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Soft curvature sensors for measuring the rotational angles of mechanical fingers

Haixiao LIU, Li LI, Zhikang OUYANG, Wei SUN

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 610-621 doi: 10.1007/s11465-020-0596-0

摘要: The design, fabrication, and testing of soft sensors that measure elastomer curvature and mechanical finger bending are described in this study. The base of the soft sensors is polydimethylsiloxane (PDMS), which is a translucent elastomer. The main body of the soft sensors consists of three layers of silicone rubber plate, and the sensing element is a microchannel filled with gallium-indium-tin (Ga-In-Sn) alloy, which is embedded in the elastomer. First, the working principle of soft sensors is investigated, and their structure is designed. Second, the relationship between curvature and resistance is determined. Third, several sensors with different specifications are built in accordance with the structural design. Experiments show that the sensors exhibit high accuracy when the curvature changes within a certain range. Lastly, the soft sensors are applied to the measurement of mechanical finger bending. Experiments show that soft curvature sensors can effectively reflect mechanical finger bending and can be used to measure the bending of mechanical fingers with high sensitivity within a certain working range.

关键词: soft sensor     Ga-In-Sn alloy     strain sensing     curvature sensing     mechanical finger bending    

Analysis of suitable geometrical parameters for designing a tendon-driven under-actuated mechanical finger

Francesco PENTA,Cesare ROSSI,Sergio SAVINO

《机械工程前沿(英文)》 2016年 第11卷 第2期   页码 184-194 doi: 10.1007/s11465-016-0385-y

摘要:

This study aims to optimize the geometrical parameters of an under-actuated mechanical finger by conducting a theoretical analysis of these parameters. The finger is actuated by a flexion tendon and an extension tendon. The considered parameters are the tendon guide positions with respect to the hinges. By applying such an optimization, the correct kinematical and dynamical behavior of the closing cycle of the finger can be obtained. The results of this study are useful for avoiding the snap-through and the single joint hyperflexion, which are the two breakdowns most frequently observed during experimentation on prototypes. Diagrams are established to identify the optimum values for the tendon guides position of a finger with specified dimensions. The findings of this study can serve as guide for future finger design.

关键词: tendon-driven fingers     mechanical finger design     under-actuated mechanical systems    

Mechanical design, modeling, and identification for a novel antagonistic variable stiffness dexterousfinger

《机械工程前沿(英文)》 2022年 第17卷 第3期 doi: 10.1007/s11465-022-0691-5

摘要: This study traces the development of dexterous hand research and proposes a novel antagonistic variable stiffness dexterous finger mechanism to improve the safety of dexterous hand in unpredictable environments, such as unstructured or man-made operational errors through comprehensive consideration of cost, accuracy, manufacturing, and application. Based on the concept of mechanical passive compliance, which is widely implemented in robots for interactions, a finger is dedicated to improving mechanical robustness. The finger mechanism not only achieves passive compliance against physical impacts, but also implements the variable stiffness actuator principle in a compact finger without adding supererogatory actuators. It achieves finger stiffness adjustability according to the biologically inspired stiffness variation principle of discarding some mobilities to adjust stiffness. The mechanical design of the finger and its stiffness adjusting methods are elaborated. The stiffness characteristics of the finger joint and the actuation unit are analyzed. Experimental results of the finger joint stiffness identification and finger impact tests under different finger stiffness presets are provided to verify the validity of the model. Fingers have been experimentally proven to be robust against physical impacts. Moreover, the experimental part verifies that fingers have good power, grasping, and manipulation performance.

关键词: multifingered hand     mechanism design     robot safety     variable stiffness actuator    

Analysis of the dynamic hysteresis characteristic of finger seal

LEI Yanni, CHEN Guoding

《机械工程前沿(英文)》 2007年 第2卷 第1期   页码 32-36 doi: 10.1007/s11465-007-0005-y

摘要: The research about hysteresis characteristic of finger seal (FS), which was carried out based on the model with static loads, could not reflect the dynamics behavior of FS system when the rotor runs at high speed. To solve this problem, the relations between the dynamics parameters, structure parameters as well as working parameters in the system were given out through the analysis of finite element analysis result. A mass spring damper dynamics model of FS system was proposed and the hysteresis characteristic of the FS system was analyzed. This work shows that the dynamics characteristic analysis of the FS is necessary and the dynamics model proposed in this paper is valid. This dynamics model is the basis for the optimization design of FS system.

关键词: FS     necessary     hysteresis characteristic     optimization     spring    

Analysis and optimal design of an underactuated finger mechanism for LARM hand

Shuangji YAO, Marco CECCARELLI, Giuseppe CARBONE, Qiang ZHAN, Zhen LU

《机械工程前沿(英文)》 2011年 第6卷 第3期   页码 332-343 doi: 10.1007/s11465-011-0229-8

摘要:

This paper aims to present general design considerations and optimality criteria for underactuated mechanisms in finger designs. Design issues related to grasping task of robotic fingers are discussed. Performance characteristics are outlined as referring to several aspects of finger mechanisms. Optimality criteria of the finger performances are formulated after careful analysis. A general design algorithm is summarized and formulated as a suitable multi-objective optimization problem. A numerical case of an underactuated robot finger design for Laboratory of Robotics and Mechatronics (LARM) hand is illustrated with the aim to show the practical feasibility of the proposed concepts and computations.

关键词: robotic finger     underactuated mechanisms     design considerations    

TA2板料激光热应力弯曲成形及其力学性能研究

周益军,张永康,游文明

《中国工程科学》 2007年 第9卷 第10期   页码 40-44

摘要:

用HVS-1000显微硬度测试仪、X-350A型X射线应力测定仪,以2.5 kW SM2000SM快轴流CO2激光器对0.6 mm厚的TA2板料进行扫描,按照正交试验理论安排成形工艺参数,研究了TA2板料弯曲成形时主要工艺参数对弯曲角度的影响,以及试样表面残余应力的分布和试样断面上的显微硬度变化。结果表明:正交试验中的4个工艺参数的作用是不同的,按其变化对弯曲变形量影响的大小排序,依次是扫描次数、光斑直径、激光束功率、扫描速度;成形参数对试样表面的残余应力分布也存在一定的影响;试样变形区断面上的显微硬度变化呈现出一定的规律。

关键词: 激光技术     热应力     板料弯曲成形     残余应力     显微硬度    

利用微机电系统技术制作弯曲结构表面无线无源柔性加速度计 Research Article

李晨1,2,贾蔓谷1,洪应平2,薛亚楠2,熊继军2

《信息与电子工程前沿(英文)》 2022年 第23卷 第5期   页码 801-809 doi: 10.1631/FITEE.2100236

摘要: 提出一种LC无线无源柔性加速度计,解决测量弯曲结构表面加速度的困难。 该加速度计由柔性聚酰亚胺(PI)衬底和平面螺旋电感(厚度为300 nm)组成,采用微机电系统(MEMS)技术,可任意弯曲或折叠,可牢固地粘附在具有弯曲结构的物体表面。利用射频无线传输原理,通过改变加速度计与天线之间的距离来测量加速度信号。与带导线的加速度计相比,该加速度计可以防止导线在振动过程中脱落,从而延长其使用寿命。通过搭建实验平台,当天线与加速度计之间的距离为5 mm时,在弯曲结构表面展示了加速度计在20至100 m/s2加速度下的传感能力。结果表明,加速度和峰峰值输出电压接近线性,加速度计灵敏度高达0.27 mV/(m•s−2)。此外,该加速度计的最大误差小于0.037%。

关键词: 弯曲结构表面;柔性加速度计;微机电系统(MEMS)技术;无线非接触式测量    

部分包裹波形钢腹板组合梁的受力性能——剪切和弯曲的共同作用

贺君, 王思豪, 刘玉擎, 吕展, 李传习

《工程(英文)》 2017年 第3卷 第6期   页码 806-816 doi: 10.1016/j.eng.2017.11.005

摘要:
提出部分包裹的混凝土和波形钢腹板组合梁(CGCSW)协同使用,以避免波形钢腹板和受压钢翼缘受到较大剪力和弯矩的共同作用发生屈曲。首先,我们对两种不同剪切跨度的试件进行了模型实验,以研究其受力性能,包括承载力、破坏模式、弯曲应力和剪切应力分布,以及混凝土开裂的过程。实验结果表明,剪力与弯矩的相互作用导致试件失效。当混凝土开裂前,弯剪比不影响组合梁在弹性阶段的剪切刚度,但对混凝土开裂后的剪切刚度影响较大。此外,弹性阶段的组合截面满足平截面假定。然而,在受拉区混凝土开裂后,由于“手风琴效应”,波形腹板的正应力变小,在平板段的应力几乎为零,但在倾斜的面板上具有较小的应力。其次,基于实验建立了考虑材料和几何非线性的三维有限元(FE)模型,并对不同长度和高度的组合梁进行了参数分析,以确定在组合荷载作用下的承载能力。最后,在实验和数值结果的基础上提出一个关于剪切和弯曲强度相互作用的公式,以评估这种组合结构的承载能力,从而为弯曲和剪切组合荷载作用下设计部分包裹波形钢腹板组合梁(PECGCSW)提供参考。

关键词: 内衬混凝土     组合梁     波形钢腹板     剪切和弯曲的共同作用    

A new meshless approach for bending analysis of thin plates with arbitrary shapes and boundary conditions

《结构与土木工程前沿(英文)》 2022年 第16卷 第1期   页码 75-85 doi: 10.1007/s11709-021-0798-5

摘要: An efficient and meshfree approach is proposed for the bending analysis of thin plates. The approach is based on the choice of a set of interior points, for each of which a basis function can be defined. Plate deflection is then approximated as the linear combination of those basis functions. Unlike traditional meshless methods, present basis functions are defined in the whole domain and satisfy the governing differential equation for plate. Therefore, no domain integration is needed, while the unknown coefficients of deflection expression could be determined through boundary conditions by using a collocation point method. Both efficiency and accuracy of the approach are shown through numerical results of plates with arbitrary shapes and boundary conditions under various loads.

关键词: plate     bending     meshless method     collocation    

Improved prediction of pile bending moment and deflection due to adjacent braced excavation

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0961-2

摘要: Deep excavations in dense urban areas have caused damage to nearby existing structures in numerous past construction cases. Proper assessment is crucial in the initial design stages. This study develops equations to predict the existing pile bending moment and deflection produced by adjacent braced excavations. Influential parameters (i.e., the excavation geometry, diaphragm wall thickness, pile geometry, strength and small-strain stiffness of the soil, and soft clay thickness) were considered and employed in the developed equations. It is practically unfeasible to obtain measurement data; hence, artificial data for the bending moment and deflection of existing piles were produced from well-calibrated numerical analyses of hypothetical cases, using the three-dimensional finite element method. The developed equations were established through a multiple linear regression analysis of the artificial data, using the transformation technique. In addition, the three-dimensional nature of the excavation work was characterized by considering the excavation corner effect, using the plane strain ratio parameter. The estimation results of the developed equations can provide satisfactory pile bending moment and deflection data and are more accurate than those found in previous studies.

关键词: pile responses     excavation     prediction     deflection     bending moments    

growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combined torsion and bending

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 905-913 doi: 10.1007/s11709-021-0683-2

摘要: In a nuclear powerplant, the rotary equipment, such as a pump directly fitted with hanger in the piping system, experiences torsional and bending loads. Higher crack growth rate occurs because of this torsional load in addition to the bending load. Hence, it is necessary to study the fatigue behavior of piping components under the influence of combined torsional and bending load. In this study, experimental fatigue life evaluation was conducted on a notched stainless steel SA312 Type 304LN straight pipe having an outer diameter of 170 mm. The experimental crack depth was measured using alternating current potential drop technique. The fatigue life of the stainless steel straight pipe was predicted using experiments, Delale and Erdogan method, and area-averaged root mean square–stress intensity factor approach at the deepest and surface points of the notch. Afterward, the fatigue crack growth and crack pattern were discussed. As a result, fatigue crack growth predicted using analytical methods are in good agreement with experimental results.

关键词: fatigue life     Delale and Erdogan method     RMS–SIF approach     stainless steel     torsion and bending load     fatigue crack growth    

A novel structural modification to eliminate the early coupling between bending and torsional mode shapes

Nazim Abdul NARIMAN

《结构与土木工程前沿(英文)》 2017年 第11卷 第2期   页码 131-142 doi: 10.1007/s11709-016-0376-4

摘要: In this paper, a novel structural modification approach has been adopted to eliminate the early coupling between the bending and torsional mode shapes of vibrations for a cable stayed bridge model generated using ABAQUS software. Two lateral steel beams are added to the middle span of the structure. Frequency analysis is dedicated to obtain the natural frequencies of the first eight mode shapes of vibrations before and after the structural modification approach. Numerical simulations of wind excitations are conducted for the 3D model of the cable stayed bridge with duration of 30 s supporting on real data of a strong wind from the literature. Both vertical and torsional displacements are calculated at the mid span of the deck to analyze both the bending and the torsional stiffness of the system before and after the structural modification. The results of the frequency analysis after applying lateral steel beams declared a safer structure against vertical and torsional vibrations and rarely expected flutter wind speed. Furthermore, the coupling between the vertical and torsional mode shapes has been removed to larger natural frequencies magnitudes with a high factor of safety. The novel structural approach manifested great efficiency in increasing vertical and torsional stiffness of the structure.

关键词: aeroelastic instability     structural damping     flutter wind speed     bending stiffness     torsional stiffness    

Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

《结构与土木工程前沿(英文)》   页码 901-914 doi: 10.1007/s11709-023-0915-8

摘要: The integrity and bearing capacity of segment joints in shield tunnels are associated closely with the mechanical properties of the joints. This study focuses on the mechanical characteristics and mechanism of a bolted circumferential joint during the entire bearing process. Simplified analytical algorithms for four stress stages are established to describe the bearing behaviors of the joint under a compressive bending load. A height adjustment coefficient, α, for the outer concrete compression zone is introduced into a simplified analytical model. Factors affecting α are determined, and the degree of influence of these factors is investigated via orthogonal numerical simulations. The numerical results show that α can be specified as approximately 0.2 for most metro shield tunnels in China. Subsequently, a case study is performed to verify the rationality of the simplified theoretical analysis for the segment joint via numerical simulations and experiments. Using the proposed simplified analytical algorithms, a parametric investigation is conducted to discuss the factors affecting the ultimate compressive bending capacity of the joint. The method for optimizing the joint flexural stiffness is clarified. The results of this study can provide a theoretical basis for optimizing the design and prediciting the damage of bolted segment joints in shield tunnels.

关键词: shield tunnel     segment joint     joint structural model     failure mechanism    

A simplified method for investigating the bending behavior of piles supporting embankments on soft ground

《结构与土木工程前沿(英文)》   页码 1021-1032 doi: 10.1007/s11709-023-0952-3

摘要: In recent years, concrete and reinforced concrete piles have been widely used to stabilize soft ground under embankments. Previous research has shown that bending failure, particularly during rapid filling on soft ground, is the critical failure mode for pile-supported embankments. Here, we propose an efficient two-stage method that combines a test-verified soil deformation mechanism and Poulos’ solution for pile–soil interaction to investigate the bending behavior of piles supporting embankments on soft ground. The results reveal that there are three possible bending failure scenarios for such piles: at the interface between the soft and firm ground layers, at mid-depths of the fan zone, and at the boundary of the soil deformation mechanism. The location of the bending failure depends on the position and relative stiffness of the given pile. Furthermore, the effect of embedding a pile into a firm ground layer on the bending behavior was investigated. When the embedded length of a pile exceeded a critical value, the bending moment at the interface between the soft and firm ground layers reached a limiting value. In addition, floating piles that are not embedded exhibit an overturning pattern of movement in the soft ground layer, and a potential failure is located in the upper part of these piles.

关键词: bending behavior     pile     embankment     soil−structure interaction     failure mode    

Erratum to: Bending and vibration of a discontinuous beam with a curvic coupling under different axial

《机械工程前沿(英文)》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0709-z

标题 作者 时间 类型 操作

Soft curvature sensors for measuring the rotational angles of mechanical fingers

Haixiao LIU, Li LI, Zhikang OUYANG, Wei SUN

期刊论文

Analysis of suitable geometrical parameters for designing a tendon-driven under-actuated mechanical finger

Francesco PENTA,Cesare ROSSI,Sergio SAVINO

期刊论文

Mechanical design, modeling, and identification for a novel antagonistic variable stiffness dexterousfinger

期刊论文

Analysis of the dynamic hysteresis characteristic of finger seal

LEI Yanni, CHEN Guoding

期刊论文

Analysis and optimal design of an underactuated finger mechanism for LARM hand

Shuangji YAO, Marco CECCARELLI, Giuseppe CARBONE, Qiang ZHAN, Zhen LU

期刊论文

TA2板料激光热应力弯曲成形及其力学性能研究

周益军,张永康,游文明

期刊论文

利用微机电系统技术制作弯曲结构表面无线无源柔性加速度计

李晨1,2,贾蔓谷1,洪应平2,薛亚楠2,熊继军2

期刊论文

部分包裹波形钢腹板组合梁的受力性能——剪切和弯曲的共同作用

贺君, 王思豪, 刘玉擎, 吕展, 李传习

期刊论文

A new meshless approach for bending analysis of thin plates with arbitrary shapes and boundary conditions

期刊论文

Improved prediction of pile bending moment and deflection due to adjacent braced excavation

期刊论文

growth behavior of a 170 mm diameter stainless steel straight pipe subjected to combined torsion and bending

期刊论文

A novel structural modification to eliminate the early coupling between bending and torsional mode shapes

Nazim Abdul NARIMAN

期刊论文

Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

期刊论文

A simplified method for investigating the bending behavior of piles supporting embankments on soft ground

期刊论文

Erratum to: Bending and vibration of a discontinuous beam with a curvic coupling under different axial

期刊论文