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Study on the effects of combustion characteristics of pyrotechnic charges on pyrotechnic shocks

Defence Technology(防务技术) 2025年第4期46卷 79-98页

作者： Jingcheng Wang Shihui Xiong Huina Mu Xiaogang Li Yuquan Wen State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of TechnologyBeijing 100081China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China

This study calculates the combustion characteristics of various gas-generating and micro gas pyrotechnic charges,including aluminium/potassium perchlorate,boron/potassium nitrate,carbon black/potassium nitrate,and silicon-based delay compositions,using thermodynamic software.A multiphase flowthermal-solid coupling model was established,and the combustion process of the pyrotechnic charges within a closed bomb was *** pyrotechnic shock generated by combustion was *** combustion pressures and pyrotechnic shocks were *** simulation results demonstrated good agreement with experimental ***,the mechanism of shock generation by the combustion of pyrotechnic charges in the closed bomb was *** effects of the combustion characteristics of the pyrotechnic charges on the resulting pyrotechnic shocks were systematically ***,the shock response spectrum of the gas-generating pyrotechnic charges is greater than that of the micro gas compositions at most frequencies,particularly in the mid-field pyrotechnic shocks(3-10 kHz).Furthermore,the pyrotechnic shocks increase approximately linearly with the impulse of the gas-generating pyrotechnic charges.

关键词： Pyrotechnic charges Pyroshock Closed bomb tests Combustion characteristics Multiphase flow-thermal-solid coupling

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Application of phononic crystals in modern engineering vibration and noise control, a review

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Noise and Vibration Worldwide 2025年第4-5期56卷 224-241页

作者： Huang, Wei Xu, Jian Yao, Yi Zhang, Yongliang Wang, Xin Han, Pengbo SINOMACH Academy of Science and Technology Co. Ltd SINOMACH Research Center of Engineering Vibration Control Technology Beijing100080 China Beijing China CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Anhui China Key Laboratory of Vibration Control for Key Process Equipment of Major Scientific Infrastructure in the Machinery Industry Beijing China

Phononic crystals are composite materials consisting of periodically distributed inclusions, and this structure enables wave band gaps under specific conditions. This characteristic allows for the suppression of elastic waves within certain frequency ranges, offering a new approach to vibration reduction and noise control. In this study, phononic crystals, with their periodic structure, tunable bandgap properties, topology optimization, and additive manufacturing technology, are reviewed. Some key hot issues, such as low-frequency vibration and noise control, intelligent materials, and tunable bandgap design, are discussed. In the future, phononic crystals will play a significant role in barrier vibration isolation, rail transit vibration isolation, power equipment vibration isolation, precision equipment vibration isolation, noise control, and underground protection engineering. This study constitutes a systematic summary and outlook of phononic crystals in modern engineering vibration and noise control. © The Author(s) 2025.

关键词： Precision engineering

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Revealing Hetero-Deformation Induced(HDI)Hardening and Dislocation Activity in a Dual-Heterostructure Magnesium Matrix Composite

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Journal of Magnesium and Alloys 2025年第2期13卷 902-921页

作者： Lingling Fan Ran Ni Lingbao Ren Peng Xiao Ying Zeng Dongdi Yin Hajo Dieringa Yuanding Huang Gaofeng Quan Wei Feng School of Mechanical Engineering Chengdu UniversitySichuanChengdu 610106PR China School of Materials Science and Engineering Southwest Jiaotong UniversitySichuanChengdu 610031PR China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityShanxiXi'an 710049PR China Institute of Material and Process Design Helmholtz-Zentrum HereonGeesthacht 21502Germany Institute of Metallic Biomaterials Helmholtz-Zentrum HereonGeesthacht 21502Germany

Integrating a heterogeneous structure can significantly enhance the strength-ductility synergy of ***,the relationship between hetero-deformation induced(HDI)strain hardening and dislocation activity caused by heterogeneous structures in the magnesium matrix composite remains *** this study,a dual-heterogeneous TiC/AZ61 composite exhibits significantly improved plastic elongation(PEL)by nearly one time compared to uniform FG composite,meanwhile maintaining a high strength(UTS:417 MPa).This is because more severe deformation inhomogeneity in heterogeneous structure leads to more geometrically necessary dislocations(GNDs)accumulation and stronger HDI stress,resulting in higher HDI hardening compared to FG and CG *** the early stage of plastic deformation,the pile-up types of GND in the FG zone and CG zone are significantly *** tend to form substructures in the FG zone instead of the CG *** only accumulate at grain boundaries of the CG region,thereby leading to obviously increased back stress in the CG *** the late deformation stage,the elevated HDI stress activates the new〈c+a〉dislocations in the CG region,resulting in dislocation entanglements and even the formation of substructures,further driving the high hardening in the heterogeneous ***,For CG composite,〈c+a〉dislocations are not activated even under large plastic strains,and only〈a〉dislocations pile up at grain boundaries and twin *** work provides an in-depth understanding of dislocation variation and HDI hardening in heterogeneous magnesium-based composites.

关键词： Mg-matrix composite Heterogeneous structure HDI hardening GND density Dislocation

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A unified multi-phase-field model for Rayleigh-Damköhler fluid-driven fracturing

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Journal of the Mechanics and Physics of Solids 2025年 200卷

作者： Li, Bo Yu, Hao Xu, WenLong Wang, Quan Huang, HanWei Wu, HengAn CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Hefei230027 China

In geological systems where fractures are driven by low-viscosity reactive fluids (e.g., CO₂ fracturing), the leak-off of the reactive fluid from fractures into the rock matrix induces Rayleigh-Taylor instability, leading to the formation of fingering invasion regions that undergo chemical damage, thereby destabilizing fracture propagation. The fracture propagation is strongly coupled with the heterogeneous chemical damage. The significant variability of Rayleigh number (buoyancy-driven convection / diffusion) and Damköhler number (chemical reaction / advection) within a wide range causes various flow and fracture patterns. Based on the principle of virtual work, a unified multi-phase-field model is proposed to model the mechanics enhanced chemical damage and dissolution-assisted fracturing process. The distinct fracture (∅f) and chemical damage (∅d) phase field order parameters are introduced to characterize fracture energy, chemical free energy and dissolution interfacial energy. The two phase fields are tightly linked through a synergistic degradation of mechanical energy. The governing equations for the Rayleigh-Damköhler fluid-driven fracturing are derived from the variational formulation of the free energy and micro-force balance. Based on the model, dimensional analysis is employed to establish the scaling laws for rock failure modes. When leak-off fluid flow aligns with fracture propagation, critical curves distinguishing different damage morphology are identified in the phase diagram using penetration lengths. In scenarios where gravity induces a misalignment between leak-off fluid flow and fracture direction, the normalized fracture number (Πf) and chemical damage number (Πd) are summarized to construct a comprehensive phase diagram encompassing various unstable fluid leak-off structures and rock failure modes. © 2025 Elsevier Ltd

关键词： Fracture energy

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Valley-dependent giant orbital moments and transport features in rhombohedral graphene multilayers

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Physical Review B 2025年第16期111卷 165102-165102页

作者： Xingchi Mu Jian Zhou Center for Alloy Innovation of Design State Key Laboratory of Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China

Recent years have witnessed a great interest in orbital-related electronics (also termed as orbitronics). In the current work, we present a first-principles density functional theory calculation on orbital magnetic moments, intrinsic orbital Hall effect, and ordinary magnetoconductivity effects in rhombohedral graphene multilayers. Our calculations suggest a giant orbital moment that arises from interatomic cycloid motion, reaching over 30 μB under an intermediate gate voltage. This leads to a valley polarization under an external magnetic field, as observed in recent experiments [T. Han et al., Nature (London) 623, 41 (2023)]. In addition, the orbital-related transport feature exhibits significant responses that are potentially observed in experiments. We also suggest that under a periodically driven field (such as a high frequency light field), the ungated graphene multilayers could host strong quantum anomalous and orbital Hall effects, engineered by the layer number. As the graphene multilayers are intrinsically nonmagnetic with negligible spin-orbit coupling, the orbital moments will not be entangled by spin-related signals. Thus, they serve as an ideal platform to conduct orbitronic measurements and utilization for next generation information read/write nanodevices.

关键词： Magnetic moments

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Laser welding of molybdenum socket joint for ultra-high-temperature heat pipes based on niobium alloying

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Transactions of Nonferrous Metals Society of China 2025年第2期35卷 511-524页

作者： Jia-xuan ZHAO Hong-da ZHANG Lin-jie ZHANG Xiang-dong DING Yuan-jun SUN Guang SUN State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China China Nuclear Power Design Co. Ltd.Shenzhen 518172China

The influence of Ti and Zr,Nb alloying on the microstructures and performance of laser-welded molybdenum socket joints was *** Nb alloying,the average microhardness of the fusion zone(FZ)increased from HV 194.7 to HV ***,Nb can react with O to form dispersed Nb_(2)O_(5) along grain boundaries,impeding grain boundary migration and dislocation movement while reducing the content of volatile Mo oxide along these *** incorporation of Nb in FZ partially inhibits pore defects and enhances joint load-bearing *** comparison to the laser-welded joints without adding Nb(LW),the tensile strength of the laser-welded joints with Nb alloying(LW-Nb)was significantly improved by approximately 69%from 327.5 to 551.7 ***,the fracture mechanism of the joints transitioned from intergranular fracture to transgranular fracture.

关键词： laser welding molybdenum heat pipe niobium alloying microstructure performance

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Achieving high strength and large ductility in a Cr30Co30Ni30Al5Ti5 alloy through intergranular precipitation

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Journal of materials Science and Technology 2025年 215卷 167-179页

作者： Zou, Jiawei Chen, Siyu Cheng, Pengming Ding, Jun Zhang, Chongle Zhang, Shengze Zhang, Bozhao Fu, Xiaoqian Chen, Yujie Zhao, Yuping Qi, Xu Gu, Lin Zhang, Ze Sha, Gang Yu, Qian Center of Electron Microscopy and State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou310027 China School of Materials Science and Engineering Herbert Gleiter Institute of Nanoscience Nanjing University of Science and Technology Nanjing210094 China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an710049 China Center for Alloy Innovation and Design State Key Laboratory for Mechanical Xi'an Jiaotong University Xi'an710049 China Pico Electron Microscopy Center Innovation Institute for Ocean Materials Characterization Technology Center for Advanced Studies in Precision Instruments Hainan University Haikou570228 China Beijing National Center for Electron Microscopy and Laboratory of Advanced Materials School of Materials Science and Engineering Tsinghua University Beijing100084 China

Precipitation at grain boundaries is typically not regarded as an efficient method for strengthening materials since it can induce grain boundary embrittlement, which detrimentally affects ductility. In this research, we developed a multi-principal element alloy (MPEA) with the composition Cr30Co30Ni30Al5Ti5 (at.%), incorporating both intragranular and intergranular nanoprecipitates. Utilizing multiscale, three-dimensional, and in-situ electron microscopy techniques, coupled with computational simulations, we established that intergranular nanoprecipitation in this material plays a crucial role in enhancing strength and promoting dislocation plasticity. The structure of intergranular nanoprecipitation comprises multiple phases with varying composition and structure. Despite the diversity, the crystal planes conducive to the easy glide of dislocations are well-matched, allowing for the sustained continuity of dislocation slipping across different phase structures. Simultaneously, this structure generates an undulated stress field near grain boundaries, amplifying the strengthening effect and facilitating multiple slip and cross-slip during deformation. Consequently, it promotes the proliferation and storage of dislocations. As a result, our material exhibits a yield strength of approximately 1010 MPa and an ultimate tensile strength of around 1500 MPa, accompanied by a significant fracture elongation of 41 %. Our findings illuminate the potential for harnessing intergranular nanoprecipitation to optimize the strength-ductility trade-off in MPEAs, emphasizing the strategy of leveraging complex compositions for the design of sophisticated functional microstructures. © 2024

关键词： Ductility

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Impact of Graphene/Substrate-Interaction on Lubrication within Moiré Heterostructures

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Tribology Letters 2025年第3期73卷 1-14页

作者： Shen, Zifu Chen, Yongchao Han, Guangchao Yan, Ruilin Wang, Hailong CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Hefei China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Science Beijing China

Understanding and controlling friction is crucial for advancements in nanoscale systems and microelectromechanical devices. Moiré superlattices formed on graphene-covered metallic substrates present a unique opportunity to modulate frictional behavior. However, the role of graphene/substrate interaction in lubrication within these heterostructures remains inadequately explored. In this study, molecular dynamics simulations combined with theoretical modeling are employed to investigate the impact of graphene-substrate interactions on friction in moiré heterostructures. The results reveal a nonmonotonic dependence of lateral forces on interaction strength, governed by the competition between graphene wrinkling and elastic energy dynamics. In the weak interaction regime, tip/graphene-adhesion-induced graphene wrinkling enhances friction by increasing pinning atoms. In contrast, strong interactions lead to elastic energy accumulation and relaxation, elevating friction during stick–slip motion. Additional factors, such as normal load, tip size, tip geometry, and tip/graphene interaction, significantly influence frictional behavior. An improved Prandtl-Tomlinson model is developed to validate the findings, demonstrating excellent agreement with simulation results. This work elucidates the mechanisms underlying graphene-substrate-interaction-dependent frictional behavior and offers a framework for tuning tribological properties in two-dimensional materials, enabling the design of advanced MEMS and NEMS with controllable lubrication.

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Decoupling tensile and shear effects in dynamic fracture of glass sphere

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Powder Technology 2025年 460卷

作者： Xiong, Ying Xu, Songlin Xie, Yushan Chen, Meiduo Yuan, Liangzhu Wang, Pengfei CAS Key Laboratory for Mechanical Behavior and Design of Materials Department of Modern Mechanics University of Science and Technology of China Anhui Hefei230027 China China Earthquake Administration Beijing100036 China

Failure in brittle materials shows evident tensile and shear coupling effects due to inner heterogeneous deformation. Based on the dynamic fragmentation experiments of four glass spheres at various strain rates, a statistical approach is established to decouple the tensile effects and the shear effects on dynamic fracture. The fractal dimension is introduced to describe the cracks distribution during sphere fracture, and the evolutions of fractal dimensions due to shear failures and tensile failures are analyzed both on the DIC images and on the numeric cracks distribution by the DEM-FEM. Under higher strain rates, the fractal dimensions of shear cracks distribution are close to those based on total cracks distribution;while under lower strain rates, the fractal dimensions of tensile cracks distribution are close to those based on total cracks distribution. The ultimate fractal dimensions due to shear failures and tensile failures show evident strain rate effects and tensile and shear coupling effects. The relation of statistical shear strength to statistical tensile strength is then established, and based on self-similarity analyses, a novel method for decoupling the effects of tensile failure and shear failure is proposed. The two intrinsic strengths (σ¯t0, σ¯s0) of spheres are obtained. The decoupled strengths are scattered around the line from point (0,0) to point (σ¯t0, σ¯s0), which could be described as σ¯s=σ¯tD∗−1+ksσ¯s0. The ratio σ¯t/σ¯s decreases with increasing strain rate, and finally decreases to σ¯t0/σ¯s0=0.189. It is helpful for a profound understanding of the formation and propagation of failures in brittle materials. © 2025 Elsevier B.V.

关键词： Fractal dimension

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Numerical Study on Natural Circulation System under Various Cooling Mediums

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Frontiers in Heat and Mass Transfer 2025年第2期23卷 397-420页

作者： Yumei Lv Wei Dai Shupeng Xie Peng Hu Fei He CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Thermal Science and Energy EngineeringUniversity of Science and Technology of ChinaHefei230027China Beijing Institute of Astronautical Systems Engineering Beijing100076China

Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve adaptive *** enhance the universality of this internal cooling pipe design and facilitate its application,numerical studies are conducted on this systemwith four commonly used cooling mediums as ***,the accuracy of the numerical method is verified through an established experimental ***,transient numerical simulations are performed on the flow states of different cooling mediums in the new self-circulation *** on the numerical result,the flow,phase change,and heat transfer characteristics of different cooling mediums are *** in fluid velocity and latent heat of phase change result in significant variation in heat exchange capacity among different coolingmediums,with the maximumdifference reaching up to 3 ***,faster circulation speed leads to greater heat transfer capacity,with a maximum of 7600 W/m^(2).Consequently,the operating mechanism and cooling laws of the natural circulation system is further investigated,providing a reference for the practical application of this system.

关键词： Transpiration cooling natural circulation loop phase change heat transfer capability flow state

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