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Mechanical behavior of nanorubber reinforced epoxy over a wide strain rate loading

Nano Materials Science 2024年第1期6卷 106-114页

作者： Yinggang Miao Jianping Yin Wenxuan Du Lianyang Chen Joint International Research Laboratory of Impact Dynamics and Its Engineering Applications School of AeronauticsNorthwestern Polytechnical UniversityXi'anShaanxi710072China State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong UniversityXi'anShaanxi710049China Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Application School of AeronauticsNorthwestern Polytechnical UniversityXi'anShaanxi710072China

Nanorubber/epoxy composites containing 0,2,6 and 10 wt%nanorubber are subjected to uniaxial compression over a wide range of strain rate from 8×10^(-4) s^(-1) to~2×10^(4) s^(-1).Unexpectedly,their strain rate sensitivity and strain hardening index increase with increasing nanorubber *** mechanisms are proposed based on numerical simulations using a unit cell *** increase in the strain rate sensitivity with increasing nanorubber content results from the fact that the nanorubber becomes less incompressible at high strain,generating a higher hydro-static *** shear localization starts to occur in the epoxy under a strain rate of 22,000 s^(-1) when the strain exceeds *** presence of nanorubber in the epoxy reduces adiabatic shear localization by preventing it from propagating.

关键词： Strain rate Strain hardening Nano rubber Epoxy Adiabatic shearing localization

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Dynamic flexural strength of Aluminosilicate glass with a perspective of impulsive and quasi-impulsive responses: An experimental-numerical coupled evaluation

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Chinese Journal of Aeronautics 2024年第12期37卷 388-403页

作者： Muhammad Aamir RAZA Tao SUO Uzair Ahmed DAR Muhammad ATIF Muhammad Zakir SHEIKH School of Aeronautics and Institute of Extreme Mechanics Northwestern Polytechnical UniversityXi’an 710072China Joint International Research Center of Impact Dynamics and Its Engineering Application Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Impact Dynamics and Engineering Application Northwestern Polytechnical UniversityXi’an 710072China National Key Laboratory of Strength and Structural Integrity Northwestern Polytechnical UniversityXi’an 710072China

The flexural strength of glass is a critical design parameter for applications encountering impact ***,the micro defects,specimen geometry,loading rate,and load transformation from a quasi-dynamic to quasi-impulsive state may influence the measurement *** to the stochastic and amorphous nature of the material,an accurate determination of the flexural strength remains a *** this two-fold study,a coupled experimental-numerical strategy was devised to evaluate the dynamic flexural *** the first phase,three-point bending experiments were conducted on a novel“Electromagnetic Split Hopkinson Pressure Bar(ESHPB)”.The incident stress signal and fracture time were recorded from experimental data,while the flexural strength was indirectly computed from a numerical algorithm.A quantitative comparison of the flexural strength with those in existing literature established the accuracy of the proposed *** of the study indicate that the specimen response became independent of the support conditions under impulsive *** being said,the specimen behaved like it had an infinite span length,and the measured flexural strength remained the same whether the specimen was supported or ***,the specimen also maintained contact at the interfaces of the incident bar and fixture supports for the entire loading *** the second part of this study,the computed flexural strength was used to calibrate the existing JH-2 *** prediction of the damage propagation corroborated with that obtained from reprography images,though *** work presents a precise and robust methodology to determine the dynamic flexural strength of brittle ceramics like Aluminosilicate glass over traditional experimental procedures to facilitate its adoption.

关键词： Dynamic flexural strength Damage mechanism Flexural fracture Numerical simulation Aluminosilicate glass

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Cross-linked polyelectrolyte reinforced SnO_(2)electron transport layer for robust flexible perovskite solar cells

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Journal of Energy Chemistry 2023年第10期85卷 335-342,I0010页

作者： Zhihao Li Zhi Wan Chunmei Jia Meng Zhang Meihe Zhang Jiayi Xue Jianghua Shen Can Li Chao Zhang Zhen Li State Key Laboratory of Solidification Processing Center for Nano Energy MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical University and Shaanxi Joint Laboratory of Graphene(NPU)Xi’an 710072ShaanxiChina Department of Aeronautical Structure Engineering School of AeronauticsNorthwestern Polytechnical UniversityXi’an 710072ShaanxiChina Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Application Joint International Research Laboratory of Impact Dynamics and Its Engineering ApplicationsXi’an 710072ShaanxiChina Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 519057GuangdongChina

SnO_(2)electron transport layer(ETL)is a vital component in perovskite solar cells(PSCs),due to its excellent photoelectric properties and facile fabrication *** this study,we synthesized a water-soluble and adhesive polyelectrolyte with ethanolamine(EA)and poly-acrylic acid(PAA).The linear PAA was crosslinked by EA,forming a 3D network that stabilized the SnO_(2)nanoparticle *** organic–inorganic hybrid ETL is developed by introducing the cross-linked PAA-EA into SnO_(2)ETL,which prevents nano particle agglomeration and facilitates uniform SnO_(2)film formation with fewer ***,the PAA-EA-modified SnO_(2)facilitated a uniform and compact perovskite film,enhancing the interface contact and carrier ***,the PAA-EA-modified PSCs exhibited excellent PCE of 24.34%and 22.88%with high reproducibility for areas of 0.045 and 1.00 cm~2,***,owing to structure reinforce effect of PAA-EA in SnO_(2)ETL,flexible device demonstrated an impressive PCE of 23.34%while maintaining 90.1%of the initial PCE after 10,000 bending cycles with a bending radius of 5 *** successful approach of polyelectrolyte reinforced hybrid organic–inorganic ETL displays great potential for flexible,large-area PSCs application.

关键词： Polyelectrolyte Cross-link Tin oxide Electron transfer layer Flexible solar cells

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Effects of Loading Direction and Strain Rate on Mechanical Properties and Failure Modes of Teak 29th

Effects of Loading Direction and Strain Rate on Mechanical P...

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29th International Conference on Computational and Experimental engineering and Sciences, ICCES 2023

作者： Yin, Jianping Du, Wenxuan Liu, Lanting Wu, Zhibo He, Xuanfu Miao, Yinggang Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Application School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China Joint International Research Laboratory of Impact Dynamics and Its Engineering Applications School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China

ISBN: (纸本)9783031425141

The mechanical response and failure mode of wood under compressive load are of great significance for structural design and integrity evaluation. The stress–strain curve of teak with strong impact resistance was investigated by compressive experimenting in the axial, tangential and radial directions under wide strain rates from 10–3 to 103. The results show that their responses behaves similarly and presents a three-stage characteristics in the same loading direction. Teak strength are distinctly directional and strain rate dependent. Deformation processes are monitored by a high-speed camera, which demonstrates that the failure modes consist mainly of fracture, buckling and separation of fiber bundles, crushing, buckling and delamination of the annual ring layer. They are confirmed by the microstructural results. Besides, the failure modes are also affected by the loading direction and strain rate. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Strain rate

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Effects of surface topography and specimen thickness on high-speed raindrop impact damage of CFRP laminates

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Chinese Journal of Aeronautics 2023年第6期36卷 186-200页

作者： Naidan HOU Renxi ZHAO Xuan WANG Zhongbin TANG Hao CUI Yulong LI School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China Joint International Research Laboratory of Impact Dynamics and Engineering Application Xi'an 710072China Shaanxi Key Laboratory of Impact Dynamics and Engineering Application Xi'an 710072China School of Civil Aviation Northwestern Polytechnical UniversitySuzhou 215400China NPU Yangzi River Delta Research Institute Suzhou 215400China

Raindrop impact erosion has been observed since early days of aviation,and can be catastrophic for exposed materials during supersonic flight.A single impact waterjet apparatus is established for mimicking drop impacts at the velocities between 350 m/s and 620 m/*** Fiber Reinforced Polymer(CFRP)laminates with three different surface morphologies and specimen thicknesses are tested here.A central region with no visible damage has been noticed,surrounded by a"failure ring"with common damage patterns including resin removal,matrix cracking,fiber breakage and mass fiber *** features are presented in the"failure ring"whose whole scope extends larger along the longitudinal direction than the transverse direction of the top *** mechanism of the resin removal is related to fiber-matrix debonding,and its onset and propagation can be facilitated by initial surface asperities with the shear action of the lateral *** cases of multiple impact,good surface quality can slow down the evolution of resin removal and fiber exposure on the CFRP surface,reducing the erosion speed and delaying the occurrence of structural damages in the subsequent *** wave dominates the occurrence of matrix cracking on the CFRP surface,and subsequently,results in material loss and peeling of the top-layer because of lateral *** the increase of the specimen thickness,both the interlaminar and intralaminar failures decrease as the impact damage mechanism changes from plate bending stress to the reflection of stress waves.

关键词： Carbon fiber reinforced plastics Failure analysis impact testing Lateral jetting Surface roughness Waterjet

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Structural Integrity Analyses on the Anti-high Overload of a Solid Rocket Motor 29th

Structural Integrity Analyses on the Anti-high Overload of a...

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29th International Conference on Computational and Experimental engineering and Sciences, ICCES 2023

作者： Du, Wenxuan Deng, Qiong Tian, Xiaotao Yin, Jianping Hu, Bowen Wang, Yongshuai He, He Miao, Yinggang Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Application School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China Joint International Research Laboratory of Impact Dynamics and Its Engineering Applications School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China Science and Technology on Combustion and Explosion Laboratory Xi’an Modern Chemistry Research Institute Shaanxi Xi’an710065 China

ISBN: (纸本)9783031425141

Solid propellant works as the most key component for solid rocket motors, and its mechanical behaviors paly a dominant role in the structural integrity of the motor. As typical viscoelastic material, it presents a strong rate-dependence, which would affect the integrity behavior. In the present work, a solid propellant was performed for its constitutive behaviors under wide strain rate loading from 30 to 3000 s−1 using the developed split Hopkinson bar apparatus. A linear viscoelastic constitutive model was then established for carrying out the finite element analysis of an engine structure. As indicated from the simulation results, the possible failure zones in solid rocket motor are revealed, and some stress concentrations localizes in its middle and rear section of the coating layer. Grain failures tend to occur in the concave turning points between the grain rear end and the cushion. The effect of high overload was also analyzed under various cushions, and it was also found that the cushions facilitate the integrity by absorbing energy and confining the deformation of the grain. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Strain rate

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An in-situ study of static recrystallization in Mg using high temperature EBSD

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Journal of Magnesium and Alloys 2024年第4期12卷 1419-1430页

作者： Xu Ye Zhe Suo Zhonghao Heng Biao Chen Qiuming Wei Junko Umeda Katsuyoshi Kondoh Jianghua Shen School of Aeronautics Northwestern Polytechnical UniversityXi’anShaanxiChina Shaanxi Key Laboratory of Impact Dynamic and Its Engineering Application Xi’anShaanxiChina School of Mechanical Engineering Qinghai UniversityXiningQinghaiChina School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’anShaanxiChina Department of Mechanical Engineering University of North Carolina at CharlotteCharlotteNCUSA Joining and Welding Research Institute Osaka University11-1 MihogaokaOsakaJapan

It has been a common method to improve the mechanical properties of metals by manipulating their microstructures via static recrystallization,i.e.,through heat ***,the knowledge of recrystallization and grain growth is critical to the success of the *** the present work,by using in-situ high temperature EBSD,the mechanisms that control recrystallization and grain growth of an extruded pure Mg were *** experimental results revealed that the grains of priority for dynamic recrystallization exhibit fading competitiveness under static *** is also found that grain boundary movement or grain growth is likely to show an inverse energy gradient effect,i.e.,low energy grains tend to swallow or grow into high energy grains,and grain boundaries of close to 30°exhibit superior growth advantage to *** finding is that{10-12}tensile twin boundaries are sites of hardly observed for recrystallization,and are finally swallowed by adjacent recrystallized *** above findings may give comprehensive insights of static recrystallization and grain growth of Mg,and may guide the design of advanced materials processing in microstructural engineering.

关键词： Pure Mg In-situ HT-EBSD Recrystallization Grain growth

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Compression Behavior of Extra-soft Porcine Lung Tissue at the Wide Strain Rate 2

Compression Behavior of Extra-soft Porcine Lung Tissue at th...

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2023 2nd International Conference on Applied Mechanics and Advanced Materials, ICAMAM 2023

作者： Liu, Yue Peng, Feiyang Wang, Yongshuai Chen, Mingwei Hu, Zhi Miao, Yinggang Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Application School of Aeronautics Northwestern Polytechnical University Shaanxi Xi'an710072 China The First Affiliated Hospital of xi'An Jiaotong University Shaanxi Xi'an710061 China

Lung is the respiratory organ and the important hematopoietic organ of the human body, which is easily damaged under impact load. Therefore, studying the mechanical behavior of the lung under impact load is an important way to understand its damage mechanism of it. Compression experiments of porcine lung tissue at a wide strain rate (0.001-3000 s-1) were carried out at room temperature. The modifications were made for the highly accurate mechanical measurement of the tissue due to its low wave impedance. The results show that its behaviors consist of three stages, linear elasticity, plateau stage, and compaction. The lung tissue presents distinct rate-dependence in the compaction stage. Furthermore, it behaves nearly similarly under both the loading directions of vertical and parallel trachea, which facilitates to a demonstration of its isotropy. © Published under licence by IOP Publishing Ltd.

关键词： Strain rate

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Energy Absorption Characteristics of Triply Periodic Minimal Surface Lattices 2

Energy Absorption Characteristics of Triply Periodic Minimal...

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2023 2nd International Conference on Applied Mechanics and Advanced Materials, ICAMAM 2023

作者： Wang, Haodong Li, Siqi Wang, Cunxian Joint International Research Laboratory of Impact Dynamics and Its Engineering Applications School of Aeronautics Northwestern Polytechnical University Shaanxi Xi'an710072 China Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Application School of Aeronautics Northwestern Polytechnical University Shaanxi Xi'an710072 China School of Engineering Heilongjiang Bayi Agricultural University Heilongjiang Da'qing163000 China

Historically, structural equipment has been studied to determine the impact and protection of its components, and common energy-absorbing materials include honeycomb, foam, bellows, and expansion tubes. According to related analyses, topological metamaterial structures designed based on mathematically known non-self-intersecting three-periodic minimal surfaces (TPMS) may possess superior mechanical properties. It is demonstrated in this study that a solid structure with a TPMS of 10 mm × 10 mm × 10 mm is constructed based on the Schwarz Primitive surface. Analyses were conducted on the effects of element type and modeling conditions on simulation results. Based on the simulation results, the solid element exhibited better analysis accuracy than the shell element. The structure had a better energy absorption capability when its surface thickness was set at approximately 1.31 mm. © Published under licence by IOP Publishing Ltd.

关键词： Energy absorption

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Syringe Needle Penetration Influence on Micro Particle Generation 30th

Syringe Needle Penetration Influence on Micro Particle Gener...

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30th International Conference on Computational and Experimental engineering and Sciences, ICCES 2024

作者： Zhu, Tingting Lian, Pei Wu, Zhibo Zhang, Chenxu Miao, Yinggang Wang, Haiying The Sixth Department Xijing Hospital of Digestive Diseases the First Affiliated Hospital of Air Force Military Medical University Shaanxi Xi’an710032 China Shaanxi Key Laboratory of Impact Dynamics and Its Engineering Application School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China

ISBN: (纸本)9783031829062

In daily medical operation, penetration of syringe needles into the rubber plug, usually produces micro particles due to plug failure, which has been attracted increasing attentions for patient’s health. In this work, the needle penetration is investigated experimentally and numerically, by focusing on penetration process. Firstly, mechanical behaviors of butyl rubber material are obtained experimentally, by performing various strain rate experiments based on Instron 5848 machine and Hopkinson tension bar technique. The distinct strain rate-dependence is found of rubber mechanic behaviors. its constitutive relation and parameters are then determined, and used for numerical simulation work. Penetrations of traditional syringe needle are designed and experimented through butyl rubber plugs of vials. As a result, plug mass loss is obtained to investigate the micro particles’ generation. Finally, the finite element model is built based on Abaqus code, of which the smoothed particle hydrodynamics method is introduced for plug fracture behavior. Numerical simulations are performed for penetration process, and the results is basically consistent with the experiment. More accurate simulation work will be performed for detailed penetration responses, and even fracture dependence on needle configuration and so on. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

关键词： Needles

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