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Investigations of the mechanical response of dummy HTPB propellant grain under ultrahigh acceleration overload conditions using onboard flight-test measurements

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Defence Technology（防务技术） 2024年第2期32卷 473-484页

作者： Yiming Zhang Ningfei Wang Weihua Ma Ran Wang Long Bai Yi Wu School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Beijing System Design Institute of Electro-mechanic Engineering Beijing 100854China Xi'an Changfeng Research Institute of Mechanism and Electricity Xi'an 710065China

In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.

关键词： Gun-launched flight test Dummy HTPB propellant Onboard measurements Utrahigh overload mechanical response

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Effect of Crystallization and Entropy Contribution Upon the mechanical response of Polymer Nano-fibers:A Steered Molecular Dynamics Study

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Chinese Journal of Polymer Science 2023年第3期41卷 465-474,I0011页

作者： Rui Ma Dan Xu Chuan-Fu Luo Xinjiang Laboratory of Phase Transitions and Microstructures in Condensed Matters College of Physical Science and TechnologyYili Normal UniversityYining 835000China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China School of Applied Chemistry and EngineeringHefei 230026China

The mechanical response of polyethylene nano-fibers with the same chain length but different chain numbers are studied by using steered molecular dynamics simulations.The shrinking or stretching forces acted on the chain ends are investigated according to the chain-end distance and temperature under isothermal or continuous warming-cooling conditions,respectively.An inflection point is found in the ForceDistance response when temperature is below 500 K.This inflection point is related to the balance between entropy force and inter-monomer interaction and it reflects the strong effect of crystallization on the mechanical response of the nano-fibers.The force at inflection point is also affected by the buckling effect due to increased stiffness when crystallization occurs.The two stages found in the Force-Temperature response and the difference between the shrinking and stretching forces indicate the hysteresis of crystallization and melting.The forces at different shrinking and stretching rates reveal the entropy contribution upon the mechanical response,indicated by the Ramachandran plot of dihedrals.The chain-conformation entropy is majorly contributed by dihedrals and is quantified by the information entropy of dihedrals,which has a highly similarity to the mechanical Force-Temperature response.The enlarged forces in multiple chains over a single chain are attributed to the enhanced dihedral-conformation entropy.Our study provides a new insight to the dynamically mechanical response of polymer nano-fibers according to the effect of crystallization and entropy contribution.

关键词： Polymer fibers Crystallization Entropy contribution mechanical response

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Structural dimension optimization and mechanical response analysis of fabricated honeycomb plastic pavement slab

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Frontiers of Structural and Civil Engineering 2022年第7期16卷 896-908页

作者： Zixuan CHEN Tao LIU Xiao MA Hanyu TANG Jianyou HUANG Jianzhong PEI School of Highway Chang’an UniversityXi’an 710064China School of Civil Engineering Tianjin UniversityTianjin 300350China

Because of favorable mechanical properties,deformation resistance and being conducive to environmental protection,honeycomb fabricated plastic pavement slabs are highly recommended these years.At present,most studies focus on the performance of plastic materials,however,the dimension optimization of fabricated plastic pavement slab is rarely mentioned.In this paper,an optimized geometry of the honeycomb pavement slab was determined through finite element analysis.mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored.Several dimension factors were taken into consideration including the side length,rib thickness,the thickness of both top and bottom slabs of honeycomb structure and the length,the width and the thickness of the fabricated plastic slab.The results showed that honeycomb pavement slab with 6 cm bottom slab,12 cm top slab,18 cm side length and 6 cm rib thickness is recommended,additionally,an external dimension of 4 m×4 m×0.45 m is suggested.Then,the mechanical responses of this optimized fabricated plastic slab were further investigated.Significance of different influencing factors,including wheel load,elastic modulus of plastic material,base layer thickness,soil foundation modulus and base layer modulus were ranked.

关键词： honeycomb structure plastic pavement dimension optimization mechanical response factor significance

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Research on pavement cracking possibility based on the load mechanical response

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Science China(Technological Sciences) 2023年第12期66卷 3549-3561页

作者： WANG Meng LI ShuCai LIU RenTai ZHANG ChunYu ZHU ZhiJing ZHANG LianZhen BAI JiWen School of Civil Engineering Geotechnical and Structural Engineering Research CenterShandong UniversityJinan 250061China College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao 266580China

Cavities under roads are one of the main reasons for early structural damage to pavements. It is necessary to conduct a structural analysis of road sections with cavities and evaluate the possibility of pavement cracking caused by different cavity sizes. In this study, an analysis method for evaluating the possibility of pavement cracking based on the load-mechanical response is proposed.An example library of the mechanical response of asphalt concrete(AC) pavements was established by numerical simulation.Based on the tensile cracking characteristics of pavements in the mechanical response research, the tensile strain at the bottom of the AC layer was selected as the key analysis parameter. Sensitivity analysis of the tensile strain was conducted, and the main factors controlling pavement cracking were determined. A tensile strain response prediction model was established using multiple linear regression, and its reliability was verified. The cavity influence coefficient(CIC) and pavement cracking factor(PCF) were constructed to analyze the cracking possibility. The variation in PCF with the cavity size and pavement structure parameters was studied. A quantitative relationship between the depth and length of the cavity for a given PCF was obtained.This law conforms to a power function. The possibility of pavement cracking can be determined by measuring the cavity size.Compared to the existing cavity management system, the proposed method provided analysis results of the cracking possibility that were more consistent when the cavity depth was small and the length was long. The findings of this study provide new insights for evaluating the possibility of pavement cracking.

关键词： pavement cracking cavity case base traffic load mechanical response risk analysis

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Unveiling the mechanical response and accommodation mechanism of pre-rolled AZ31 magnesium alloy under high-speed impact loading

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Journal of Magnesium and Alloys 2022年第4期10卷 1096-1108页

作者： Xiao Liu Hui Yang Biwu Zhu Yuanzhi Wu Wenhui Liu Changping Tang Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province Hunan University of Science and TechnologyXiangtanHunan 411201China Research Institute of Automobile Parts Technology Hunan Institute of TechnologyHengyangHunan 421002China

Split Hopkinson pressure bar(SHPB)tests were conducted on pre-rolled AZ31 magnesium alloy at 150–350℃ with strain rates of 2150s-1,3430s^(-1) and 4160s-1.The mechanical response,microstructural evolution and accommodation mechanism of the pre-rolled AZ31 magnesium alloy under high-speed impact loading were investigated.The twin and shear band are prevailing at low temperature,and the coexistence of twins and recrystallized grains is the dominant microstructure at medium temperature,while at high temperature,dynamic recrystallization(DRX)is almost complete.The increment of temperature reduces the critical condition difference between twinning and DRX,and the recrystallized temperature decreases with increasing strain rate.The mechanical response is related to the competition among the shear band strengthen,the twin strengthen and the fine grain strengthen and determined by the prevailing grain structure.The fine grain strengthen could compensate soften caused by the temperature increase and the reduction of twin and shear band.During high-speed deformation,different twin variants,introduced by pre-rolling,induce different deformation mechanism to accommodate plastic deformation and are in favor for non-basal slip.At low temperature,the high-speed deformation is achieved by twinning,dislocation slip and the following deformation shear band at different deformation stages.At high temperature,the high-speed deformation is realized by twinning and dislocation slip of early deformation stage,transition shear band of medium deformation stage and DRX of final deformation stage.

关键词： mechanical response Pre-twinning Accommodation mechanism Pre-rolled AZ31 magnesium alloy High-speed impact loading

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Analytical method for the mechanical response of buried pipeline under the action of strike-slip faulting

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Underground Space 2022年第2期7卷 268-277页

作者： Zhiping Hu Xiang Ren Qiyao Wang Rui Wang Rui Pan School of Civil Engineering Chang’an UniversityXi’an 710061China Institute of Underground Structure and Engineering Chang’an UniversityXi’an 710061China

Buried pipelines are commonly damaged when laid across strike-slip faults,always leading to some level of destruction with fault movement.The moment of the neutral axis of a pipe section was obtained by integration,and the equations for the bending moment and the bending strain on a pipeline’s section were presented here,based on a trilinear stress–strain model.The calculation method for the lateral soil pressure and pipeline’s bending strain near the fault-crossing point was improved.Lateral soil pressure was regarded as being related to lateral pipeline movement and,for accurate calculation,this part of the pipeline was divided into finite element segments.An iterative process for solving for pipe bending strain was derived,and the algorithm and program for calculating bending strain and the potential damage position of the pipeline’s sections was compiled based on Matlab software.Compared with finite element method(FEM)results and the current standard method,in the situation of a pipeline being in tension under the action of a strike-slip fault(intersection angleresponse analysis of tensile steel pipelines under strike-slip faulting.

关键词： Strike-slip fault Buried pipeline Analytical method mechanical response

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Dynamic asymmetric mechanical responsive carbon nanotube fiber for ionic logic gate

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Chinese Chemical Letters 2024年第6期35卷 249-253页

作者： Pei Cao Yilan Wang Lejian Yu Miao Wang Liming Zhao Xu Hou State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) Xiamen 361005China The Higher Educational Key Laboratory for Biomedical Engineering of Fujian Province Department of BiomaterialsResearch Center of Biomedical Engineering of XiamenCollege of MaterialsXiamen UniversityXiamen 361005China Key Laboratory of Multifunctional Nanomaterials and Smart Systems Advanced Materials DivisionSuzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123China Institute of Artificial Intelligence Xiamen UniversityXiamen 361005China Department of Physics Research Institute for Biomimetics and Soft MatterFujian Provincial Key Laboratory for Soft Functional Materials ResearchJiujiang Research InstituteCollege of Physical Science and TechnologyXiamen UniversityXiamen 361005China Engineering Research Center of Electrochemical Technologies of Ministry of Education Xiamen UniversityXiamen 361005China

Inspired by biological ion channels,numerous artificial asymmetric ion channels have been synthesized to facilitate the fabrication of ionic circuits.Nevertheless,the creation of biomimetic asymmetric ion channels necessitates expensive scientific apparatus and intricate material processing procedures,which constrains its advancement within the realm of ionic devices.In this study,we have devised dynamic asymmetric ion channels with mechanical responsiveness by combining polymers of varying elastic modulus along the longitudinal axis of carbon nanotube fiber(CNTF).The ion rectification can be modulated via the disparate response of CNTF-based ion channels to mechanical stress.We have effectively employed these asymmetric ion channels with mechanical sensitivity in the design of a logic gate device,achieving logic operations such as“AND”and“OR”.The conception of these dynamic asymmetric ion channels with mechanical sensitivity offers a straightforward,cost-effective,and versatile approach for generating ion channels,highlighting their potential application in intricate,highly integrated ionic circuits.

关键词： Carbon nanotubes fibers mechanical response Rectification effect Ionic logic gate

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Comparative analysis of thermodynamic and mechanical responses between underground hydrogen storage and compressed air energy storage in lined rock caverns

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International Journal of Mining Science and Technology 2024年第4期34卷 531-543页

作者： Bowen Hu Liyuan Yu Xianzhen Mi Fei Xu Shuchen Li Wei Li Chao Wei Tao Zhang State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China Key Laboratory of Large Structure Health Monitoring and Control Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116China

Underground hydrogen storage(UHS)and compressed air energy storage(CAES)are two viable largescale energy storage technologies for mitigating the intermittency of wind and solar power.Therefore,it is meaningful to compare the properties of hydrogen and air with typical thermodynamic storage processes.This study employs a multi-physical coupling model to compare the operations of CAES and UHS,integrating gas thermodynamics within caverns,thermal conduction,and mechanical deformation around rock caverns.Gas thermodynamic responses are validated using additional simulations and the field test data.Temperature and pressure variations of air and hydrogen within rock caverns exhibit similarities under both adiabatic and diabatic simulation modes.Hydrogen reaches higher temperature and pressure following gas charging stage compared to air,and the ideal gas assumption may lead to overestimation of gas temperature and pressure.Unlike steel lining of CAES,the sealing layer(fibre-reinforced plastic FRP)in UHS is prone to deformation but can effectively mitigates stress in the sealing layer.In CAES,the first principal stress on the surface of the sealing layer and concrete lining is tensile stress,whereas UHS exhibits compressive stress in the same areas.Our present research can provide references for the selection of energy storage methods.

关键词： Underground hydrogen storage Compressed air energy storage mechanical response Thermodynamic response Lined rock caverns

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Numerical Study of the mechanical response of Turtle Shell

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Journal of Bionic Engineering 2012年第3期9卷 330-335页

作者： Wei Zhang Chengwei Wu Chenzhao Zhang Zhen Chen State Key Laboratory of Structural Analysis for Industrial Equipment Faculty of Vehicle Engineering and MechanicsDalian University of TechnologyDalian 116024P.R.China Department of Civil and Environmental Engineering University of MissouriColumbiaMO 65211-2200USA School of Materials Science&Engineering Dalian University of TechnologyDalian 116024P.R.China

The turtle shell is an amazing structure optimized through the long-term evolution by nature. This paper reports the me- chanical respor/se of the shell （Red-ear turtle） to static and dynamic loads, respectively. It is found that the turtle shell under a compressive load yields the maximum vertical displacement at the rear end, but the vertical displacement at the front end is only half of that at the rear end. The maximum horizontal displacement of the shell also occurs at the rear end. It is believed that such a deformation pattern is helpful for protecting the turtle＇s internal organs and its head. The principal stress directions in the inside surface of the shell under a compressive load are almost the same as those of the biofiber distribution in the inside surface, which results in the strong bending resistance of the turtle shell.

关键词： biomaterial turtle shell mechanical response static and dynamic loads

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Analysis and finite element simulation for mechanical response of wheat to wind and rain loads

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International Journal of Agricultural and Biological Engineering 2008年第1期1卷 82-88页

作者： Liang Li Guo Yuming College of Engineering and Technology Shanxi Agricultural UniversityTaigu 030801China

The morphological characteristics and stalk biomechanical properties at the dough stage of wheat were determined using the variety of wheat in the breeding process.Their mechanical responses to wind and rain loads for an individual and a group of wheat were simulated using finite element method by ANSYS.The stress and displacement of each finite element can be outputted through stress nephogram and displacement nephogram,respectively.In order to judge whether the wheat could return to its original position after deformation,elastic mechanics theory was utilized to analyze the critical load of instability under both axial rain load and transverse wind load.The large displacement situation was analyzed with large displacement elastic nonlinear theory and the numerical value was obtained by ANSYS.The results show that it is possible to apply various load types on models using ANSYS and the dynamic response can be simulated well under different rain and wind loads.The location of maximum Von Mises stress can be calculated and the variation of stress can be described clearly,which are helpful to predict the wheat lodging under wind and rain loads.

关键词： wheat wind and rain loads finite element analysis mechanical response

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