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铝纤维增强铝/聚四氟乙烯活性材料力学性能及反应特性

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兵工学报 2024年第5期45卷 1573-1581页

作者：赵涵任会兰宁建国北京理工大学爆炸科学与技术国家重点实验室北京100081

为研究纤维含量对铝(Al)/聚四氟乙烯(Polytetrafluoroethylene,PTFE)力学性能及反应特性的影响,针对模压烧结法制备的铝纤维增强型活性材料,采用材料试验机和冲击加载实验技术开展静态、动态力学响应和冲击反应研究,并结合细观结构特征... 详细信息

为研究纤维含量对铝(Al)/聚四氟乙烯(Polytetrafluoroethylene,PTFE)力学性能及反应特性的影响,针对模压烧结法制备的铝纤维增强型活性材料,采用材料试验机和冲击加载实验技术开展静态、动态力学响应和冲击反应研究,并结合细观结构特征揭示纤维增强活性材料的变形失效机制。研究结果表明:Al纤维含量(质量比)为1%~4%时,随机分布的Al纤维抑制了基体内裂纹扩展,提高了Al/PTFE的静态屈服强度和动态抗压强度;Al纤维含量1%的动态力学性能最优,随着纤维含量的增加,Al纤维穿出基体的破坏是限制材料动力学性能持续增强的主要因素;在保证Al/PTFE理论释能不变的前提下,Al纤维的加入提高了Al/PTFE的冲击反应阈值,无纤维时最小反应比入射能为50.7 J/cm^(2),纤维含量增加至4%时提高到61.3 J/cm^(2),活性材料的冲击不敏感性得到提升。

关键词：铝纤维铝/聚四氟乙烯活性材料力学特性反应阈值

新时代高校党团和班级组织育人共同体构建:逻辑、挑战和路径

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上海理工大学学报（社会科学版） 2024年第1期46卷 71-76页

作者：曹军任惠兰上海理工大学组织部上海200093

构建新时代高校党团和班级组织育人共同体,是新形势下高校学生党支部、团支部和班级三个组织之间寻求育人功能优化和思政价值整合“最大公约数”的必由之路。构建此组织育人共同体具有显然的制度、目标和价值认可逻辑,但也面临着政治和... 详细信息

构建新时代高校党团和班级组织育人共同体,是新形势下高校学生党支部、团支部和班级三个组织之间寻求育人功能优化和思政价值整合“最大公约数”的必由之路。构建此组织育人共同体具有显然的制度、目标和价值认可逻辑,但也面临着政治和社会角色切换、管理运行与内容需求融合、资源配置转变、发展模式演进等诸多挑战。因此,要在此三个组织自身内部梳理整合的基础上,更多侧重组织间纵向层面的建设理念创新、制度衔接通畅、资源平台整合、队伍优化等方面的有效探索,才能充分发挥出新时代高校党团和班级组织育人共同体在思想引领、制度推进、资源整合和人才培养上的优势和合力。

关键词：学生党支部团支部班级组织育人共同体

Study on cell size variation in overdriven gaseous detonations

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Acta Mechanica Sinica 2021年第6期37卷 938-953,I0001页

作者： huilan ren Tianyu Jing Jian Li State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

The cell size variation in overdriven gaseous detonations is studied in hydrogen/oxygen and acetylene/oxygen *** local self-similarity of Mach reflection of detonations on the wedge in the far field renders the presence of a steady overdriven Mach stem to be *** study focuses on the cell size change of overdriven Mach stem on the wedge surface other than on the *** detonation cell pattern on the wedge surface has a complicated process of three-stage pattern,i.e.,the cells decreasing from large to small size,and then increasing asymptotically to a medium size and keeping *** cell size ratio with increasing the degree of overdrive is also *** is found that the ratio decays as the degree of overdrive ***,as the wedge angle increases to a critical value,finer cells are not created on the smoke ***’s model used to predict the cell size is also found to be valid only for detonations with relative large instability parameters,but presents large errors for highly overdriven detonations with low instability.A modification to Ng’s model is proposed based on the experimental results.

关键词： Cellular detonations Overdriven factor Mach reflection Cell size

Mechanical behaviors and damage constitutive model of ceramics under shock compression

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Acta Mechanica Sinica 2008年第3期24卷 305-315页

作者： Jianguo Ning huilan ren Ping Li State Key Laboratory ot Explosion Science and Technology Beijing Institute of Technology 100081 Beijing China Laboratory for Shock Wave and Detonation Physics Research Institute of Fluid Physics CAEE 621900 Mianyang China

One-stage light gas gun was utilized to study the dynamic mechanical properties of AD90 alumina subjected to the shock loading. Manganin gauges were adopted to obtain the stress-time histories. The velocity interferometer system for any reflector （VISAR） was used to obtain the free surface velocity profile and determine the Hugoniot elastic limit. The Hugoniot curves were fitted with the experimental data. From Hugoniot curves the compressive behaviors of AD90 alumina were found to change typically from elastic to ＂plastic＂. The dynamic mechanical behaviors for alumina under impact loadings were analyzed by using the path line principle of Lagrange analysis, including the nonlinear characteristics, the strain rate dependence, the dispersion and declination of shock wave in the material. A damage model applicable to ceramics subjected to dynamic compressive loading has been developed. The model was based on the damage micromechanics and wing crack nucleation and growth. The effects of parameters of both the micro-cracks nucleation and the initial crack size on the dynamic fracture strength were discussed. The results of the dynamic damage evolution model were compared with the experimental results and a good agreement was found.

关键词： Mechanical behaviors Lagrange analysis Damage Tensile wing crack

Functional Morphology and Bending Characteristics of the Honeybee Forewing

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Journal of Bionic Engineering 2017年第1期14卷 111-118页

作者： Yun Ma huilan ren Jianguo Ning Pengfei Zhang State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China

The present work aimed to reveal the functional morphology and bending characteristics of the worker honeybee （Apis mellifera） forewing. Honeybee wings including the forewing and hindwing, which are mainly composed of veins and membranes, are a kind of typical hierarchical biomaterials. We investigated the cross-sections of membranes, veins and wing hairs through Scanning Electron Microscopy （SEM）. Based on the microscopic observation, it was found that the vein is a thick-walled cylinder, and the membrane possesses multilayered structure and so does the wing hair which shows the thread surface. At the vein-membrane conjunctive position, membranes and veins are assembled seamlessly and veins are packed smoothly and tightly by membranes into a whole, allowing honeybees to perform excellent flapping flight. In such a case, we also conducted the cantilevered bending experiment of honeybee forewing to explore their bending characteristics using a MTS Tytron 250 micro force tester. Experiment results indicate that the anti-bending capacity of the forewing along the spanwise direction is higher than that along the chordwise direction which is partly caused by the wing corrugation along the wing span detected by the micro-Computed Tomography （micro-CT）, and ventral load bearing ability is better than dorsal one along the spanwise and chordwise direction of the wing which is due to the stress-stiffening of membranes. It could be concluded that the structural configuration of the wing is closely relevant to wing biomechanical behaviors. All results above would provide a significant support for the design of bioinspired wings for Flapping Micro Aerial Vehicles （FMAV）.

关键词： honeybee forewing functional morphology hierarchical structure bending stiffness

Failure behavior of cellular titanium under dynamic loading

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Science China(Technological Sciences) 2017年第4期60卷 613-623页

作者： ren huilan WANG Jing HAO Li SHEN HaiTing State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology School of Sciences Beijing University of Civil Engineering and Architecture

The dynamic compressive deformation of cellular titanium with regularly distributed cylindrical pores is investigated to evaluate the effect of shock attenuation and obtain the shock Hugoniot relationship of the material. Dynamic compression experiments are conducted at room temperature using a single-stage light gas gun. The Hugoniot relations between shock wave velocity and particle velocity for the cellular titanium samples with porosities 20% and 30% are obtained. The shock response of the regular cellular titanium shows a clear wave attenuation effect. Numerical simulations are also conducted to supplement the experimental *** deformation is observed in the samples using optical micrographs, indicating that the deformation of pores contributes significantly to the shock wave attenuation of the cellular titanium material.

关键词： plate impact cellular titanium Hugoniot relation dynamic compression

Numerical studies of penetration problems by an improved particle method

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Science China(Physics,Mechanics & Astronomy) 2012年第12期55卷 2273-2283页

作者： ren huilan MA TianBao YAO XiaoHu State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Department of Engineering Mechanics School of Civil Engineering and TransportationSouth China University of TechnologyGuangzhou 510640China

A particle mapping transportation algorithm was proposed on the basis of the particle-in-cell *** particles with rectangular influence domains were employed in the transportation algorithm to reduce the numerical *** on the error analysis in the process of particle motion computation,a prediction-correction algorithm was introduced to improve the computational ***,the performance of the particle mapping transportation method was evaluated by using the rotation,the slotted disk and the shear advection tests,and the results were compared with other interface reconstruction ***,the hemispherical projectile penetration into a steel target was numerically *** results showed that the proposed method produced less numerical fluctuations and exhibited clear material interfaces,which indicated that it is accurate and effective.

关键词： numerical simulation particle-in-cell particle mapping transportation method interface tracking penetration

A constitutive model based on the evolution and coalescence of elliptical micro-cracks for quasi-brittle materials

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Chinese Science Bulletin 2012年第28期57卷 3773-3781页

作者： NING JianGuo ren huilan FANG MinJie State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100081 China

Damage and failure of quasi-brittle materials are caused by the evolution and coalescence of *** solve the problem of elliptical micro-crack growth at the elastic deformation stage,a method of complex potential functions is proposed and the effect of the initial orientation on micro-crack growth and deflection is *** critical stress condition for the initial damage is derived according to the criterion of micro-crack *** on energy conservation during wing-crack propagation,a damage constitutive model is developed with the strain criterion created in the condition of micro-crack *** stress-strain curves of quasi-brittle materials in uniaxial compression obtained based on this model are examined with the experimental results.

关键词：损伤本构模型准脆性材料微裂纹椭圆形合并基础演变裂纹生长

Additive Runge-Kutta methods for H_2/O_2/Ar detonation with a detailed elementary chemical reaction model

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Chinese Science Bulletin 2013年第11期58卷 1216-1227页

作者： LI Jian ren huilan NING JianGuo State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology

We report here the additive Runge-Kutta methods for computing reactive Euler equations with a stiff source term, and in particular, their applications in gaseous detonation simulations. The source term in gaseous detonation is stiff due to the presence of wide range of time scales during thermal-chemical non-equilibrium reactive processes and some of these time scales are much smaller than that of hydrodynamic flow. The high order, L-stable, additive Runge-Kutta methods proposed in this paper resolved the stiff source term into the stiff part and non-stiff part, in which the stiff part was solved implicitly while the non-stiff part was handled explicitly. The proposed method was successfully applied to simulating the gaseous detonation in a stoichiometric H2/O2 /Ar mixture based on a detailed elementary chemical reaction model comprised of 9 species and 19 elementary reactions. The results showed that the stiffly accurate additive Runge-Kutta methods can capture the discontinuity well, and describe the detonation complex wave configurations accurately such as the triple wave structure and cellular pattern.

关键词：化学反应模型添加剂塔引爆气相爆轰热化学非平衡应用程序时间尺度