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A Cyclic Constitutive Model Based on Crystal Plasticity for Body-Centered Cubic Cyclic Softening Metals

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Acta Mechanica Solida Sinica 2024年第1期37卷 33-42页

作者： Xuehong Ren Wenjie Zhao Shaopu Yang Guilin Wen State Key laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China School of mechanical Engineering Tianjin Sino-German University of Applied SciencesTianjin 300350China State Key laboratory of mechanical Behavior in Traffic Engineering structure and System Safety Shijiazhuang Tiedao UniversityShijiazhuang 050043China

Under the framework of the small deformation crystal plasticity theory,a crystal plastic cyclic constitutive model for body-centered cubic(BCC)cyclic softening polycrystalline metals is *** constitutive model introduces the isotropic softening rule that includes two different mechanisms:namely softening under monotonic deformation and softening under cyclic deformation on each slip ***,a modified Armstrong-Frederick nonlinear kinematic hardening rule is *** appropriate explicit scale transition rule is selected to extend the single crystal constitutive model to the polycrystalline constitutive *** the model is used to predict the uniaxial and multiaxial ratcheting deformation of BCC axle steel EA4T to verify the rationality of the proposed *** simulation results indicate that the newly established crystal plasticity model can not only describe the cyclic softening characteristics of BCC axle steel EA4T well,but also reasonably describe the evolution laws of uniaxial ratcheting and nonproportional multiaxial ratcheting ***,the established crystal plastic cyclic constitutive model can reasonably predict the ratcheting behavior of BCC single crystal as well.

关键词： Crystal plasticity Constitutive model Softening Ratcheting

Polymer-to-Monomers Chemically Recyclable Poly(imide-imine)Plastics with Extreme-Condition Resistance and Flame Retardancy

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Chinese Journal of Polymer Science 2024年第10期42卷 1525-1535,I0012页

作者： Zhen-Yu Wang Xiao-Kong Liu State Key laboratory of Supramolecular structure and Materials College of ChemistryJilin UniversityChangchun130012China

Polyimides are a family of high-tech plastics that have irreplaceable applications in the fields of aerospace,defense,and opto-electronics,but polyimides are difficult to be reprocessed and recycled at the end of their service life,resulting in a significant waste of ***,it is of great significance to develop recyclable polyimides with comparable properties to the commercial ***,we report a novel polymer-to-monomers chemically recyclable poly(imide-imine)(PtM-CR-PII)plastic,synthesized by cross-linking the amine-terminated aromatic bisimide monomer and the hexa-vanillin terminated cyclophosphazene monomer via dynamic imine *** PtM-CR-PII plastic exhibits comparable mechanical and thermal properties as well as chemical stability to the commercial *** PtM-CR-PII plastic possesses a high Young’s modulus of≈3.2 GPa and a tensile strength as high as≈108 MPa,which also exhibits high thermal stability with a glass transition temperature of≈220℃.Moreover,the PtM-CR-PII plastic exhibits outstanding waterproofness,acid/alkali-resistance,and solvent-resistance,its appearance and mechanical properties can be well maintained after long-term soaking in water,highly concentrated acid and base,and various organic ***,the cyclophosphazene moieties endow the PtM-CR-PII plastic with excellent flame *** PtM-CR-PII plastic exhibits the highest UL-94 flame-retarding rating of V-0 and a limiting oxygen index(LOI)value of 45.5%.Importantly,the PtM-CR-PII plastic can be depolymerized in an organic solvents-acid mixture medium at room temperature,allowing easy separation and recovery of both monomers in high *** recovered pure monomers can be used to regenerate new PtM-CR-PII plastics,enabling sustainable polymer-monomers-polymer circulation.

关键词： Chemical recyclability Polyimides Polyimines Dynamic imine bonds mechanical properties Chemical stability

Application of interpolated double network model for carbon nanotube composites in electrothermal shape memory behaviors

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Acta Mechanica Sinica 2024年第8期40卷 133-153页

作者： Ting Fu Zhao Yan Li Zhang Ran Tao Yiqi Mao Department of Engineering Mechanics College of Mechanical and Vehicle EngineeringHunan UniversityChangsha410082China State Key laboratory of Explosion Science and Technology Institute of Advanced Structure TechnologyBeijing Institute of TechnologyBeijing100081China

Multi-wall carbon nanotube filled shape memory polymer composite(MWCNT/SMC)possessed enhanced modulus,strength,and electric conductivity,as well as excellent electrothermal shape memory properties,showing wide design scenarios and engineering application *** thermoelectrically triggered shape memory process contains complex multi-physical mechanisms,especially when coupled with finite deformation rooted on micro-mechanisms.A multi-physical finite deformation model is necessary to get a deep understanding on the coupled electro-thermomechanical properties of electrothermal shape memory composites(ESMCs),beneficial to its design and wide *** into consideration of micro-physical mechanisms of the MWCNTs interacting with double-chain networks,a finite deformation theoretical model is developed in this work based on two superimposed network chains of physically crosslinked network formed among MWCNTs and the chemically crosslinked *** intact crosslinked chemical network is considered featuring with entropic-hyperelastic properties,superimposed with a physically crosslinked network where percolation theory is based on electric conductivity and electric-heating *** model is calibrated by experiments and used for shape recoveries triggered by heating and electric *** captures the coupled electro-thermomechanical behavior of ESMCs and provides design guidelines for MWCNTs filled shape memory polymers.

关键词： Shape memory polymer composite Viscoplastic constitutive relations Electro-thermomechanics Double network model Multiple shape memory

structure and mechanical properties of windmill palm fiber with different delignification treatments

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Journal of Bioresources and Bioproducts 2024年第1期9卷 102-112页

作者： Changjie Chen Pengfei Xu Xinhou Wang Key laboratory of Textile Science&Technology(Donghua University) Ministry of EducationCollege of Textiles2999 Renmin North RoadShanghai 201620China Basalt Fiber and Composite Key laboratory of Sichuan Province Sichuan 635000China College of mechanical Engineering Donghua UniversityShanghai 201620China National Engineering laboratory for Modern Silk Soochow UniversitySuzhou 215123China Shanghai Composite Technology Co.Ltd. Shanghai 201112China

The removal of lignin from natural cellulose fibers is a crucial step in preparing high-performance materials,such as compressed high-toughness *** process can eliminate non-cellulosic impurities,create abundant compressible pores,and expose a greater number of active functional *** this study,biomass waste windmill palm fiber was used as the raw mate-rial to prepare holocellulose fibers through various chemical *** structure,chemical composition,Fourier transform infrared spectroscopy analysis,X-ray diffraction analysis,ther-mal properties,and mechanical properties,particularly fatigue performance,were *** sodium chlorite treated fiber had the highest crystallinity index(61.3%)and the most complete appearance *** sodium sulfite treated fiber had the highest tensile strength(227.34±52.27)*** peroxide treatment removed most of the lignin and hemicellulose,increas-ing the cellulose content to 68.83%±0.65%.However,all the chemical treatments decreased the thermal property of the fibers.

关键词： Windmill palm fiber Delignification treatment Morphonology mechanical property Fatigue property

Bioinspired Tactile Sensation Based on Synergistic Microcrack-Bristle structure Design toward High mechanical Sensitivity and Direction-Resolving Capability

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Research 2024年第1期2023卷 611-624页

作者： Yiqun Zhang Qi Liu Wenjuan Ren Yangyang Song Hua Luo Yangyang Han Liang He Xiaodong Wu Zhuqing Wang School of mechanical Engineering Sichuan UniversityChengdu 610065China Med+X Center for Manufacturing West China HospitalSichuan UniversityChengdu 610041China State Key laboratory of Polymer Materials Engineering Polymer Research Institute of Sichuan UniversityChengdu 610065China

Natural tactile sensation is complex,which involves not only contact force intensity detection but also the perception of the force direction,the surface texture,and other mechanical ***,the vast majority of the developed tactile sensors can only detect the normal force,but usually cannot resolve shear force or even distinguish the directions of the ***,we present a new paradigm of bioinspired tactile sensors for resolving both the intensity and the directions of mechanical stimulations via synergistic microcrack-bristle structure design and cross-shaped configuration *** microcrack sensing structure gives high mechanical sensitivity to the tactile sensors,and the synergistic bristle structure further amplifies the sensitivity of the *** cross-shaped configuration engineering of the synergistic microcrack-bristle structure further endows the tactile sensors with good capability to detect and distinguish the directions of the applied mechanical *** as-fabricated tactile sensors exhibit a high sensitivity(25.76 N^(−1)),low detection limit(5.4 mN),desirable stability(over 2,500 cycles),and good capability to resolve both mechanical intensity and directional *** promising application scenarios,surface texture recognition and biomimetic path explorations are successfully demonstrated with these tactile *** newly proposed tactile sensation strategy and technology have great potential applications in ingenious tactile sensation and construction of various robotic and bionic prostheses with high operational dexterity.

关键词： crack sensation directions

Synergy Between Soft Feet and an Active Tail to Enhance the Climbing Ability of a Bio-inspired Climbing Robot

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Journal of Bionic Engineering 2024年第2期21卷 729-739页

作者： Pongsiri Borijindakul Tachadol Suthisomboon Alihong Ji Zhendong Dai Poramate Manoonpong Institute of Bio-inspired structure and Surface Engineering College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China Bio-inspired Robotics and Neural Engineering laboratory School of Information Science and TechnologyVidyasirimedhi Institute of Science and TechnologyRayong21210Thailand

Lizards use the synergy between their feet and tail to climb on slopes and vertical *** use their soft adhesive feet with millions of small hairs to increase their contact area with the terrain surface and press their tails against the terrain to actively maintain stability during *** by this,we propose a bio-inspired climbing robot based on a new approach wherein the synergy between soft feet and an active tail with a soft adhesive tip allows the robot to climb stably on even and uneven terrains at different slope *** evaluate and compare the climbing performance of the robot on three different terrains(hard,soft,and fluffy)at different slope *** robot configurations are employed,including those with standard hard feet and soft feet in combination with an active tail-with and without a soft *** experimental results show that the robot having soft feet and a tail with the soft tip achieves the best climbing performance on all terrains,with maximum climbing slopes of 40°,45°,and 50°on fluffy,soft,and hard terrains,*** payload capacity depends on the type of terrain and the inclination ***,our robot performs multi-terrain transitions(climbing from horizontal to sloped terrains)on three different terrains of a *** approach can allow a climbing robot to walk and climb on different terrains,extending the operational range of the robot to areas with complex terrains and slopes,e.g.,in inspection,exploration,and construction.

关键词： Bio-inspired climbing robots Climbing robots Soft foot Active tail Soft terrain Terrain transitions

mechanical responses of anchoring structure under triaxial cyclic loading

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 545-560页

作者： Peng Wang Nong Zhang Qun Wei Xingliang Xu Guangzhen Cui Aoran Li Sen Yang Jiaguang Kan State Key laboratory of Coal Resources and Safe Mining School of MinesChina University of Mining and TechnologyXuzhou221116China School of Civil Engineering Xuzhou University of TechnologyXuzhou221116China School of mechanical Engineering Jiangsu University of TechnologyChangzhou213001China

Dynamic load on anchoring structures(AS)within deep roadways can result in cumulative damage and *** study develops an experimental device designed to test AS under triaxial *** device enables the investigation of the mechanical response,failure mode,instability assessment criteria,and anchorage effect of AS subjected to combined cyclic dynamic-static triaxial stress *** results show that the peak bearing strength is positively correlated with the anchoring matrix strength,anchorage length,and edgewise compressive *** bearing capacity decreases significantly when the anchorage direction is severely *** free face failure modes are typically transverse cracking,concave fracturing,V-shaped slipping and detachment,and spallation ***,when the anchoring matrix strength and the anchorage length decrease while the edgewise compressive strength,loading rate,and anchorage inclination angle increase,the failure intensity *** is determined by a negative tangent modulus of the displacement-strength curve or the continued deformation increase against the general downward *** cyclic loads,the driving force that breaks the rock mass along the normal vector and the rigidity of the AS are the two factors that determine roadway ***,a control measure for surrounding rock stability is proposed to reduce the internal driving force via a pressure relief method and improve the rigidity of the AS by full-length anchorage and grouting modification.

关键词： Triaxial stress Dynamic-static combination load Cyclic loading Anchoring structure(AS) Cumulative damage

Identification of Motor Nuclei in the Medulla Oblongata of Carp for Biological Control

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Journal of Bionic Engineering 2024年第2期21卷 842-851页

作者： Yang Zhao Yong Peng Yudong Wen Lingjun Han Yanhong Yan Xueying Dong Hui Zhang Zheng Zhao Xiaoyue Liu School of Electrical Engineering Yanshan UniversityQinhuangdao066004China School of mechanical Engineering Yanshan UniversityQinhuangdao066004China Key laboratory of National Defense of mechanical structure and Material Science Under Extreme Conditions Yanshan UniversityQinhuangdao066004China Institute of Marine Science and Engineering Yanshan UniversityQinhuangdao066004China Shijiazhuang University Shijiazhuang050035China

Brain-controlled technology is the key technology in biological control,and the corresponding relationship between animal brain nuclei and motor behavior is the *** purpose of this study was to explore the motor nuclei of the medulla oblongata in *** carps were subjected to electrical stimulation and chemical stimulation experiments,respectively,in the water-free state,and the effective chemical stimulation sites were injected with the pontamine sky blue *** brain tissue sections were obtained by paraffin tissue section technology and the neutral red staining *** comparing the positions of the brain nuclei shown in earlier studies,the motor nerve nuclei in the medulla oblongata were *** brain electrode was implanted into the motor nucleus of the medulla oblongata,and the underwater control experiment and behavioral tests were carried out with different electrical stimulation *** results showed that the abducens nucleus(NVI)was the motor nucleus that controls the ipsilateral steering,and the facial nucleus(NVII)was the motor nucleus that controls the forward *** adjusting the stimulation voltage and the stimulation pulse number,the carp can be stably controlled to achieve a left–right steering motion of 30°–180°and a forward motion of more than 80 cm/*** study indicated that the quantitative control of the steering and forward behavior of the carp can be achieved by electrical stimulation of the NVI and NVII,which provided a certain experimental basis for the accurate control of the carp robot.

关键词： Biological control Carp Medulla oblongata motor nucleus Electrical stimulation technique Chemical stimulation technique

A variable structure passivity control method for elastic joint robots based on cascaded high-order state estimation

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Science China(Technological Sciences) 2024年第2期67卷 395-407页

作者： ZHANG JieXin NIE PingYun ZHANG Bo State Key laboratory of mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240China

Passivity-based controllers are widely used to facilitate physical interaction between humans and elastic joint robots,as they enhance the stability of the interaction ***,the joint position tracking performance can be limited by the structures of these controllers when the system is faced with uncertainties and rough high-order system state measurements(such as joint accelerations and jerks).This study presents a variable structure passivity(VSP)control method for joint position tracking of elastic joint robots,which combines the advantages of passive control and variable structure *** method ensures the tracking error converges in a finite time,even when the system faces *** method also preserves the passivity of the ***,a cascaded observer,called CHOSSO,is also proposed to accurately estimate high-order system states,relying only on position and velocity *** observer allows independent implementation of disturbance compensation in the acceleration and jerk estimation *** particular,the observer has an enhanced ability to handle fast time-varying disturbances in physical human-robot *** effectiveness of the proposed method is verified through simulations and experiments on a lower limb rehabilitation robot equipped with elastic joints.

关键词： motion control elastic joint robot finite-time convergence high-order system state estimation physical human-robot interaction