Journal of Zhejiang University-SCIENCE A最新文献

{"title":"Regimes of near-stoichiometric hydrogen/air combustion under reciprocating engine conditions","authors":"A. E. Smygalina, A. Kiverin","doi":"10.1631/jzus.A2200217","DOIUrl":"https://doi.org/10.1631/jzus.A2200217","url":null,"abstract":"目 的 采用与火花点火往复式发动机相关的初始条件和参数, 对近化学计量氢气/空气混合物在圆柱形燃烧室内运动活塞下的燃烧进行数值研究, 并特别研究以强压振荡为特征的氢气燃烧模式是否可以被视为爆震. 创新点 1. 明确考虑了在高含氢量的火花点火发动机条件下氢气/空气混合物的燃烧情况. 2. 根据初始含氢量的不同, 燃烧可分为爆燃、 快速燃烧和缓慢燃烧三种模式. 3. 研究证明了以高幅高频压力振荡为特征的快速燃烧模式不能被视为爆震. 方 法 1. 采用“粗颗粒”数值方法求解二维圆柱坐标系下的纳维-斯托克斯气体动力方程组. 2. 模拟往复式发动机条件下可燃混合气体的动力学状态. 结 论 从输出参数 (压力振幅全程的快速傅里叶变换) 来看, 近化学计量的氢气/空气燃烧与爆震相似. 然而, 尾气区域的温度不足以使该区域发生自燃, 因此不能将该燃烧模式视为爆震.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"73 1 1","pages":"838-844"},"PeriodicalIF":3.2,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78052970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrodynamics of high-speed robots driven by the combustion-enabled transient driving method","authors":"Yang Yang, Yingzhong Lou, Guanzhen Lin, Zhiguo He, Pengcheng Jiao","doi":"10.1631/jzus.A2200331","DOIUrl":"https://doi.org/10.1631/jzus.A2200331","url":null,"abstract":"Underwater vehicles play important roles in underwater observation, ocean resource exploration, and sample collection. Soft robots are a unique type of underwater vehicles due to their good environmental adaptability and motion flexibility, although they are weak in terms of actuation and response ability. The transient driving method (TDM) was developed to resolve these shortcomings. However, the interaction between the robots’ swift motions and flow fields has not yet been fully studied. In this study, a computational fluid dynamic model is developed to simulate the fluid fields disturbed by transient high-speed motions generated by the robots. Focusing on the dependence of robot dynamics on thrust force and eccentricity, typical structures of both flow and turbulence fields around the robots are obtained to quantitatively analyze robot kinematic performance, velocity distribution, vortex systems, surface pressure, and turbulence. The results demonstrate the high-speed regions at the robots’ heads and tails and the vortex systems due to sudden expansion, indicating a negative relationship between the maximum fluid velocity and eccentricity. The reported results provide useful information for studying the environmental interaction abilities of robots during operating acceleration and steering tasks. 目 的 水下航行器在水下观测、 海洋资源勘探和样本采集中发挥着重要作用. 软机器人是一种独特的水下机器人, 具有良好的环境适应性和运动灵活性, 但它们的驱动和响应能力较弱. 同时, 机器人的快速运动与流场之间的相互作用尚未得到充分研究. 为解决这些问题, 本文旨在开发一种计算流体动力学模型, 以模拟由机器人产生的瞬态高速运动所干扰的流场. 创新点 1. 通过流固耦合与动网格技术开发了瞬变速机器人水下运动的数模模型. 2. 基于偏心率和化学放能反应驱动过程, 建立二者与机器人水下运动表现、 压力场、 速度场和湍流结构的关系. 方 法 1. 关注机器人动力学对推力和偏心率的依赖性, 并开发基于流固耦合方法与动网格技术的计算流体力学模型. 2. 获得机器人周围湍流场的典型结构, 并定量分析速度分布、 涡流结构、 压力和湍流特性. 结 论 1. 机器人头部和尾部都会因突然加速而出现高流速区域, 且在推力较高的一侧拐角处出现湍涡; 机器人尾部产生的高 k (湍流动能) 区域随运动向内发展. 2. 本研究揭示了最大流速与偏心率之间的关系. 3. 机器人表面上的最大压力与推力呈正相关, 与偏心率呈负相关; 偏心率使机器人旋转, 会增强流场的扰动, 也会使头部区域的 k 和 ε (湍流耗散率) 降低.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"44 1","pages":"820-831"},"PeriodicalIF":3.2,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86827161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of bump parameters on hypersonic inlet starting performance","authors":"Shang-cheng Xu, Yi Wang, Zhengguo Wang, Xiaoqiang Fan, B. Xiong","doi":"10.1631/jzus.A2200155","DOIUrl":"https://doi.org/10.1631/jzus.A2200155","url":null,"abstract":"Unstart is an unwanted flow phenomenon in a hypersonic inlet. When an unstart occurs, the captured airflow flowing through the engine significantly decreases with strong unsteady characteristics, which may lead to thrust loss or even combustor flameout. In this study, various bump configurations were designed to be integrated with a hypersonic inlet to improve its starting ability. A bump was defined as an integrated 3D compression surface installed upstream of the inlet entrance. The starting processes of these bump inlets were numerically simulated to investigate the effect laws and flow mechanisms of the bump parameters. Tests on bump height revealed that the starting performance could be significantly improved by increasing bump height, with the starting Mach number decreasing by 0.55 for the inlet with the highest bump. The high bump facilitates the side movement of the subsonic flow in the separation zone, which leads to a small separation bubble, thus accelerating the starting process. Further, the starting ability can be improved by designing a relatively wide bump, which results in a decline in the starting Mach number by 0.44. When the bump has the same or greater width compared with the airflow capture range, a growing spillage along the transverse direction can be formed so that the airflow in the separation bubble can be easily excluded, improving the starting ability.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"48 1","pages":"807 - 819"},"PeriodicalIF":3.2,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84659225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anthropomorphic hand based on twisted-string-driven da Vinci’s mechanism for approaching human dexterity and power of grasp","authors":"Yong-bin Jin, Shao-wen Cheng, Yan-yan Yuan, Hong-Tao Wang, Wei Yang","doi":"10.1631/jzus.A2200216","DOIUrl":"https://doi.org/10.1631/jzus.A2200216","url":null,"abstract":"Designing anthropomorphic prosthetic hands that approach human-level performance remains a great challenge. Commercial prosthetics are still inferior to human hands in several important properties, such as weight, size, fingertip force, grasp velocity, and active and passive dexterities. We present a novel design based on the under-actuated da Vinci’s mechanism driven by a flexible twisted string actuator (TSA). The distributed drive scheme allows structural optimization using a motion capture database to reproduce the natural movement of human hands while keeping adaptability to free-form objects. The application of TSA realizes a high conversion from motor torque to tendon contraction force while keeping the structure light, flexible, and compact. Our anthropomorphic prosthetic hand, consisting of six active and 15 passive degrees of freedom, has a weight of 280 g, approximately 70% of that of a human hand. It passed 30 of the 33 Feix grasp tests on objects in daily living and retained a loading capacity of 5 kg. This simple but intelligent mechanism leads to excellent stability and adaptability and renders feasible wide applications in prosthetics and in service robots.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"36 1","pages":"771 - 782"},"PeriodicalIF":3.2,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84721288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the optimal compensation capacitance of a giant magnetostrictive ultrasonic transducer with a loosely-coupled contactless power transfer system","authors":"Tian Lan, Pingping Feng, Jianjian Wang, Jianfu Zhang, Huizhong Zhou","doi":"10.1631/jzus.A2200367","DOIUrl":"https://doi.org/10.1631/jzus.A2200367","url":null,"abstract":"The giant magnetostrictive rotary ultrasonic processing system (GMUPS) with a loosely-coupled contactless power transfer (LCCPT) has emerged as a high-performance technique for the processing of hard and brittle materials, owing to its high power density. A capacitive compensation is required to achieve the highest energy efficiency of GMUPS to provide sufficient vibration amplitude when it works in the resonance state. In this study, an accurate model of the optimal compensation capacitance is derived from a new electromechanical equivalent circuit model of the GMUPS with LCCPT, which consists of an equivalent mechanical circuit and an electrical circuit. The phase lag angle between the mechanical and electrical circuits is established, taking into account the non-negligible loss in energy conversion of giant magnetostrictive material at ultrasonic frequency. The change of system impedance characteristics and the effectiveness of the system compensation method under load are analyzed. Both idle vibration experiments and machining tests are conducted to verify the developed model. The results show that the GMUPS with optimal compensation capacitance can achieve the maximum idle vibration amplitude and smallest cutting force. In addition, the effects of magnetic conductive material and driving voltages on the phase lag angle are also evaluated.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"28 1 1","pages":"757 - 770"},"PeriodicalIF":3.2,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77265232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional flow field mathematical model inside the pilot stage of the deflector jet servo valve","authors":"Shuang Li, Yaochen Yin, Jiang-yang Yuan, Sheng-rong Guo","doi":"10.1631/jzus.A2200030","DOIUrl":"https://doi.org/10.1631/jzus.A2200030","url":null,"abstract":"A new flow field mathematical model is proposed to describe accurately the flow field structure and calculate the static characteristics of the pilot stage in a deflector jet servo valve (DJSV). The flow field is divided into five regions, a 3D turbulent jet is adopted to describe the free jet region, and a velocity distribution expression of the jet is proposed. The jet entrainment model is put forward in the pressure recovery region to describe the coupling relationship between the pressure in the receiving chamber and the jet flow. The static characteristics, including pressure-flow characteristics, pressure characteristics, and flow characteristics of the pilot stage are obtained. The flow field structure and the static characteristics are verified by finite element analysis (FEA) and experiment, respectively, and the mathematical model results are in good agreement with the experimental and simulation results.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"5 1","pages":"795 - 806"},"PeriodicalIF":3.2,"publicationDate":"2022-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75196212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CFD-DEM modelling of suffusion in multi-layer soils with different fines contents and impermeable zones","authors":"Pei Wang, Y. Ge, Tuo Wang, Qi-wei Liu, Shun-xiang Song","doi":"10.1631/jzus.A2200108","DOIUrl":"https://doi.org/10.1631/jzus.A2200108","url":null,"abstract":"目的 不同细颗粒含量及含不透水区域层状土中的潜蚀过程与均质土中的潜蚀过程存在差异。本文旨在探讨非均质土以及复杂边界条件下间断级配土的潜蚀过程。 创新点 1. 建立计算流体动力学-离散元法(CFD-DEM)耦合数值模型, 并通过单颗粒下落速度和Ergun测试进行模型验证, 确认该方法的准确性; 2. 分析不同细颗粒含量层状土对潜蚀量的影响, 从而阐述非均质土中潜蚀的演化过程; 3. 揭示层状土中不同分布的不透水区域对潜蚀的影响。 方法 1. 采用颗粒下落以及Ergun测试对CFD-DEM耦合数值模拟中流体及颗粒参数进行标定(图2); 2. 利用标定参数对具有不同细颗粒含量的层状土试样进行潜蚀模拟(图7); 3. 对含有不透水区域的层状土试样进行潜蚀模拟。 结论 1. 对于层状土样, 累积侵蚀质量主要由底层土层决定; 一般来说, 底层土层的细颗粒含量越多, 累积侵蚀量越大; 此外, 当底层以上的土层细颗粒含量较高时, 潜蚀得到缓解; 反之, 则潜蚀较为严重。2. 对具有不同不透水区域的试样进行的测试表明, 流量在决定累积质量方面起主要作用; 土样内部的不透水区域可以增加周围区域的流速, 有利于细颗粒的迁移, 加剧潜蚀; 但当不透水区域较多时, 由于增加了流动路径的长度, 阻碍细颗粒的迁移, 潜蚀程度则有所降低。 Suffusion in broadly graded granular soils is caused by fluid flow and is a typical cause of geo-hazards. Previous studies of it have mainly focused on suffusion in homogeneous soil specimens. In this study, the coupled discrete element method (DEM) and computational fluid dynamics (CFD) approach is adopted to model suffusion in multi-layered soils with different fines contents, and soils with one or more impermeable zones. The parameters of the CFD-DEM model are first calibrated with the classic Ergun test and a good match with experiment is obtained. Then suffusion in multi-layered soils with different fines contents and impermeable zones is simulated and discussed. The simulation results show that, for soils with multiple layers, the cumulative eroded mass is mainly determined by the fines content of the bottom layer. In general, the higher the fines content of the bottom soil layer, the higher the cumulative eroded mass. In addition, suffusion is more severe if the fines content of the layer above is decreased. Impermeable zones inside soil specimens can increase the flow velocity around those zones, facilitating the migration of fine particles and intensifying suffusion.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"7 1","pages":"6-19"},"PeriodicalIF":3.2,"publicationDate":"2022-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89648733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of morphological gene mutation and decay on energy dissipation behaviour of granular soils","authors":"Wei Xiong, Qi-min Zhang, Jian-feng Wang","doi":"10.1631/jzus.A2200226","DOIUrl":"https://doi.org/10.1631/jzus.A2200226","url":null,"abstract":"目的 本文旨在探讨不同尺度颗粒形貌特征对于砂土应力-应变以及能量耗散行为的影响。 方法 1. 通过同步X射线计算断层扫描实验,提取高精度的真实颗粒形貌,并通过三维点云表征;2. 通过基于球谐分析的主成分分析方法,构建不同尺度下颗粒形貌的突变与衰减;3. 通过离散单元法仿真,模拟不同形貌试件的三轴剪切过程,并进一步讨论不同尺度颗粒形貌对于颗粒材料应力-应变以及能量耗散行为的影响。 结论 1. 通过比较较松散和较密实的试件,发现对于较松散试件,颗粒形貌对颗粒材料的初始刚度、应力-应变、体积应变和摩擦能量耗散等响应的影响更为明显;2. 对于不同尺度下的颗粒形貌,局部圆度较长径比对颗粒材料宏观响应的影响更大;3. 颗粒材料的能量耗散行为由颗粒形貌和初始孔隙率共同决定。 In this paper, the X-ray micro-computed tomography (X-ray µCT), spherical harmonical-based principal component analysis (SH-PCA), and discrete element method (DEM) were incorporated to generate virtual samples with morphological gene mutation at different length scales. All samples were subjected to axial compression and constant confining stress. The effects of multiscale particle morphology on the stress-strain and energy storage/dissipation responses of granular soils were investigated. It is found that: (a) the effects of particle morphology on the initial stiffness, stress-strain, volumetric strain, and frictional energy dissipation behaviours are more pronounced for looser samples than for denser ones; (b) among different length scales, the particle morphology at the local roundness-level outperforms the one at the general form-level in dictating the macro-scale responses of granular soils; (c) the energy dissipation of a granular assemblage is a result of competition between particle morphology and initial void ratio.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"46 1","pages":"303-318"},"PeriodicalIF":3.2,"publicationDate":"2022-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82357415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visualizing the dynamic progression of backward erosion piping in a Hele-Shaw cell","authors":"Gang Zheng, Jing-bo Tong, Tian-qi Zhang, Ziwen Wang, Xun Li, Ji-qing Zhang, Chun-yu Qi, Hai-zuo Zhou, Y. Diao","doi":"10.1631/jzus.A2100686","DOIUrl":"https://doi.org/10.1631/jzus.A2100686","url":null,"abstract":"With the utilization of underground space, backward erosion piping (BEP) has been observed in many underground structures (e.g., shield tunnels) founded on sandy aquifers. However, due to invisibility, the geometry of the eroded pipe and its spatial evolution with time during the piping process was still not clear. In this study, we developed a Hele-Shaw cell to visualize the dynamic progression of BEP. With imaging process technology, we obtained a typical process of BEP (the erosion process can be divided into a piping progression phase and a piping stabilization phase), quantitatively characterized the formation of erosion pipes, and compared the patterns of erosion (e.g., the erosion area A and the maximum erosion radius R max ) that spontaneously develop under different fluxes of water. The most interesting finding is that the sand grains in a thicker Hele-Shaw model are easier to dislodge, which is possibly due to the granular system in a thicker model having more degrees of freedom, reducing the stability of the sand grains. 目的 粉土、粉（细）砂土承压含水层中的盾构隧道出现渗漏时，土颗粒会在渗流力作用下液化悬浮并随地下水涌入隧道，致使隧道外土层在高速水流侵蚀下快速流失，引起隧道受力模式改变，进而造成衬砌结构的连续破坏（损）甚至垮塌。特别地，当渗漏点位于隧道底部时，侵蚀过程类似于水利大坝中的向源侵蚀，即逆着水流方向在隧道结构底部产生侵蚀空腔，从而导致隧道底部因失去土层支撑而产生大范围沉降和错台。为研究盾构隧道结构底部某点处由径向水流（水流向漏点汇聚）引起的向源侵蚀过程及侵蚀区形态，本文采用物理学中的经典装置，即赫尔-肖氏薄板，开展一系列可视化的模型试验，研究了水流速度及试样厚度对侵蚀过程及侵蚀形态的影响，以加深对向源侵蚀机制的理解。 创新点 1. 研制了用于研究汇聚流下向源侵蚀过程的赫尔-肖氏薄板仪器；2.清晰地捕捉了向源侵蚀动态发展过程；3. 揭示水流速度及试样厚度对侵蚀过程及侵蚀形态的影响。 方法 1. 采用恒流速试验，模拟瞬间施加水流下的向源侵蚀过程；2. 通过数字图像处理技术，定量描述向源侵蚀动态发展过程；3. 通过调整板间距及入流速度，分析试样厚度及水流大小对侵蚀过程及形态的影响。 结论 1. 瞬时恒流下的向源侵蚀过程可分为侵蚀发展和侵蚀稳定两个阶段。2. 瞬时水流速度越大，侵蚀区的形状表现为分叉越多，最大侵蚀半径越大。3. 试样越厚，向源侵蚀越容易在赫尔-肖氏薄板中启动；同时侵蚀区面积越大，半径也越大。","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"1 1","pages":"945-954"},"PeriodicalIF":3.2,"publicationDate":"2022-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90037702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the breakage parameters of railway ballast based on the discrete element method","authors":"Gan-zhong Liu, Jia-cheng Dai, Ping Wang, Rong Chen, Hao Liu, Xiankui Wei","doi":"10.1631/jzus.A2200019","DOIUrl":"https://doi.org/10.1631/jzus.A2200019","url":null,"abstract":"目的 有砟轨道在长期服役下频繁出现道砟颗粒掉角、破碎等劣化现象,降低了有砟轨道的稳定性。而道砟的破碎与其形状、大小、应力状态等有较大的关系,因此合理确定道砟的破碎参数是研究和解决这一问题的关键。本文旨在探索基于Hertz-Mindlin本构模型的道砟破碎参数,研究道砟的破碎性能,以期为实际服役的铁路有砟轨道提供参考。 创新点 1. 采用统计学方法分析了道砟破碎的主要影响因素及其临界压碎强度和临界剪碎强度;2. 采用响应面法确定了离散元道砟的最优破碎参数组合;3. 通过直剪试验分析了道砟的抗剪性能和破碎状况,为实际服役的有砟轨道提供参考。 方法 1. 通过单轴压缩破碎和单轴剪切破碎实测试验,确定简单应力状态下道砟破碎的主要影响因素及其临界压碎强度和临界剪碎强度（图1和2,表3）;2. 建立可破碎道砟的精细化离散元模型,采用Box-Behnken法进行仿真试验的工况设计,并对仿真试验结果进行响应曲面分析以获取最优破碎参数（图9,表7）;3. 通过对比实测与仿真的直剪试验结果,验证离散元道砟破碎参数的正确性,并探明道砟堆积体的抗剪性能（图12和13）。 结论 1. 对于粒径范围为22.4~63.0 mm的道砟,其压碎特征应力和剪碎特征应力受道砟粒径的影响不大,而受道砟形状的影响较大;2. 针状道砟更容易破碎;3. 直剪试验中,道砟的累积破碎率逐渐增大,最终达到13.97%;4. 道砟的最优破碎参数可参考本研究的结论进行取值,且具有较高的应用价值。 During the service lives of ballasted tracks, the ballast experiences degradation, such as breakage and fragmentation, which reduces the stability of the tracks. Ballast breakage is directly related to the shapes, sizes, and stress states of particles. The key to solving this problem is to determine the breakage parameters of railway ballast. In this study, through uniaxial compression and uniaxial shear tests, the factors associated with ballast breakage for a simple stress state were obtained. Then, a refined discrete element model of railway ballast was established. The Box-Behnken method was used to design a simulation test, and a response surface method was used to obtain the optimal ballast breakage parameters. Lastly, the results of a direct shear test were compared with the simulation results to verify the correctness of the parameters and to study the shear resistance of the ballast aggregates. The results showed that for ballast particles with sizes of 22.4–63.0 mm, the characteristic stresses of compression and shear were not significantly affected by the size of the particles, but were greatly affected by their shape. In particular, long particles were more likely to break. During the direct shear test, the cumulative ballast breakage ratio gradually increased to 13.97%. The optimal breakage parameters of the ballast determined by this approach have high application value in the management of ballasted tracks.","PeriodicalId":17508,"journal":{"name":"Journal of Zhejiang University-SCIENCE A","volume":"52 1","pages":"257-271"},"PeriodicalIF":3.2,"publicationDate":"2022-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73648734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}