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Vibration attenuation of meta-mortar with spring-mass resonators

Defence Technology（防务技术） 2023年第2期20卷 11-23页

作者： San-feng Liu Hai-long Chen Yang Liu Hu-guang He Xi-yue An Feng-nian Jin Hua-lin Fan State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing210007China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing210016China

Metamaterial based on local resonance has excellent vibration attenuation ability in low *** this research,an attempt was performed to make meta-mortar with spring-mass resonators to attenuate vibration and shock ***-spring-mass resonators and dual-spring-mass resonators were designed and made using lead or aluminum blocks and SWPB springs encased by PMMA(polymethyl methacrylate)or aluminum *** resonators were placed into mortar blocks to make metamortar *** attenuation effect was investigated by sweeping vibration with frequency from 50 Hz to 2000 *** these meta-mortar blocks exhibit excellent vibration attenuation ability in the designed band *** dual-spring-mass resonators,meta-mortar blocks have two distinct vibration attenuation bands.

关键词： Meta-mortar Vibration attenuation Spring-mass resonators

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Layered metastructure containing freely-designed local resonators for wave attenuation

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Defence Technology（防务技术） 2024年第2期32卷 23-31页

作者： Yu Li Huguang He Jiang Feng Hailong Chen Fengnian Jin Hualin Fan State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing 210007China Rocket Force University of Engineering Xi'an 710025China Henan International Joint Laboratory of Dynamics of Impact and Disaster of Engineering Structures Department of Civil EngineeringNanyang Institute of TechnologyNanyang 473004China Guangxi Key Laboratory of Disaster Prevention and Engineering Safety and Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China

Combining periodic layered structure with three-dimensional cylindrical local resonators,a hybrid metastructure with improved wave isolation ability was designed and investigated through theoretical and numerical *** metastructure is composed of periodic rubber layers and concrete layers embedded with three-dimensional resonators,which can be freely designed with multi local resonant frequencies to attenuate vibrations at required frequencies and widen the attenuation *** metastructure can also effectively attenuate seismic *** with layered rubber-based structures,the metastructure has more excellent wave attenuation effects with greater attenuation and wider bandgap.

关键词： Layered metastructure Local resonator Wave attenuation

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Sensitivity analysis and probability modelling of the structural response of a single-layer reticulated dome subjected to an external blast loading

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Defence Technology（防务技术） 2023年第5期23卷 152-163页

作者： Shao-bo Qi Guang-yan Huang Xu-dong Zhi Feng Fan State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China Key Lab of Structure Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of TechnologyHarbin150090China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin150090China Beijing Institute of Technology Chongqing Innovation Center Chongqing401120China

The structural response of a single-layer reticulated dome to external explosions is shaped by many variables,and the associated uncertainties imply non-deterministic *** deterministic methods for predicting the consequences of specific explosions do not account for these ***,the impact of the uncertainties associated with these input variables on the structures’response needs to be studied and *** this study,a parametric uncertainty analysis was conducted ***,local and global sensitivity analyses were carried out to identify the drivers of the structural dynamic response.A probabilistic structural response model was established based on sensitive variables and a reasonable sample ***,some deterministic empirical methods for explosion-resistance design,including the plane blast load model of CONWEP,the curved blast load model under the 50%assurance level,and the 20%mass-increased method,were used for evaluating their *** results of the analyses revealed that the structural response of a single-layer reticulated dome to an external blast loading is lognormally ***,the MB0.5 method based on the curved reflector load model yielded results with a relatively stable assurance rate and reliability,but CONWEP did not;thus,the 1.2MB0.5 method can be used for making high-confidence simple *** addition,the results indicated that the structural response is very sensitive to the explosion *** on these results,it is suggested that for explosion proofing,setting up a defensive barrier is more effective than structural strengthening.

关键词： Dome structure Blast load uncertainty Sensitivity analysis Probabilistic investigation Reliability evaluation

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External blast flow field evolution and response mechanism of single-layer reticulated dome structure

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Defence Technology（防务技术） 2023年第6期24卷 241-253页

Single-layer reticulated dome structure are commonly high-profile building in the public and can be attractive targets for terrorist bombings,so the public can benefit from enhanced safety with a stronger understanding of the behavior of single-layer reticulated dome structure under *** paper investigates the fluid-structure interaction process and the dynamic response performance of the singlelayer reticulated dome under external blast *** experimental and numerical results shown that structural deformation is remarkably delayed compared with the velocity of blast wave,which advises the dynamic response of large-span reticulated dome structure has a negligible effect on the blast wave propagation under *** failure modes are identified by comparing the plastic development of each ring and the residual spatial geometric of the structure,i.e.,minor vibration,local depression,severe damage,and overall *** plastic deformation energy and the displacement potential energy of the structure are the main consumers of the blast *** addition,the stress performance of the vertex member and the deep plastic ratio of the whole structure can serve as qualitative indicators to distinguish different failure modes.

关键词： External blast loading Reticulated dome structure Fluid-structure interaction Dynamic response mode Response mechanism

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Crushing behaviors of buckling-induced metallic meta-lattice structures

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Defence Technology（防务技术） 2022年第8期18卷 1301-1310页

作者： Jian-hua Dong Yong-jun Wang Feng-nian Jin Hua-lin Fan State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing210007China Department of Civil Engineering Nanyang Institute of TechnologyNanyang473004China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Thin-walled lattice materials can be applied as energy absorbers in protective structures of civil defense. In this paper, quasi-static in-plane crushing tests were carried out to investigate the crushing behavior and energy absorption of buckling induced meta-lattice structures (BIMSs) with different central angles made of plastic iron material DT3 and formed by wire cutting technique. Three crushing patterns were revealed and analyzed. The test results clearly show that the initial peak force (IPF), the crushing force efficiency (CFE), the specific energy absorption (SEA) and the mean crushing force (MCF) can be substantially improved by introducing buckling pattern into the straight-walled lattice structure. The MCF of the BIMS was consistently predicted based on the simplified super folding element (SSFE) and the flattening element.

关键词： Buckling induced meta-lattice structure (BIMS) Crushing force efficiency

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Stability mechanism and control of the pumpable supports in longwall recovery room

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International Journal of Mining Science and Technology 2024年第7期34卷 957-974页

作者： Dong Zhang Jianbiao Bai Zhijun Tian Zizheng Zhang Yonghong Guo Rui Wang Ying Xu Hao Fu Shuai Yan Min Deng Shuaigang Liu State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyXuzhou 221116China Key Laboratory of Xinjiang Coal Resources Green Mining Xinjiang Key Laboratory of Coal-bearing Resources Exploration and ExploitationXinjiang Engineering Research Center of Green Intelligent Coal MiningXinjiang Institute of EngineeringUrumqi 830023China Work Safety Key Laboratory on Prevention and Control of Gas and Roof Disasters for Southern Goal Mines Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal MinesHunan University of Science and TechnologyXiangtan 411201China School of Mines China University of Mining and TechnologyXuzhou 221116China

The load-bearing performance(LBP)of pumpable supports(PPS)is crucial for the stability of longwall pre-driven recovery room(PRR)surrounding ***,the unbalanced bearing coefficient(UBC)of the PPS(undertaking unequal load along the mining direction)has not been investigated.A mechanical model of the PRR was established,considering the main roof cantilever beam structure,to derive an assessment formula for the load,the failure criteria,and the UBC of the ***,the generation mechanisms,and influencing factors of the UBC were *** sensitivity analysis shows that the main roof hanging length(l_(2))and the spacing between the PPS(r)significantly impact the UBC.A novel design of the PPS and the coupling control technology were proposed and applied to reduce the UBC of the PPS in the adjacent longwall *** results showed no failure of the PPS at the test site,with the UBC(ζ)reduced to 1.1 consistent with the design value(1.15)basically,fully utilizing the collaborative LBP of the ***,the maximum roof-to-floor convergence of the PRR was 234 mm,effectively controlling the stability of the surrounding rock of the PRR and ensuring the mining equipment recovery.

关键词： Pre-driven recovery room Pumpable supports Unbalanced bearing coefficient Hydraulic fracture Stability analysis Surrounding rock control

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External blast load factors for dome structures based on reliability

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Defence Technology（防务技术） 2022年第2期18卷 170-182页

作者： Shao-bo Qi Guang-yan Huang Xu-dong Zhi Feng Fan Richard GJFlay State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081PR China Key Lab of Structure Dynamic Behaviour and Control of the Ministry of Education Harbin Institute of TechnologyHarbin150090China Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of Ministry of Industry and Information Technology Harbin Institute of TechnologyHarbin150090China Department of Mechanical Engineering University of AucklandPrivate Bag 92019Auckland1142New Zealand

Dome structures have been used extensively for industrial,residential,and military ***,it is necessary to understand the damage risk potential for such structures for blast-resistant design *** paper investigates the effect of blast load variability on the design value and the structural dynamic ***,the sources of uncertainty in the external blast load on dome structures were discussed *** based on the probabilistic blast load model for the dome,the rationality of a deterministic mass-increase safety method was *** was found that previous deterministic design method cannot provide a consistent and sound assurance factor or reliability index on the entire dome *** addition,it was also proved that the assurance-based load method fails to ensure compliance with structural safety design standards on the dome roof when compared with the reliability-based blast method.A sensitivity analysis on the probabilistic blast load was conducted,and the results indicate that stand-off distance and explosive mass both act as dominant sources to influence the mean and variability of blast ***,based on the Latin hypercube sampling method,a reliability-based external blast load factor technique was *** technique was further used to estimate structural damage levels of a single-layer reticulated dome under different reliability requirements,associated with a low,medium,and high level of protection grades for a specific explosion scenario,and it indicated that this technique can be useful in the building design to achieve a higher structural anti-explosion *** study herein can serve as a reference for the calculation method of designed blast load.

关键词： Dome structure Airblast variability Deterministic design Assurance factor Reliability-based blast load factor Structural damage levels

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Advanced modeling of the absorption enhancement of black carbon particles in chamber experiments by considering the morphology and coating thickness

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Frontiers of Environmental Science & Engineering 2024年第9期18卷 129-142页

作者： Xiaodong Wei Jianlin Hu Chao Liu Xiaodong Xie Junjie Yin Song Guo Min Hu Jianfei Peng Huijun Wang Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science&TechnologyNanjing 210044China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Key Laboratory of Meteorological Disaster(Ministry of Education)Nanjing University of Information Science and TechnologyNanjing 210044China Nansen−Zhu International Research Centre Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China East China Air Traffic Management Bureau CAAC Shanghai 200335China State Key Joint Laboratory of Environmental Simulation and Pollution Control International Joint Laboratory for Regional Pollution Control(IJRC)(Ministry of Education)College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Tianjin Key Laboratory of Urban Transport Emission Research&State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control College of Environmental Science and EngineeringNankai UniversityTianjin 300071China

Measurements studies have shown that the absorption of radiation by black carbon(BC)increases as the particles ***,there are significant discrepancies between the measured and modeled absorption enhancement(E_(abs)),largely due to the simplifications used in modeling the mixing states and shape *** took advantage of chamber experiments on BC aging and developed an efficient method to resolve the particle shape based on the relationship between the coating fraction(ΔD_(ve)/D_(ve),0)and fractal dimension(D_(f)),which can also reflect the variations of D_(f)during the whole BC aging *** with externally and partly mixed states(0≤ΔD_(ve)/D_(ve),0≤0.5)can be considered to be uniformly distributed with the D_(f)values of 1.8–2.1,whereas the Df values are constrained in the range 2.2–2.8 for fully mixed states(ΔD_(ve)/D_(ve),0>0.5).The morphological parameters(i.e.,the effective density and the dynamic shape factor)were compared with the measured values to verify the simulated *** simulated mean deviations of morphological parameters were smaller than 8%for the method resolving the particle *** applying a realistic shape and refractive index,the mass absorption cross for fully mixed states can be improved by 11%compared with a simplified core–shell *** on our understanding of the influence of D_(f)andΔD_(ve)/D_(ve),0 on E_(abs),we propose a two-stage calibration equation to correct the E_(abs)values estimated by the core–shell model,which reduces the simulation error in the Mie calculation by 6%–14%.

关键词： Black carbon Mixing states Fractal dimension Dynamic shape factor Absorption enhancement

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Blast responses of shallow-buried prefabricated modular concrete tunnels reinforced by BFRP-steel bars

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Underground Space 2022年第2期7卷 184-198页

作者： Chengjie Zhao Zexun Tang Peng Wang Jiang Feng Jiannan Zhou Xinli Kong Hansheng Geng Fengnian Jin Hualin Fan State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing 210007China Rocket Force University of Engineering Xi’an 710025China c Department of Civil Engineering Nanyang Institute of TechnologyNanyang 473004China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

This paper reports the anti-blast performance of shallow-buried prefabricated modular tunnel reinforced by basalt fiber-reinforced polymer(BFRP)-steel *** concrete arch members with steel bars and three concrete arch members with BFRP-steel bars were fabricated,with the other arch parameters kept *** three identical arches were assembled into an integral structure and then buried in soil for field anti-blast *** the experiment,the pressure on the vault,the displacement and acceleration of the vault,the strain in the reinforcement bars and the macroscopic damage of the arches under the blast load were *** evaluate the damage of the arch tunnel,a residual load-bearing capacity test was conducted on the arch members after the explosion *** experimental results showed that the BFRP-steel bars reinforced concrete arch exhibited a higher load-bearing capacity and more safety redundancy than the steel bars reinforced concrete arch,and that the BFRP-steel bars could inhibit the occurrence of concrete cracks to a certain extent.A comparison between the arches assembled at different positions showed that the prefabricated modular tun-nel can be simplified directly as a two-dimensional arch structure under the blast load for analysis and calculation.

关键词： BFRP-steel bars Concrete arch Shallow-buried protective tunnel Anti-blast performance

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Blast resistance evaluation of urban utility tunnel reinforced with BFRP bars

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Defence Technology（防务技术） 2021年第2期17卷 512-530页

作者： Qiang Zhou Hu-guang He San-feng Liu Xiao-shuo Chen Ze-xun Tang Yang Liu Zhen-yu Qiu Sen-sen Li He Wang Yin-zhi Zhou Jian-nan Zhou Hua-lin Fan Feng-nian Jin State Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing210007China Research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing210016China

To improve corrosion-resistance of shallow-buried concrete urban utility tunnels(UUTs),basalt fiber reinforced polymer(BFRP)bars are applied to reinforce *** the UUT must have excellent survival capability under accidental explosions,a shallow-buried BFRP bars reinforced UUT(BBRU)was designed and *** blast experiments were carried out on this *** responses,damage evolutions and failure styles of the BBRU under repetitive explosions were *** tunnel roof is the most vulnerable component and longitudinal cracks develop along the *** the scaled distance is larger than 1.10 m/kg1/3,no cracks are observed in the *** the BBRU is severely damaged,there are five cracks forming and developing along the *** roof is simplified as a clamped-supported one-way slab,proved by the observation that the maximum strain of the transverse bar is much larger than that of the longitudinal *** responses of the roof slab are predicted by dynamic Euler beam theory,which can consistently predict the roof displacement under large-scaleddistance *** with the UUT reinforced with steel bars,the BBRU has advantages in blast resistance with smaller deflections and more evenly-distributed cracks when the scaled distance is smaller than 1.260 m/kg1/3 and the steel bars enter plastic *** elastic defamation of the BFRP bars endows the UUT more excellent blast resistance under small-scaled-distance explosions.

关键词： Utility tunnel BFRP bars explosion Dynamic response Crack Dynamic theory

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