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摩擦系数 2

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Vibration control efficiency of piezoelectric shunt damping system

Dan WU, Zhichun YANG, Hao SUN,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 441-446 doi: 10.1007/s11465-009-0055-4

摘要: The piezoelectric shunt damping technique based on the direct piezoelectric effect has been known as a simple, low-lost, lightweight, and easy to implement method for passive damping control of structural vibration. In this technique, a piezoelectric material is used to transform mechanical energy to electrical energy. When applying the piezoelectric shunt damping technique to passively control structural vibration, the piezoelectric materials must be bonded on or embedded in host structure where large strain is induced during vibration, thus to ensure vibrational mechanical energy to be transformed into electrical energy as much as possible. In this paper, the concept of vibration control efficiency of a piezoelectric shunt damping system is proposed and studied theoretically and experimentally. In the study, PZT patches are used as energy converter, and the vibration control efficiency is expressed by the vibration reduction rate per area of the PZT patches. Emphasis is laid on the effect of the generalized electromechanical coupling coefficient on the vibration control efficiency. Four PZT patches with different sizes are bonded on the geometrical central area of four similar clamped aluminum plates, respectively, and vibration control experiments are conducted for these plates using the R-L shunt circuit. The results indicate that the bigger the coupling coefficient , the larger the rate of vibration reduction, and hence, the higher the vibration control efficiency. It also shows that the vibration responses of the first mode of the plates bonded with different PZT patches can be reduced by about 30.5%,48.58%,85.47%, and 89.91%, respectively. It comes to a conclusion that the vibration control efficiency of the piezoelectric shunt damping system decreases with the increase of the area of the PZT patch, whereas the vibration reduction of the plate increases with the area of the PZT patch. Therefore, it is necessary to make topology optimization for the PZT patch in the vibration control utilizing the piezoelectric shunt damping technique.

关键词: piezoelectric shunt     vibration control efficiency     clamped plate     generalized electromechanical coupling coefficient    

Dimensionality reduction and prediction of soil consolidation coefficient using random forest coupling

Hai-Bang LY; Huong-Lan Thi VU; Lanh Si HO; Binh Thai PHAM

《结构与土木工程前沿(英文)》 2022年 第16卷 第2期   页码 224-238 doi: 10.1007/s11709-022-0812-6

摘要: The consolidation coefficient of soil (Cv) is a crucial parameter used for the design of structures leaned on soft soi. In general, the Cv is determined experimentally in the laboratory. However, the experimental tests are time-consuming as well as expensive. Therefore, researchers tried several ways to determine Cv via other simple soil parameters. In this study, we developed a hybrid model of Random Forest coupling with a Relief algorithm (RF-RL) to predict the Cv of soil. To conduct this study, a database of soil parameters collected from a case study region in Vietnam was used for modeling. The performance of the proposed models was assessed via statistical indicators, namely Coefficient of determination (R2), Root Mean Squared Error (RMSE), and Mean Absolute Error (MAE). The proposal models were constructed with four sets of soil variables, including 6, 7, 8, and 13 inputs. The results revealed that all models performed well with a high performance (R2 > 0.980). Although the RF-RL model with 13 variables has the highest prediction accuracy ( R2 = 0.9869), the difference compared with other models was negligible (i.e., R2 = 0.9824, 0.9850, 0.9825 for the cases with 6, 7, 8 inputs, respectively). Thus, it can be concluded that the hybrid model of RF-RL can be employed to predict Cv based on the basic soil parameters.

关键词: soil consolidation coefficient     machine learning     random forest     Relief    

Modeling of specific structure crystallization coupling with dissolution

Yuanhui JI, Hongliang QIAN, Chang LIU, Xiaohua LU, Xin FENG, Xiaoyan JI,

《化学科学与工程前沿(英文)》 2010年 第4卷 第1期   页码 52-56 doi: 10.1007/s11705-009-0301-7

摘要: In this paper, the research framework for specific structure crystallization modeling has been proposed in which four steps are required in order to investigate the rigorous crystallization modeling by thermodynamics. The first is the activity coefficient model of the solution, the second is Solid-Liquid equilibrium, the third and fourth are the dissolution and crystallization kinetics modeling, respectively. Our investigations show that the mechanisms of complex structure formation and microphase transition can be analyzed by combining the dissolution and crystallization kinetics modeling. Moreover, the formation mechanism of the porous KCl has been analyzed, which may provide a reference for the porous structure formation in the advanced material synthesis.

关键词: structure crystallization     activity coefficient     reference     KCl     dissolution    

IPMC gripper static analysis based on finite element analysis

Hanmin PENG, Yao HUI, Qingjun DING, Huafeng LI, Chunsheng ZHAO,

《机械工程前沿(英文)》 2010年 第5卷 第2期   页码 204-211 doi: 10.1007/s11465-010-0005-1

摘要: Recently, a type of flexible grippers with low power supply (0–5 V) has been designed and developed for grasping small but precision parts. In previous work, the authors manufactured a soft gripper whose actuating components are made of ionic polymer-metal composite (IPMC) materials; however, there is not a comprehensive model to analyze the complete mechanics for this IPMC gripper. Therefore, this paper provides a finite element method for analyzing its static mechanics characteristics in the state with maximal stress and strain (i.e., the gripper opening largest, including the IPMC deformation, stress, and strain). Further, these electromechanical coupling relationships can be simulated by using the piezoelectric analysis module based on ANSYS software. The simulation results show that the maximal tip displacement of IPMC strips can nearly reach their own free length, the maximal stress is 54 MPa in the center of copper electrodes, and the maximal strain is 0.0286 on the IPMC strip. The results provide detailed numerical solutions and appropriate finite element analysis methodologies beneficial for further research on the optimization design, forecast analysis, and control field.

关键词: ionic polymer-metal composite (IPMC)     artificial muscles     actuator     flexible gripper     finite element analysis     electromechanical coupling    

Polymer nanocomposites for microactuation and magneto-electric transduction

Kaori YUSE, Benoit GUIFFARD, Rabah BELOUADAH, Lionel PETIT, Laurence SEVEYRAT, Daniel GUYOMAR

《机械工程前沿(英文)》 2009年 第4卷 第3期   页码 350-354 doi: 10.1007/s11465-009-0056-3

摘要: In the last decade, electroactive polymers have attracted much attention especially because of their very actuating capabilities. Large strain is experimentally observed, but under quite high electrical field, which can be a severe drawback for actuating applications. First part of the present paper is concerned with the reduction of applied field onto electroactive polymer films to get a given strain level. Polyurethane (PU) films filled with carbon black (CB) nanoparticles exhibit relatively high strain level under a field of only 12.5 kV/mm. The simple easy-to-make method solution cast method was applied. Even though the generated stress level is still quite low, the present work shows high strain level under quite low field appliance by easy manufacturing, lightweight, and flexible polymer film. Besides, another interest of the present paper is in magneto-elasto-electric effect of a polymer film filled with some magnetic nano particles. Films filled with nonpiezoelectric but with magnetite particles has still short history. With the use of magneto materials, a large magnetic DC bias field is generally required, and it causes big problem on application. The films filled with some magnetite nanoparticles (Fe3O4 and Nickel) are fabricated then examined. It is clearly demonstrated that our films do not require any DC bias. Although linear polarization value is relatively small, the first step of the studies on magnetite nano-filled film is presented.

关键词: electroactive polymers     carbon filling     actuator     nanocarbon     electromechanical coupling     dielectric polymer actuators     polymer actuators     microactuation     magneto-electric effect    

磁力金属带传动的传动特性分析

罗善明,郭迎福,陈安华,余以道,陈立锋

《中国工程科学》 2005年 第7卷 第7期   页码 76-80

摘要:

介绍了磁力金属带传动的工作原理,分析和探讨了其有效拉力、线速度及弹性滑动率等传动性能,并通过实验测定了相关性能参数。结果表明,磁力金属带传动主要是利用磁场吸引力与初拉力的耦合作用来增加摩擦力进而传递运动和动力的,其传动效率可达95%~98%,而弹性滑动率一般在0.1%以下。

关键词: 带传动     金属带     磁场吸引力     机电耦合    

Isomorphism analysis on generalized modules oriented to the distributed parameterized intelligent product

Shasha ZENG, Weiping PENG, Tiaoyu LEI

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 12-23 doi: 10.1007/s11465-019-0555-9

摘要: The distributed parameterized intelligent product platform (DPIPP) contains many agents of a product minimum approximate autonomous subsystem (generalized module). These distributed agents communicate, coordinate, and cooperate using their knowledge and skills and eventually accomplish the design for mass customization in a loosely coupled environment. In this study, a new method of isomorphism analysis on generalized modules oriented to DPIPP is proposed. First, on the basis of the bill of material partition and generalized module mining, the parameters of the main characteristics are extracted to construct the main characteristic parameter matrix. Second, similarity calculation of generalized modules is realized by improving the clustering using representatives algorithm, and isomorphism model sets are obtained. Generalized modules with a similar structure are combined to complete the isomorphism analysis. The effectiveness of the proposed method is verified by taking high- and medium-pressure valve data as an example.

关键词: distributed parameterized intelligent product platform     generalized module     isomorphism analysis     product family    

Novel method of constructing generalized Hoberman sphere mechanisms based on deployment axes

Xuemin SUN, Yan-An YAO, Ruiming LI

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 89-99 doi: 10.1007/s11465-019-0567-5

摘要: This study proposes a method of constructing type II generalized angulated elements (GAEs II) Hoberman sphere mechanisms on the basis of deployment axes that intersect at one point. First, the constraint conditions for inserting GAEs II into deployment axes to form a loop are given. The angle constraint conditions of the deployment axes are obtained through a series of linear equations. Second, the connection conditions of two GAEs II loops that share a common deployable center are discussed. Third, a flowchart of constructing the generalized Hoberman sphere mechanism on the basis of deployment axes is provided. Finally, four generalized Hoberman sphere mechanisms based on a fully enclosed regular hexahedron, arithmetic sequence axes, orthonormal arithmetic sequence axes, and spiral-like axes are constructed in accordance with the given arrangement of deployment axes that satisfy the constraint conditions to verify the feasibility of the proposed method.

关键词: deployable mechanism     type II generalized angulated elements     Hoberman sphere mechanism     deployment axes     constraint conditions    

Special issue: Micro-electromechanical systems (MEMS)

Zhuangde JIANG

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 457-458 doi: 10.1007/s11465-017-0492-4

Design and characteristic research of a novel electromechanical-hydraulic hybrid actuator with two transmission

《机械工程前沿(英文)》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0735-x

摘要: Servo-hydraulic actuators (SHAs) are widely used in mechanical equipment to drive heavy-duty mechanisms. However, their energy efficiency is low, and their motion characteristics are inevitably affected by uncertain nonlinearities. Electromechanical actuators (EMAs) possess superior energy efficiency and motion characteristics. However, they cannot easily drive heavy-duty mechanisms because of weak bearing capacity. This study proposes and designs a novel electromechanical-hydraulic hybrid actuator (EMHA) that integrates the advantages of EMA and SHA. EMHA mainly features two transmission mechanisms. The piston of the hydraulic transmission mechanism and the ball screw pair of the electromechanical transmission mechanism are mechanically fixed together through screw bolts, realizing the integration of two types of transmission mechanisms. The control scheme of the electromechanical transmission mechanism is used for motion control, and the hydraulic transmission mechanism is used for power assistance. Then, the mathematical model, structure, and parameter design of the new EMHA are studied. Finally, the EMHA prototype and test platform are manufactured. The test results prove that the EMHA has good working characteristics and high energy efficiency. Compared with the valve-controlled hydraulic cylinder system, EMHA exhibits a velocity tracking error and energy consumption reduced by 49.7% and 54%, respectively, under the same working conditions.

关键词: electromechanical-hydraulic hybrid actuator (EMHA)     integration     transmission mechanisms     power assistance     energy efficiency     working characteristics    

Multiscale RBF-based central high resolution schemes for simulation of generalized thermoelasticity problems

Hassan YOUSEFI, Alireza TAGHAVI KANI, Iradj MAHMOUDZADEH KANI

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 429-455 doi: 10.1007/s11709-018-0483-5

摘要: In this study, average-interpolating radial basis functions (RBFs) are successfully integrated with central high-resolution schemes to achieve a higher-order central method. This proposed method is used for simulation of generalized coupled thermoelasticity problems including shock (singular) waves in their solutions. The thermoelasticity problems include the LS (systems with one relaxation parameter) and GN (systems without energy dissipation) theories with constant and variable coefficients. In the central high resolution formulation, RBFs lead to a reconstruction with the optimum recovery with minimized roughness on each cell: this is essential for oscillation-free reconstructions. To guarantee monotonic reconstructions at cell-edges, the nonlinear scaling limiters are used. Such reconstructions, finally, lead to the total variation bounded (TVB) feature. As RBFs work satisfactory on non-uniform cells/grids, the proposed central scheme can handle adapted cells/grids. To have cost effective and accurate simulations, the multiresolution–based grid adaptation approach is then integrated with the RBF-based central scheme. Effects of condition numbers of RBFs, computational complexity and cost of the proposed scheme are studied. Finally, different 1-D coupled thermoelasticity benchmarks are presented. There, performance of the adaptive RBF-based formulation is compared with that of the adaptive Kurganov-Tadmor (KT) second-order central high-resolution scheme with the total variation diminishing (TVD) property.

关键词: central high resolution schemes     RBFs     higher order accuracy     generalized thermoelasticity     multiresolution-based adaptation    

Design and analysis of the gripper mechanism based on generalized parallel mechanisms with configurable

《机械工程前沿(英文)》 2021年 第16卷 第4期   页码 765-781 doi: 10.1007/s11465-021-0655-1

摘要: Generalized parallel mechanisms with a configurable moving platform have become popular in the research field of parallel mechanism. This type of gripper mechanism can be applied to grasp large or heavy objects in different environments that are dangerous and complex for humans. This study proposes a family of novel (5 + 1) degrees of freedom (three translations and two rotations plus an additional grasping motion) gripper mechanisms based on the generalized parallel mechanisms with a configurable moving platform. First, the configurable moving platform, which is a closed loop, is designed for grasping manipulation. The hybrid topological arrangement is determined to improve the stiffness of the manipulator and realize high load-to-weight ratios. A sufficient rule based on Lie group theory is proposed to synthesize the mechanism. The hybrid limb structure is also enumerated. A family of novel gripper mechanisms can be assembled through the hybrid limbs by satisfying the rule. Two examples of the gripper mechanisms with and without parallelogram pairs are shown in this study. A kinematic analysis of the example mechanism is presented. The workspace shows that the mechanism possesses high rotational capability. In addition, a stiffness analysis is performed.

关键词: generalized parallel mechanism     configurable moving platform     gripper mechanism     type synthesis     kinematic analysis    

An approach for mechanical fault classification based on generalized discriminant analysis

LI Wei-hua, SHI Tie-lin, YANG Shu-zi

《机械工程前沿(英文)》 2006年 第1卷 第3期   页码 292-298 doi: 10.1007/s11465-006-0022-2

摘要: To deal with pattern classification of complicated mechanical faults, an approach to multi-faults classification based on generalized discriminant analysis is presented. Compared with linear discriminant analysis (LDA), generalized discriminant analysis (GDA), one of nonlinear discriminant analysis methods, is more suitable for classifying the linear non-separable problem. The connection and difference between KPCA (Kernel Principal Component Analysis) and GDA is discussed. KPCA is good at detection of machine abnormality while GDA performs well in multi-faults classification based on the collection of historical faults symptoms. When the proposed method is applied to air compressor condition classification and gear fault classification, an excellent performance in complicated multi-faults classification is presented.

关键词: generalized discriminant     non-separable     abnormality     classification     multi-faults classification    

The convexity about ultimate bearing hypersurfaces of structures

Chengxi GUO,Tingting GUO

《结构与土木工程前沿(英文)》 2016年 第10卷 第4期   页码 456-461 doi: 10.1007/s11709-016-0334-1

摘要: The relationship between the convexity on the ultimate bearing surface of a structure and the second-order effects of loads is discussed. All of generalized non-overload forces acted on a structure forms a convex set when ignoring the second-order effects (coupling effects between the generalized forces). It is true also when the Hessian matrix composed of the second-order partial derivatives on the hypersurface about the ultimate bearing of the structure is negative definite. The outward convexity is kept when the surface is expressed by certain dimensionless parameters. A series of properties based on the convexity are pointed out. Some applications in the analysis of bearing capacity of structures were illustrated with examples. The study shows that an evaluation about the bearing capacity state of a complex structure can be made on the basis of several points on the surface of the ultimate bearing of the structure.

关键词: service     limit load     ultimate bearing surface     convexity     generalized force     generalized displacement     frame structure    

Microdamage study of granite under thermomechanical coupling based on the particle flow code

《结构与土木工程前沿(英文)》   页码 1413-1427 doi: 10.1007/s11709-023-0953-2

摘要: The thermomechanical coupling of rocks refers to the interaction between the mechanical and thermodynamic behaviors of rocks induced by temperature changes. The study of this coupling interaction is essential for understanding the mechanical and thermodynamic properties of the surrounding rocks in underground engineering. In this study, an improved temperature-dependent linear parallel bond model is introduced under the framework of a particle flow simulation. A series of numerical thermomechanical coupling tests are then conducted to calibrate the micro-parameters of the proposed model by considering the mechanical behavior of the rock under different thermomechanical loadings. Good agreement between the numerical results and experimental data are obtained, particularly in terms of the compression, tension, and elastic responses of granite. With this improved model, the thermodynamic response and underlying cracking behavior of a deep-buried tunnel under different thermal loading conditions are investigated and discussed in detail.

关键词: thermomechanical coupling effect     granite     improved linear parallel bond model     thermal property     particle flow code    

标题 作者 时间 类型 操作

Vibration control efficiency of piezoelectric shunt damping system

Dan WU, Zhichun YANG, Hao SUN,

期刊论文

Dimensionality reduction and prediction of soil consolidation coefficient using random forest coupling

Hai-Bang LY; Huong-Lan Thi VU; Lanh Si HO; Binh Thai PHAM

期刊论文

Modeling of specific structure crystallization coupling with dissolution

Yuanhui JI, Hongliang QIAN, Chang LIU, Xiaohua LU, Xin FENG, Xiaoyan JI,

期刊论文

IPMC gripper static analysis based on finite element analysis

Hanmin PENG, Yao HUI, Qingjun DING, Huafeng LI, Chunsheng ZHAO,

期刊论文

Polymer nanocomposites for microactuation and magneto-electric transduction

Kaori YUSE, Benoit GUIFFARD, Rabah BELOUADAH, Lionel PETIT, Laurence SEVEYRAT, Daniel GUYOMAR

期刊论文

磁力金属带传动的传动特性分析

罗善明,郭迎福,陈安华,余以道,陈立锋

期刊论文

Isomorphism analysis on generalized modules oriented to the distributed parameterized intelligent product

Shasha ZENG, Weiping PENG, Tiaoyu LEI

期刊论文

Novel method of constructing generalized Hoberman sphere mechanisms based on deployment axes

Xuemin SUN, Yan-An YAO, Ruiming LI

期刊论文

Special issue: Micro-electromechanical systems (MEMS)

Zhuangde JIANG

期刊论文

Design and characteristic research of a novel electromechanical-hydraulic hybrid actuator with two transmission

期刊论文

Multiscale RBF-based central high resolution schemes for simulation of generalized thermoelasticity problems

Hassan YOUSEFI, Alireza TAGHAVI KANI, Iradj MAHMOUDZADEH KANI

期刊论文

Design and analysis of the gripper mechanism based on generalized parallel mechanisms with configurable

期刊论文

An approach for mechanical fault classification based on generalized discriminant analysis

LI Wei-hua, SHI Tie-lin, YANG Shu-zi

期刊论文

The convexity about ultimate bearing hypersurfaces of structures

Chengxi GUO,Tingting GUO

期刊论文

Microdamage study of granite under thermomechanical coupling based on the particle flow code

期刊论文