigate the feasibility of applying these new materials to Mars explorations. Firstly, according to the requirements of the “Tianwen-1” mission, a self-deployable flag mechanism was proposed. Then from the perspectives of static tensile mechanical properties, dynamic mechanical analysis and shape memory performance, γ and UV irradiation and long-term storage (temperatures (−196 ℃, 25 ℃ and 85 ℃) for 30 days and −196 ℃ for 457 days) effects on shape memory polymer composites were investigated. Finally, according to the photos from the “Zhurong” rover, the National Flag of China was successfully released, and the flag pattern was clear and distinct. This shows that the shape memory polymer composites have been successfully applied to Mars explorations. In the future, it is expected to assist China’s Mars sample return program and other interstellar exploration missions in diverse structural architectures.

2023, 53(1): 256-269.

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2023, 53(1): 270-272.

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2023 Vol. 53, No. 1

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