搜索到15266篇“ CANTILEVER“的相关文章
The Effects of the Longitudinal Axis of Loading upon Bending, Shear and Torsion of a Thin-Walled Cantilever Channel Beam
2024年
Three aluminium channel sections of US standard extruded dimension are mounted as cantilevers with x-axis symmetry. The flexural bending and shear that arise with applied axial torsion are each considered theoretically and numerically in terms of two longitudinal axes of loading not coincident with the shear centre. In particular, the warping displacements, stiffness and stress distributions are calculated for torsion applied to longitudinal axes passing through the section’s centroid and its web centre. The stress conversions derived from each action are superimposed to reveal a net sectional stress distribution. Therein, the influence of the axis position upon the net axial and shear stress distributions is established compared to previous results for each beam when loading is referred to a flexural axis through the shear centre. Within the net stress analysis is, it is shown how the constraint to free warping presented by the end fixing modifies the axial stress. The latter can be identified with the action of a ‘bimoment’ upon each thin-walled section.
David W. A. ReesAbdelraouf M. Sami Alsheikh
关键词:WARPINGBIMOMENTCENTROID
内侧支承大悬挑轮辐式桁架结构悬挑提升关键技术研究被引量:1
2024年
常规采用液压提升施工方法的实施项目中,被提升结构均有双边或多边提升支承边界条件,结构稳定性好,但对于悬挑结构,特别是高度特别高的悬挑结构,因无法设置均衡吊点,使得结构很难采用提升施工方法。西安丝路欢乐世界中心塔项目为全钢结构异形塔,由内筒钢框架、外筒网壳、大悬挑轮辐式裙摆桁架、顶部莫比乌斯圆环和外筒造型丝带组成。以西安丝路塔项目为对象,对内侧支承的大悬挑轮辐式裙摆桁架钢结构施工所采用的悬挑提升施工技术进行研究;通过数值分析对比了不采取加固措施、设置1道环向杆加固和设置1道环向桁架加固对提升施工过程中结构的影响,根据对比分析结果,建议采用设置1道环向桁架方式对被提升结构进行加固;研究了设置5个提升吊点、7个提升吊点和10个提升吊点对提升过程中结构的影响,给出了建议的提升吊点数量,对本工程而言,吊点数量5个为最优;对施工过程中技术要点进行了探讨和经验总结,阐述了大悬挑轮辐式裙摆桁架钢结构悬挑提升施工和临时措施设计中须注意的关键点,并拓展了液压提升施工技术的应用范围。
丁利贾尚瑞吴楚桥徐常森
关键词:大悬挑结构
Microstructured Cantilever Probe on Optical Fiber Tip for Microforce Sensor
2024年
Benefiting from the great advances of the femtosecond laser two-photon polymerization(TPP)technology,customized microcantilever probes can be accurately 3-dimensional(3D)manufactured at the nanoscale size and thus have exhibited considerable potentials in the fields of microforce,micro-vibration,and microforce sensors.In this work,a controllable microstructured cantilever probe on an optical fiber tip for microforce detection is demonstrated both theoretically and experimentally.The static performances of the probe are firstly investigated based on the finite element method(FEM),which provides the basis for the structural design.The proposed cantilever probe is then 3D printed by means of the TPP technology.The experimental results show that the elastic constant k of the proposed cantilever probe can be actively tuned from 2.46N/m to 62.35N/m.The force sensitivity is 2.5nm/μN,the Q-factor is 368.93,and the detection limit is 57.43nN.Moreover,the mechanical properties of the cantilever probe can be flexibly adjusted by the geometric configuration of the cantilever.Thus,it has an enormous potential for matching the mechanical properties of biological samples in the direct contact mode.
Famei WANGChangrui LIAOMengqiang ZOUDejun LIUHaoqiang HUANGChao LIUYiping WANG
高空异形悬挑结构施工风险技术管控
2024年
在建筑设计中出于外观或功能需求,高空外挑且不规整的悬挑结构(投影面积内下部无结构)随处可见,对施工提出了巨大的挑战。以上海临港冰雪世界工程为例,从挑梁施工平台计算、高空悬挑结构施工、临边高空作业安全、架体监测等方面进行技术管控,有效保障了高空异形悬挑结构安全施工,为类似工程积累了经验。
付鑫
Investigation of high-quality-factor aluminum nitride MEMS cantilever resonators
2024年
This paper presents the design,fabrication,and characterization of cantilever-type resonators with a novel stacked structure.Aluminum nitride is adopted as the material for both the structural layer and the piezoelectric layer;this simplifies the fabrication process and improves the quality factor of the resonator.Both in-plane and out-of-planeflexural modes were investigated.The effect of the structural dimensions and electrode patterns on the resonator’s performance were also studied.Finite-element simulations and experiments examining anchor loss and thermoelastic damping,which are the main loss mechanisms affecting the quality factor of these resonators,were carried out.The optimal structural dimensions and electrode patterns of the cantilever-type resonators are presented.A quality factor of 7922 with a motional impedance of 88.52 kΩand a quality factor of 8851 with a motional impedance of 67.03 kΩwere achieved for the in-plane and out-of-planeflexural-mode resonators,respectively.The proposed resonator design will contribute to the development of high-performance devices such as accelerometers,gyroscopes,and pressure sensors.
Shuai ShiQingrui YangYi YuanHaolin LiPengfei NiuWenlan GuoChen SunWei Pang
关键词:MEMSALN
高速铁路大跨度钢桁架桥接触网腕臂安装技术研究被引量:1
2024年
高速铁路大跨度钢桁架桥纵向伸缩量大且变位复杂,是影响接触网腕臂偏移等系统能否正常、安全运行的重要因素,如何解决接触网腕臂安装、偏移调整与钢梁伸缩之间的协同配合,目前国内在此方面鲜有研究。通过阐述受导线伸缩影响的腕臂偏移机理和大跨度钢桁架桥梁体纵向伸缩机理,分析在不同接触网锚段布置方式下大跨度钢桁架桥梁体伸缩对腕臂偏移的影响,并采用逐工点分析法总结不同工况下钢梁伸缩与导线伸缩对腕臂偏移影响的相互关系,揭示了接触网腕臂安装曲线在导线伸缩及钢梁伸缩共同作用下的计算方法。结合典型案例计算分析,建议采用不同钢梁跨度下的推荐锚段布置方式能有效降低腕臂偏移量,并提出应重点关注伸缩缝两侧锚段腕臂偏移问题、腕臂偏移为叠加关系时缩小半锚长度、钢梁跨度大于720 m时应重点计算伸缩缝两侧双腕臂间距等优化事项。研究内容及计算公式可为系统性解决高速铁路大跨度钢桁架桥接触网腕臂偏移设计、施工及运营维护等技术难题提供理论支持。
卢广苗
关键词:高速铁路大跨度桥钢桁架桥接触网
长阳天池口清江特大桥主拱圈悬臂浇筑斜拉扣挂系统设计
2024年
长阳天池口清江特大桥主桥为净跨径242 m的非对称上承式钢筋混凝土拱桥,主拱圈采用单箱单室截面,宽9.5 m、高4.0 m。资丘岸和五峰岸半跨主拱圈各分为24个和21个节段,第1个节段采用支架现浇,其余节段采用斜拉扣挂悬臂浇筑法施工。扣索采用星式和扇形组合方式布置,位于墩顶和扣塔的扣索为星式布置,位于交界墩墩身的扣索为扇形布置,并将墩身上的扣锚索设计成连续索以避免在墩身上搭设张拉平台;扣塔由8根∅800 mm×16 mm钢管组成,两岸扣塔分别高52.68 m和60.12 m;根据锚索最大索力,设计了能承受800 kN张拉力的岩锚索。建立主拱圈悬臂浇筑施工阶段MIDAS Civil有限元模型,对斜拉扣挂系统扣锚索索力进行计算,通过拆除部分扣索和调整扣锚索索力,施工期间主拱圈截面最大拉应力、扣塔最大偏位、主拱圈成拱后线形均满足要求。
周水兴孙峰段佳旺
关键词:钢筋混凝土拱桥主拱圈悬臂浇筑拉应力
Snap-through behaviors and nonlinear vibrations of a bistable composite laminated cantilever shell:an experimental and numerical study
2024年
The snap-through behaviors and nonlinear vibrations are investigated for a bistable composite laminated cantilever shell subjected to transversal foundation excitation based on experimental and theoretical approaches.An improved experimental specimen is designed in order to satisfy the cantilever support boundary condition,which is composed of an asymmetric region and a symmetric region.The symmetric region of the experimental specimen is entirely clamped,which is rigidly connected to an electromagnetic shaker,while the asymmetric region remains free of constraint.Different motion paths are realized for the bistable cantilever shell by changing the input signal levels of the electromagnetic shaker,and the displacement responses of the shell are collected by the laser displacement sensors.The numerical simulation is conducted based on the established theoretical model of the bistable composite laminated cantilever shell,and an off-axis three-dimensional dynamic snap-through domain is obtained.The numerical solutions are in good agreement with the experimental results.The nonlinear stiffness characteristics,dynamic snap-through domain,and chaos and bifurcation behaviors of the shell are quantitatively analyzed.Due to the asymmetry of the boundary condition and the shell,the upper stable-state of the shell exhibits an obvious soft spring stiffness characteristic,and the lower stable-state shows a linear stiffness characteristic of the shell.
Lele RENWei ZHANGTing DONGYufei ZHANG
基于铝合金腕臂自动预配的腕臂管废料减省方法研究
2024年
铝合金以其机械强度高、防腐性能强的特点成为我国高速铁路接触网腕臂的优选材质。传统的腕臂管分选主要由人工完成,工作效率低,劳动强度高,科学的腕臂管分选有利于资源合理分配,降低废料率,提高经济效益。本文结合我国高速铁路发展现状,总结接触网铝合金腕臂预配的特点,分析现阶段铝合金腕臂预配中腕臂管的废料率,研究腕臂自动化预配过程中原料管减省方法,并通过实践验证腕臂管优选算法的优势,为接触网腕臂预配材料减省提供一种解决方案,助力降低轨道交通建设成本。
刘志兵刘洪生
关键词:高速铁路接触网
Inter-well internal resonance analysis of rectangular asymmetric cross-ply bistable composite laminated cantilever shell under transverse foundation excitation
2024年
The chaotic dynamic snap-through and complex nonlinear vibrations are investigated in a rectangular asymmetric cross-ply bistable composite laminated cantilever shell,in cases of 1:2 inter-well internal resonance and primary resonance.The transverse foundation excitation is applied to the fixed end of the structure,and the other end is in a free state.The first-order approximate multiple scales method is employed to perform the perturbation analysis on the dimensionless two-degree-of-freedom ordinary differential motion control equation.The four-dimensional averaged equations are derived in both polar and rectangular coordinate forms.Deriving from the obtained frequency-amplitude and force-amplitude response curves,a detailed analysis is conducted to examine the impacts of excitation amplitude,damping coefficient,and tuning parameter on the nonlinear internal resonance characteristics of the system.The nonlinear softening characteristic is exhibited in the upper stable-state,while the lower stable-state demonstrates the softening and linearity characteristics.Numerical simulation is carried out using the fourth-order Runge-Kutta method,and a series of nonlinear response curves are plotted.Increasing the excitation amplitude further elucidates the global bifurcation and chaotic dynamic snap-through characteristics of the bistable cantilever shell.
Lele RENWei ZHANGYufei ZHANG

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