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Effects of Non-Uniform Needled Microstructure on Failure Mechanisms of 3d Needled C/C-Zrc-Sic composites Thick-Walled Cylinder Under Axial Compression and Internal Pressure

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SSRN 2022年

作者： Wang, Zhangwen Wang, Bing Jiang, Xinyu Wang, Xiaosong Sun, Wei Fang, Guodong Meng, Songhe Science and Technology on Advanced Composites in Special Environments Key Laboratory Harbin Institute of Technology Harbin150001 China National Key Laboratory of Precision Hot Processing of Metals Harbin Institute of Technology Harbin150001 China State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China

Three dimensional (3D) needled ZrC-SiC modified C/C composites (C/C-ZrC-SiC composites) as cutting-edge materials for throat or expansion section of rocket nozzle are mainly subjected to complex loads conditions of internal pressure and axial force. The coupled axial compression and internal pressure experiments of 3D needled C/C-ZrC-SiC composites thick-walled cylinder were carried out to study the damage modes and failure mechanisms combing with the optical microscope and micro computed tomography (Micro-CT). A meso-macro finite element (FE) model considering local needling fiber regions was also established to investigate the failure process of the thick-walled cylinder under the complex loads. The predicted strength, failure strain and ultimate crack morphologies obtained by the proposed model were in good agreement with the experimental results. The effect of needled region distribution on the crack evolution and damage mechanisms was further analyzed. The non-uniform distribution of needled fiber region can induce the stress concentration of no needled regions under circumferential tension, which can trigger crack initiation and deflection. This study can be helpful of establishing the relationship between the structural behavior of ultra-high temperature ceramics modified C/C composites nozzle and the 3D needled composites design. © 2022, The Authors. All rights reserved.

关键词： Finite element method

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Power Law Analysis of Thermal Conductivity of Bulk Diamond Under Isotropic and Uniaxial (100) Strains: First-Principles Predictions

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SSRN 2023年

作者： Wang, Biao He, Yurong Rodionov, Nikolay Zhu, Jiaqi National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150080 China School of Energy Science and Engineering Harbin Institute of Technology Harbin150001 China State Research Center of Russian Federation Troitsk Institute for Innovation and Fusion Research Troitsk Moscow108840 Russia Key Laboratory of Micro-systems and Micro-structures Manufacturing Ministry of Education Harbin150080 China

The miniaturization of high-frequency electronic devices is associated with significant heat accumulation by individual components. Diamond exhibits ultrahigh thermal conductivity and is thus an ideal material for heat dissipation. Considering the sensitive stress-thermal responses of diamond, this study uses first-principles calculations and the phonon Boltzmann transport equation to compare and analyze the effects of uniaxial strain along the crystal direction, as well as isotropic strain, on the thermal conductivity of bulk diamond. Under isotropic strain, the thermal conductivity is principally influenced by bond length;the relationship between thermal conductivity and the bond length deformation index follows a power law. During uniaxial strain, the bond angle and bond length change simultaneously, superimposing their effects on thermal conductivity. This study provides essential insights into the mechanisms of diamond thermal conductivity under different strains;the findings can guide prediction of the strain-thermal conductivity relationships of other crystalline materials. © 2023, The Authors. All rights reserved.

关键词： Strain

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Design and Bandgap Tuning of Kresling Origami-Inspired Metamaterials

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SSRN 2024年

作者： Zhang, Ji Gao, Tianyu Wang, Changguo School of Civil Engineering and Mechanics Yanshan University Qinhuangdao066004 China Hebei Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures Yanshan University Qinhuangdao066004 China School of Mechanical Engineering Yanshan University Qinhuangdao066004 China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150080 China Center for Composite Materials and Structures Harbin Institute of Technology Harbin150001 China

In this study, a resonant system based on Kresling origami was designed, utilizing the unique geometric properties of the structure to achieve bandwidth tuning for effective vibration control. Finite element analysis was employed to systematically investigate how variations in folding angles, the number of layers, and overall structural symmetry affect the system’s vibration bandgap characteristics. The analysis revealed that significant vibration bandgaps in the low-frequency range, specifically between 60 Hz and 150 Hz, could be achieved through careful adjustments to the Kresling origami configuration. By manipulating the folding patterns and geometric parameters, the structure was able to suppress vibrations within specific frequency ranges, providing a precise and adaptable approach to vibration isolation. This method eliminates the need for additional materials or complex mechanical systems, significantly simplifying the design and fabrication process while enhancing flexibility. Moreover, the inherent adaptability of Kresling origami structures was demonstrated, showing that the design could be extended beyond spiral bases to incorporate a wide variety of origami forms, further broadening its application potential. These findings demonstrate the practical viability of Kresling origami-based systems in real-world engineering, especially in environments requiring efficient and customizable vibration and noise reduction. The study highlights the structure’s potential in industries such as aerospace, automotive, and civil engineering, where adaptable vibration control is crucial under challenging conditions. © 2024, The Authors. All rights reserved.

关键词： Vibration analysis

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Investigation on Potential Barrier of Terminal Pinned Schottky Junction

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SSRN 2022年

作者： Zhang, Sen Liu, Kang Liu, Benjian Dai, Bing Zhang, Xiaohui Qiao, Pengfei Zhao, Jiwen Li, Yicun Hao, Xiaobin Yang, Lei Cao, Wenxin Han, Jiecai Zhu, Jiaqi National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150080 China Key Laboratory of Micro-systems and Micro-structures Manufacturing Ministry of Education Harbin150080 China of unmanned Equipment & AI Zhongshan528400 China

The diamond Schottky theory needs to be further improved before exertising its full advantages, especially in terms of the physical properties of the diamond surface and the interface between metals and diamond. In our previous work, we experimentally verified that the oxygen terminal with a ketone bond introduces an acceptor surface state, 2.22 eV above valence band maximum (VBM), into bandgap at a diamond surface. Here, we further investigated the contact band diagram between metals (Au, Ag, Pt, W, and Pd) with different work function and oxygen terminated diamond using X-ray photoelectron spectroscopy. Results showed that the contact Fermi level was at 2.38 eV, 2.33 eV, 2.32 eV, 2.28 eV, and 2.29 eV above VBM, respectively. In addition, the similar symmetrical photocurrent-voltage characteristics under positive and negative bias were observed between Au-Ag and Ag-Pt electrodes deposited on the same oxygen terminated diamond plate. All the data above could be drawn a conclusion that the oxygen-terminal can pin the Schottky barrier height. We believe that the results obtained herein will help in the design and theoretical analysis of diamond Schottky devices. © 2022, The Authors. All rights reserved.

关键词： Oxygen

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Design and Analysis of Kresling Origami-Inspired Reconfigurable Intelligent Dynamic Shading System

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SSRN 2024年

作者： Zhang, Ji Gao, Tianyu Liu, Shuai Mi, Yueying Liu, Jiatong Wang, Changguo School of Civil Engineering and Mechanics Yanshan University Qinhuangdao066004 China Hebei Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures Yanshan University Qinhuangdao066004 China School of Mechanical Engineering Yanshan University Qinhuangdao066004 China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150080 China Center for Composite Materials and Structures Harbin Institute of Technology Harbin150001 China

This work presents a reconfigurable intelligent dynamic shading system based on the Kresling origami structure, and conducts mechanical analysis and photothermal coupling research. Initially, unit cell of intelligent system is created by incorporating a fan blade unit with adjustable ventilation into the upper section of the Kresling origami structure. The reconfigurable intelligent dynamic shading system is formed by arranging the unit cells based on the concept of kirigami. The crease portion utilizes Shape Memory Polymer (SMP) polymers to enable the structure to intelligently fold and unfold. Simultaneously, Carbon Fiber Reinforced Polymer (CFRP) is employed in the panel components to guarantee the robustness and steadiness of the framework. Subsequently, a mechanical model was formulated and the mechanical mechanism governing the evolution of its configuration was derived using the principle of minimum potential energy. Additionally, 4D printing was conducted, where specimens were manufactured and subjected to compression testing and simulations. The results shown strong concurrence with the theoretical predictions, so enabling the characterization of the mechanical properties of intelligent dynamic shading system. Research on the flow field characteristics of the system demonstrates the favorable attributes of this technology in intelligent ventilation. Ultimately, the investigation of the system's photothermal coupling demonstrated the discerning influence of structural photothermal factors. Through the implementation of a mathematical model, the intelligent system has the capability to autonomously adapt the shade angle in response to dynamic environmental variations, thereby enhancing the illumination and thermal conditions within the building. This system offers superior control over light and heat flow compared to conventional permanent shade facilities. It effectively reduces energy consumption and greatly enhances the comfort of living and working enviro

关键词： Dynamics

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Influence of Assembly Parameters on Tensile Behavior of Hybrid CMC and Superalloy Bolted Joints by Progressive Damage Analysis

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Journal of Harbin Institute of technology(New Series) 2021年第3期28卷 53-60页

作者： Chao Lv Feng Li Shuyuan Zhao Qian Sun Mingrui Li Xinyang Sun China Academy of Aerospace Aerodynamics Beijing 100074China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150080China Shenyang Aircraft Design and Research Institute Aviation Industry Corporation of ChinaShenyang 110000China School of Aeronautics and Astronautics Harbin Institute of TechnologyHarbin 150001China

With the considerable applications of ceramic matrix composites(CMC) in aircraft engineering, the design of CMC bolted joint gains paramount attention because of its capacity to to improve load-bearing efficiency of aircraft key structure. In this work, a 3 D finite element model was established to predict tensile performance and failure modes of single-lap, single-bolt 2 D C/SiC composite, and superalloy joint, which considers the progressive damage behavior of 2 D woven C/SiC composites. On the basis of the developed progressive damage model, a parametric study was carried out to illustrate the effects of bolt preload and bolt-hole clearance on mechanical behaviors of the hybrid bolted joint. It was found that the increase in the value of bolt preload made the failure load grow first and then drop, and the optimum value of bolt preload 5.00 kN generated 56.47% rise in the initial failure load and 22.83% rise in the final failure load for the bolted joint in comparison with zero preload case. As the clearance increased from 0 to 2.00%, the initial and final failure loads respectively declined by 45.88% and 24.02% for 2.00% bolt-hole clearance relative to the neat-fit case. The loss in failure loads can be reduced to compressive stress concentration around the fastening hole-edge area, leading to the appearance of earlier damages by the introduction of increasing bolt hole clearance.

关键词： ceramic matrix composite progressive damage analysis tensile performance bolt preload bolt-hole clearance

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Efficient Carbon Nanotube Growth from Pyrolysis of Citric Acid-Based Small Organic Molecules

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SSRN 2022年

作者： Liu, Xue Li, Jingwei Luo, Yuan Li, Jianjun Wei, Zhonglin Cao, Jungang Lu, Haibao Zhang, Dongxing National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150080 China School of Materials Science and Engineering Harbin Institute of Technology Harbin150080 China College of Chemistry Jilin University Changchun130012 China

We prepare carbon nanotubes based on the cross-linking reaction between small organic molecules citric acid and amino urea or ethylenediamine. Factors affecting the yield of carbon nanotube are optimized and catalytic effect of hydrated metal nitrate on carbon nanotube growth is investigated. The results demonstrate that carbon nanotube can grow in a wide range of urea content. Even two-dimensional sheet assembled by the prepared carbon nanotubes is observed when ethylenediamine is used. It is believed that such competitive strategy can expand the techniques for efficient, large-scale and low-cost synthesis of carbon nanotubes. © 2022, The Authors. All rights reserved.

关键词： Carbon nanotubes

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Efficient Carbon Nanotube Growth from Pyrolysis of Citric Acid-Based Small Organic Molecules

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SSRN 2022年

关键词： Carbon nanotubes

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Chirality tuning and reversing with resonant phase-change metasurfaces

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arXiv 2024年

作者： Sha, Xinbo Du, Kang Zeng, Yixuan Lai, Fangxing Yin, Jun Zhang, Hanxu Song, Bo Han, Jiecai Xiao, Shumin Kivshar, Yuri Song, Qinghai Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic Systems Harbin Institute of Technology Shenzhen518055 China Pengcheng Laboratory Shenzhen518055 China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150080 China Nonlinear Physics Center Research School of Physics Australian National University CanberraACT2601 Australia Collaborative Innovation Center of Extreme Optics Shanxi University Shanxi Taiyuan030006 China

Dynamic control of circular dichroism in photonic structures is critically important for compact spectrometers, stereoscopic displays, and information processing exploiting multiple degrees of freedom. Metasurfaces can help miniaturize chiral devices but only produce static and limited chiral responses. While external stimuli are able to tune resonances, their modulations are often weak, and reversing continuously the sign of circular dichroism is extremely challenging. Here, we demonstrate dynamically tunable chiral response of resonant metasurfaces supporting chiral bound states in the continuum combining them with phase-change materials. Phase transition between amorphous and crystalline phases allows to control chiral response and vary chirality rapidly from −0.947 to +0.958 backward and forward via chirality continuum. Our demonstrations underpin the rapid development of chiral photonics and its applications. © 2024, CC BY.

关键词： Chirality

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Phase Engineering of Cu@Cu2o Core-Shell Nanospheres for Boosting Tandem Electrochemical Co2 Reduction to C2+ Products

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SSRN 2022年

作者： Ye, Meng Shao, Tao Liu, Junyan Li, Chuanhao Song, Bo Liu, Shengwei School of Environmental Science and Engineering Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology Sun Yat-sen University Guangzhou510006 China Northwest Normal University China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology Harbin150001 China

Cu-based CO2 electrochemical reduction (CO2ER) is promising for reducing greenhouse gas emission and producing high-value multicarbon (C2+) chemicals and fuels. Unfortunately, the C2+ selectivity is still quite low. In this work, well-defined Cu@Cu2O core-shell nanospheres with time-dependent evolution of phase composition, crystallinity and morphology were specifically designed by a facile chemically induced self-transformation strategy. A maximum C2+ Faradaic efficiency (FE) exceeding 79%, including FEC2H4 reaching 44%, was achieved using phase-engineered Cu@Cu2O nanospheres. Based on the temperature-programmed desorption analyses and in-situ Raman spectroscopy, the adsorption behaviors of both CO2 reactant and *CO intermediate can be synergistically tuned by phase engineering of Cu@Cu2O nanospheres: Cu2O shell enhances *CO2 and *CO adsorption coverage, while porous Cu core concentrate and strengthens *CO intermediates for subsequent CO-CO coupling towards C2+ products. This work will shed new light on the phase engineering of Cu-based tandem electrocatalysts for tuning CO2/CO-catalyst interaction and modulating CO2ER processes and selectivity. © 2022, The Authors. All rights reserved.

关键词： Carbon dioxide

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