Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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Wavelet-based numerical methods and their applications in computational mechanics
YANG Bing, WANG Jizeng, LIU Xiaojing, ZHOU Youhe, FENG Yonggu
 doi: 10.6052/1000-0992-24-009
Abstract(192) HTML(19) PDF(96)
Abstract:
Mechanics research advances towards interdisciplinary research, cross-scale correlations, and extreme environmental impacts. Strong nonlinearity, strong discontinuity, significant multi-physics coupling, multiscale, and complex geometries have become common characteristics in solving various mechanics problems quantitatively. Long-term quantitative research indicates that one of the core ingredients for solving such problems effectively lies in constructing numerical methods that can accurately identify, locate, capture, and separate different scale characteristics especially small-scale local characteristics, under multiscale and nonlinearity circumstances. These numerical methods should also possess the capacity to isolate and decouple the large-scale lower-order approximation from the small-scale higher-order truncation error effectively. The intrinsic multiresolution analysis and time-frequency localization characteristics of wavelet theory, as well as the various selectivity of basis functions, align precisely with the demands of this mathematical feature. Therefore, they can provide fundamental theory and diverse approaches for developing efficient quantitative methods to address various complex mechanics problems. Based on this fact, this paper provides a comprehensive discussion of wavelet theory, focusing on the theoretical framework of biorthogonal multi-resolution analysis and the construction method of frequently used wavelet bases. Furthermore, wavelet approximation of the function defined on a finite domain is presented in detail. The fundamental principles, development, merits, and shortcomings of different wavelet-based numerical methods are systematically elucidated. Several novel wavelet-based methods with outstanding performance developed recently are elaborated especially, and their applications in solving typical mechanics problems are reviewed. Meanwhile, the present paper also points out challenges encountered by the existing wavelet-based numerical methods when addressing complex and strongly nonlinear mechanics problems. This may provide valuable references for the development of wavelet-based numerical methods and their applications in complex mechanics and engineering problems, and introduce new perspectives and methods for solving these problems efficiently, accurately, and universally.
Progress in assessing hazards of asteroid impact on Earth
DANG Leining, BAI Zhiyong, SHI Yilei, HUANG Jie
 doi: 10.6052/1000-0992-23-047
Abstract(213) HTML(77) PDF(53)
Abstract:
Asteroid impact on earth poses a potential threat to humanity. Over the past 20 years, planetary defense has become a hot research area internationally, and it is also a crucial security requirement for our country. Assessing the hazards of asteroid impact on earth is a significant research topic within planetary defense. It is noted that asteroid impacts on earth exhibit characteristics of low probability, high hazard and randomness. These hazards include overpressure, thermal radiation, earthquake, tsunami, and global effects. Hazard assessment is applied in three scenarios: defense decision-making, defense implementation, and ground civil defense. The input and output of hazard assessment, the progress of numerical simulation and engineering computation in hazard assessment in terms of model, method and software, as well as the research status of the five types of hazards, are summarized. Furthermore the advancement of hypervelocity issues of earth impact by asteroid is presented. Finally, the current research limitations are identified, and prospects for future work are provided.
The progress in nuclear biomechanics
LIU Zhongqian, QI Yingxin
 doi: 10.6052/1000-0992-23-053
Abstract(340) HTML(109) PDF(89)
Abstract:
The nucleus, which plays crucial roles in regulating life activities, is the largest and stiffest organelle in the cell and serves as the center of genetic information storage, replication, and transcription. Biomechanical factors have been shown to be of paramount importance in regulating dynamic changes of nuclear structures and functions. As typical mechanical responsive elements of the nucleus, nucleoskeletal proteins and nuclear pore complexes maintain the morphology and structure of the nucleus, and transmit mechanical forces from the cytoskeleton to chromatin. These factors affect a range of nuclear-related processes, including chromatin conformation and gene expression, and ultimately regulate cellular functions. The sensation and transduction of mechanical signals via nuclear components are one of the emerging cutting edges in biomechanics. To gain a deeper understanding of the mechanical properties of the nucleus in physiological and pathological states, and to elucidate its roles and mechanisms in cell fate determination, this review summarizes the research progresses related to nuclear biomechanics, focusing on the physical structures of nucleoskeleton, nuclear pore complex, and chromatin, the processes of mechanical responses, the interactions among these nuclear components, and the technological advances in nuclear biomechanics. Finally, the relationship between nucleus and the progeria, neurodegeneration or cardiovascular diseases and the future advancements of nuclear biomechanics are prospected.
Research progress of process and structures optimization for 3D printed continuous fiber-reinforced polymers
YE Hongling, DONG Yongjia, MAO Pengqi, XIAO Yang, XIE Jialin
 doi: 10.6052/1000-0992-23-048
Abstract(603) HTML(142) PDF(133)
Abstract:
Continuous fiber-reinforced polymers (CFRP) has been broadly applied in the aerospace engineering due to its excellent specific strength, specific stiffness, designability and lightweight feature. The development of 3D printing has changed the manufacturing process of CFRP structures, which makes the free form of complex structures possible and provides more design space for advanced structural materials. In order to give full play to the performance advantages of CFRP and the flexibility of 3D printing process, and achieve innovative structural design and performance improvement, researchers explored the solutions of design and manufacturing integration for 3D printing CFRP from the aspects of material performance and structural design, respectively. In this paper, the development of properties analysis, process improvement and structure optimization of CFRP is reviewed systematically. Various multi-scale optimization methods of CFRP are summarized and illustrated, the development trend of real-time, functional and intelligent structural design method of advanced materials in the future is discussed and prospected.
Research progress of fatigue crack propagation method based on finite element technology
SU Yukun, MA Tao, ZHAO Xiaoxin, ZHANG Guangliang, ZHU Jialei, ZHANG Peng
 doi: 10.6052/1000-0992-23-049
Abstract(633) HTML(131) PDF(241)
Abstract:
Fatigue cracks are one of the important factors causing fracture and failure of engineering structures. At present, the commercial software for fatigue crack propagation finite element simulation includes ANSYS, ABAQUS, FRANC3D, ZENCRACK, etc., which provide strong support for the study of fatigue crack propagation process. The current finite element simulation methods for fatigue crack propagation are reviewed in this paper. The definition of fatigue crack and the necessity of studying fatigue crack propagation behavior are clarified. Three finite element methods for simulating fatigue crack propagation are introduced: Extended Finite Element Method(XFEM), Cohesive Zone Model (CZM) and Virtual Crack Closure Technique (VCCT). The basic theories and core ideas of the three methods were summarized, and the application as well as development of the three methods were classified and summarized. Finally, the three finite element methods are analyzed, the advantages and limitations of each method are pointed out, and suggestions are given for the future improvement of the finite element simulation technology for fatigue crack propagation.
Research on structure topology optimization design empowered by deep learning method
CHEN Xiaoqian, ZHANG Zeyu, LI Yu, YAO Wen, ZHOU Weien
 doi: 10.6052/1000-0992-23-052
Abstract(877) HTML(297) PDF(272)
Abstract:
This article comprehensively discusses the relevant research progress in the field of structural topology optimization and the cross-integration development of deep learning technology in recent years. Focusing on the core methods and key modules of structural topology optimization design, two major types of empowerment methods are systematically sorted out from the perspective of deep learning empowerment. The study points out that the global surrogate model construction method for structural optimization design based on deep learning technology, as a direct mapping structural design method, has been widely studied because of its simple and typical design ideas. However, the global surrogate model has limitations in computation and generalization. The limitations and deficiencies in performance are also particularly obvious. The structural optimization design method with local sub-link acceleration and replacement integrated with deep learning technology is a more flexible and diverse form of local empowerment, with good universality and unique advantages. The article looks forward to the future development of intelligently empowered structural optimization. Further research work would focus on the organic combination of deep learning and structural design, as well as the co-driven design paradigm of data and knowledge.
Review on dynamics and control of space structure in the process of on-orbit assembly
WU Zhigang, JIANG Jianping, WU Shunan, LI Qingjun, WANG Xing, TAN Shujun, DENG Zichen
 doi: 10.6052/1000-0992-23-041
Abstract(1399) HTML(91) PDF(307)
Abstract:
On-orbit assembly is a crucial means to construct large and ultra-large space structures such as space stations, large satellite antennas, large-aperture space telescopes, and space solar power stations. However, complicated dynamics and control problems, such as the configuration increasement, parameter variations, orbit-attitude-structure coupled effects, and contact problems, will be encountered during the process of on-orbit assembly and bring challenges to accomplishing the assembly task accurately, efficiently, and safely. The development status of dynamic modelling methods of large space structures, special dynamic phenomena of ultra-large space structures, and dynamic modelling studies of space structures during on-orbit assembly process were reviewed. Then, the control methods of the on-orbit operation stage, the assembly sequence planning methods, and the control methods for the on-orbit assembly process were introduced. In addition, the key techniques of gravity unloading, scale model design and testing, nonlinearity and uncertainty quantification techniques with ground tests in the assembly process were summarized. Finally, to address the increasing configuration and discontinuously varying parameters of the ultra-large space structures during on-orbit assembly process, a few suggestions were put forward to deal with the dynamic and control problems.
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